Strength Retrogression Mechanisms of Silica-Enriched Oil Well Cement under 240°C Curing Conditions

Strength Retrogression Mechanisms of Silica-Enriched Oil Well Cement under 240°C Curing Conditions | 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 Research Article Strength Retrogression Mechanisms of Silica-Enriched Oil Well Cement under 240°C Curing Conditions guodong cheng, He Li, Haoya Liu, Haoguang Wei, Shiming Zhou, Kuizhen Fang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7415053/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 19 Nov, 2025 Read the published version in Chemical Papers → Version 1 posted 6 You are reading this latest preprint version Abstract The long-term strength retrogression of silica-enriched oil well cement poses a significant threat to wellbore integrity in deep and ultra-deep wells. This study tested the performance evolution of silica-rich cement under two setting temperatures (80°C and 240°C) followed by 240°C/20 MPa curing. Results indicated that 80°C-set cement exhibited strength growth during curing, whereas 240°C-set cement suffered strength decline over 28 days; increasing the dosage of silica sand and adding coal gangue powder both cannot prevent this decline trend. SEM combined with XRD quantitative analysis revealed that, the content of C-(A)-S-H of set cement at low-temperature setting increased cured from 3d to 28d and it directly generated more xonotlite at 3d early stage, although this mineral phase was unfavorable relative to the compressive strength of set cement, it was structurally stable at this temperature, which was the reason for its stable strength, in contrast, the C-(A)-S-H of set cement at high-temperature setting decreased cured from 3d to 28d and the content of xonotlite continued to increase during the long-term curing process, resulting in the coarsening of the microstructure and retrogression in strength; this difference may be due to the different structure of C-(A)-S-H under the two setting temperatures; in addition, increasing the dosage of silica sand and adding coal gangue powder both cannot prevent the above-mentioned structural and compositional changes of set cement. The results of above microanalysis can explain all systems compressive strength. silica-enriched oil well cement strength retrogression set temperature high temperature Quantitative X-ray diffraction (QXRD) Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 1. Introduction As the exploration and development of global oil and gas resources progresses, ultra-high-temperature wells with downhole temperatures exceeding 200°C are gradually becoming the primary domain for energy extraction[ 1 – 3 ]. In such a harsh service environment, the efficacy of cementing cement ring as a crucial barrier to maintaining the integrity of the wellbore and achieving effective interlayer sealing is subject to severe testing[ 4 , 5 ]. As a commonly used cementitious material in cementing engineering, neat oil well cement systems experience significant strength declines when they are cured at temperatures above approximately 110 o C[ 6 ], caused by the change of hydration products from amorphous C-S-H to high calcium crystalline hydration products. In order to prevent this crystallization, the prevailing industry practice is adding silica sand, with a proportion ranging from 30–40%[ 7 ]. The fundamental principle underpinning this approach entails the reduction of the aggregate calcium-silica ratio within the system to a range of 0.8 to 1.0 to facilitate the transformation of cement hydration products into relatively good mechanical properties of tobermorite (C 5 S 6 H 5.5 ) and xonotlite (C 6 S 6 H)[ 8 ], while when the temperature exceeds 150°C, this modified system with the simple addition of silica sand still suffers from strength retrogression[ 6 , 9 , 10 ], therefore, it is necessary to continue to optimize silica sand (including dosage, particle size, and crystallinity) to stop this strength retrogression, but the latest research indicated that the optimized silica-enriched oil well cement systems still experienced a severe strength decline due to microstructural coarsening caused by the crystallization of C-S-H into tobermorite and xonolite after long term cuing period under simulated high-temperature deep-well conditions at 200 o C and 50–150 MPa[ 4 , 5 , 11 , 12 ]. Practice has proved that the set temperature of cement paste has a very strong influence on the performance of set cement[ 10 , 13 , 14 ], and the optimized silica-rich sand system is usually only suitable for thick oil hot recovery wells, but not for deep and ultra-deep wells[ 15 ]. The fundamental distinction between the two cementing conditions is the different setting temperatures of cement paste, in thick oil hot recovery wells, a "two-step" setting method is employed, whereby the cement slurry is initially set at a low temperature (typically 80°C) and subsequently cured at a high temperature. In contrast, in deep and ultra-deep wells, a “one-step” molding technique is used, in which the cement paste is directly set and cured at high temperature and pressure conditions, and it required that the cement paste was in a fluid state before reaching the specified temperature. The two methods exerts a substantial influence on the high-temperature stability of silica-enriched oil well cement systems, but the specific mechanism is still unclear. In addition, recent studies have shown that the addition of a certain proportion of aluminum-containing mineral materials[ 16 – 18 ], such as fly ash, to silica-enriched oil well cement systems can effectively prevent the strength retrogression of set cement high temperature and pressure conditions, and the coal gangue powder, as a kind of industrial solid waste[ 19 – 21 ], has a similar composition to that of fly ash, and it should also have an anti- retrogression effect. In this study, based on SEM, XRD combined with Rietveld quantitative analysis, the influence mechanism of setting temperature on the compressive strength of silica-enriched oil well cement was investigated, and the influence of coal gangue powder on the strength stability of high-temperature deep-well set cement was also explored. 2. Materials and experimental methods2.1 Materials The raw materials used in this study mainly include Class G oil-well cement, silica sand, and coal gangue powder; their chemical compositions and particle size distributions are presented in Table 1 and Tables 2 , respectively. The oxide composition of the cement was measured by X-Ray fluorescence (XRF) analysis and the particle size distribution was measured using a particle size1 analyzer (Mastersizer 2000). The free lime content in raw cement was determined according to GB/T 176 2017 China national standard. Table 1 Main oxides of bulk materials used(%) Oxide name Class G cement silica coal gangue powder Al 2 O 3 3.00 1.028 22.049 CaO 63.10 1.379 0.894 Fe 2 O 3 5.13 0.786 5.178 TiO 2 - - 0.891 K 2 O 0.45 0.257 3.011 MgO 2.84 0.412 1.969 Na 2 O 0.33 0.176 1.451 SO 3 3.76 0.310 0.216 P 2 O 5 0.043 0.014 0.150 SiO 2 20.01 95.640 64.027 Free Lime 1.360 - 0.8 Table 2 Summary of material properties: particle size and specific gravity. Material D10 µm D50 µm D90 µm Specific gravity coal gangue powder 3.29 9.77 29.48 2.71 silica 6.71 46.08 108.33 2.67 Class G cement 1.93 13.12 42.92 3.25 2.2 Formulation design and slurry preparation Table 2 presents the formulation design used in this study. All slurries were designed with a final density of 1.9 g/cm 3 . Slurry T1 was a low-temperature setting system, while slurries T2 to T4 were high-temperature setting systems (with thickening times all longer than the heating-up time of the curing autoclave). Specifically, both T1 and T2 had a silica sand content of 50% by weight of