Investigating the Performance of Cassava-Based Starches as Viscosifiers on Class-G Cement Slurry for Oil-Well Cementing Operations

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Ipinsokan, Rachael O. Nkatta, Humphrey Dike, Peter O. Ojegbile, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7694400/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 Cementing technology has evolved significantly over time as one of the most critical completion tasks in the petroleum industry. Viscosity is pivotal in slurry formulation, impacting pumpability, thickening time, and overall slurry behaviour. Therefore, viscosifiers are always incorporated to modify slurry viscosity to achieve ultimate performance under varying downhole conditions. However, environmental concerns and the high costs of synthetic viscosifiers have driven interest in natural, organic alternatives. This study evaluates cassava starch, a locally sourced and renewable biopolymer, as a viscosifier in Class-G cement slurries. Cassava starch was extracted, processed into powder, and incorporated into cement formulations at concentrations of 0.1–0.4% BWOC. Rheological properties, gel strength, thickening time, compressive strength, free fluid, and pH stability were assessed following API standards and benchmarked against a synthetic viscosifier. Results showed that cassava starch enhanced plastic viscosity and yield point, with shear stress values of 105–127 lbf/100 ft² at 300 rpm, providing more stable flow behaviour after conditioning compared to synthetic starches. Thickening time was extended to 107 minutes, offering longer pumpability windows essential for deep and complex wells. Compressive strength exceeded 2600 psi at 24 hours, confirming that cassava starch did not hinder hydration. Free fluid values (0.36–1.2 ml) remained within API limits, though slightly higher than synthetic controls. The pH decreased from 6.3 to 5.8 over three days, confirming biodegradability. The findings demonstrate that cassava starch is an effective and environmentally friendly alternative to synthetic viscosifiers, offering enhanced thickening time, comparable compressive strength, and rheological stability. Cassava starch cement slurry compressive strength green additives thickening time rheology test viscosifier 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 Cementing plays a critical role in ensuring the structural integrity and zonal isolation of oil and gas wells, as shown in Fig. 1 . It involves the placement of cement slurry between the casing and the borehole wall to form a seal that prevents fluid migration between formations. Correct cementing increases the mechanical stability of the casing string and gives the well long term survival. This operation greatly relies on the properties of cement slurry. Some of the most important parameters in slurry design include rheological behaviour, time to thicken, gel strength, fluid loss and compressive strength. Additives are usually added in order to alter these properties and provide optimal performance in the downhill conditions. The main additives that are used to reach a higher slurry rheology include viscosifiers, in order to achieve the suspension of the particles and to transport the fluid uniformly. Rheological modifications which have seen the wide usage of conventional viscosifiers include hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), and other synthetic polymers. Nevertheless, these substances tend to be imported, expensive and harmful to the environment causing concern about the long-term environmental effects and sustainability of operations. This paper was developed in response to these concerns, hence the emphasis on cassava starch as an alternative viscosifier. Cassava (Manihot esculenta) is a widely-grown crop in Nigeria, and some other countries in the tropics (Abegunde et al., 2024 ; Ojewumi et al., 2021 ) The starch component of cassava is biodegradable, locally available, and affordable. Although it has been investigated in the case of drilling muds, its full capacity in the use of cement slurry has not been reviewed. This work investigates the effectiveness of cassava starch as a viscosifier on Class-G cement slurry, analysing its impact on slurry rheology, thickening time, gel strength, compressive strength, pH behaviour, and free fluid content compared to synthetic starch. The goal is to provide a sustainable, affordable, and eco-friendly solution for cement slurry enhancement in oilfield operations. Several researchers have explored the use of starch-based materials in drilling and cementing operations. Some researchers (Adebayo et al., 2021 ; Adewumi et al., 2024 ; Afolalu et al., 2021 ; Amadi et al., 2021 ) investigated five local cassava starch samples in water-based drilling fluids (Okoro et al., 2025 ). Their findings revealed that starches with higher amylose content had greater viscosity and reduced fluid loss. The influence of starches on concrete properties was examined, a 4.9% increase in compressive strength when cassava starch was used. Their study concluded that natural starches not only enhance strength but also improve early-age performance, making them viable for rapid-strength development scenarios (Okon et al., 2020 ; Sybis & Konował, 2022 ; Usman et al., 2024 ). Amadi et al. ( 2021 ) conducted a comparative evaluation of cassava starch, hydroxyethyl cellulose, and bentonite in drilling fluids. Although hydroxyethyl cellulose outperformed others, cassava starch showed promising rheological behaviour. The authors suggested that cassava cultivars with higher amylose content could yield better results, identifying the cassava variety as a potential gap. Cassava starch is primarily composed of two polysaccharides: amylose (Fig. 2 ) (linear α-1,4-linked glucose units) and amylopectin (highly branched α-1,6-linked glucose chains) (Mohsin et al., 2025 ). The ratio of amylose to amylopectin determines swelling, solubility, and gelatinisation behaviour, which in turn influence the viscosity of aqueous dispersions and cement slurries. The hydroxyl groups along the polymer chains impart hydrogen bonding capacity, allowing starch molecules to interact with water molecules and hydration products of cement. This hydrogen bonding is central to its role as a viscosifier and fluid-loss reducer (Amadi et al., 2021 ). In cement slurries, cassava starch undergoes partial gelatinisation when exposed to elevated temperatures, resulting in an increase in slurry viscosity and enhanced water retention. Gelatinisation temperature for native cassava starch typically falls within 60–70°C, which overlaps with common oil-well cementing conditions (Konował & Sybis, 2024 ; Sybis et al., 2022 ; Sybis & Konował, 2022 ). One concern with using organic polymers in cement systems is the potential compromise of compressive strength. However, studies have shown that cassava starch-modified slurries achieve compressive strengths comparable to those obtained with synthetic viscosifiers after 24 hours of curing (Sybis & Konował, 2022 ). The presence of starch does not significantly interfere with the hydration of tricalcium silicate (C₃S) or dicalcium silicate (C₂S), the main strength-developing phases in cement. Instead, it contributes to improved slurry homogeneity, which supports long-term mechanical stability. Modified starches, such as acetylated or crosslinked derivatives, can extend thermal stability up to 120–150°C, making them more suitable for HPHT wells (Liu et al., 2025 ; Zhou et al., 2025 ). The anionic character of some modified starches also contributes to electrostatic interactions with calcium ions (Ca²⁺) in the cement pore solution, slowing down hydration reactions (Opeyemi, 2019 ). This effect is reflected in extended thickening time, which is desirable in deep well cementing to allow longer pumpability windows (Sybis & Konował, 2022 ). Furthermore, the hydrophilic functional groups on starch chains facilitate adsorption on cement particles, creating a polymer layer that enhances dispersion, prevents premature settling, and stabilises slurry rheology ( Liu et al., 2025 ). Vasiliou et al. (2022) focused on starch ethers in cementitious systems and reported their effectiveness in modifying rheology and minimising segregation. Their work emphasised the importance of starch