Integrated 2D seismic interpretation and 3D geological modeling for reservoir characterization of the upper Cretaceous Formations in the Silah field, Egypt

Integrated 2D seismic interpretation and 3D geological modeling for reservoir characterization of the upper Cretaceous Formations in the Silah field, Egypt | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Integrated 2D seismic interpretation and 3D geological modeling for reservoir characterization of the upper Cretaceous Formations in the Silah field, Egypt Mohamed Osman Ebraheem, Hamza Ahmed Ibrahim, Ahmed Hosny Senosy This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6055654/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract A comprehensive geophysical interpretation was applied to investigate the subsurface structural features and recognize the promising hydrocarbon zones in the Silah reservoir rocks. The study looks closely at the subsurface geological features that control oil accumulation. This helps us figure out where to drill and how to develop reservoirs. These objectives were achieved using well logging, 2D seismic interpretation, and 3D geological modeling. This was accomplished by creating a synthetic seismogram and using vertical seismic profiling (VSP). Different maps, cross-sections, and 3D structural models were constructed to visualize the subsurface structural configuration and architecture of the Silah Field. A calibration process between sonic logs and the velocity of the existing VSP data was carried out to produce a more accurate and detailed time-depth relationship at the well location. All information deduced from TWTs, seismic-structure depth, isochore maps, and depth-structural cross-section was used to identify and determine the locations of the depocenter and the shoulder of the basin. The study area is characterized by a complex fault pattern and trend. The structure features were due to an extensional rift stress followed by a compressional force. The resulting depth structural map displays several NW-SE and NE-SW normal faults along with a master E-W to ENE fault direction on top of the Early Cenomanian Abu Roash (F) and (G). These normal faults extended to the Khoman Formation. The extensional faults formed grabens and half grabens structures in the north and northwest portions of the study area. The compressional stress event created folding and fold-related fault structures in the central part of the study area. The depocenter area is present in the NW portion of the study area at a depth reaching 8000 ft. The structural elements, such as fault-bounded closures and half-graben systems, act as primary petroleum traps, influencing reservoir connectivity and fluid migration pathways. The findings indicate that further exploratory wells should be drilled in the Silah area to boost production from the carbonates and sandstones of the Abu Roash reservoir. Other promising oil-bearing zones within the area under investigation could also be proposed. Earth and environmental sciences/Environmental sciences Earth and environmental sciences/Solid earth sciences 2D seismic interpretation 3D geological modeling reservoir architecture upper Cretaceous Formations Silah field Egypt Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Figure 19 1. Introduction There is an extensive background in energy resource prospection in Egypt with noteworthy findings in the Western Desert, especially in the north. The Western Desert of Egypt is a huge platform consisting of thick sedimentary rocks affected by different tectonic movements with a slight northward regional slope and dip [ 1 ]. These movements initiated many sedimentary rift basins, such as the Shushan and El-Gindi. These basins are considered the most prolific areas for hydrocarbon exploitation and range from Mesozoic to early Tertiary [ 2 ]. Most of these basins lie north of the Qattara Ridge, which is separated from the Abu El-Gharadig major basin. One of the most promising areas for hydrocarbon exploration and drilling is El-Gindi Basin (Fig. 1 a). Geophysical imaging techniques provide crucial insights into subsurface geology, particularly in basins with complex stratigraphy, facilitating accurate reservoir characterization and exploration. This is particularly crucial in basins where the geological record under the surface is highly ambiguous due to either the stratigraphic trend or the absence of an outcrop. One of the biggest issues facing petroleum geoscientists is the characterization of reservoirs near and far from wells. When seismic data is available, this issue can be effectively resolved, but it is exacerbated in exploratory areas with inadequate data [ 3 , 4 ]. Most researchers provide a framework to identify hydrocarbon potential through integrated geological, seismic, and petrophysical evaluations in comparable Egyptian petroleum fields. While these studies focused on the neighboring regions, they underscore the significance of detailed seismic data, fault structure analysis, and petrophysical modeling in delineating prospective hydrocarbon zones [ 5 , 6 ]. When applied to either two-dimensional lines or three-dimensional volumes, seismic reflection is the most popular and adaptable technique for imaging the subsurface [ 7 , 8 ]. The development and assessment of oil fields, as well as the identification of appropriate sites for exploratory wells, depend heavily on seismic interpretation techniques. By offering in-fill information on the rock characteristics between wells, 2D seismic reflection data in SEG-Y format was processed using advanced interpretation techniques, integrating well-log calibration, velocity modeling, and fault mapping to delineate reservoir structures [ 9 , 10 , 11 ]. To improve the information that might be faint in a conventional seismic image, the seismic attribute is a parameter that is taken or derived from seismic data and can be examined [ 12 , 13 ]. The present study is performed on a new virgin area called the Silah field. This field in El-Gindi basin is located at El-Fayoum Concession, west of the River Nile (Fig. 1 b). The exploration of petroleum in this area remains a relatively underexplored domain compared to other prolific fields in the Western Desert and Nile Delta regions. No or little subsurface geological information is known about this field. Comprehensive exploration efforts in the Silah should employ multidisciplinary approaches, including advanced seismic interpretation, potential trap determination, and subsurface modeling, to overcome challenges posed by lithological and structural heterogeneity. So, this study is based mainly on seismic reflection data in 2D and well-logging data, including the VSP data (Fig. 1 d). The analysis and interpretation of these data were made by Petrel 2017 and Techlog software. The primary step in the interpretation process is to establish the connection between seismic reflections and the structural pattern of the field. The objectives of the present work are to 1) create the connection between the well logging data and the seismic reflections, 2) visualize the main structure pattern affecting the upper Cretaceous units through the studied area, 3) evaluate the main reservoir architecture of the Silah field, and 4) determine the most potential areas for hydrocarbon accumulations. 2. Geological setting Stratigraphically, according to the interpretation and analysis of the well logging and mud logging data (Fig. 1 c), a truncated lower Cretaceous section immediately above the Precambrian basement marked the beginning of the sedimentary succession of El-Gindi (4200 m) [ 14 ]. Generally, the subsurface Mesozoic–Tertiary sedimentary successions in El-Gindi basin consist of seven formations from the top to the base: the Moghra, Dabaa (Late Eocene–Oligocene), Apollonia (Early–Middle Eocene), Khoman (Campanian–Maastrichtian), Abu Roash (Late Cenomanian–Santonian), Baharyia (Early Cenomanian), and Kharita (Albian) Formations [ 14 ]. Three main unconformities are present in the lithostratigraphic column of the Silah field in El-Gindi basin: 1) the Albian Kharita Formation non-conformably overlies the basement rocks, 2) the Abu Roash Formation conformably overlies the Bahariya Formation and unconformably underlies the Khoman Formation, and 3) The Appollonia Formation unconformably overlies the Khoman Formation. It is believed that several Mesozoic extensional rift basins that originated in northern Egypt are part of the Tethyan passive margin [ 15 , 16 , 17 ]. During the beginning of Gondwana's split and the Neo-Tethys Ocean's early opening in the Permo-Triassic, these basins were formed [ 17 , 18 ]. The Tethys shoreline moved across the area when the Jurassic to Cretaceous principal reservoirs were deposited. Coastal and tidal sandstones were deposited when the Tethys moved southward [ 19 ]. Shells and marine carbonate mud were deposited on the sea floor during other ages when the Tethys covered the whole Western Desert region. During the early Cretaceous, an expansion direction shifted clockwise into the NE-SW direction, creating new sedimentary basins such as Beni Suef and Asyut. Additionally, a subsequent derivation continued the expansion, creating a rift basin similar to El-Gindi-oriented NE-SW [ 20 ]. El-Gindi is a rift basin formed in the early Cretaceous. It is located at El-Fayium Concession, covering a surface area of about 9500 km 2 and delineated by latitudes 29° 15′ to 29° 55′ N and longitudes 30° 10′ to 31° 10′ E. This basin, which has significant hydrocarbon potential, is part of Egypt's north-central exploration plan [ 21 , 22 , 23 ]. The dominant developed structures were controlled by normal faults and folding, and some of these faults had strike-slip movements that affected the orientation of the fold axes [ 1 ]. The syn-rift Jurassic, lower, and upper Cretaceous sedimentary successions are primarily characterized by convenient source rocks and reservoirs [ 22 , 24 , 25 ]. 