cement (BWOC). The main difference lies in that T1 does not contain high-temperature retarders to ensure rapid setting at low temperature (80°C), whereas T2 contains an adequate amount of high-temperature retarders, with its high-temperature thickening time exceeding 4 hours, which was longer than the heating-up time of the curing autoclave, meeting the requirements for high-temperature setting. The silica sand content in the slurry T3 reaches 110% BWOC, aiming to explore the stability of set cement under the condition of high silica sand content. In addition, the dosages for slurry T4 of silica and coal gangue powder were 30% and 60% BWOC, respectively. This was to investigate the effect of coal gangue powder on preventing strength retrogression of silica-enriched oil well cement systems. Except that the suspending agent and dispersant were solid powders, all other admixtures had a solid content of 80%, and all were supplied by Sinopec Petroleum Engineering Technology Research Institute Co., Ltd. It was noteworthy that studies have indicated under the specified ultra-high-temperature curing conditions (240°C), the hydration reaction of cement in hardened cement paste has been largely completed[16, 18 ]. Consequently, the impact of chemical admixtures (e.g., retarders) on the thermal stability during long-term service (≥ 2 days) in ultra-high-temperature environments was practically negligible. The dosages for slurry T1 of suspending agent and defoamer were 1%,and 1% by weight of cement, respectively, and no other additives; the dosages for slurries T2, T3 and T4 of dispersant(USZ), retarder(SCR-4), retarder(SCR-7), fluid loss additive(240W), suspending agent and defoamer were 1%, 8%, 1.8%, 4% ,1%,and 1% BWOC. All cement slurries were prepared in strict accordance with API Recommended Practice 10B-2, then cast into square stainless-steel moulds measuring 5 cm × 5 cm × 5cm. The slurry T1 was first allowed to set and pre-cure at 80°C for 24 h prior to demoulding; the other slurries were set and pre-cured directly at 240°C and 20 MPa for the same duration to demoulding. After demoulding, all specimens were transferred to identical high-temperature curing conditions (240°C, 20 MPa) and maintained until the prescribed testing age was reached. Table 3 Formulation design of dry blend compositions and added water Formulation cement silica coal gangue powder Added water T1 100 50 - 57 T2 100 50 - 46.9 T3 100 110 - 66.0 T4 100 30 60 48.4 3 Test method Compressive strength tests were performed using a TG-300B load frame from Shenyang Tiger Petroleum Instruments Manufacturing Co., Ltd. A field emission SEM by JEOL (Model JSM-IT500LV) was used to obtain microstructure images. XRD data were collected using a Panalytical diffractometer (Model Aeris with a 600W Cu-anode source, λ = 1.541 Å) operated at 40 kV and 15 mA. All scans were measured over an angular range of 7º to 70º (2θ angle) with a 0.01° 2θ step size and scanning time per step of 75.22 s, resulting in a total measurement time of about 30min per scan. Rietveld refinement analysis was carried out using Highscore Plus 5.0 software with Crystallography Open Database (COD) to assess the quantities of main crystal phases as well as the amorphous phase. Similar to our previous study[ 16 , 18 ], a single crystal silicon was ground into fine powders and used as an external standard. The following equation was used to calculate the phase content of a sample[ 22 ]. \(\:{W}_{j}=\frac{{S}_{j}{\rho\:}_{j}{V}_{j}^{2}}{{S}_{s}{\rho\:}_{s}{V}_{s}^{2}}{W}_{s}\frac{{u}_{m}}{{u}_{s}}\) (1) where W j is the weight fraction of phase j in the sample, 𝑆 j is the scale factor obtained in the Rietveld refinement for phase j, 𝜌 j is the unit cell density of phase j, V j designates the unit cell volume of phase j; similarly, 𝑆 s , 𝜌 s , and V S represent the corresponding parameters of the standard material; W S is the weight fraction of the standard phase in the external standard material (100% in our study); 𝜇 m and 𝜇 s are the mass absorption coefficients (MAC) of the sample and the standard material, respectively. The calculation of MAC was based on the oxide composition of solid components and water-cement ratio. 4. Test results and discussion 4.1 Compressive strength Figure 1 summarizes the compressive strength test results of cured slurries cured from 3d to 28d. The compressive strength of slurry T1 increased from 18.27 MPa to 31.10 MPa from 3 d to 28d curing time, suggesting that the low-temperature setting silica-enriched system had superior high-temperature stability in long curing period. In contrast, the compressive strength of slurry T2 decreased from 22.70 MPa to 16.15 MPa (28.8% decline), during the same curing period, suggesting that the traditional silica-enriched system experienced severe strength retrogression at the condition of high-temperature setting, consistent with our studies[ 16 , 18 ]. The above observations indicated that the low-temperature setting system slurry T1 may possesses a superior microstructure and mineralogical assemblage over long curing period compared to slurry T2, which will be elaborated in the following sections. Furthermore, although slurry T3 exhibited a modest increase in 3-day compressive strength relative to slurry T2, its 28-day strength declined markedly, demonstrating that raising the silica sand dosage was insufficient to arrest strength retrogression under 240°C setting and curing conditions. Analogously, the slurry T4 incorporating both silica sand and coal gangue powder also suffered strength retrogression after 28 days curing period at 240°C. This observation contrasts with the widely reported inhibitory effect of Al-rich mineral admixtures on strength retrogression in traditional silica-enriched systems; coal gangue powder was, in fact, rich in such phases. The limited efficacy observed here was presumably attributable to variations in the structural state and speciation of Al-bearing constituents among different mineral sources, which in turn govern their anti-retrogression performance. 4.2 SEM Based on the scanning electron microscope (SEM) observation results as shown in Fig. 2 and Fig. 3 , a systematic analysis of the microstructure evolution of different slurries (T1, T2, T3, T4) at different maintenance ages showed that the matrix microstructure of slurry T1 was significantly better than that at the age of 3 days after 28 days curing period. In contrast, the microstructures of slurries T2 and T3 showed obvious coarsening at the end of 28-day curing period, and the microstructural coarsening phenomenon of slurry T4 seemed to be more serious at the end of 28-day curing period, which indicated that increasing silica sand dosing and adding coal gangue powder cannot prevent the trend of microstructure coarsening of set cement under high-temperature setting and curing conditions; It was noteworthy that, at the conclusion of the 3-day curing period, slurry T2 exhibited a markedly finer microstructure than slurry T1; this may ascribe to the accelerated early-age hydration kinetics under elevated temperature that promoted a higher abundance of C-(A)-S-H, while a detailed analysis of Fig. 3 showed that a large amount of xonotlite was observed in slurry T1 cured from 3d to 28d, but the tobermorite was difficult to observe; whereas, a large amount of C-(A)-S-H gel can be observed in slurry T2 at the early stage (3 days), and loose stacking of xonotlite can be observed after 28 days of curing period. The slurries T3 and T2 behaved similarly. The above results indicated that, on the one hand, the low-temperature 80°C setting may have accelerated the transformation of C-(A)-S-H gel directly to xonotlite, although xonotlite can have adverse effects on the strength of set cement, the mineral structure was relatively stable under this temperature condition and would not undergo mineral transformation again, whereas, although the high-temperature setting may promote the generation of large amounts of C-(A)-S-H gel in early stage of set cement, early C-(A)-S-H gel would continue to crystallize into xonotlite, thus the microstructure was coarsened seriously, producing strength decline. In addition, a large amount of tobermorite can be observed in the early stage of slurry T4, while a large amount of xonotlite was observed after 28 days of curing period, seemed to be accompanied by the gradual transformation of tobermorite to xonotlite, which may be one of the main reason for its strength decline. More detailed analysis will be discussed in the XRD section. 