molecular structure and processing method in determining performance. Cassava starch and its derivatives also act as fluid-loss agents by forming a semi-permeable filter cake on slurry surfaces, reducing filtrate invasion into the formation. This can be compared to the drilling fluids mechanism wherein starch polymers seal the throats of the pores and keep the wellbores stable (Zhou et al., 2025 ). t is experimentally established that viscosifiers made of starch can hold water well, but small amounts of free water can be observed when compared to synthetic ones (Sulaimon et al., 2020 ). Alterations, including grafting with inorganic diatomites or the addition of polyphenols, enhance resistance to filtration in HPHT (Liu et al., 2025 ). All these findings attest to the fact that cassava starch is an effective natural polymer with rheological as well as structural modification properties. Nevertheless, its full-scale performance with oilfield cementing conditions was not tested by most. This study fills this gap by comparing the starch of cassava to synthetic viscosifiers at high pressure and high temperature (HPHT) and determining real-time compressive strength, gel strength, and thickening time. 2. Materials And Methodology 2.1 Materials The materials employed in this study were cassava starch, synthetic starch viscosifier, Class G cement, and distilled water. Cassava starch was extracted from locally sourced cassava tubers and subsequently processed for use as a natural viscosifier. An industrial-based synthetic viscosifier was procured for comparison. Class G cement, commonly used in oil-well cementing due to its suitability for high-pressure, high-temperature (HPHT) conditions, was selected as the base cementing material. Distilled water served as the mixing medium for slurry preparation. 2.2 Preparation of Cassava Starch Fresh cassava tubers were selected, peeled, and thoroughly washed to remove surface impurities. The cleaned tubers were then grated into a fine pulp and soaked in water to facilitate starch extraction. The suspension obtained was filtered through a muslin cloth to separate fibrous materials from the starch-rich filtrate. The filtrate was allowed to settle under gravity, after which the sedimented starch was carefully collected. The starch was initially sun-dried and subsequently oven-dried at 70°C to ensure the removal of residual moisture. The dried product was sieved through a standard mesh to achieve a uniform particle size before use in cement slurry preparation. 2.3 Slurry Formulation Cement slurries were formulated using Class G oilwell cement and water at a water-to-cement (w/c) ratio of 0.44. Cassava starch and synthetic starch viscosifiers were incorporated into the slurry at a concentration of 0.1% by weight of cement (BWOC). Mixing was carried out in accordance with the API Recommended Practice 10B procedure using a high-speed blender to ensure homogeneity. The prepared slurries were subjected to a series of standard performance evaluations as described below, while the formulation of the slurry samples is summarised in Table 1 according to the best practices in the industry: Rheology: The rheological behaviour of the slurries was determined using a rotational viscometer. Viscosity readings were taken at 600 rpm and 300 rpm, from which the plastic viscosity (PV) and yield point (YP) were calculated. Thickening Time: Thickening time was assessed with a high-temperature high-pressure (HTHP) consistometer. The slurry was exposed to elevated temperatures of up to 100°C and pressurised conditions to monitor gel development and setting characteristics. Compressive Strength: Uniaxial compressive strength tests were performed on cured cement samples using a destructive compressive strength testing machine. Measurements were taken after 12 and 24 hours of curing at ambient temperature. Free Fluid Test: Free fluid separation was evaluated by allowing slurry samples to remain undisturbed in a graduated cylinder for 2 hours, after which the volume of separated fluid was recorded. pH Analysis: The pH of cassava starch solutions was monitored over a period of three days to assess both biodegradability and chemical stability under aqueous conditions. Table 1 Formulation of cement slurries with organic starch and synthetic viscosifiers S/N Composition S (Neat Slurry) O1 O2 O3 O4 S1 S2 S3 S4 1 Cement (g) 781.67 781.79 781.92 782.05 782.17 781.16 780.66 780.15 779.65 2 Water (g) 348.09 327.18 346.27 346.36 344.45 341.32 334.56 327.81 321.07 3 Antifoam (g) 6.94 6.94 6.94 6.94 6.94 6.93 6.93 6.92 6.92 4 Organic starch (gal/sk) – 0.1 0.2 0.3 0.4 – – – – 5 Synthetic viscosifier (% BWOC) – – – – – 0.1 0.2 0.3 0.4 Note that S represents the neat cement slurry without viscosifiers. NU as unconditioned slurry and NC as conditioned slurry. O1–O4 are slurries formulated with organic cassava starch viscosifiers at concentrations of 0.1, 0.2, 0.3, and 0.4 gal/sk, respectively. S1–S4 are slurries prepared with synthetic viscosifiers at 0.1, 0.2, 0.3, and 0.4% BWOC, respectively. All slurries were prepared with Class G cement, distilled water, and a constant amount of antifoam additive. The unconditioned organic samples are labelled as OU1-OU4, unconditioned synthetic samples are SU1-SU4, conditioned organic samples are OC1-OC4 and conditioned synthetic samples are SC1-SC4. 3. Results And Discussion 3.1 FTIR Test Result Analysis The FTIR spectrum of the analysed sample is presented in Fig. 3 . The major absorption peaks were identified and assigned to corresponding functional groups. From the spectrum, the cassava starch is confirmed to contain Hydroxyl groups (–OH), Alkane groups (–CH₂, –CH₃), Carbonyl groups (C = O), Glycosidic linkages (C–O–C) and Polysaccharide rings (pyranose structures) which aligns with the findings by Adewumi et al., ( 2024 ). These chemical groups are directly responsible for its ability to act as a green viscosifier in cement slurry, which improves rheology, extends thickening time, supports compressive strength, and offers biodegradability compared to synthetic additives. 3.2 Rheological Properties The addition of cassava starch improved the plastic viscosity (PV) and yield point (YP) of the cement slurry compared to the neat sample. At 300 rpm, cassava starch-modified slurries exhibited shear stress values ranging from 105–127 lbf/100 ft², while synthetic starches recorded higher values (109–210 lbf/100 ft²). Although the peak viscosities of synthetics were greater, cassava starch displayed more stable rheological behaviour after conditioning (Fig. 4 , Fig. 5 and Fig. 6 ). Stable viscosity is vital in cementing since it ensures suspension of solids and uniform placement, particularly in deviated wells where gravitational settling is pronounced (Amadi et al., 2021 ). Similar observations were reported by Koko et al., (2022), who noted that biopolymer-based additives maintained more consistent viscosity under dynamic conditions compared to synthetic polymers. The practical implication of this behaviour is significant: in real field applications, erratic viscosity leads to poor solids suspension, higher energy requirements for pumping, and uneven slurry placement. Cassava starch, by maintaining steady viscosity, ensures continuous suspension of cement particles and additives, particularly under turbulent flow in deviated or horizontal wells. Its performance highlights a shear-thinning behaviour, meaning viscosity decreases with higher shear rates, which is desirable in cementing, that is, easy to pump at high rates but stable enough to suspend solids when circulation slows. This aligns with the general theory of natural polysaccharides (e.g., amylose and amylopectin in cassava starch), forming hydrogen-bonded networks that provide controlled viscosity. By contrast, synthetic polymers often exhibit sharper shear-thinning curves, which, while boosting peak values, may cause instability under changing shear conditions. Gel strength evaluation (Fig. 6 ) revealed that cassava starch-modified slurries developed moderate values, which effectively suspended solids during static periods without causing high restart pressures. Synthetic starches, by contrast, produced higher gel strength, which, though beneficial for suspension, risked excessive pump pressures during re-circulation. This balance offered by cassava starch aligns with findings by Sulaimon et al., ( 2020 ), who emphasised that moderate gel strength enhances operational safety by minimising surge pressures in HPHT wells. Cassava starch offers a balanced mechanism: the amylose fraction promotes controlled structuring of the slurry, giving enough suspension capacity to prevent sedimentation, while the amylopectin chains limit over-structuring. This ensures easy restart of pumping operations after static periods, which is critical during well-control events or operational pauses. Thus, cassava starch not only provides stability during shutdowns but also reduces risks associated with excessive surge pressures, which is a safety advantage in HPHT and deviated well cementing. 