3. Data and Methods Seismic data collection is a proven method of gathering subsurface information for hydrocarbon exploration and production operations. The seismic (S-GEY files) and well-logging data were provided by the PetroSilah Petroleum Company. 2D seismic profiles included 20 inlines (dip lines) running in the N-S direction and 10 crosslines (strike lines) orientated in the E-W direction (Fig. 1 d). These profiles covered an area of approximately 9500 km 2 in El-Gindi basin. Also, the wireline logging data are available for five drilled wells (Silah-1X, Silah-6X, Silah-7, Silah-15, and South Silah-1X). The vertical seismic profiling data are utilized to establish the connection between the well logging and the seismic reflection data [ 26 ]. In this study, the analysis of geophysical data includes twelve steps: correlation of seismic events, tying their travel times, reflector identification, horizon tracking, correlation of reflectors, fault location, closing loops, posting their time values and fault segments, construction of geo-seismic cross-sections, time-to-depth conversion, construction of the isochronous, and construction of the structural contour maps. Linking between seismic reflections and stratigraphy is the essential step in seismic interpretation (tie geological horizons to seismic reflectors and time-depth relationships) by using check shot data and creating a synthetic seismogram or velocity model. The next phase is to combine 2D seismic data with wireline logs of the selected wells to build a 3D structural geological model, an isopach contour map, and a structure-tectonic map (time and depth) of the reservoirs of the Abu Roash members. Lastly, identify the structural characteristics (fault patterns, seismic reflectors, and depth value contouring) that may serve as a trap for the buildup of hydrocarbons and identify the promising region or zone of oil and/or gas production in the Silah Field. A synthetic seismogram is a record created from velocity log data by convolving the product of acoustic and density logs (reflectivity function) with wavelets. It is generated by using Petrel 2018 software [ 27 , 28 ]. The petrophysical logs, Sonic (DT), and Bulk Density (RHOB) offer the inverse velocity and density information of subsurface layers in this process. Velocity and density data are used to calculate a set of reflection coefficients called reflectivity series. The result is a source Ricker wavelet with a dominating frequency of 35 Hz. The source wavelet was convolved with the reflectivity series. The synthetic seismogram is matched with the interpreted seismic depth section at the well point to correlate the succession of reflectors. It is also used to calibrate our seismic velocities [ 11 , 28 ]. 4. Results The analysis and interpretation of reflection seismic and velocity data in the Silah field as a part of El-Gindi basin include: 4.1. Geological subsurface cross-section Before the interpretation and analysis process of the 2D seismic data, the geological correlation section is created to understand the relationship between the drilled wells and recognize the variation in thickness laterally and vertically (Fig. 2 ). This subsurface geological cross-section shows that the formations might have been subjected to tectonic forces. These forces have led to the formation of normal faults, which assisted in forming the basin. The dip direction of these faults is toward the Silah-6X and Silah-7 drilled wells. The basin extension started in the early Cretaceous with high accommodation space toward the Silah-7 (depocenter). 4.2. Fault detection The realization of structural features is implemented to shorten the time required for data processing and to remove any information that is not required for the study, leaving only the area of interest (Fig. 3 ). The faults are identified and picked on the cross-lines while the continuity was viewed on the in-lines (Fig. 4 ). Nine major faults are picked and mapped. Within the major fault blocks, four minor faults can be inferred, both synthetic and antithetic (Fig. 5 ). The whole interpreted fault seems to have cut the top of the Khoman and the base of the Baharyia Formations (Upper Cretaceous). To comprehend the impact of these faults on the various rock units, the fault polygon that was constructed is combined with the time-structure maps of the top and base of the upper Cretaceous Formations. All major and minor faults are depicted in a model generated using the Petrel software (Fig. 5 ). Three primary fault trends with EW to ENE, NW-SW, and NE-SW orientations have been identified. The NW-SE-orientated faults are normal and were active at least during the early and late Cretaceous to Eocene. The NE faults are characterized by a downthrown towards the WNW, but the major fault trend is NW-SE, which is characterized by a downthrown towards the SW; otherwise, the E-W faults are characterized by two different downthrown towards the N and the S directions (Fig. 4 ). The main structural features affecting the Silah field were formed from a series of normal faults and built the half-graben (Fig. 5 ). 4.3. Seismic well-tie (synthetic seismogram) The seismic-to-well tie is performed for the two wells (Silah-1X and South Silah-1X) using the sonic log and VSP data. To create a high-exact time-depth relationship throughout the drilled wells, the sonic log and velocity data are first calibrated with the VSP data for each well (Fig. 6 ). Extended white-1 is the most effective of the four seismic wavelets that were created using different techniques. Finally, the acoustic impedance log is generated to produce the series of reflection coefficients, which are then convolved with this wavelet to produce the synthetic seismogram. The synthetic seismogram created for the south Silah-1X and the two-way time data from the VSP at the same location are used to tie the well logs (Fig. 7 ). Following the creation of the synthetic generation, the retrieved traces close to the well are compared to the seismogram. To connect the formation tops on the synthetic seismogram to the horizons on the vertical seismic sections close to the well location, the seismogram is then shown on the vertical seismic sections (Fig. 8 ). 4.4. Horizon tracking An illustration of horizon picking using the four seismic lines for fault interpretation of different formations, the Khoman, Abu Roash (A, B, E, F, and G), in the seismic section is constructed (Fig. 9 ). The interpreted seismic section (lines 18 − 2), orientated in the N-S direction, is located in the western part of the area (Figs. 9 a). The region is traversed by the faults F1, F3, and F6, which dip to the S and SE, respectively, and run from E-W to ENE-WSW. The F2, F4, and F5 faults, on the other hand, dip toward the NE as they cut through the region in NW-SE directions. From the Khoman to the Bahariya Formations, all of these faults are broken down one after the other. These faults formed a half-graben and graben block system. The interpreted seismic section (X 10530), orientated in the E-W direction, is located in the southern portion of the study area (Figs. 9 b). This section shows the same structural regime as the previous one, in addition to folds having gentle and broad slopes. The faults F7 and F8 are striking in the NE-SW direction, with a dip direction to the NW, but F9 is striking in the NW-SE direction with a dip direction to the SW through the area (Figs. 9 b). All these detected faults dissected the succession from the Khoman to lower Bahariya Formations, except F3 and F4, which started from the Abu Roash F member (Fig. 10 ). 4.5. Isochronous map (Two-Way Time Map) Time-surface maps from the top of the Khoman, Abu Roash (D, E, F, and G members) are constructed (Fig. 11 ). These maps are used to build isochronous maps as well as in time-depth conversion to get the isochore maps. Analyzing these maps reveals the existence of three normal faults in E-W to ENE, NNW-SSE to NW, and NE-SW directions. The E-W and NE trends represent the main faults. Also, the Two-Way Time (TWT) values range from 1400 ms at the depocenter in the NNE part (structurally low) to 720 ms at the shoulder of the basin in the southwestern part of the studied area (structurally high) (Fig. 11 ). Four seismic signatures are chosen for the following horizons: the top of Khoman, Abu Roash E, F, and G members. Some interpreted seismic lines are selected to show the picking of the horizons and the structural features in the study area (Fig. 11 ). The TWTs decrease toward the N and NNW parts of the studied area, reaching a minimum value (816 ms to 1400 ms) indicating the depocenter of the basin. While the TWTs increase toward the S and central parts of the area, reaching maximum values (670 ms to 1020 ms), they represent the shoulders of the basin (Fig. 11 ). 4.6. Conversion of reflection time to depth The correlation between the depth and time sections of the Silah-1X and South Silah-1X drilled wells is carried out by using available VSP data, which shows a good correlation (Fig. 12 ). The velocity model in this study is constructed using the time-depth relationship from a synthetic seismogram. Using the developed velocity model, the reflection time is converted to depth using the isochronous map (Fig. 11 ) and the average velocity values. The purpose of this procedure is to produce the contour map of the depth structure for the upper Cretaceous Formations in the Silah oil field. 