4.3 XRD XRD was used to identify the mineral compositions of set cement. It can be seen from Fig. 4 that the main hydration products of silica-enriched oil well cement systems (slurries T1 to T3) mainly included semi-crystalline C-S-H (reflected by broadened peaks ranging from 28.5º to 30.5º), tobermorite and xonotlite. The peak profile of semi-crystalline C-S-H remains relatively stable cured from 3d to 28d, and the peak hight of xonotlite observed in slurry T1 was higher than these in slurries T2 and T3, indicated that the low setting temperature did not change the type of crystal hydration products but promoted to generate more xonotlite, consistent with SEM observations. The recent study demonstrated that the generation of xonotlite typically compromised the compressive strength of set cement. However, slurry T1 exhibited significantly higher compressive strength compared to slurry T2 after 28d curing period, which may be due to the different content and structure of C-(A)-S-H formed under two temperature setting conditions. A closer observation revealed that the semicrystalline C-A-S-H peak morphology in slurry T1 appeared to be more stable, while the C-A-S-H morphology in slurry T2 exhibited a sharpening after 28 days of curing; the sharpening degree of C-A-S-H morphology in slurry T3 underwent a slight reduction due to the augmented dosage of silica sand. This phenomenon was identified as the primary cause of observed decline in compressive strength setting and curing under high temperature conditions. Furthermore, the addition of coal gangue powder changed the hydration product of silica-enriched oil well cement systems to include alumina-bearing phase grossular and possibly some new semi-crystalline phases (including C-A-S-H) as reflected by broadened peaks ranging from 28.5º to 33.5º, consistent with our studies[ 16 , 18 ], but the morphological of this new semi-crystalline phases (including C-A-S-H) seemed to be different in that of silica-enriched oil well cement systems modified by fly ash, and exhibited a sharpening after 28 days of curing, indicated the structure of these two new semi-crystalline phases(including C-A-S-H) were different, which may be the reason why coal gangue powder was ineffective over fly ash. In order to further explore the working mechanism, quantitative analysis of mineral composition was conducted. The refined phase contents of selected systems were presented in Fig. 5 . Refinement results of the diffractograms were presented in the Fig. 6 to Fig. 11 . The quantitative results were consistent with the patterns shown in the XRD spectra. The content of crystalline phases in slurry T1 remains basically stable during the 28-day curing process, while the amorphous phase representing C-(A)-S-H increased with time, which was the primary reason for the sustained strength Another obvious feature was that, the content of xonotlite in T1 was significantly higher than that in slurries T2 and T3, while the content of tobermorite was little, indicated that under low-temperature setting and high-temperature curing conditions, the C-(A)-S-H crystaled mainly formed more stable xonotlite, avoiding the transformation process from tobermorite to xonotlite. Although the increase in xonotlite was unfavorable to the strength of set cement, but its structural was stable at this temperature, which was another key factor enabling slurry T1 to maintain its strength more effectively than slurries T2 and T3. In addition, although the content of C-(A)-S-H and xonotlite in slurry T1 was the same as that of slurry T2 after 28 days of curing, the compressive strength of slurry T1 was significantly higher than that of slurry T2, indicated that the structure of C-(A)-S-H contained in the two may be different. 5. Conclusion The strength retrogression mechanisms of different silica-enriched cementing systems cured at 240℃/20MPa were studied experimentally. The following main conclusions can be drawn: (1) The compressive strength of low-temperature setting slurry increased with increasing curing time, while the compressive strength of all slurries setting at high-temperature decreased by 21.2% to 28.8% from 3 d to 28 d, indicated that the setting temperature had big influence on the stability of mechanical properties; increasing the dosage of silica and the addition of coal gangue powder cannot prevent this strength retrogression. (2) The microstructure of low-temperature setting slurry coarsened seriously at early 3d, but get more dense after 28d curing period; in contrast, the microstructures of set cement setting at high temperature showed a completely opposite trend of change and changed from be dense to be coarsening from 3 d to 28 d; a large amount of xonotlite was observed in low-temperature setting slurry at early stage (3 days) but no tobermorite was observed, possibly indicated the C-(A)-S-H in low-temperature setting system directly crystallization to xonotlite at early stage, avoiding the transformation of tobermorite into xonotlite. (3) The low-temperature setting cement slurry directly generated more xonotlite but no tobermorite at early stage, and the content of crystalline phases remains basically stable during the 28-day curing process; the amorphous phase representing C-(A)-S-H increased with time, which may explain its stable compressive strength, while other slurries showed varing degrees conversion of amorphous C-(A)-S-H to xonotlite and tobermorite during curing, which were possibly the cause of strength retrogression of these systems. (4) Gangue powder could not prevent the strength decline of cementite under high temperature molding conditions, probably due to the type of aluminum-containing components. Declarations Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. 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1","display":"","copyAsset":false,"role":"figure","size":101862,"visible":true,"origin":"","legend":"\u003cp\u003eCompressive strength test results of cured slurries cured from 2d to 28d\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/2efdbc6ee3a819285a73c19c.png"},{"id":90676980,"identity":"1235a93f-feb1-4336-bdbf-cdd1e65736ad","added_by":"auto","created_at":"2025-09-05 14:48:58","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":714537,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of slurries T1 to T4 at 3 d and 28 d (×50)\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/e913fbc40207ceffc95615af.png"},{"id":90676613,"identity":"83949e93-0c69-4d84-84e6-2db0af8b0fea","added_by":"auto","created_at":"2025-09-05 14:40:58","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":729907,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of slurries T1 to T4 at 3 d and 28 d at different magnifications\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/e24873fdbea89de773428273.png"},{"id":90676978,"identity":"3f985a1c-fb99-424c-a348-e6b6450eec1e","added_by":"auto","created_at":"2025-09-05 14:48:58","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":88208,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray diffraction analysis of set cement at various curing time\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/26471210c206f08712ea284e.png"},{"id":90676608,"identity":"bcd2cd8f-fb0f-4505-b360-f4fa2bfdd1bf","added_by":"auto","created_at":"2025-09-05 14:40:58","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":55218,"visible":true,"origin":"","legend":"\u003cp\u003ePhase compositions of selected slurries T1 to T3 at various curing time (amorphous phases mainly consists of C-(A)-S-H)\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/e24604adc33c75edfed1a428.png"},{"id":90676977,"identity":"428ec212-42b1-4184-9812-92c08f19ab36","added_by":"auto","created_at":"2025-09-05 14:48:58","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":17234,"visible":true,"origin":"","legend":"\u003cp\u003eRefinement results of slurry T1 (3 d)\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/d1ad2f7d0ceb4776b086b30b.png"},{"id":90676609,"identity":"2dfca838-844c-4d38-90f9-ebcac9fdb83a","added_by":"auto","created_at":"2025-09-05 14:40:58","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":16968,"visible":true,"origin":"","legend":"\u003cp\u003eRefinement results of slurry T1 (28 d)\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/85aab1491eccb8565846cde7.png"},{"id":90676616,"identity":"3d4d51c8-e850-4718-8fc6-e4c7e097c2c9","added_by":"auto","created_at":"2025-09-05 14:40:58","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":18532,"visible":true,"origin":"","legend":"\u003cp\u003eRefinement results of slurry T2 (3 d)\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/58bb129079d19b122c7db7a2.png"},{"id":90678187,"identity":"7bf87138-2343-4421-9347-9294ba0e7643","added_by":"auto","created_at":"2025-09-05 15:04:58","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":16279,"visible":true,"origin":"","legend":"\u003cp\u003eRefinement results of slurry T2 (28d)\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/597a8cd41ba0a6fc3dd739bc.png"},{"id":90676618,"identity":"f884e614-52ef-4382-8974-d5875a610974","added_by":"auto","created_at":"2025-09-05 14:40:58","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":13860,"visible":true,"origin":"","legend":"\u003cp\u003eRefinement results of slurry T3 (3d)\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/942f7015de2b02f4c92e2a34.png"},{"id":90677978,"identity":"6a42f6a5-30a0-44b0-a262-9a2fbf6252c5","added_by":"auto","created_at":"2025-09-05 14:56:58","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":14702,"visible":true,"origin":"","legend":"\u003cp\u003eRefinement results of slurry T3 (28d)\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/9d0f10664cdb1849e2b16c1d.png"},{"id":96650241,"identity":"25395fad-131a-4b2e-b148-d9648b146b63","added_by":"auto","created_at":"2025-11-24 16:10:14","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2189212,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/b8633f3d-d644-49e8-afd1-9e1f731d5224.pdf"},{"id":90677977,"identity":"2cf867cc-1713-48a1-a0d5-78425dade06d","added_by":"auto","created_at":"2025-09-05 14:56:58","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":17992,"visible":true,"origin":"","legend":"","description":"","filename":"Highlights.docx","url":"https://assets-eu.researchsquare.com/files/rs-7415053/v1/73b0e0117e35150b0471843f.docx"}],"financialInterests":"","formattedTitle":"Strength Retrogression Mechanisms of Silica-Enriched Oil Well Cement under 240°C Curing Conditions","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eAs the exploration and development of global oil and gas resources progresses, ultra-high-temperature wells with downhole temperatures exceeding 200\u0026deg;C are gradually becoming the primary domain for energy extraction[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. In such a harsh service environment, the efficacy of cementing cement ring as a crucial barrier to maintaining the integrity of the wellbore and achieving effective interlayer sealing is subject to severe testing[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAs a commonly used cementitious material in cementing engineering, neat oil well cement systems experience significant strength declines when they are cured at temperatures above approximately 110\u003csup\u003eo\u003c/sup\u003eC[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], caused by the change of hydration products from amorphous C-S-H to high calcium crystalline hydration products. In order to prevent this crystallization, the prevailing industry practice is adding silica sand, with a proportion ranging from 30\u0026ndash;40%[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The fundamental principle underpinning this approach entails the reduction of the aggregate calcium-silica ratio within the system to a range of 0.8 to 1.0 to facilitate the transformation of cement hydration products into relatively good mechanical properties of tobermorite (C\u003csub\u003e5\u003c/sub\u003eS\u003csub\u003e6\u003c/sub\u003eH\u003csub\u003e5.5\u003c/sub\u003e) and xonotlite (C\u003csub\u003e6\u003c/sub\u003eS\u003csub\u003e6\u003c/sub\u003eH)[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], while when the temperature exceeds 150\u0026deg;C, this modified system with the simple addition of silica sand still suffers from strength retrogression[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], therefore, it is necessary to continue to optimize silica sand (including dosage, particle size, and crystallinity) to stop this strength retrogression, but the latest research indicated that the optimized silica-enriched oil well cement systems still experienced a severe strength decline due to microstructural coarsening caused by the crystallization of C-S-H into tobermorite and xonolite after long term cuing period under simulated high-temperature deep-well conditions at 200 \u003csup\u003eo\u003c/sup\u003eC and 50\u0026ndash;150 MPa[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\u003cp\u003ePractice has proved that the set temperature of cement paste has a very strong influence on the performance of set cement[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e], and the optimized silica-rich sand system is usually only suitable for thick oil hot recovery wells, but not for deep and ultra-deep wells[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. The fundamental distinction between the two cementing conditions is the different setting temperatures of cement paste, in thick oil hot recovery wells, a \"two-step\" setting method is employed, whereby the cement slurry is initially set at a low temperature (typically 80\u0026deg;C) and subsequently cured at a high temperature. In contrast, in deep and ultra-deep wells, a \u0026ldquo;one-step\u0026rdquo; molding technique is used, in which the cement paste is directly set and cured at high temperature and pressure conditions, and it required that the cement paste was in a fluid state before reaching the specified temperature. The two methods exerts a substantial influence on the high-temperature stability of silica-enriched oil well cement systems, but the specific mechanism is still unclear.\u003c/p\u003e\u003cp\u003eIn addition, recent studies have shown that the addition of a certain proportion of aluminum-containing mineral materials[\u003cspan additionalcitationids=\"CR17\" citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], such as fly ash, to silica-enriched oil well cement systems can effectively prevent the strength retrogression of set cement high temperature and pressure conditions, and the coal gangue powder, as a kind of industrial solid waste[\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e], has a similar composition to that of fly ash, and it should also have an anti- retrogression effect. In this study, based on SEM, XRD combined with Rietveld quantitative analysis, the influence mechanism of setting temperature on the compressive strength of silica-enriched oil well cement was investigated, and the influence of coal gangue powder on the strength stability of high-temperature deep-well set cement was also explored.