3.3 Thickening Time Analysis Thickening time results demonstrated that cassava starch extended the pumpability window to 107 minutes at 100 BC compared to 94 minutes for synthetic starch (Fig. 7 ). Longer setting times are advantageous in deepwater and extended-reach wells where unexpected delays are frequent. Previous research by Okon et al., ( 2020 ) indicated that natural starch derivatives provide delayed hydration effects, thereby prolonging thickening time without compromising final strength development. Chemically, this effect is attributed to the slower hydration kinetics of cassava starch molecules, which delay the setting of cement particles. The presence of carbonyl groups allows interaction with calcium ions in cement, delaying hydration and extending thickening time. The polysaccharide chains absorb water and form a protective coating around cement grains, thereby retarding hydration reactions without completely inhibiting them. This results in a controlled delay in gelation while still ensuring strong final compressive strength. The field implication is clear: cassava starch reduces the likelihood of premature setting during pumping, improving placement reliability. However, the delay is not excessive, meaning operational efficiency is preserved. 3.5 Compressive Strength Performance Cassava starch-modified cement slurries exceeded 500 psi at 12 hours and attained more than 2600 psi at 24 hours (Fig. 8 and Fig. 9 ). This demonstrates that cassava starch does not interfere with cement hydration but supports robust strength development. Comparable findings were reported by Adewumi et al., ( 2024 ) and Oni et al., ( 2020 ) who confirmed that biopolymer viscosifiers facilitated adequate hydration and early strength gain, often matching or surpassing the performance of synthetics. Such strength levels satisfy API minimum requirements for well integrity, confirming cassava starch as a reliable additive. Mechanistically, cassava starch interacts with the hydration products of tricalcium silicate (C₃S) and dicalcium silicate (C₂S), influencing the growth of calcium silicate hydrate (C–S–H) gels. The polysaccharide backbone stabilises water distribution, ensuring uniform hydration and good strength development. Instead of obstructing hydration, the starch molecules help to control water distribution, preventing rapid consumption and micro-cracking. From a well integrity perspective, the results confirm that cassava starch ensures reliable zonal isolation by maintaining early strength development (> 500 psi within 12 hours meets API standards) and long-term durability. This balance of delayed thickening and robust strength gain is often difficult to achieve with synthetic viscosifiers, which sometimes sacrifice one for the other. 3.6 Free Fluid Content Cassava starch-modified slurries exhibited free fluid values between 0.36–1.2 ml, slightly higher than the near-zero values of synthetics (Fig. 10 ). Although this may appear as a limitation, it remains within API standards (< 1.5 ml) and can be corrected with minor formulation adjustments. Studies by Amadi et al., ( 2021 ) have shown that biopolymer-based additives often require optimisation with secondary dispersants to further minimise free fluid, highlighting opportunities for blended formulations. In practice, small volumes of free fluid may lead to micro-channelling, which affects zonal isolation. However, this limitation can be addressed through formulation adjustments, such as blending cassava starch with minor amounts of dispersants or fluid-loss additives. Importantly, the fact that cassava starch alone keeps free fluid within API standards demonstrates its baseline effectiveness. 3.7 pH Behaviour and Biodegradability The pH of cassava starch solutions decreased from 6.3 on Day 1 to 5.83 by Day 3 due to microbial activity (Fig. 11 ). This indicates natural biodegradability, which presents environmental advantages in terms of disposal and ecological safety. Hydroxyl-rich polysaccharide structure is susceptible to microbial attack, explaining the observed pH drop during the biodegradability test. In contrast, synthetic starches exhibited stable pH values, reflecting non-biodegradability and possible long-term ecological risks. Similar biodegradation patterns of natural starches have been documented by Oni et al., ( 2020 ), who noted that such behaviour enhances sustainability without compromising slurry performance. On the other hand, microbial degradation could limit its shelf life or affect slurry stability during extended storage. Synthetic viscosifiers, by maintaining static pH values, resist biodegradation but pose challenges for waste management and environmental compliance. With increasing regulatory pressure on oilfield chemicals, cassava starch’s biodegradability becomes a competitive advantage, aligning with sustainability goals in the petroleum industry. From a mechanistic perspective, the pH decline reflects fermentation of starch molecules by microorganisms, releasing organic acids that lower alkalinity. While this does not hinder slurry performance in the short term, it confirms cassava starch as a green additive that minimises long-term environmental risks. 4. Conclusion This study has demonstrated that cassava starch is a viable and sustainable alternative to conventional synthetic viscosifiers in Class-G cement slurries for oil-well cementing operations. The results revealed that cassava starch improved the rheological properties of the slurry, providing stable viscosity behaviour even after conditioning. This stability ensures effective suspension of solids and uniform placement, particularly in deviated wells where gravitational settling is a challenge. Importantly, cassava starch also extended the thickening time of the slurry, offering a wider operational window that is advantageous for deep and complex well completions. The compressive strength performance further confirmed that cassava starch does not interfere with cement hydration, achieving strengths above 2600 psi after 24 hours, comparable to those obtained with synthetic viscosifiers. Although the cassava starch-modified samples exhibited slightly higher free fluid values, these remained within API permissible limits and can be optimised with minor formulation adjustments. In addition, the observed pH decline over time highlights the biodegradable nature of cassava starch, underscoring its environmental compatibility and positioning it as a green alternative for cementing applications. Overall, the findings confirm that cassava starch combines operational reliability, cost-effectiveness, and environmental sustainability, making it a promising additive for oil-well cementing in regions seeking locally available, eco-friendly solutions. Field trials should be conducted to validate the lab findings and establish confidence in cassava starch application under real wellbore conditions. Declarations Declaration of Competing Interest Authors have no conflicts of interest to disclose. Funding Declarations This research received no external funding. Ethics declaration Not applicable. Acknowledgements Many thanks to Covenant University for creating a conducive environment for research and paying the fee for the publication. Data availability The data that supports the findings of this study are available from the corresponding author upon request References Abegunde, I. O., Efekemo, O. P., Onile-ere, O., Otitolaye, F., Idehen, E. O., & Eni, A. O. (2024). Datasets on agromorphological characters and distribution of cassava (Manihot esculenta L.) accessions cultivated in South-West and North-Central regions of Nigeria. 