4.7. Seismic structure-depth maps The same structural features are shown on the seismic structure-depth maps, but they can be differentiated according to the times of their respective units. The generated depth-structure contour maps of the area reveal that the regional structural features (normal faults) are trending in the E-W to ENE, NW-SE, and NE directions as well as the presence of folding and fold-related fault structures (Fig. 13 ). It is observed that the shallow part of the basin is located in the N-E to the NNW portion of the area. The deepest part (8000 ft) is towards the NNW direction, while the shallowest one (3500 ft) is detected towards the south and central parts direction (Fig. 13 ). The depth values of the Abu Roash D vary between 3600 and 4600 ft (TVD), while those values in the Abu Roash E vary from 5100 to 6000 ft (TVD). The maximum values (high-relief) are recognized in the N to NW part of the study area, while the minimum (low-relief) is in the central part. The depth contour maps of Abu Roash F and G, on the other hand, indicate that the values range from 5700 to 7500 feet (TVD). The central portion of the study area (depocenter) has low-relief areas (minimum values), while the northwest portion (maximum values) has high-relief areas (maximum values) (Fig. 13 ). 4.8. Isochore maps Isochore maps are generated by using the Petrel software 2017 as an indication of TVTs (Fig. 14 ). The spatial changes in thickness within the Abu Roash D vary from 250 ft at NW, NE, and SW parts to 750 ft at E and SW parts of the area. The main fault system that affected the region was responsible for this variation. The constructed isochore map shows that the small thickness ranges from 250 ft to 300 ft, but the large thickness varies from 500 ft to 750 ft (Fig. 14 a). The thickness map of the Abu Roash E ranges from a large thickness (750 to 1000 ft) at the NW and SW parts to a small thickness (300 ft) at the E and NE parts of the studied area (Fig. 14 b). However, the thickness of the Abu Roash F represents a low distribution from 300 ft at the SW and W parts to 600 ft at the NE and central parts of the study area (Fig. 14 c). The small thickness (390 ft) is observed in the E to NE, but the large thickness (750–1170 ft) is observed in the Abu Roash G at the SW, W, and NW parts of the studied area (Fig. 14 d). Thickness, depth maps, and fault planes deduced from seismic and well-logging data are among the numerous important features that define the reservoir's geometry in the Silah field (Figs. 15 and 16 ). There are eight distinctive zones, each of them containing the layers that show the vertical facies alteration (the Abu Roash A, B, C, D, E, F, and G zones and Khoman Formation) (Fig. 16 ). To demonstrate the lateral extension and thickness variation, as well as faults and folding structure features, subsurface structural cross-sections are extracted in various orientations (Figs. 17 and 18 ). 5. Discussion The present study aims to delineate and evaluate the subsurface structural features and to determine the hydrocarbon potentialities of El-Gindi basin, particularly in the Silah oil field. The seismic reflection and VSP data are interpreted, analyzed, and integrated carefully with the geological and well-logging data to evaluate the main reservoir architecture of the field. The critical interpretation of these data is used to pick and determine the top of the upper Cretaceous reservoirs, and different faults controlled the shape and structural features of the basin during its evolution. Also, various maps and subsurface sections are constructed to identify and follow the economic zones of interest within the Abu Roash E, F, and G members. The Paleozoic to Jurassic sedimentary successions are not recorded, most probably due to the phase of non-deposition over a platform area. The extensional compressional stress began in the early Cretaceous to Eocene. The upper Cretaceous formations were subjected to the force in the EW direction to form a series of anticline- and syncline-related fault traps. Then, the folding and fold-related fault systems that resulted from this stress were started in the Santonian. The E-W-orientated deep-seated faults were formed during the rifting of the early Cretaceous period. This rifting phase had originated a passive continental margin of the Tethys in the East Mediterranean region. The two-way time maps of the Abu Roash E and G vary from − 1080 to -1320 ms and from − 1100 to -1420 ms, respectively. These maps reach maximum values toward the northwest parts of the study area. The low-relief parts are detected in the central portion of the study area (folding and faulting uplift). The basin's structural highs and lows are distributed similarly to how they were found on the seismic structure-depth maps. The structural-lows are located in the northern and northwestern parts, while the structural-highs are in the central to southern parts of the area. The time and depth maps of all horizons show a general dipping toward the north where the time and depth increase. The depth-contour maps reveal the shallowest depth (3500 ft to 5000 ft) detected in the S and center, but the deepest one (5500 ft to 8000 ft) detected in the N and NNW parts of the Silah (Fig. 19 ). While the major faults that are oriented NE and NW are thought to have an effect on the region, the subsurface faults that are oriented E-W can be tracked eastward. The province of Silah stratigraphy is where folding is most noticeable. These symmetrical folds are closer to the axial planes, which are often oriented NE-SW, and have a comparatively soft flank. The depth structure contour maps demonstrate the influence of normal faults trending E-W to ENE and NW-SE directions on the entire area. The fault polygons of the two horizons generally indicate the formation of three-way dip closure, tilted fault blocks, half-grabens, and graben blocks. Two tectonic forces influenced the deep-seated limestone of the Abu Roash F and the sandstone of the Abu Roash G. The first is the folding brought on by inversion processes, and the second is the subsidence brought on by extension. As a result of these forces, possible traps for the accumulation of hydrocarbons in the field have formed. 6. Conclusion The critical interpretation of seismic and well logging data in the Silah indicates the following: Three deformational phenomena had a regional impact on the Silah strata. Locally, they developed and expanded the hydrocarbon system in the El-Gindi basin. These include some NW-oriented faults' early Cenozoic reactivation, late Cretaceous inversion, and early Cretaceous rifting. Due to past tensional forces, faulting produced a large number of grabens and half-grabens. The pre-identified extensional regime from the early Jurassic to the lower Cretaceous period is most likely responsible for the major structural elements that constructed the Silah's half-graben and graben systems. The shallower portion of the basin lies in the middle, whereas the depocenter is situated in the N and NNW sections. One important regional structural element that controls the basin's location and trend is the EW to ENE direction. Two significant fault systems that extended in the EW and NE-SW directions had a significant structural impact on the basin's upper Cretaceous and deeper strata. The structural high is considered a half-graben and grabens bounded by normal faults (NW-SE and NE-SW). Generally, the steep dip throw is toward the NNW part of the area at a depth of 8000 ft in the Abu Roash G member, which supports the possibility of hydrocarbon accumulation. The best reservoirs in the region are thought to be the Abu Roash F and G members. These reservoirs' distributions are low in the S and SE regions of the research area and high in the N to NW region. This structural style was probably generated by the dragging of the Cretaceous in the NE-SW oriented main fault, which resulted in tectonic inversion and dip reversal of the Jurassic-Early Cretaceous half-graben. These conclusions are detected from the created time and depth structural contour maps on the top of these reservoirs with the subsurface cross-section through the structure model. The northwestern part of the area is a promising development site for future hydrocarbon exploration due to the presence of a structurally high area, which is located above a graben block (Fig. 19 ). Also, the central parts are proposed for future drilling plans because they have structure closure, which makes the three-way dip closure a tilted fault block (three-way anticlinal closure in the upthrown block of normal faults). These high structural features make them good structural traps for hydrocarbon accumulation. The two target zones in the Silah are the Abu Roash F (carbonates) and G (sandstones). Two new well-proposed locations (A and B) are chosen carefully. Area A is located in the NW portion, while Area B is in the central part of the area near the Silah-1X and the Silah-6X wells. Declarations Conflict of interest There are no conflicts of interest. Acknowledgment This paper is based upon work supported by Science, Technology & Innovation Funding Authority (STDF) under grant no (48777). The authors are grateful to The Petorsilah Petroleum Company for supplying the raw material, the required reports from their archives, and the digital logs. Author contributions The 1st author [Mohamed Osman Ebraheem] and 2nd author [Hamza Ahmed Ibrahim] contributed to the study’s conception and design, revised the manuscript, restructured, rewrote, and provided additional interpretations to a section of the paper, whereas the 3rd author [Ahmed Hosny Senosy] contributed to the study’s conception. Material preparation, data collection, proposal writing, and the approval process to use the data used in this research from the Petorsilah Petroleum Company were performed by the first and second authors. The first draft of the manuscript was written by the 3rd author, edited by the 1st and 2nd authors, and reedited by the 1st and 2nd authors until submission. Funding Open access funding was provided by the Science, Technology & Innovation Funding Authority (STDF) in cooperation with the Egyptian Knowledge Bank (EKB). Competing interests The authors declare that they have no competing interests. 