\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"2. Materials and experimental methods2.1 Materials","content":"\u003cp\u003eThe raw materials used in this study mainly include Class G oil-well cement, silica sand, and coal gangue powder; their chemical compositions and particle size distributions are presented in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e and Tables \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e, respectively. The oxide composition of the cement was measured by X-Ray fluorescence (XRF) analysis and the particle size distribution was measured using a particle size1 analyzer (Mastersizer 2000). The free lime content in raw cement was determined according to GB/T 176 2017 China national standard.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"char\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eMain oxides of bulk materials used(%)\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOxide name\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eClass G\u003c/p\u003e\n \u003cp\u003ecement\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003esilica\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ecoal gangue powder\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n 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align=\"char\"\u003e\n \u003cp\u003e3.011\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMgO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.412\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.969\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNa\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.176\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.451\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSO\u003csub\u003e3\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.76\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.310\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.216\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eP\u003csub\u003e2\u003c/sub\u003eO\u003csub\u003e5\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.043\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.014\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.150\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.01\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e95.640\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e64.027\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFree Lime\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.360\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"char\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003cdiv align=\"char\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eSummary of material properties: particle size and specific gravity.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMaterial\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eD10\u003c/p\u003e\n \u003cp\u003e\u0026micro;m\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eD50\u003c/p\u003e\n \u003cp\u003e\u0026micro;m\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eD90\u003c/p\u003e\n \u003cp\u003e\u0026micro;m\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSpecific gravity\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ecoal gangue powder\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e9.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e29.48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003esilica\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e6.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e46.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e108.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eClass G cement\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1.93\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e42.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e2.2 Formulation design and slurry preparation\u003c/strong\u003eTable 2 presents the formulation design used in this study. All slurries were designed with a final density of 1.9 g/cm\u003csup\u003e3\u003c/sup\u003e. Slurry T1 was a low-temperature setting system, while slurries T2 to T4 were high-temperature setting systems (with thickening times all longer than the heating-up time of the curing autoclave). Specifically, both T1 and T2 had a silica sand content of 50% by weight of cement (BWOC). The main difference lies in that T1 does not contain high-temperature retarders to ensure rapid setting at low temperature (80\u0026deg;C), whereas T2 contains an adequate amount of high-temperature retarders, with its high-temperature thickening time exceeding 4 hours, which was longer than the heating-up time of the curing autoclave, meeting the requirements for high-temperature setting. The silica sand content in the slurry T3 reaches 110% BWOC, aiming to explore the stability of set cement under the condition of high silica sand content. In addition, the dosages for slurry T4 of silica and coal gangue powder were 30% and 60% BWOC, respectively. This was to investigate the effect of coal gangue powder on preventing strength retrogression of silica-enriched oil well cement systems. Except that the suspending agent and dispersant were solid powders, all other admixtures had a solid content of 80%, and all were supplied by Sinopec Petroleum Engineering Technology Research Institute Co., Ltd. It was noteworthy that studies have indicated under the specified ultra-high-temperature curing conditions (240\u0026deg;C), the hydration reaction of cement in hardened cement paste has been largely completed[16, \u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]. Consequently, the impact of chemical admixtures (e.g., retarders) on the thermal stability during long-term service (\u0026ge;\u0026thinsp;2 days) in ultra-high-temperature environments was practically negligible. The dosages for slurry T1 of suspending agent and defoamer were 1%,and 1% by weight of cement, respectively, and no other additives; the dosages for slurries T2, T3 and T4 of dispersant(USZ), retarder(SCR-4), retarder(SCR-7), fluid loss additive(240W), suspending agent and defoamer were 1%, 8%, 1.8%, 4% ,1%,and 1% BWOC. All cement slurries were prepared in strict accordance with API Recommended Practice 10B-2, then cast into square stainless-steel moulds measuring 5 cm \u0026times; 5 cm \u0026times; 5cm. The slurry T1 was first allowed to set and pre-cure at 80\u0026deg;C for 24 h prior to demoulding; the other slurries were set and pre-cured directly at 240\u0026deg;C and 20 MPa for the same duration to demoulding. After demoulding, all specimens were transferred to identical high-temperature curing conditions (240\u0026deg;C, 20 MPa) and maintained until the prescribed testing age was reached.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv align=\"left\" class=\"colspec\"\u003e\u003cbr\u003e\u003c/div\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eFormulation design of dry blend compositions and added water\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFormulation\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ecement\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003esilica\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ecoal gangue powder\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAdded water\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eT1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eT2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e46.