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The Open Construction and Building Technology Journal , 13 (1), 331–343. https://doi.org/10.2174/1874836801913010331 Oni, D., Mwero, J., & Kabubo, C. (2020). The Effect of Cassava Starch on the Durability Characteristics of Concrete. The Open Civil Engineering Journal , 14 (1), 289–301. https://doi.org/10.2174/1874149502014010289 Opeyemi, B. E. (2019). RHEOLOGICAL PROPERTIES OF CASSAVA AND CORN STARCH Official Publication of Center for International Research Development . 5 (March), 1–11. Sulaimon, A. A., Akintola, S. A., Mohd Johari, M. A. Bin, & Isehunwa, S. O. (2020). Evaluation of drilling muds enhanced with modified starch for HPHT well applications. Journal of Petroleum Exploration and Production Technology , 11 (1), 203–218. https://doi.org/10.1007/s13202-020-01026-9 Sybis, M., & Konował, E. (2022). Influence of Modified Starch Admixtures on Selected Physicochemical Properties of Cement Composites . 1–12. Sybis, M., Konował, E., & Prochaska, K. (2022). Dextrins as Green and Biodegradable Modifiers of Physicochemical Properties of Cement Composites . Usman, S. A., Abubakar, A., & Olubunmi, A. (2024). Performance Evaluation of Cassava Starch as Concrete Admixture . 2 (2), 114–121. Zhou, G., Zhang, X., Yan, W., & Qiu, Z. (2025). Preparation , Performance Evaluation and Mechanisms of a Diatomite-Modified Starch-Based Fluid Loss Agent . Cmc , 1–16. 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-7694400","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":529998472,"identity":"e589191d-8983-409e-ba39-9722926f6406","order_by":0,"name":"Sunday B. Ipinsokan","email":"data:image/png;base64,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","orcid":"","institution":"Covenant University","correspondingAuthor":true,"prefix":"","firstName":"Sunday","middleName":"B.","lastName":"Ipinsokan","suffix":""},{"id":529998473,"identity":"b8064410-339a-4928-9326-71bbf8f370e2","order_by":1,"name":"Rachael O. Nkatta","email":"","orcid":"","institution":"Covenant University","correspondingAuthor":false,"prefix":"","firstName":"Rachael","middleName":"O.","lastName":"Nkatta","suffix":""},{"id":529998474,"identity":"121e9f1e-aff1-4448-901b-f6827c5b7d33","order_by":2,"name":"Humphrey Dike","email":"","orcid":"","institution":"Covenant University","correspondingAuthor":false,"prefix":"","firstName":"Humphrey","middleName":"","lastName":"Dike","suffix":""},{"id":529998475,"identity":"ba392ee2-3688-4829-92ce-caddbed2f68b","order_by":3,"name":"Peter O. Ojegbile","email":"","orcid":"","institution":"Covenant University","correspondingAuthor":false,"prefix":"","firstName":"Peter","middleName":"O.","lastName":"Ojegbile","suffix":""},{"id":529998476,"identity":"cd302f91-caa6-41ba-80b0-25956a41c22c","order_by":4,"name":"Kehinde Awelewa","email":"","orcid":"","institution":"Covenant University","correspondingAuthor":false,"prefix":"","firstName":"Kehinde","middleName":"","lastName":"Awelewa","suffix":""}],"badges":[],"createdAt":"2025-09-23 12:38:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7694400/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7694400/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":94468202,"identity":"7394e25d-9c23-4edb-9dbd-20c7788fae5d","added_by":"auto","created_at":"2025-10-27 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15:25:09","extension":"html","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":83484,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/4b6c2d17897daa8f0b287658.html"},{"id":94468456,"identity":"e7099299-96f6-41c3-9013-eb31a21569f1","added_by":"auto","created_at":"2025-10-27 15:25:06","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1159374,"visible":true,"origin":"","legend":"\u003cp\u003eThe schematic diagram for primary oil-well cementing (Maagi et al., 2020)\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/8020fdae9dd58e4c9c58b738.png"},{"id":94468448,"identity":"b1d286a4-018a-475b-b557-998f4610155f","added_by":"auto","created_at":"2025-10-27 15:25:04","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":281535,"visible":true,"origin":"","legend":"\u003cp\u003eBasic structure of the starch molecule (Hassan et al., 2022)\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/4b0d212917b84a1b787c271e.png"},{"id":94468455,"identity":"77d9b9a1-da5a-42b1-ad96-4b071a552369","added_by":"auto","created_at":"2025-10-27 15:25:06","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":358908,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectrum of Cassava Starch\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/eddcf98bb72b036e51feca7d.png"},{"id":94468265,"identity":"f408f68f-5103-4128-b6ab-2ca3920c7604","added_by":"auto","created_at":"2025-10-27 15:24:36","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":183568,"visible":true,"origin":"","legend":"\u003cp\u003eCombined Viscometer plot of samples before conditioning\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/a94666e93db00850ecdf00ca.png"},{"id":94468434,"identity":"bacdf50c-ddd9-470f-b2cd-606eabeed7e8","added_by":"auto","created_at":"2025-10-27 15:25:02","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":168121,"visible":true,"origin":"","legend":"\u003cp\u003eCombined Viscometer plot of samples after conditioning\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/5bfc632191117aac3969bdde.png"},{"id":94468266,"identity":"2a470529-7ea7-454c-82ec-63c0ec690acb","added_by":"auto","created_at":"2025-10-27 15:24:36","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":108497,"visible":true,"origin":"","legend":"\u003cp\u003eGel Strength, PV and YP of Conditioned and Unconditioned Samples\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/f659445f39bf3c88cf15291c.png"},{"id":94468210,"identity":"89876048-8013-4e18-80f2-a365f3629ef7","added_by":"auto","created_at":"2025-10-27 15:24:15","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":510235,"visible":true,"origin":"","legend":"\u003cp\u003eThickenings Time Results of the Slurry Samples\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/8669dedf5f02d2e9e0a49b78.png"},{"id":94468261,"identity":"026ac079-f0bd-4f45-a0f9-e602446ce6bf","added_by":"auto","created_at":"2025-10-27 15:24:34","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":408973,"visible":true,"origin":"","legend":"\u003cp\u003eCompressive Strength for Pressure of Slurry Samples\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/45b6ae58d81f4b9690393170.png"},{"id":94468358,"identity":"172d2200-b004-43b3-9d46-bd44c760d1a3","added_by":"auto","created_at":"2025-10-27 15:24:48","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":192924,"visible":true,"origin":"","legend":"\u003cp\u003eCompressive Strength for Time of Slurry Samples\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/fb2d2eb7e2c2f0a9c4fd8b68.png"},{"id":94468506,"identity":"79ff65f4-bb5a-41ec-9fcf-78fa10000309","added_by":"auto","created_at":"2025-10-27 15:25:15","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":32211,"visible":true,"origin":"","legend":"\u003cp\u003eFree water chart for the samples\u003c/p\u003e","description":"","filename":"10.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/e56965629516b8365b68227e.png"},{"id":94468495,"identity":"33750749-9d35-44f0-817b-ad554526ba18","added_by":"auto","created_at":"2025-10-27 15:25:12","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":233386,"visible":true,"origin":"","legend":"\u003cp\u003epH values of the cassava starch over 3 days\u003c/p\u003e","description":"","filename":"11.png","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/b8e329afc2a2fd8798fbd0c3.png"},{"id":99317701,"identity":"54e5859e-35df-4ee1-a4d3-e7494501f450","added_by":"auto","created_at":"2025-12-31 16:30:37","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":5218753,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7694400/v1/4f809e07-13b3-460f-b5a1-ccd121a04405.