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Palynological and palaeoenvironmental analyses of the upper Albian-Cenomanian succession in Gindi Basin, Egypt: Implication for transgressive/regressive systems tracts. J. Afr. Earth Sc. 147 , 603–622. https://doi.org/10.1016/j.jafrearsci.2018.07.007 (2018). El Gazzar, A., Moustafa, A. & Bentham, P. Structural evolution of the Abu Gharadig field area, northern Western Desert, Egypt. J. Afr. Earth Sc. 124 , 340–354. https://doi.org/10.1016/j.jafrearsci.2016.09.027 (2016). Sestini, G. Tectonic and sedimentary history of the NE African margin (Egypt—Libya). Geological Society, London, Special Publications, 17(1), 161–175 (1984). https://doi.org/10.1144/GSL.SP.1984.017.01.1 Bosworth, W., El-Hawat, A. S., Helgeson, D. E. & Burke, K. Cyrenaican shock absorber and associated inversion strain shadow in the collision zone of northeast Africa. Geology 36 (9), 695–698. https://doi.org/10.1130/G24909A.1 (2008). Meshref, W. Tectonic Framework of Egypt. In: Said, R., Ed., Geology of Egypt, Balkema/Rotterdam/Bookfield, Netherlands, 113–156 (1990). El Beialy, S. Y., El Atfy, H. S., Zavada, M. S., El Khoriby, E. M. & Abu-Zied, R. H. Palynological, palynofacies, paleoenvironmental and organic geochemical studies on the Upper Cretaceous succession of the GPTSW-7 well, North Western Desert, Egypt. Mar. Pet. Geol. 27 (2), 370–385 (2010). Ebraheem, M. O., Ibrahim, H. A. & Senosy, A. H. A comparative petrophysical evaluation of the Abu Roash, Bahariya, and Kharita reservoirs using well-logging data, East El-Fayoum, Egypt. Sci. Rep. 15 (1), 2732 (2025). El Diasty, W., Beialy, E., Littke, S., Farag, F. & R., & Source rock evaluation and nature of hydrocarbons in the Khalda Concession, Shushan Basin, Egypt’s Western Desert. Int. J. Coal Geol. 162 , 45–60 (2016). Leila, M., Awadalla, A., Farag, A. & Moscariello, A. Organic geochemistry and oil-source rock correlation of the Cretaceous succession in West Wadi El-Rayan (WWER) concession: implications for a new Cretaceous petroleum system in the north Western Desert, Egypt. J. Petrol. Sci. Eng. 219 , 111071 (2022). White, R., Simm, R. & Tutorial Good practice in well ties. First Break . 21 (10). https://doi.org/10.3997/1365-2397.21.10.25640 (2023). Schlumberger, S. Petrel introduction course, v, Schlumberger. Houston: 621.Taha, M. A. and Aziz, H., Mesozoic rifting in Upper Egypt Concession (abs.): 14th International Petroleum Conference, (abstract), 5, (2010). (1998). Sarhan, M. A. & Abdel-Fattah, M. I. Integrating well logs and seismic data for a comprehensive geophysical appraisal of post-Albian oil reservoirs in the SWQ-4X well, Gindi Basin, Egypt. Egypt. J. Petroleum . 33 (2), 2. https://doi.org/10.62593/2090-2468.1021 (2024). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6055654","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":439731732,"identity":"914a003d-6a20-4f10-8a9f-a5f88dab5e9b","order_by":0,"name":"Mohamed Osman Ebraheem","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDUlEQVRIiWNgGAWjYDACCQYGZgiL+QADgwFUlIc4LWwJJGvhMUCI4tPCL9378HNBhU00g9iZzx9+FDDkGdxIYHzwto1BTt4BuxbJOceNpWecScttkM7dJtljwFAM1MJsOLeNwdjwAHYtBjfSGKR52w6DtTAD/ZI4c0YCG1CEIXFjA3Yt9jfSmH/z/vsP1JLz+DNUC/tvoJZ6XFoMJNKAZjYcAGlhkAZp6ZdIYGMGakmQx+F9iTvH2Kx5jiXntkmnmQH9IpHYz/OwWXLOOQnDDbhCbHYb822eGrvcfunkxx9+/LFJbGNPPvjhTZmNvDwOh8EBG9RWIGZsADMMDhDQggkI2jIKRsEoGAUjBQAA7P5RpE+QCm4AAAAASUVORK5CYII=","orcid":"","institution":"New Valley University","correspondingAuthor":true,"prefix":"","firstName":"Mohamed","middleName":"Osman","lastName":"Ebraheem","suffix":""},{"id":439731735,"identity":"871e6cb4-0217-494f-9a29-897ae869b9dc","order_by":1,"name":"Hamza Ahmed Ibrahim","email":"","orcid":"","institution":"Assiut University","correspondingAuthor":false,"prefix":"","firstName":"Hamza","middleName":"Ahmed","lastName":"Ibrahim","suffix":""},{"id":439731740,"identity":"0a0d1166-2d77-457e-b329-0ac1656a8010","order_by":2,"name":"Ahmed Hosny Senosy","email":"","orcid":"","institution":"New Valley University","correspondingAuthor":false,"prefix":"","firstName":"Ahmed","middleName":"Hosny","lastName":"Senosy","suffix":""}],"badges":[],"createdAt":"2025-02-18 11:23:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6055654/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6055654/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":80321356,"identity":"19346f30-7479-4712-8e78-2f7b9d2afc52","added_by":"auto","created_at":"2025-04-10 13:30:38","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":328379,"visible":true,"origin":"","legend":"\u003cp\u003eA map showing the location of El-Gindi basin in the northwestern Desert, Egypt (was obtained from Wikipedia, source link; https://geology.com/world/egypt-satellite-image.shtml#google_vignette, then was modified by using Surfer software, Version 13.6, https://www.goldensoftware.com/surfer ) a), the location of the Silah field in El-Fayoum development blocks (was created by using Petrel software, Version 2017) b), a constructed lithostratigraphic column in the Silah (was created by using Surfer software, Version 13.6) c), and a base map of 2D seismic lines in the studied area (was created by using Petrel software, Version 2017) d).\u003c/p\u003e","description":"","filename":"image1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/1a912c7784d31a7b2f7f3239.jpeg"},{"id":80320271,"identity":"8338fdce-0c0a-4dde-9bca-0157a7f6c624","added_by":"auto","created_at":"2025-04-10 13:22:38","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":243323,"visible":true,"origin":"","legend":"\u003cp\u003eA correlation stratigraphic cross section of the Silah drilled wells related to the formation tops.\u003c/p\u003e","description":"","filename":"image2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/86d39b2cff8dff687ae397ab.jpeg"},{"id":80321357,"identity":"1c665ee8-62a4-487c-915b-0284ae6a0758","added_by":"auto","created_at":"2025-04-10 13:30:38","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1942385,"visible":true,"origin":"","legend":"\u003cp\u003e2D seismic line section before cropping a), after cropping and realization b).\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/90478c45471ca134a9477580.png"},{"id":80321359,"identity":"c91f8d41-522c-4536-a535-eb4b00151491","added_by":"auto","created_at":"2025-04-10 13:30:39","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":561749,"visible":true,"origin":"","legend":"\u003cp\u003eAn example showing the interpreted faults picked from the seismic line; N-S direction (Inline 18-2).\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/87aed53729298d291c0117dc.jpeg"},{"id":80321365,"identity":"da44c993-679b-40b4-b892-bfb0e80ca931","added_by":"auto","created_at":"2025-04-10 13:30:39","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":242193,"visible":true,"origin":"","legend":"\u003cp\u003eMajor and minor faults affecting the Silah field.\u003c/p\u003e","description":"","filename":"image5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/adfd5a8a5bd7b60bcf6e4b42.jpeg"},{"id":80321358,"identity":"69883036-cb58-48ac-9267-79791143f1cd","added_by":"auto","created_at":"2025-04-10 13:30:39","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":556714,"visible":true,"origin":"","legend":"\u003cp\u003eSonic calibrations of the Silah-1X a), South Silah-1X b) drilled well.\u003c/p\u003e","description":"","filename":"image6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/12f957e41d9ab3690151dcbd.jpeg"},{"id":80320272,"identity":"49a87bc3-5f47-4fb0-afd9-193e15d6369a","added_by":"auto","created_at":"2025-04-10 13:22:38","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":211667,"visible":true,"origin":"","legend":"\u003cp\u003eGenerated synthetic seismogram for the South Silah-1X drilled well.\u003c/p\u003e","description":"","filename":"image7.png","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/103013ae6a50961f871d1bd0.png"},{"id":80320279,"identity":"afd96843-1205-44dc-987f-39d76d5aa8f9","added_by":"auto","created_at":"2025-04-10 13:22:39","extension":"jpeg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":194326,"visible":true,"origin":"","legend":"\u003cp\u003eThe reflectors on the top of the seismic horizon in the Silah-1X a) and South Silah-1X b).\u003c/p\u003e","description":"","filename":"image8.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/1388b07e9874c257048c3897.jpeg"},{"id":80321364,"identity":"21339f4a-36c5-40eb-98a3-d1d5ad1b3b16","added_by":"auto","created_at":"2025-04-10 13:30:39","extension":"jpeg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":583731,"visible":true,"origin":"","legend":"\u003cp\u003ePicking seismic horizons along the seismic lines; N-S (Inline 18-2)a) and E-W (X 10530) b).\u003c/p\u003e","description":"","filename":"image9.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/2b652afc54544277b9352d96.jpeg"},{"id":80321361,"identity":"2201dc84-d646-4851-abe9-4838eb3ee572","added_by":"auto","created_at":"2025-04-10 13:30:39","extension":"jpeg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":496348,"visible":true,"origin":"","legend":"\u003cp\u003eInterpreted faults picked from the E-W direction seismic lines show the folds-related fault due to compressional stress: syncline-related fault (X10740) a) and anticline-related fault (X10620) b).\u003c/p\u003e","description":"","filename":"image10.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/3d1c0dc45c49470bc4be8385.jpeg"},{"id":80320308,"identity":"f39076e0-d7fc-4fa9-84c2-741f19aa2791","added_by":"auto","created_at":"2025-04-10 13:22:39","extension":"jpeg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":644855,"visible":true,"origin":"","legend":"\u003cp\u003eTime-structure contour maps for the top of the Khoman Fm. a), the Abu Roash (E) b), Abu Roash (F) c), and Abu Roash (G) d).\u003c/p\u003e","description":"","filename":"image11.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/f919b760f8d7f5ac384ac5a0.jpeg"},{"id":80321368,"identity":"93115e07-5ad0-4767-b2bc-4723a60c873e","added_by":"auto","created_at":"2025-04-10 13:30:39","extension":"jpeg","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":217918,"visible":true,"origin":"","legend":"\u003cp\u003eTime-depth relationship for the Silah-1X a) and South Silah-1X b).\u003c/p\u003e","description":"","filename":"image12.