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eT3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e110\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e66.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eT4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e"},{"header":"3 Test method","content":"\u003cp\u003eCompressive strength tests were performed using a TG-300B load frame from Shenyang Tiger Petroleum Instruments Manufacturing Co., Ltd. A field emission SEM by JEOL (Model JSM-IT500LV) was used to obtain microstructure images. XRD data were collected using a Panalytical diffractometer (Model Aeris with a 600W Cu-anode source, λ\u0026thinsp;=\u0026thinsp;1.541 \u0026Aring;) operated at 40 kV and 15 mA. All scans were measured over an angular range of 7\u0026ordm; to 70\u0026ordm; (2θ angle) with a 0.01\u0026deg; 2θ step size and scanning time per step of 75.22 s, resulting in a total measurement time of about 30min per scan.\u003c/p\u003e\u003cp\u003eRietveld refinement analysis was carried out using Highscore Plus 5.0 software with Crystallography Open Database (COD) to assess the quantities of main crystal phases as well as the amorphous phase. Similar to our previous study[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e], a single crystal silicon was ground into fine powders and used as an external standard. The following equation was used to calculate the phase content of a sample[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:{W}_{j}=\\frac{{S}_{j}{\\rho\\:}_{j}{V}_{j}^{2}}{{S}_{s}{\\rho\\:}_{s}{V}_{s}^{2}}{W}_{s}\\frac{{u}_{m}}{{u}_{s}}\\)\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e(1)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003ewhere W\u003csub\u003ej\u003c/sub\u003e is the weight fraction of phase j in the sample, \u0026#119878;\u003csub\u003ej\u003c/sub\u003e is the scale factor obtained in the Rietveld refinement for phase j, \u0026#120588;\u003csub\u003ej\u003c/sub\u003e is the unit cell density of phase j, V\u003csub\u003ej\u003c/sub\u003e designates the unit cell volume of phase j; similarly, \u0026#119878;\u003csub\u003es\u003c/sub\u003e, \u0026#120588;\u003csub\u003es\u003c/sub\u003e, and V\u003csub\u003eS\u003c/sub\u003e represent the corresponding parameters of the standard material; \u003cem\u003eW\u003c/em\u003e\u003csub\u003e\u003cem\u003eS\u003c/em\u003e\u003c/sub\u003e is the weight fraction of the standard phase in the external standard material (100% in our study); \u0026#120583;\u003csub\u003em\u003c/sub\u003e and \u0026#120583;\u003csub\u003es\u003c/sub\u003e are the mass absorption coefficients (MAC) of the sample and the standard material, respectively. The calculation of MAC was based on the oxide composition of solid components and water-cement ratio.\u003c/p\u003e"},{"header":"4. Test results and discussion","content":"\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003e4.1 Compressive strength\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e summarizes the compressive strength test results of cured slurries cured from 3d to 28d. The compressive strength of slurry T1 increased from 18.27 MPa to 31.10 MPa from 3 d to 28d curing time, suggesting that the low-temperature setting silica-enriched system had superior high-temperature stability in long curing period. In contrast, the compressive strength of slurry T2 decreased from 22.70 MPa to 16.15 MPa (28.8% decline), during the same curing period, suggesting that the traditional silica-enriched system experienced severe strength retrogression at the condition of high-temperature setting, consistent with our studies[\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]. The above observations indicated that the low-temperature setting system slurry T1 may possesses a superior microstructure and mineralogical assemblage over long curing period compared to slurry T2, which will be elaborated in the following sections. Furthermore, although slurry T3 exhibited a modest increase in 3-day compressive strength relative to slurry T2, its 28-day strength declined markedly, demonstrating that raising the silica sand dosage was insufficient to arrest strength retrogression under 240\u0026deg;C setting and curing conditions. Analogously, the slurry T4 incorporating both silica sand and coal gangue powder also suffered strength retrogression after 28 days curing period at 240\u0026deg;C. This observation contrasts with the widely reported inhibitory effect of Al-rich mineral admixtures on strength retrogression in traditional silica-enriched systems; coal gangue powder was, in fact, rich in such phases. The limited efficacy observed here was presumably attributable to variations in the structural state and speciation of Al-bearing constituents among different mineral sources, which in turn govern their anti-retrogression performance.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e4.2 SEM\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eBased on the scanning electron microscope (SEM) observation results as shown in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e and Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e, a systematic analysis of the microstructure evolution of different slurries (T1, T2, T3, T4) at different maintenance ages showed that the matrix microstructure of slurry T1 was significantly better than that at the age of 3 days after 28 days curing period. In contrast, the microstructures of slurries T2 and T3 showed obvious coarsening at the end of 28-day curing period, and the microstructural coarsening phenomenon of slurry T4 seemed to be more serious at the end of 28-day curing period, which indicated that increasing silica sand dosing and adding coal gangue powder cannot prevent the trend of microstructure coarsening of set cement under high-temperature setting and curing conditions; It was noteworthy that, at the conclusion of the 3-day curing period, slurry T2 exhibited a markedly finer microstructure than slurry T1; this may ascribe to the accelerated early-age hydration kinetics under elevated temperature that promoted a higher abundance of C-(A)-S-H, while a detailed analysis of Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e showed that a large amount of xonotlite was observed in slurry T1 cured from 3d to 28d, but the tobermorite was difficult to observe; whereas, a large amount of C-(A)-S-H gel can be observed in slurry T2 at the early stage (3 days), and loose stacking of xonotlite can be observed after 28 days of curing period. The slurries T3 and T2 behaved similarly. The above results indicated that, on the one hand, the low-temperature 80\u0026deg;C setting may have accelerated the transformation of C-(A)-S-H gel directly to xonotlite, although xonotlite can have adverse effects on the strength of set cement, the mineral structure was relatively stable under this temperature condition and would not undergo mineral transformation again, whereas, although the high-temperature setting may promote the generation of large amounts of C-(A)-S-H gel in early stage of set cement, early C-(A)-S-H gel would continue to crystallize into xonotlite, thus the microstructure was coarsened seriously, producing strength decline. In addition, a large amount of tobermorite can be observed in the early stage of slurry T4, while a large amount of xonotlite was observed after 28 days of curing period, seemed to be accompanied by the gradual transformation of tobermorite to xonotlite, which may be one of the main reason for its strength decline. More detailed analysis will be discussed in the XRD section.