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Investigating the Performance of Cassava-Based Starches as Viscosifiers on Class-G Cement Slurry for Oil-Well Cementing Operations","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eCementing plays a critical role in ensuring the structural integrity and zonal isolation of oil and gas wells, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. It involves the placement of cement slurry between the casing and the borehole wall to form a seal that prevents fluid migration between formations. Correct cementing increases the mechanical stability of the casing string and gives the well long term survival. This operation greatly relies on the properties of cement slurry. Some of the most important parameters in slurry design include rheological behaviour, time to thicken, gel strength, fluid loss and compressive strength. Additives are usually added in order to alter these properties and provide optimal performance in the downhill conditions. The main additives that are used to reach a higher slurry rheology include viscosifiers, in order to achieve the suspension of the particles and to transport the fluid uniformly. Rheological modifications which have seen the wide usage of conventional viscosifiers include hydroxyethyl cellulose (HEC), carboxymethyl cellulose (CMC), and other synthetic polymers. Nevertheless, these substances tend to be imported, expensive and harmful to the environment causing concern about the long-term environmental effects and sustainability of operations. This paper was developed in response to these concerns, hence the emphasis on cassava starch as an alternative viscosifier. Cassava (Manihot esculenta) is a widely-grown crop in Nigeria, and some other countries in the tropics (Abegunde et al., \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Ojewumi et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) The starch component of cassava is biodegradable, locally available, and affordable. Although it has been investigated in the case of drilling muds, its full capacity in the use of cement slurry has not been reviewed.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eThis work investigates the effectiveness of cassava starch as a viscosifier on Class-G cement slurry, analysing its impact on slurry rheology, thickening time, gel strength, compressive strength, pH behaviour, and free fluid content compared to synthetic starch. The goal is to provide a sustainable, affordable, and eco-friendly solution for cement slurry enhancement in oilfield operations.\u003c/p\u003e\u003cp\u003eSeveral researchers have explored the use of starch-based materials in drilling and cementing operations. Some researchers (Adebayo et al., \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Adewumi et al., \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Afolalu et al., \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Amadi et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) investigated five local cassava starch samples in water-based drilling fluids (Okoro et al., \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Their findings revealed that starches with higher amylose content had greater viscosity and reduced fluid loss. The influence of starches on concrete properties was examined, a 4.9% increase in compressive strength when cassava starch was used. Their study concluded that natural starches not only enhance strength but also improve early-age performance, making them viable for rapid-strength development scenarios (Okon et al., \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Sybis \u0026amp; Konował, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Usman et al., \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). Amadi et al. (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) conducted a comparative evaluation of cassava starch, hydroxyethyl cellulose, and bentonite in drilling fluids. Although hydroxyethyl cellulose outperformed others, cassava starch showed promising rheological behaviour. The authors suggested that cassava cultivars with higher amylose content could yield better results, identifying the cassava variety as a potential gap. Cassava starch is primarily composed of two polysaccharides: amylose (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) (linear α-1,4-linked glucose units) and amylopectin (highly branched α-1,6-linked glucose chains) (Mohsin et al., \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). The ratio of amylose to amylopectin determines swelling, solubility, and gelatinisation behaviour, which in turn influence the viscosity of aqueous dispersions and cement slurries. The hydroxyl groups along the polymer\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003echains impart hydrogen bonding capacity, allowing starch molecules to interact with water molecules and hydration products of cement. This hydrogen bonding is central to its role as a viscosifier and fluid-loss reducer (Amadi et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). In cement slurries, cassava starch undergoes partial gelatinisation when exposed to elevated temperatures, resulting in an increase in slurry viscosity and enhanced water retention. Gelatinisation temperature for native cassava starch typically falls within 60\u0026ndash;70\u0026deg;C, which overlaps with common oil-well cementing conditions (Konował \u0026amp; Sybis, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Sybis et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Sybis \u0026amp; Konował, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). One concern with using organic polymers in cement systems is the potential compromise of compressive strength. However, studies have shown that cassava starch-modified slurries achieve compressive strengths comparable to those obtained with synthetic viscosifiers after 24 hours of curing (Sybis \u0026amp; Konował, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The presence of starch does not significantly interfere with the hydration of tricalcium silicate (C₃S) or dicalcium silicate (C₂S), the main strength-developing phases in cement. Instead, it contributes to improved slurry homogeneity, which supports long-term mechanical stability. Modified starches, such as acetylated or crosslinked derivatives, can extend thermal stability up to 120\u0026ndash;150\u0026deg;C, making them more suitable for HPHT wells (Liu et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Zhou et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2025\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe anionic character of some modified starches also contributes to electrostatic interactions with calcium ions (Ca\u0026sup2;⁺) in the cement pore solution, slowing down hydration reactions (Opeyemi, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). This effect is reflected in extended thickening time, which is desirable in deep well cementing to allow longer pumpability windows (Sybis \u0026amp; Konował, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). Furthermore, the hydrophilic functional groups on starch chains facilitate adsorption on cement particles, creating a polymer layer that enhances dispersion, prevents premature settling, and stabilises slurry rheology ( Liu et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). Vasiliou et al. (2022) focused on starch ethers in cementitious systems and reported their effectiveness in modifying rheology and minimising segregation. Their work emphasised the importance of starch molecular structure and processing method in determining performance. Cassava starch and its derivatives also act as fluid-loss agents by forming a semi-permeable filter cake on slurry surfaces, reducing filtrate invasion into the formation. This can be compared to the drilling fluids mechanism wherein starch polymers seal the throats of the pores and keep the wellbores stable (Zhou et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). t is experimentally established that viscosifiers made of starch can hold water well, but small amounts of free water can be observed when compared to synthetic ones (Sulaimon et al., \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Alterations, including grafting with inorganic diatomites or the addition of polyphenols, enhance resistance to filtration in HPHT (Liu et al., \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2025\u003c/span\u003e). All these findings attest to the fact that cassava starch is an effective natural polymer with rheological as well as structural modification properties. Nevertheless, its full-scale performance with oilfield cementing conditions was not tested by most. This study fills this gap by comparing the starch of cassava to synthetic viscosifiers at high pressure and high temperature (HPHT) and determining real-time compressive strength, gel strength, and thickening time.