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/c960948906e94d8a5737ee52.jpeg"},{"id":80321360,"identity":"6bd6dbf9-749e-4eba-8b70-103b8175c3bb","added_by":"auto","created_at":"2025-04-10 13:30:39","extension":"jpeg","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":674481,"visible":true,"origin":"","legend":"\u003cp\u003eDepth-structure contour maps for the top of the Khoman Fm. a), the Abu Roash (E) b), Abu Roash (F) c), and Abu Roash (G) d).\u003c/p\u003e","description":"","filename":"image13.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/b8bebf678c6c4a9f8efa29f3.jpeg"},{"id":80322700,"identity":"4ff287eb-29ec-4aa1-bd5f-ab1df4c0290c","added_by":"auto","created_at":"2025-04-10 13:46:39","extension":"jpeg","order_by":14,"title":"Figure 14","display":"","copyAsset":false,"role":"figure","size":656281,"visible":true,"origin":"","legend":"\u003cp\u003eIsochore thickness maps of the Abu Roash (D) a), Abu Roash (E) b), Abu Roash (F) c), and Abu Roash (G) d).\u003c/p\u003e","description":"","filename":"image14.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/609c892a83b1f11357dbd3d8.jpeg"},{"id":80320286,"identity":"a0c6d28a-5bb4-4c7a-b81c-28eef0b60ce0","added_by":"auto","created_at":"2025-04-10 13:22:39","extension":"jpeg","order_by":15,"title":"Figure 15","display":"","copyAsset":false,"role":"figure","size":1174226,"visible":true,"origin":"","legend":"\u003cp\u003eA constructed structural geological model through the Abu Roash Formation of the Silah field a) and faults (major and minor) affecting the area b).\u003c/p\u003e","description":"","filename":"image15.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/11c34cfc56f9ada61b8bed6e.jpeg"},{"id":80321369,"identity":"68ebbabd-6e23-4b27-a8fa-824fe5262507","added_by":"auto","created_at":"2025-04-10 13:30:39","extension":"jpeg","order_by":16,"title":"Figure 16","display":"","copyAsset":false,"role":"figure","size":96554,"visible":true,"origin":"","legend":"\u003cp\u003eA geometrically main zone index for the upper Cretaceous formations of Silah.\u003c/p\u003e","description":"","filename":"image16.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/1f5e21143dd765e43e6403aa.jpeg"},{"id":80320296,"identity":"71a0c9e1-0daa-4d15-b8cb-11fbf0632e78","added_by":"auto","created_at":"2025-04-10 13:22:39","extension":"jpeg","order_by":17,"title":"Figure 17","display":"","copyAsset":false,"role":"figure","size":278080,"visible":true,"origin":"","legend":"\u003cp\u003eDepth-structural cross-section of the upper Cretaceous through the Silah field in S-N direction a) and W-E direction b).\u003c/p\u003e","description":"","filename":"image17.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/5f4065d77ba0d06aaf78b271.jpeg"},{"id":80322282,"identity":"577f1387-cfdb-4dc3-8730-06203ee632f8","added_by":"auto","created_at":"2025-04-10 13:38:39","extension":"jpeg","order_by":18,"title":"Figure 18","display":"","copyAsset":false,"role":"figure","size":383857,"visible":true,"origin":"","legend":"\u003cp\u003eDepth-structural cross-section across the studied area through the upper Cretaceous strata at the center of the study area for the Silah-1X and Silah-6X b).\u003c/p\u003e","description":"","filename":"image18.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/8cb1e47f6a9a8f7df2508b2c.jpeg"},{"id":80320293,"identity":"12e7831f-5c28-483c-b335-976f8122d7ab","added_by":"auto","created_at":"2025-04-10 13:22:39","extension":"jpeg","order_by":19,"title":"Figure 19","display":"","copyAsset":false,"role":"figure","size":160145,"visible":true,"origin":"","legend":"\u003cp\u003eA map showing the location of the future promising area (Grey Circle) in the Silah field.\u003c/p\u003e","description":"","filename":"image19.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/82bba7b42f1b55976cddb676.jpeg"},{"id":91154382,"identity":"9522bf1f-7e24-442f-a40c-b7a7405ccabd","added_by":"auto","created_at":"2025-09-12 07:47:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":10998445,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6055654/v1/dda97e06-76a7-4023-aa86-81604b14c264.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Integrated 2D seismic interpretation and 3D geological modeling for reservoir characterization of the upper Cretaceous Formations in the Silah field, Egypt","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThere is an extensive background in energy resource prospection in Egypt with noteworthy findings in the Western Desert, especially in the north. The Western Desert of Egypt is a huge platform consisting of thick sedimentary rocks affected by different tectonic movements with a slight northward regional slope and dip [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. These movements initiated many sedimentary rift basins, such as the Shushan and El-Gindi. These basins are considered the most prolific areas for hydrocarbon exploitation and range from Mesozoic to early Tertiary [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Most of these basins lie north of the Qattara Ridge, which is separated from the Abu El-Gharadig major basin. One of the most promising areas for hydrocarbon exploration and drilling is El-Gindi Basin (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e1\u003c/span\u003ea).\u003c/p\u003e \u003cp\u003eGeophysical imaging techniques provide crucial insights into subsurface geology, particularly in basins with complex stratigraphy, facilitating accurate reservoir characterization and exploration. This is particularly crucial in basins where the geological record under the surface is highly ambiguous due to either the stratigraphic trend or the absence of an outcrop. One of the biggest issues facing petroleum geoscientists is the characterization of reservoirs near and far from wells. When seismic data is available, this issue can be effectively resolved, but it is exacerbated in exploratory areas with inadequate data [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Most researchers provide a framework to identify hydrocarbon potential through integrated geological, seismic, and petrophysical evaluations in comparable Egyptian petroleum fields. While these studies focused on the neighboring regions, they underscore the significance of detailed seismic data, fault structure analysis, and petrophysical modeling in delineating prospective hydrocarbon zones [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhen applied to either two-dimensional lines or three-dimensional volumes, seismic reflection is the most popular and adaptable technique for imaging the subsurface [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The development and assessment of oil fields, as well as the identification of appropriate sites for exploratory wells, depend heavily on seismic interpretation techniques. By offering in-fill information on the rock characteristics between wells, 2D seismic reflection data in SEG-Y format was processed using advanced interpretation techniques, integrating well-log calibration, velocity modeling, and fault mapping to delineate reservoir structures [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. To improve the information that might be faint in a conventional seismic image, the seismic attribute is a parameter that is taken or derived from seismic data and can be examined [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe present study is performed on a new virgin area called the Silah field. This field in El-Gindi basin is located at El-Fayoum Concession, west of the River Nile (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). The exploration of petroleum in this area remains a relatively underexplored domain compared to other prolific fields in the Western Desert and Nile Delta regions. No or little subsurface geological information is known about this field. Comprehensive exploration efforts in the Silah should employ multidisciplinary approaches, including advanced seismic interpretation, potential trap determination, and subsurface modeling, to overcome challenges posed by lithological and structural heterogeneity. So, this study is based mainly on seismic reflection data in 2D and well-logging data, including the VSP data (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). The analysis and interpretation of these data were made by Petrel 2017 and Techlog software. The primary step in the interpretation process is to establish the connection between seismic reflections and the structural pattern of the field. The objectives of the present work are to 1) create the connection between the well logging data and the seismic reflections, 2) visualize the main structure pattern affecting the upper Cretaceous units through the studied area, 3) evaluate the main reservoir architecture of the Silah field, and 4) determine the most potential areas for hydrocarbon accumulations.\u003c/p\u003e"},{"header":"2. Geological setting","content":"\u003cp\u003eStratigraphically, according to the interpretation and analysis of the well logging and mud logging data (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e1\u003c/span\u003ec), a truncated lower Cretaceous section immediately above the Precambrian basement marked the beginning of the sedimentary succession of El-Gindi (4200 m) [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Generally, the subsurface Mesozoic\u0026ndash;Tertiary sedimentary successions in El-Gindi basin consist of seven formations from the top to the base: the Moghra, Dabaa (Late Eocene\u0026ndash;Oligocene), Apollonia (Early\u0026ndash;Middle Eocene), Khoman (Campanian\u0026ndash;Maastrichtian), Abu Roash (Late Cenomanian\u0026ndash;Santonian), Baharyia (Early Cenomanian), and Kharita (Albian) Formations [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Three main unconformities are present in the lithostratigraphic column of the Silah field in El-Gindi basin: 1) the Albian Kharita Formation non-conformably overlies the basement rocks, 2) the Abu Roash Formation conformably overlies the Bahariya Formation and unconformably underlies the Khoman Formation, and 3) The Appollonia Formation unconformably overlies the Khoman Formation.