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n \u003ch2\u003e4.3 XRD\u003c/h2\u003e\n \u003cp\u003eXRD was used to identify the mineral compositions of set cement. It can be seen from Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e that the main hydration products of silica-enriched oil well cement systems (slurries T1 to T3) mainly included semi-crystalline C-S-H (reflected by broadened peaks ranging from 28.5\u0026ordm; to 30.5\u0026ordm;), tobermorite and xonotlite. The peak profile of semi-crystalline C-S-H remains relatively stable cured from 3d to 28d, and the peak hight of xonotlite observed in slurry T1 was higher than these in slurries T2 and T3, indicated that the low setting temperature did not change the type of crystal hydration products but promoted to generate more xonotlite, consistent with SEM observations. The recent study demonstrated that the generation of xonotlite typically compromised the compressive strength of set cement. However, slurry T1 exhibited significantly higher compressive strength compared to slurry T2 after 28d curing period, which may be due to the different content and structure of C-(A)-S-H formed under two temperature setting conditions. A closer observation revealed that the semicrystalline C-A-S-H peak morphology in slurry T1 appeared to be more stable, while the C-A-S-H morphology in slurry T2 exhibited a sharpening after 28 days of curing; the sharpening degree of C-A-S-H morphology in slurry T3 underwent a slight reduction due to the augmented dosage of silica sand. This phenomenon was identified as the primary cause of observed decline in compressive strength setting and curing under high temperature conditions.\u003c/p\u003e\n \u003cp\u003eFurthermore, the addition of coal gangue powder changed the hydration product of silica-enriched oil well cement systems to include alumina-bearing phase grossular and possibly some new semi-crystalline phases (including C-A-S-H) as reflected by broadened peaks ranging from 28.5\u0026ordm; to 33.5\u0026ordm;, consistent with our studies[\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e], but the morphological of this new semi-crystalline phases (including C-A-S-H) seemed to be different in that of silica-enriched oil well cement systems modified by fly ash, and exhibited a sharpening after 28 days of curing, indicated the structure of these two new semi-crystalline phases(including C-A-S-H) were different, which may be the reason why coal gangue powder was ineffective over fly ash.\u003c/p\u003e\n \u003cp\u003eIn order to further explore the working mechanism, quantitative analysis of mineral composition was conducted. The refined phase contents of selected systems were presented in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e. Refinement results of the diffractograms were presented in the Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e to Fig. \u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e. The quantitative results were consistent with the patterns shown in the XRD spectra. The content of crystalline phases in slurry T1 remains basically stable during the 28-day curing process, while the amorphous phase representing C-(A)-S-H increased with time, which was the primary reason for the sustained strength Another obvious feature was that, the content of xonotlite in T1 was significantly higher than that in slurries T2 and T3, while the content of tobermorite was little, indicated that under low-temperature setting and high-temperature curing conditions, the C-(A)-S-H crystaled mainly formed more stable xonotlite, avoiding the transformation process from tobermorite to xonotlite. Although the increase in xonotlite was unfavorable to the strength of set cement, but its structural was stable at this temperature, which was another key factor enabling slurry T1 to maintain its strength more effectively than slurries T2 and T3. In addition, although the content of C-(A)-S-H and xonotlite in slurry T1 was the same as that of slurry T2 after 28 days of curing, the compressive strength of slurry T1 was significantly higher than that of slurry T2, indicated that the structure of C-(A)-S-H contained in the two may be different.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eThe strength retrogression mechanisms of different silica-enriched cementing systems cured at 240℃/20MPa were studied experimentally. The following main conclusions can be drawn:\u003c/p\u003e\n\u003cp\u003e(1) The compressive strength of low-temperature setting slurry increased with increasing curing time, while the\u0026nbsp;compressive strength of all slurries setting at high-temperature decreased by 21.2% to 28.8% from 3 d to 28 d, indicated that the setting temperature had big influence on the stability of mechanical properties; increasing the dosage of silica and the addition of coal gangue powder cannot prevent this strength retrogression.\u003c/p\u003e\n\u003cp\u003e(2) The microstructure of low-temperature setting slurry coarsened seriously at early 3d, but get more dense after 28d curing period; in contrast, the microstructures of set cement setting at high temperature showed a completely opposite trend of change and changed from be dense to be coarsening from 3 d to 28 d; a large amount of xonotlite was observed in low-temperature setting slurry at early stage (3 days) but no tobermorite was observed, possibly indicated the C-(A)-S-H in low-temperature setting system directly crystallization to xonotlite at early stage, avoiding the transformation of tobermorite into xonotlite.\u003c/p\u003e\n\u003cp skip=\"true\"\u003e(3) The low-temperature setting cement slurry directly generated more xonotlite but no tobermorite at early stage, and the content of crystalline phases remains basically stable during the 28-day curing process; the amorphous phase representing C-(A)-S-H increased with time, which may explain its stable compressive strength, while other slurries showed varing degrees conversion of amorphous C-(A)-S-H to xonotlite and tobermorite during curing, which were possibly the cause of strength retrogression of these systems. \u003c/p\u003e\n\u003cp skip=\"true\"\u003e(4) Gangue powder could not prevent the strength decline of cementite under high temperature molding conditions, probably due to the type of aluminum-containing components.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eDeclaration of interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003eThe authors declare the following financial interests/personal relationships which may be considered as potential competing interests:\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eJ.Qin, X. Pang, Y. Bu, et al., Research advances in oil well cement subjected to high temperature and high pressure curing environment, Journal of Oil and Gas Technology, 42 (2020) 13-23.\u003c/li\u003e\n \u003cli\u003eZ. Dang, X. Chen, X. Yao, Z. Xu, M. Zhou, W. Yang, X. Song, Wellbore temperature prediction model and influence law of ultra-deep wells in Shunbei field, China, Processes, 12 (2024) 1715.\u003c/li\u003e\n \u003cli\u003eJ. Peng, C. Deng, F. Wei, S. Ding, R. Hu, X. Luo, A hybrid thermal management system combining liquid cooling and phase change material for downhole electronics, Journal of Energy Storage, 72 (2023) 108610.\u003c/li\u003e\n \u003cli\u003eX. Pang, J. Qin, L. Sun, G. Zhang, H. Wang, Long-term strength retrogression of silica-enriched oil well cement: A comprehensive multi-approach analysis, Cement Concrete Research, 144 (2021) 106424.\u003c/li\u003e\n \u003cli\u003eJ. Qin, X. Pang, G. Cheng, Y. Bu, H. Liu, Influences of different admixtures on the properties of oil well cement systems at HPHT conditions, Cement and Concrete Composites, 123 (2021) 104202.\u003c/li\u003e\n \u003cli\u003eK.J. Krakowiak, J.J. Thomas, S. Musso, S. James, A.-T. Akono, F.-J. Ulm, Nano-chemo-mechanical signature of conventional oil-well cement systems: Effects of elevated temperature and curing time, Cement and concrete research, 67 (2015) 103-121.