\u003c/p\u003e"},{"header":"2. Materials And Methodology","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1 Materials\u003c/h2\u003e\u003cp\u003eThe materials employed in this study were cassava starch, synthetic starch viscosifier, Class G cement, and distilled water. Cassava starch was extracted from locally sourced cassava tubers and subsequently processed for use as a natural viscosifier. An industrial-based synthetic viscosifier was procured for comparison. Class G cement, commonly used in oil-well cementing due to its suitability for high-pressure, high-temperature (HPHT) conditions, was selected as the base cementing material. Distilled water served as the mixing medium for slurry preparation.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2 Preparation of Cassava Starch\u003c/h2\u003e\u003cp\u003eFresh cassava tubers were selected, peeled, and thoroughly washed to remove surface impurities. The cleaned tubers were then grated into a fine pulp and soaked in water to facilitate starch extraction. The suspension obtained was filtered through a muslin cloth to separate fibrous materials from the starch-rich filtrate. The filtrate was allowed to settle under gravity, after which the sedimented starch was carefully collected. The starch was initially sun-dried and subsequently oven-dried at 70\u0026deg;C to ensure the removal of residual moisture. The dried product was sieved through a standard mesh to achieve a uniform particle size before use in cement slurry preparation.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3 Slurry Formulation\u003c/h2\u003e\u003cp\u003eCement slurries were formulated using Class G oilwell cement and water at a water-to-cement (w/c) ratio of 0.44. Cassava starch and synthetic starch viscosifiers were incorporated into the slurry at a concentration of 0.1% by weight of cement (BWOC). Mixing was carried out in accordance with the API Recommended Practice 10B procedure using a high-speed blender to ensure homogeneity. The prepared slurries were subjected to a series of standard performance evaluations as described below, while the formulation of the slurry samples is summarised in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e according to the best practices in the industry:\u003c/p\u003e\u003cp\u003e\u003cul\u003e\u003cli\u003e\u003cp\u003eRheology: The rheological behaviour of the slurries was determined using a rotational viscometer. Viscosity readings were taken at 600 rpm and 300 rpm, from which the plastic viscosity (PV) and yield point (YP) were calculated.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThickening Time: Thickening time was assessed with a high-temperature high-pressure (HTHP) consistometer. The slurry was exposed to elevated temperatures of up to 100\u0026deg;C and pressurised conditions to monitor gel development and setting characteristics.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eCompressive Strength: Uniaxial compressive strength tests were performed on cured cement samples using a destructive compressive strength testing machine. Measurements were taken after 12 and 24 hours of curing at ambient temperature.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eFree Fluid Test: Free fluid separation was evaluated by allowing slurry samples to remain undisturbed in a graduated cylinder for 2 hours, after which the volume of separated fluid was recorded.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003epH Analysis: The pH of cassava starch solutions was monitored over a period of three days to assess both biodegradability and chemical stability under aqueous conditions.\u003c/p\u003e\u003c/li\u003e\u003c/ul\u003e\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFormulation of cement slurries with organic starch and synthetic viscosifiers\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"11\"\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\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eS/N\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eComposition\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eS (Neat Slurry)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eO1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eO2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003eO3\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eO4\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003eS1\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003eS2\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eS3\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c11\"\u003e\u003cp\u003eS4\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCement (g)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e781.67\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e781.79\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e781.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e782.05\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e782.17\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e781.16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e780.66\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e780.15\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e779.65\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eWater (g)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e348.09\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e327.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e346.27\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e346.36\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e344.45\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e341.32\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e334.56\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e327.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e321.07\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAntifoam (g)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e6.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e6.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e6.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e6.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e6.94\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e6.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e6.93\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e6.92\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e6.92\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eOrganic starch (gal/sk)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e0.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eSynthetic viscosifier (% BWOC)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c5\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c6\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c7\"\u003e\u003cp\u003e\u0026ndash;\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u003cp\u003e0.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u003cp\u003e0.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u003cp\u003e0.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c11\"\u003e\u003cp\u003e0.4\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"11\"\u003eNote that S represents the neat cement slurry without viscosifiers. NU as unconditioned slurry and NC as conditioned slurry. O1\u0026ndash;O4 are slurries formulated with organic cassava starch viscosifiers at concentrations of 0.1, 0.2, 0.3, and 0.4 gal/sk, respectively. S1\u0026ndash;S4 are slurries prepared with synthetic viscosifiers at 0.1, 0.2, 0.3, and 0.4% BWOC, respectively. All slurries were prepared with Class G cement, distilled water, and a constant amount of antifoam additive. The unconditioned organic samples are labelled as OU1-OU4, unconditioned synthetic samples are SU1-SU4, conditioned organic samples are OC1-OC4 and conditioned synthetic samples are SC1-SC4.