\u003c/p\u003e \u003cp\u003eIt is believed that several Mesozoic extensional rift basins that originated in northern Egypt are part of the Tethyan passive margin [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. During the beginning of Gondwana's split and the Neo-Tethys Ocean's early opening in the Permo-Triassic, these basins were formed [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The Tethys shoreline moved across the area when the Jurassic to Cretaceous principal reservoirs were deposited. Coastal and tidal sandstones were deposited when the Tethys moved southward [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Shells and marine carbonate mud were deposited on the sea floor during other ages when the Tethys covered the whole Western Desert region. During the early Cretaceous, an expansion direction shifted clockwise into the NE-SW direction, creating new sedimentary basins such as Beni Suef and Asyut. Additionally, a subsequent derivation continued the expansion, creating a rift basin similar to El-Gindi-oriented NE-SW [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eEl-Gindi is a rift basin formed in the early Cretaceous. It is located at El-Fayium Concession, covering a surface area of about 9500 km\u003csup\u003e2\u003c/sup\u003e and delineated by latitudes 29\u0026deg; 15\u0026prime; to 29\u0026deg; 55\u0026prime; N and longitudes 30\u0026deg; 10\u0026prime; to 31\u0026deg; 10\u0026prime; E. This basin, which has significant hydrocarbon potential, is part of Egypt's north-central exploration plan [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. The dominant developed structures were controlled by normal faults and folding, and some of these faults had strike-slip movements that affected the orientation of the fold axes [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The syn-rift Jurassic, lower, and upper Cretaceous sedimentary successions are primarily characterized by convenient source rocks and reservoirs [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e].\u003c/p\u003e"},{"header":"3. Data and Methods","content":"\u003cp\u003eSeismic data collection is a proven method of gathering subsurface information for hydrocarbon exploration and production operations. The seismic (S-GEY files) and well-logging data were provided by the PetroSilah Petroleum Company. 2D seismic profiles included 20 inlines (dip lines) running in the N-S direction and 10 crosslines (strike lines) orientated in the E-W direction (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e1\u003c/span\u003ed). These profiles covered an area of approximately 9500 km\u003csup\u003e2\u003c/sup\u003e in El-Gindi basin. Also, the wireline logging data are available for five drilled wells (Silah-1X, Silah-6X, Silah-7, Silah-15, and South Silah-1X). The vertical seismic profiling data are utilized to establish the connection between the well logging and the seismic reflection data [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this study, the analysis of geophysical data includes twelve steps: correlation of seismic events, tying their travel times, reflector identification, horizon tracking, correlation of reflectors, fault location, closing loops, posting their time values and fault segments, construction of geo-seismic cross-sections, time-to-depth conversion, construction of the isochronous, and construction of the structural contour maps. Linking between seismic reflections and stratigraphy is the essential step in seismic interpretation (tie geological horizons to seismic reflectors and time-depth relationships) by using check shot data and creating a synthetic seismogram or velocity model. The next phase is to combine 2D seismic data with wireline logs of the selected wells to build a 3D structural geological model, an isopach contour map, and a structure-tectonic map (time and depth) of the reservoirs of the Abu Roash members. Lastly, identify the structural characteristics (fault patterns, seismic reflectors, and depth value contouring) that may serve as a trap for the buildup of hydrocarbons and identify the promising region or zone of oil and/or gas production in the Silah Field.\u003c/p\u003e \u003cp\u003eA synthetic seismogram is a record created from velocity log data by convolving the product of acoustic and density logs (reflectivity function) with wavelets. It is generated by using Petrel 2018 software [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. The petrophysical logs, Sonic (DT), and Bulk Density (RHOB) offer the inverse velocity and density information of subsurface layers in this process. Velocity and density data are used to calculate a set of reflection coefficients called reflectivity series. The result is a source Ricker wavelet with a dominating frequency of 35 Hz. The source wavelet was convolved with the reflectivity series. The synthetic seismogram is matched with the interpreted seismic depth section at the well point to correlate the succession of reflectors. It is also used to calibrate our seismic velocities [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e"},{"header":"4. Results","content":"\u003cp\u003eThe analysis and interpretation of reflection seismic and velocity data in the Silah field as a part of El-Gindi basin include:\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e4.1. Geological subsurface cross-section\u003c/h2\u003e \u003cp\u003eBefore the interpretation and analysis process of the 2D seismic data, the geological correlation section is created to understand the relationship between the drilled wells and recognize the variation in thickness laterally and vertically (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e2\u003c/span\u003e). This subsurface geological cross-section shows that the formations might have been subjected to tectonic forces. These forces have led to the formation of normal faults, which assisted in forming the basin. The dip direction of these faults is toward the Silah-6X and Silah-7 drilled wells. The basin extension started in the early Cretaceous with high accommodation space toward the Silah-7 (depocenter).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e4.2. Fault detection\u003c/h2\u003e \u003cp\u003eThe realization of structural features is implemented to shorten the time required for data processing and to remove any information that is not required for the study, leaving only the area of interest (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The faults are identified and picked on the cross-lines while the continuity was viewed on the in-lines (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNine major faults are picked and mapped. Within the major fault blocks, four minor faults can be inferred, both synthetic and antithetic (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The whole interpreted fault seems to have cut the top of the Khoman and the base of the Baharyia Formations (Upper Cretaceous). To comprehend the impact of these faults on the various rock units, the fault polygon that was constructed is combined with the time-structure maps of the top and base of the upper Cretaceous Formations. All major and minor faults are depicted in a model generated using the Petrel software (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThree primary fault trends with EW to ENE, NW-SW, and NE-SW orientations have been identified. The NW-SE-orientated faults are normal and were active at least during the early and late Cretaceous to Eocene. The NE faults are characterized by a downthrown towards the WNW, but the major fault trend is NW-SE, which is characterized by a downthrown towards the SW; otherwise, the E-W faults are characterized by two different downthrown towards the N and the S directions (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e4\u003c/span\u003e). The main structural features affecting the Silah field were formed from a series of normal faults and built the half-graben (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e4.3. Seismic well-tie (synthetic seismogram)\u003c/h2\u003e \u003cp\u003eThe seismic-to-well tie is performed for the two wells (Silah-1X and South Silah-1X) using the sonic log and VSP data. To create a high-exact time-depth relationship throughout the drilled wells, the sonic log and velocity data are first calibrated with the VSP data for each well (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Extended white-1 is the most effective of the four seismic wavelets that were created using different techniques. Finally, the acoustic impedance log is generated to produce the series of reflection coefficients, which are then convolved with this wavelet to produce the synthetic seismogram. The synthetic seismogram created for the south Silah-1X and the two-way time data from the VSP at the same location are used to tie the well logs (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e7\u003c/span\u003e). Following the creation of the synthetic generation, the retrieved traces close to the well are compared to the seismogram. To connect the formation tops on the synthetic seismogram to the horizons on the vertical seismic sections close to the well location, the seismogram is then shown on the vertical seismic sections (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e8\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003e4.4. Horizon tracking\u003c/h2\u003e \u003cp\u003eAn illustration of horizon picking using the four seismic lines for fault interpretation of different formations, the Khoman, Abu Roash (A, B, E, F, and G), in the seismic section is constructed (Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e9\u003c/span\u003e). The interpreted seismic section (lines 18\u0026thinsp;\u0026minus;\u0026thinsp;2), orientated in the N-S direction, is located in the western part of the area (Figs.