Gautam Ramaswamy, Hazra Abhinav, Faujdar Prashant, Sen Suvendu, Mishra Bibhash Chandra, Sharma Tushar, Kumar Shailesh
EOR Research Laboratory, Department of Petroleum Engineering and Geoengineering, Rajiv Gandhi Institute of Petroleum Technology Jais, Amethi, Uttar Pradesh 229304, India.
Cementing (R&D) Unit, Institute of Drilling Technology, ONGC, Dehradun 248195, India.
ACS Omega. 2024 Nov 19;9(48):47739-47755. doi: 10.1021/acsomega.4c07871. eCollection 2024 Dec 3.
The optimal design of cement slurry by balancing various cement additives and cement is critical for effective oil well cementation job. However, given adverse circumstances of application, existing additives may not be sufficient to perform suitably in challenging conditions, leading to premature cement hydration, formation of microcracks, and gas channeling pathways. Thus, this study explores the use of a single-step silica nanofluid (NP size: 5-10, 90-100, and 250-300 nm and concentration: 1, 3, and 5 wt %) as an additive and explores its effect on thickening time, fluid loss, and rheological behavior of class G cement slurry at high-pressure and high-temperature (HPHT) conditions (135 °C and 3625 psi). The improvement in thickening time, fluid loss, and rheology of conventional slurry was greater for low NP size than the nanofluid of high NP size: the nanofluid size, e.g., 5-10 nm, and concentration (1 wt %) were found to accelerate the thickening time by 30-40% while reducing fluid loss from 38 mL (no silica, slurry CS) to 30 mL (with silica, slurry C1). The rheological behavior was studied via shear (viscosity) and dynamic (elastic moduli, ') modes to evaluate the viscosity, hysteresis, and elastic response of slurry with and without nanofluid. The inclusion of nanofluid slightly reduced the slurry viscosity; however, all slurries exhibited shear thinning with superior fitting with the power law model. As compared to slurry CS, hysteresis of slurry C1 was least dependent on shear deformation, and thus, it showed that it almost matched viscosity profiles during loading and unloading cycles. The addition of silica was found to maintain the original properties of cement slurry, establishing that cement had not agglomerated, and no sedimentation was observed even at shear rates of 1000 s. The results of this study greatly promote the use of silica nanofluid as an important additive in class G cement for cementation operations, which is unlikely with a two-step nanofluid where nanoparticles are expensive, and upon mixing, they tend to agglomerate and make large size clusters.
通过平衡各种水泥添加剂和水泥来实现水泥浆的优化设计，对于有效的油井固井作业至关重要。然而，考虑到应用中的不利情况，现有的添加剂可能不足以在具有挑战性的条件下正常发挥作用，从而导致水泥过早水化、形成微裂纹和气窜通道。因此，本研究探索使用单步二氧化硅纳米流体（纳米颗粒尺寸：5 - 10、90 - 100和250 - 300纳米，浓度：1、3和5重量%）作为添加剂，并研究其在高压高温（HPHT）条件（135°C和3625磅力/平方英寸）下对G级水泥浆稠化时间、滤失量和流变行为的影响。对于低纳米颗粒尺寸的纳米流体，传统水泥浆在稠化时间、滤失量和流变性能方面的改善比高纳米颗粒尺寸的纳米流体更大：例如，发现纳米流体尺寸为5 - 10纳米且浓度为1重量%时，可使稠化时间加快30 - 40%，同时滤失量从38毫升（无二氧化硅，CS水泥浆）降至30毫升（有二氧化硅，C1水泥浆）。通过剪切（粘度）和动态（弹性模量）模式研究流变行为，以评估含纳米流体和不含纳米流体的水泥浆粘度、滞后现象和弹性响应。纳米流体的加入略微降低了水泥浆粘度；然而，所有水泥浆均表现出剪切变稀特性，且与幂律模型拟合良好。与CS水泥浆相比，C1水泥浆的滞后现象对剪切变形的依赖性最小，因此，它在加载和卸载循环期间的粘度曲线几乎匹配。发现添加二氧化硅可保持水泥浆的原始性能，表明水泥未发生团聚，即使在1000秒的剪切速率下也未观察到沉降现象。本研究结果极大地推动了二氧化硅纳米流体作为G级水泥固井作业重要添加剂的应用，而两步法纳米流体则不太可能如此，因为纳米颗粒成本高昂，混合时容易团聚并形成大尺寸团簇。