\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results And Discussion","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e3.1 FTIR Test Result Analysis\u003c/h2\u003e\u003cp\u003eThe FTIR spectrum of the analysed sample is presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The major absorption peaks were identified and assigned to corresponding functional groups. From the spectrum, the cassava starch is confirmed to contain Hydroxyl groups (\u0026ndash;OH), Alkane groups (\u0026ndash;CH₂, \u0026ndash;CH₃), Carbonyl groups (C\u0026thinsp;=\u0026thinsp;O), Glycosidic linkages (C\u0026ndash;O\u0026ndash;C) and Polysaccharide rings (pyranose structures) which aligns with the findings by Adewumi et al., (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). These chemical groups are directly responsible for its ability to act as a green viscosifier in cement slurry, which improves rheology, extends thickening time, supports compressive strength, and offers biodegradability compared to synthetic additives.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e3.2 Rheological Properties\u003c/h2\u003e\u003cp\u003eThe addition of cassava starch improved the plastic viscosity (PV) and yield point (YP) of the cement slurry compared to the neat sample. At 300 rpm, cassava starch-modified slurries exhibited shear stress values ranging from 105\u0026ndash;127 lbf/100 ft\u0026sup2;, while synthetic starches recorded higher values (109\u0026ndash;210 lbf/100 ft\u0026sup2;). Although the peak viscosities of synthetics were greater, cassava starch displayed more stable rheological behaviour after conditioning (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). Stable viscosity is vital in cementing since it ensures suspension of solids and uniform placement, particularly in deviated wells where gravitational settling is pronounced (Amadi et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Similar observations were reported by Koko et al., (2022), who noted that biopolymer-based additives maintained more consistent viscosity under dynamic conditions compared to synthetic polymers. The practical implication of this behaviour is significant: in real field applications, erratic viscosity leads to poor solids suspension, higher energy requirements for pumping, and uneven slurry placement. Cassava starch, by maintaining steady viscosity, ensures continuous suspension of cement particles and additives, particularly under turbulent flow in deviated or horizontal wells. Its performance highlights a shear-thinning behaviour, meaning viscosity decreases with higher shear rates, which is desirable in cementing, that is, easy to pump at high rates but stable enough to suspend solids when circulation slows. This aligns with the general theory of natural polysaccharides (e.g., amylose and amylopectin in cassava starch), forming hydrogen-bonded networks that provide controlled viscosity. By contrast, synthetic polymers often exhibit sharper shear-thinning curves, which, while boosting peak values, may cause\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003einstability under changing shear conditions. Gel strength evaluation (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e) revealed that cassava starch-modified slurries developed moderate values, which effectively suspended solids during static periods without causing high restart pressures. Synthetic starches, by contrast, produced higher gel strength, which, though beneficial for suspension, risked excessive pump pressures during re-circulation. This balance offered by cassava starch aligns with findings by Sulaimon et al., (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), who emphasised that moderate gel strength enhances operational safety by minimising surge pressures in HPHT wells.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eCassava starch offers a balanced mechanism: the amylose fraction promotes controlled structuring of the slurry, giving enough suspension capacity to prevent sedimentation, while the amylopectin chains limit over-structuring. This ensures easy restart of pumping operations after static periods, which is critical during well-control events or operational pauses. Thus, cassava starch not only provides stability during shutdowns but also reduces risks associated with excessive surge pressures, which is a safety advantage in HPHT and deviated well cementing.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e3.3 Thickening Time Analysis\u003c/h2\u003e\u003cp\u003eThickening time results demonstrated that cassava starch extended the pumpability window to 107 minutes at 100 BC compared to 94 minutes for synthetic starch (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e). Longer setting times are advantageous in deepwater and extended-reach wells where unexpected delays are frequent. Previous research by Okon et al., (\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) indicated that natural starch derivatives provide delayed hydration effects, thereby prolonging thickening time without compromising final strength development.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eChemically, this effect is attributed to the slower hydration kinetics of cassava starch molecules, which delay the setting of cement particles. The presence of carbonyl groups allows interaction with calcium ions in cement, delaying hydration and extending thickening time. The polysaccharide chains absorb water and form a protective coating around cement grains, thereby retarding hydration reactions without completely inhibiting them. This results in a controlled delay in gelation while still ensuring strong final compressive strength. The field implication is clear: cassava starch reduces the likelihood of premature setting during pumping, improving placement reliability. However, the delay is not excessive, meaning operational efficiency is preserved.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e3.5 Compressive Strength Performance\u003c/h2\u003e\u003cp\u003eCassava starch-modified cement slurries exceeded 500 psi at 12 hours and attained more than 2600 psi at 24 hours (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e). This demonstrates that cassava starch does not interfere with cement hydration but supports robust strength development. Comparable findings were reported by Adewumi et al., (\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) and Oni et al., (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) who confirmed that biopolymer viscosifiers facilitated adequate hydration and early strength gain, often matching or surpassing the performance of synthetics. Such strength levels satisfy API minimum requirements for well integrity, confirming cassava starch as a reliable additive.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eMechanistically, cassava starch interacts with the hydration products of tricalcium silicate (C₃S) and dicalcium silicate (C₂S), influencing the growth of calcium silicate hydrate (C\u0026ndash;S\u0026ndash;H) gels. The polysaccharide backbone stabilises water distribution, ensuring uniform hydration and good strength development. Instead of obstructing hydration, the starch molecules help to control water distribution, preventing rapid consumption and micro-cracking. From a well integrity perspective, the results confirm that cassava starch ensures reliable zonal isolation by maintaining early strength development (\u0026gt;\u0026thinsp;500 psi within 12 hours meets API standards) and long-term durability. This balance of delayed thickening and robust strength gain is often difficult to achieve with synthetic viscosifiers, which sometimes sacrifice one for the other.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e3.6 Free Fluid Content\u003c/h2\u003e\u003cp\u003eCassava starch-modified slurries exhibited free fluid values between 0.36\u0026ndash;1.2 ml, slightly higher than the near-zero values of synthetics (Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e). Although this may appear as a\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003elimitation, it remains within API standards (\u0026lt;\u0026thinsp;1.5 ml) and can be corrected with minor formulation adjustments. Studies by Amadi et al., (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) have shown that biopolymer-based additives often require optimisation with secondary dispersants to further minimise free fluid, highlighting opportunities for blended formulations. In practice, small volumes of free fluid may lead to micro-channelling, which affects zonal isolation. However, this limitation can be addressed through formulation adjustments, such as blending cassava starch with minor amounts of dispersants or fluid-loss additives. Importantly, the fact that cassava starch alone keeps free fluid within API standards demonstrates its baseline effectiveness.