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e9\u003c/span\u003ea). The region is traversed by the faults F1, F3, and F6, which dip to the S and SE, respectively, and run from E-W to ENE-WSW. The F2, F4, and F5 faults, on the other hand, dip toward the NE as they cut through the region in NW-SE directions. From the Khoman to the Bahariya Formations, all of these faults are broken down one after the other. These faults formed a half-graben and graben block system. The interpreted seismic section (X 10530), orientated in the E-W direction, is located in the southern portion of the study area (Figs.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e9\u003c/span\u003eb). This section shows the same structural regime as the previous one, in addition to folds having gentle and broad slopes. The faults F7 and F8 are striking in the NE-SW direction, with a dip direction to the NW, but F9 is striking in the NW-SE direction with a dip direction to the SW through the area (Figs.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e9\u003c/span\u003eb). All these detected faults dissected the succession from the Khoman to lower Bahariya Formations, except F3 and F4, which started from the Abu Roash F member (Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e10\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e4.5. Isochronous map (Two-Way Time Map)\u003c/h2\u003e \u003cp\u003eTime-surface maps from the top of the Khoman, Abu Roash (D, E, F, and G members) are constructed (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e11\u003c/span\u003e). These maps are used to build isochronous maps as well as in time-depth conversion to get the isochore maps. Analyzing these maps reveals the existence of three normal faults in E-W to ENE, NNW-SSE to NW, and NE-SW directions. The E-W and NE trends represent the main faults. Also, the Two-Way Time (TWT) values range from 1400 ms at the depocenter in the NNE part (structurally low) to 720 ms at the shoulder of the basin in the southwestern part of the studied area (structurally high) (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFour seismic signatures are chosen for the following horizons: the top of Khoman, Abu Roash E, F, and G members. Some interpreted seismic lines are selected to show the picking of the horizons and the structural features in the study area (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e11\u003c/span\u003e). The TWTs decrease toward the N and NNW parts of the studied area, reaching a minimum value (816 ms to 1400 ms) indicating the depocenter of the basin. While the TWTs increase toward the S and central parts of the area, reaching maximum values (670 ms to 1020 ms), they represent the shoulders of the basin (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e11\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e4.6. Conversion of reflection time to depth\u003c/h2\u003e \u003cp\u003eThe correlation between the depth and time sections of the Silah-1X and South Silah-1X drilled wells is carried out by using available VSP data, which shows a good correlation (Fig.\u0026nbsp;\u003cspan refid=\"Fig15\" class=\"InternalRef\"\u003e12\u003c/span\u003e). The velocity model in this study is constructed using the time-depth relationship from a synthetic seismogram. Using the developed velocity model, the reflection time is converted to depth using the isochronous map (Fig.\u0026nbsp;\u003cspan refid=\"Fig14\" class=\"InternalRef\"\u003e11\u003c/span\u003e) and the average velocity values. The purpose of this procedure is to produce the contour map of the depth structure for the upper Cretaceous Formations in the Silah oil field.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.7. Seismic structure-depth maps\u003c/h2\u003e \u003cp\u003eThe same structural features are shown on the seismic structure-depth maps, but they can be differentiated according to the times of their respective units. The generated depth-structure contour maps of the area reveal that the regional structural features (normal faults) are trending in the E-W to ENE, NW-SE, and NE directions as well as the presence of folding and fold-related fault structures (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e13\u003c/span\u003e). It is observed that the shallow part of the basin is located in the N-E to the NNW portion of the area. The deepest part (8000 ft) is towards the NNW direction, while the shallowest one (3500 ft) is detected towards the south and central parts direction (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e13\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe depth values of the Abu Roash D vary between 3600 and 4600 ft (TVD), while those values in the Abu Roash E vary from 5100 to 6000 ft (TVD). The maximum values (high-relief) are recognized in the N to NW part of the study area, while the minimum (low-relief) is in the central part. The depth contour maps of Abu Roash F and G, on the other hand, indicate that the values range from 5700 to 7500 feet (TVD). The central portion of the study area (depocenter) has low-relief areas (minimum values), while the northwest portion (maximum values) has high-relief areas (maximum values) (Fig.\u0026nbsp;\u003cspan refid=\"Fig16\" class=\"InternalRef\"\u003e13\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003e4.8. Isochore maps\u003c/h2\u003e \u003cp\u003eIsochore maps are generated by using the Petrel software 2017 as an indication of TVTs (Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e14\u003c/span\u003e). The spatial changes in thickness within the Abu Roash D vary from 250 ft at NW, NE, and SW parts to 750 ft at E and SW parts of the area. The main fault system that affected the region was responsible for this variation. The constructed isochore map shows that the small thickness ranges from 250 ft to 300 ft, but the large thickness varies from 500 ft to 750 ft (Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e14\u003c/span\u003ea). The thickness map of the Abu Roash E ranges from a large thickness (750 to 1000 ft) at the NW and SW parts to a small thickness (300 ft) at the E and NE parts of the studied area (Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e14\u003c/span\u003eb). However, the thickness of the Abu Roash F represents a low distribution from 300 ft at the SW and W parts to 600 ft at the NE and central parts of the study area (Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e14\u003c/span\u003ec). The small thickness (390 ft) is observed in the E to NE, but the large thickness (750\u0026ndash;1170 ft) is observed in the Abu Roash G at the SW, W, and NW parts of the studied area (Fig.\u0026nbsp;\u003cspan refid=\"Fig17\" class=\"InternalRef\"\u003e14\u003c/span\u003ed).\u003c/p\u003e \u003cp\u003eThickness, depth maps, and fault planes deduced from seismic and well-logging data are among the numerous important features that define the reservoir's geometry in the Silah field (Figs.\u0026nbsp;\u003cspan refid=\"Fig18\" class=\"InternalRef\"\u003e15\u003c/span\u003e and \u003cspan refid=\"Fig19\" class=\"InternalRef\"\u003e16\u003c/span\u003e). There are eight distinctive zones, each of them containing the layers that show the vertical facies alteration (the Abu Roash A, B, C, D, E, F, and G zones and Khoman Formation) (Fig.\u0026nbsp;\u003cspan refid=\"Fig19\" class=\"InternalRef\"\u003e16\u003c/span\u003e). To demonstrate the lateral extension and thickness variation, as well as faults and folding structure features, subsurface structural cross-sections are extracted in various orientations (Figs.\u0026nbsp;\u003cspan refid=\"Fig20\" class=\"InternalRef\"\u003e17\u003c/span\u003e and \u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e18\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e"},{"header":"5. Discussion","content":"\u003cp\u003eThe present study aims to delineate and evaluate the subsurface structural features and to determine the hydrocarbon potentialities of El-Gindi basin, particularly in the Silah oil field. The seismic reflection and VSP data are interpreted, analyzed, and integrated carefully with the geological and well-logging data to evaluate the main reservoir architecture of the field. The critical interpretation of these data is used to pick and determine the top of the upper Cretaceous reservoirs, and different faults controlled the shape and structural features of the basin during its evolution. Also, various maps and subsurface sections are constructed to identify and follow the economic zones of interest within the Abu Roash E, F, and G members.\u003c/p\u003e \u003cp\u003eThe Paleozoic to Jurassic sedimentary successions are not recorded, most probably due to the phase of non-deposition over a platform area. The extensional compressional stress began in the early Cretaceous to Eocene. The upper Cretaceous formations were subjected to the force in the EW direction to form a series of anticline- and syncline-related fault traps. Then, the folding and fold-related fault systems that resulted from this stress were started in the Santonian. The E-W-orientated deep-seated faults were formed during the rifting of the early Cretaceous period. This rifting phase had originated a passive continental margin of the Tethys in the East Mediterranean region.\u003c/p\u003e \u003cp\u003eThe two-way time maps of the Abu Roash E and G vary from \u0026minus;\u0026thinsp;1080 to -1320 ms and from \u0026minus;\u0026thinsp;1100 to -1420 ms, respectively. These maps reach maximum values toward the northwest parts of the study area. The low-relief parts are detected in the central portion of the study area (folding and faulting uplift).\u003c/p\u003e \u003cp\u003eThe basin's structural highs and lows are distributed similarly to how they were found on the seismic structure-depth maps. The structural-lows are located in the northern and northwestern parts, while the structural-highs are in the central to southern parts of the area. The time and depth maps of all horizons show a general dipping toward the north where the time and depth increase. The depth-contour maps reveal the shallowest depth (3500 ft to 5000 ft) detected in the S and center, but the deepest one (5500 ft to 8000 ft) detected in the N and NNW parts of the Silah (Fig.