\u003c/li\u003e\n \u003cli\u003eM. Swayze, Effects of High Pressures and Temperatures on Strength of Oil-Well Cements, Drilling and Production Practice, (1954) 72.\u003c/li\u003e\n \u003cli\u003eR.B. Pernites, A.K. Santra, Portland cement solutions for ultra-high temperature wellbore applications, Cement and Concrete Composites, 72 (2016) 89-103.\u003c/li\u003e\n \u003cli\u003eK.J. Krakowiak, J.J. Thomas, S. James, M. Abuhaikal, F.-J. Ulm, Development of silica-enriched cement-based materials with improved aging resistance for application in high-temperature environments, Cement Concrete Research, 105 (2018) 91-110.\u003c/li\u003e\n \u003cli\u003eB. Reddy, J. Zhang, M. Ellis, Cement Strength Retrogression Issues in Offshore Deep Water Applications-Do We Know Enough for Safe Cementing?, Offshore Technology Conference, OnePetro, 2016.\u003c/li\u003e\n \u003cli\u003eJ. Qin, X. Pang, A. Santra, G. Cheng, H. Li, Various admixtures to mitigate the long-term strength retrogression of Portland cement cured under high pressure and high temperature conditions, Journal of Rock Mechanics and Geotechnical Engineering, (2022).\u003c/li\u003e\n \u003cli\u003eL. Sun, X. Pang, S. Ghabezloo, H. Wang, J. Sun, Hydration kinetics and strength retrogression mechanism of silica-cement systems in the temperature range of 110\u0026deg; C\u0026ndash;200\u0026deg; C, Cement Concrete Research, 167 (2023) 107120.\u003c/li\u003e\n \u003cli\u003eF.Lu, F.Li, N. Tian, etc, Composite sand added high-temperature resistant and anti-aging cement slurry system [J]. Drilling fluid and completion fluid, 34.4(2017):5.\u003c/li\u003e\n \u003cli\u003eZ.Zhang, Z.Qi, Q. Feng, etc Indoor study on latex cement under high temperature [J]. Drilling and completion fluids, 2013, 30 (6): 3\u003c/li\u003e\n \u003cli\u003eH. Liu, Y. Bu, A. Zhou, J. Du, L. Zhou, X. Pang, Silica sand enhanced cement mortar for cementing steam injection well up to 380\u0026deg; C, Construction and Building Materials, 308 (2021) 125142.\u003c/li\u003e\n \u003cli\u003eG.-D. Cheng, X.-Y. Pang, J.-S. Sun, Z.-S. Qiu, C.-C. Wang, J.-K. Qin, N. Li, Combined use of fly ash and silica to prevent the long-term strength retrogression of oil well cement set and cured at HPHT conditions, Petroleum Science, 21 (2024) 1122-1134.\u003c/li\u003e\n \u003cli\u003eG. Cheng, X. Pang, Z. Qiu, J. Qin, N. Li, Well Cement Composition Optimization for Deep Well Applications, ISRM Congress, ISRM, 2023, pp. ISRM-15CONGRESS-2023-2358.\u003c/li\u003e\n \u003cli\u003eG. Cheng, X. Pang, H. Wang, J. Sun, Z. Qiu, Anti-strength retrogression cementing materials for deep and ultra-deep wells, Construction Building Materials, 411 (2024) 134407.\u003c/li\u003e\n \u003cli\u003eD. Wu, T. Chen, D. Hou, X. Zhang, M. Wang, X. Wang, Utilization of coal gangue powder to improve the sustainability of ultra-high performance concrete, Construction Building Materials, 385 (2023) 131482.\u003c/li\u003e\n \u003cli\u003eM. Murtaza, J. Zhang, C. Yang, X. Cui, C. Su, A.N. Ramadan, Performance analysis of self compacting concrete by incorporating fly ash, coal gangue powder, cement kiln dust and recycled concrete powder by absolute volume method, Construction Building Materials, 431 (2024) 136601.\u003c/li\u003e\n \u003cli\u003eC. Wu, W. Jiang, C. Zhang, J. Li, S. Wu, X. Wang, Y. Xu, W. Wang, M. Feng, Preparation of solid-waste-based pervious concrete for pavement: A two-stage utilization approach of coal gangue, Construction Building Materials, 319 (2022) 125962.\u003c/li\u003e\n \u003cli\u003eK. Scrivener, R. Snellings, B. Lothenbach, A practical guide to microstructural analysis of cementitious materials, Crc Press Boca Raton, FL, USA:2016.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"chemical-papers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"chpa","sideBox":"Learn more about [Chemical Papers](http://link.springer.com/journal/11696)","snPcode":"11696","submissionUrl":"https://www.editorialmanager.com/CHPA/default.aspx","title":"Chemical Papers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"silica-enriched oil well cement, strength retrogression, set temperature, high temperature, Quantitative X-ray diffraction (QXRD)","lastPublishedDoi":"10.21203/rs.3.rs-7415053/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7415053/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe long-term strength retrogression of silica-enriched oil well cement poses a significant threat to wellbore integrity in deep and ultra-deep wells. This study tested the performance evolution of silica-rich cement under two setting temperatures (80\u0026deg;C and 240\u0026deg;C) followed by 240\u0026deg;C/20 MPa curing. Results indicated that 80\u0026deg;C-set cement exhibited strength growth during curing, whereas 240\u0026deg;C-set cement suffered strength decline over 28 days; increasing the dosage of silica sand and adding coal gangue powder both cannot prevent this decline trend. SEM combined with XRD quantitative analysis revealed that, the content of C-(A)-S-H of set cement at low-temperature setting increased cured from 3d to 28d and it directly generated more xonotlite at 3d early stage, although this mineral phase was unfavorable relative to the compressive strength of set cement, it was structurally stable at this temperature, which was the reason for its stable strength, in contrast, the C-(A)-S-H of set cement at high-temperature setting decreased cured from 3d to 28d and the content of xonotlite continued to increase during the long-term curing process, resulting in the coarsening of the microstructure and retrogression in strength; this difference may be due to the different structure of C-(A)-S-H under the two setting temperatures; in addition, increasing the dosage of silica sand and adding coal gangue powder both cannot prevent the above-mentioned structural and compositional changes of set cement. The results of above microanalysis can explain all systems compressive strength.\u003c/p\u003e","manuscriptTitle":"Strength Retrogression Mechanisms of Silica-Enriched Oil Well Cement under 240°C Curing Conditions","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-05 14:40:53","doi":"10.21203/rs.3.rs-7415053/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Minor revisions","date":"2025-10-09T04:07:57+00:00","index":"","fulltext":""},{"type":"reviewerAgreed","content":"","date":"2025-09-15T12:18:45+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-29T09:33:29+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Chemical Papers","date":"2025-08-26T05:26:51+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-26T04:07:31+00:00","index":"","fulltext":""},{"type":"submitted","content":"Chemical Papers","date":"2025-08-24T23:29:23+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"chemical-papers","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"chpa","sideBox":"Learn more about [Chemical Papers](http://link.springer.com/journal/11696)","snPcode":"11696","submissionUrl":"https://www.editorialmanager.com/CHPA/default.aspx","title":"Chemical Papers","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"8cd1aac5-bd97-4623-ab67-44cc2d96dca6","owner":[],"postedDate":"September 5th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-11-24T16:04:52+00:00","versionOfRecord":{"articleIdentity":"rs-7415053","link":"https://doi.org/10.1007/s11696-025-04478-7","journal":{"identity":"chemical-papers","isVorOnly":false,"title":"Chemical Papers"},"publishedOn":"2025-11-19 15:59:03","publishedOnDateReadable":"November 19th, 2025"},"versionCreatedAt":"2025-09-05 14:40:53","video":"","vorDoi":"10.1007/s11696-025-04478-7","vorDoiUrl":"https://doi.org/10.1007/s11696-025-04478-7","workflowStages":[]},"version":"v1","identity":"rs-7415053","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7415053","identity":"rs-7415053","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}