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e3.7 pH Behaviour and Biodegradability\u003c/h2\u003e\u003cp\u003eThe pH of cassava starch solutions decreased from 6.3 on Day 1 to 5.83 by Day 3 due to microbial activity (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e). This indicates natural biodegradability, which presents environmental advantages in terms of disposal and ecological safety. Hydroxyl-rich polysaccharide structure is susceptible to microbial attack, explaining the observed pH drop during the biodegradability test. In contrast, synthetic starches exhibited stable pH values, reflecting non-biodegradability and possible long-term ecological risks. Similar biodegradation patterns of natural starches have been documented by Oni et al., (\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), who noted that such behaviour enhances sustainability without compromising slurry performance.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eOn the other hand, microbial degradation could limit its shelf life or affect slurry stability during extended storage. Synthetic viscosifiers, by maintaining static pH values, resist biodegradation but pose challenges for waste management and environmental compliance. With increasing regulatory pressure on oilfield chemicals, cassava starch\u0026rsquo;s biodegradability becomes a competitive advantage, aligning with sustainability goals in the petroleum industry. From a mechanistic perspective, the pH decline reflects fermentation of starch molecules by microorganisms, releasing organic acids that lower alkalinity. While this does not hinder slurry performance in the short term, it confirms cassava starch as a green additive that minimises long-term environmental risks.\u003c/p\u003e\u003c/div\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study has demonstrated that cassava starch is a viable and sustainable alternative to conventional synthetic viscosifiers in Class-G cement slurries for oil-well cementing operations. The results revealed that cassava starch improved the rheological properties of the slurry, providing stable viscosity behaviour even after conditioning. This stability ensures effective suspension of solids and uniform placement, particularly in deviated wells where gravitational settling is a challenge. Importantly, cassava starch also extended the thickening time of the slurry, offering a wider operational window that is advantageous for deep and complex well completions. The compressive strength performance further confirmed that cassava starch does not interfere with cement hydration, achieving strengths above 2600 psi after 24 hours, comparable to those obtained with synthetic viscosifiers. Although the cassava starch-modified samples exhibited slightly higher free fluid values, these remained within API permissible limits and can be optimised with minor formulation adjustments. In addition, the observed pH decline over time highlights the biodegradable nature of cassava starch, underscoring its environmental compatibility and positioning it as a green alternative for cementing applications.\u003c/p\u003e\u003cp\u003eOverall, the findings confirm that cassava starch combines operational reliability, cost-effectiveness, and environmental sustainability, making it a promising additive for oil-well cementing in regions seeking locally available, eco-friendly solutions. Field trials should be conducted to validate the lab findings and establish confidence in cassava starch application under real wellbore conditions.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eDeclaration of Competing Interest\u003c/p\u003e\n\u003cp\u003eAuthors have no conflicts of interest to disclose.\u003c/p\u003e\n\u003cp\u003eFunding Declarations\u003c/p\u003e\n\u003cp\u003eThis research received no external funding.\u003c/p\u003e\n\u003cp\u003eEthics declaration\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eMany thanks to Covenant University for creating a conducive environment for research and paying the fee for the publication.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eData availability\u003c/p\u003e\n\u003cp\u003eThe data that supports the findings of this study are available from the corresponding author upon request\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbegunde, I. 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(2022). \u003cem\u003eDextrins as Green and Biodegradable Modifiers of Physicochemical Properties of Cement Composites\u003c/em\u003e.\u003c/li\u003e\n\u003cli\u003eUsman, S. A., Abubakar, A., \u0026amp; Olubunmi, A. (2024). \u003cem\u003ePerformance Evaluation of Cassava Starch as Concrete Admixture\u003c/em\u003e. \u003cem\u003e2\u003c/em\u003e(2), 114\u0026ndash;121.\u003c/li\u003e\n\u003cli\u003eZhou, G., Zhang, X., Yan, W., \u0026amp; Qiu, Z. (2025). \u003cem\u003ePreparation , Performance Evaluation and Mechanisms of a Diatomite-Modified Starch-Based Fluid Loss Agent\u003c/em\u003e. \u003cem\u003eCmc\u003c/em\u003e, 1\u0026ndash;16.\u003c/li\u003e\n\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":"Cassava starch, cement slurry, compressive strength, green additives, thickening time, rheology test, viscosifier","lastPublishedDoi":"10.21203/rs.3.rs-7694400/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7694400/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eCementing technology has evolved significantly over time as one of the most critical completion tasks in the petroleum industry. Viscosity is pivotal in slurry formulation, impacting pumpability, thickening time, and overall slurry behaviour. Therefore, viscosifiers are always incorporated to modify slurry viscosity to achieve ultimate performance under varying downhole conditions. However, environmental concerns and the high costs of synthetic viscosifiers have driven interest in natural, organic alternatives. This study evaluates cassava starch, a locally sourced and renewable biopolymer, as a viscosifier in Class-G cement slurries. Cassava starch was extracted, processed into powder, and incorporated into cement formulations at concentrations of 0.1\u0026ndash;0.4% BWOC. Rheological properties, gel strength, thickening time, compressive strength, free fluid, and pH stability were assessed following API standards and benchmarked against a synthetic viscosifier. Results showed that cassava starch enhanced plastic viscosity and yield point, with shear stress values of 105\u0026ndash;127 lbf/100 ft\u0026sup2; at 300 rpm, providing more stable flow behaviour after conditioning compared to synthetic starches. Thickening time was extended to 107 minutes, offering longer pumpability windows essential for deep and complex wells. Compressive strength exceeded 2600 psi at 24 hours, confirming that cassava starch did not hinder hydration. Free fluid values (0.36\u0026ndash;1.2 ml) remained within API limits, though slightly higher than synthetic controls. The pH decreased from 6.3 to 5.8 over three days, confirming biodegradability. The findings demonstrate that cassava starch is an effective and environmentally friendly alternative to synthetic viscosifiers, offering enhanced thickening time, comparable compressive strength, and rheological stability.\u003c/p\u003e","manuscriptTitle":"Investigating the Performance of Cassava-Based Starches as Viscosifiers on Class-G Cement Slurry for Oil-Well Cementing Operations","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-10-27 13:38:20","doi":"10.21203/rs.3.rs-7694400/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":"f8b8b15a-e723-457d-82ea-de16b0a5f1ac","owner":[],"postedDate":"October 27th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-01-13T11:08:33+00:00","versionOfRecord":[],"versionCreatedAt":"2025-10-27 13:38:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7694400","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7694400","identity":"rs-7694400","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}