\u0026nbsp;\u003cspan refid=\"Fig21\" class=\"InternalRef\"\u003e19\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWhile the major faults that are oriented NE and NW are thought to have an effect on the region, the subsurface faults that are oriented E-W can be tracked eastward. The province of Silah stratigraphy is where folding is most noticeable. These symmetrical folds are closer to the axial planes, which are often oriented NE-SW, and have a comparatively soft flank.\u003c/p\u003e \u003cp\u003eThe depth structure contour maps demonstrate the influence of normal faults trending E-W to ENE and NW-SE directions on the entire area. The fault polygons of the two horizons generally indicate the formation of three-way dip closure, tilted fault blocks, half-grabens, and graben blocks. Two tectonic forces influenced the deep-seated limestone of the Abu Roash F and the sandstone of the Abu Roash G. The first is the folding brought on by inversion processes, and the second is the subsidence brought on by extension. As a result of these forces, possible traps for the accumulation of hydrocarbons in the field have formed.\u003c/p\u003e"},{"header":"6. Conclusion","content":"\u003cp\u003eThe critical interpretation of seismic and well logging data in the Silah indicates the following:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eThree deformational phenomena had a regional impact on the Silah strata. Locally, they developed and expanded the hydrocarbon system in the El-Gindi basin. These include some NW-oriented faults' early Cenozoic reactivation, late Cretaceous inversion, and early Cretaceous rifting.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eDue to past tensional forces, faulting produced a large number of grabens and half-grabens. The pre-identified extensional regime from the early Jurassic to the lower Cretaceous period is most likely responsible for the major structural elements that constructed the Silah's half-graben and graben systems. The shallower portion of the basin lies in the middle, whereas the depocenter is situated in the N and NNW sections.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eOne important regional structural element that controls the basin's location and trend is the EW to ENE direction. Two significant fault systems that extended in the EW and NE-SW directions had a significant structural impact on the basin's upper Cretaceous and deeper strata.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThe structural high is considered a half-graben and grabens bounded by normal faults (NW-SE and NE-SW). Generally, the steep dip throw is toward the NNW part of the area at a depth of 8000 ft in the Abu Roash G member, which supports the possibility of hydrocarbon accumulation.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThe best reservoirs in the region are thought to be the Abu Roash F and G members. These reservoirs' distributions are low in the S and SE regions of the research area and high in the N to NW region. This structural style was probably generated by the dragging of the Cretaceous in the NE-SW oriented main fault, which resulted in tectonic inversion and dip reversal of the Jurassic-Early Cretaceous half-graben. These conclusions are detected from the created time and depth structural contour maps on the top of these reservoirs with the subsurface cross-section through the structure model.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eThe northwestern part of the area is a promising development site for future hydrocarbon exploration due to the presence of a structurally high area, which is located above a graben block (Fig.\u0026nbsp;\u003cspan refid=\"Fig21\" class=\"InternalRef\"\u003e19\u003c/span\u003e). Also, the central parts are proposed for future drilling plans because they have structure closure, which makes the three-way dip closure a tilted fault block (three-way anticlinal closure in the upthrown block of normal faults). These high structural features make them good structural traps for hydrocarbon accumulation. The two target zones in the Silah are the Abu Roash F (carbonates) and G (sandstones).\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eTwo new well-proposed locations (A and B) are chosen carefully. Area A is located in the NW portion, while Area B is in the central part of the area near the Silah-1X and the Silah-6X wells.\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThere are no conflicts of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis paper is based upon work supported by Science, Technology \u0026amp; Innovation Funding Authority (STDF) under grant no (48777). The authors are grateful to The Petorsilah Petroleum Company for supplying the raw material, the required reports from their archives, and the digital logs.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe 1st author [Mohamed Osman Ebraheem] and 2nd author [Hamza Ahmed Ibrahim] contributed to the study\u0026rsquo;s conception and design, revised the manuscript, restructured, rewrote, and provided additional interpretations to a section of the paper, whereas the 3rd author [Ahmed Hosny Senosy] contributed to the study\u0026rsquo;s conception. Material preparation, data collection, proposal writing, and the approval process to use the data used in this research from the Petorsilah Petroleum Company were performed by the first and second authors. The first draft of the manuscript was written by the 3rd author, edited by the 1st and 2nd authors, and reedited by the 1st and 2nd authors until submission.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOpen access funding was provided by the Science, Technology \u0026amp; Innovation Funding Authority (STDF) in cooperation with the Egyptian Knowledge Bank (EKB).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSaid, R. The Geology of Egypt. 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Integrating well logs and seismic data for a comprehensive geophysical appraisal of post-Albian oil reservoirs in the SWQ-4X well, Gindi Basin, Egypt. \u003cem\u003eEgypt. J. Petroleum\u003c/em\u003e. \u003cb\u003e33\u003c/b\u003e (2), 2. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.62593/2090-2468.1021\u003c/span\u003e\u003cspan address=\"10.62593/2090-2468.1021\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e (2024).\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"2D seismic interpretation, 3D geological modeling, reservoir architecture, upper Cretaceous Formations, Silah field, Egypt","lastPublishedDoi":"10.21203/rs.3.rs-6055654/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6055654/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA comprehensive geophysical interpretation was applied to investigate the subsurface structural features and recognize the promising hydrocarbon zones in the Silah reservoir rocks. The study looks closely at the subsurface geological features that control oil accumulation. This helps us figure out where to drill and how to develop reservoirs. These objectives were achieved using well logging, 2D seismic interpretation, and 3D geological modeling. This was accomplished by creating a synthetic seismogram and using vertical seismic profiling (VSP). Different maps, cross-sections, and 3D structural models were constructed to visualize the subsurface structural configuration and architecture of the Silah Field. A calibration process between sonic logs and the velocity of the existing VSP data was carried out to produce a more accurate and detailed time-depth relationship at the well location. All information deduced from TWTs, seismic-structure depth, isochore maps, and depth-structural cross-section was used to identify and determine the locations of the depocenter and the shoulder of the basin. The study area is characterized by a complex fault pattern and trend. The structure features were due to an extensional rift stress followed by a compressional force. The resulting depth structural map displays several NW-SE and NE-SW normal faults along with a master E-W to ENE fault direction on top of the Early Cenomanian Abu Roash (F) and (G). These normal faults extended to the Khoman Formation. The extensional faults formed grabens and half grabens structures in the north and northwest portions of the study area. The compressional stress event created folding and fold-related fault structures in the central part of the study area. The depocenter area is present in the NW portion of the study area at a depth reaching 8000 ft. The structural elements, such as fault-bounded closures and half-graben systems, act as primary petroleum traps, influencing reservoir connectivity and fluid migration pathways. The findings indicate that further exploratory wells should be drilled in the Silah area to boost production from the carbonates and sandstones of the Abu Roash reservoir. Other promising oil-bearing zones within the area under investigation could also be proposed.\u003c/p\u003e","manuscriptTitle":"Integrated 2D seismic interpretation and 3D geological modeling for reservoir characterization of the upper Cretaceous Formations in the Silah field, Egypt","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-10 13:22:34","doi":"10.21203/rs.3.rs-6055654/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"4982c6bd-5d69-4541-9dbf-3a17659d478a","owner":[],"postedDate":"April 10th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":46814149,"name":"Earth and environmental sciences/Environmental sciences"},{"id":46814150,"name":"Earth and environmental sciences/Solid earth sciences"}],"tags":[],"updatedAt":"2025-09-12T07:38:47+00:00","versionOfRecord":[],"versionCreatedAt":"2025-04-10 13:22:34","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6055654","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6055654","identity":"rs-6055654","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}