Ahmed Abdulmalek, Mahmoud Ahmed Abdulhamid, Elkatatny Salaheldin, Al Shehri Dhafer, Ayranci Korhan
Department of Petroleum Engineering, King Fahd University of Petroleum and Minerals, 31261, Dhahran, Saudi Arabia.
Department of Geosciences, College of Petroleum Engineering and Geosciences, King Fahd University of Petroleum and Minerals, 31261, Dhahran, Saudi Arabia.
Sci Rep. 2024 Oct 29;14(1):25914. doi: 10.1038/s41598-024-76914-9.
High-density cement slurries used in oil well cementing often face challenges such as particle settling, poor rheological properties, permeability, and compressive strength degradation, which can compromise zonal isolation and well integrity. This study focuses on using kaolinite, a clay mineral, as an additive due to its potential to improve the performance of high-density cement by modifying key properties. Several concentrations of kaolinite were examined to evaluate their influence on several cement properties such as rheology, thickening time, permeability, porosity, and compressive strength. Additionally, it assesses the impact of kaolinite on cement sheath solids settling using both conventional methods and nuclear magnetic resonance (NMR). The results revealed that an optimal concentration of 1% kaolinite by weight of cement (BWOC) significantly reduced particle settling by 74.4%, enhanced compressive strength by 13%, and lowered permeability and porosity by 74% and 7%, respectively. Additionally, kaolinite improved rheological properties by an 8.4% reduction in plastic viscosity, a 19.4% increase in yield point, and a 30% increase in gel strength. Kaolinite also acted as a retarder, increasing thickening time. These improvements contribute to better cement sheath integrity and wellbore stability, highlighting kaolinite's potential as an effective additive for high-density cement.
油井固井中使用的高密度水泥浆常常面临诸如颗粒沉降、流变性能差、渗透率和抗压强度降低等挑战，这些会损害层间封隔和井的完整性。本研究着重于使用高岭土（一种粘土矿物）作为添加剂，因为它有潜力通过改变关键性能来改善高密度水泥的性能。研究了几种浓度的高岭土，以评估它们对水泥的流变学、稠化时间、渗透率、孔隙率和抗压强度等性能的影响。此外，还使用传统方法和核磁共振（NMR）评估了高岭土对水泥环固体沉降的影响。结果表明，水泥重量的1%（BWOC）的最佳高岭土浓度可显著减少74.4%的颗粒沉降，提高13%的抗压强度，并分别降低74%的渗透率和7%的孔隙率。此外，高岭土通过降低8.4%的塑性粘度、提高19.4%的屈服点和提高30%的凝胶强度来改善流变性能。高岭土还起到缓凝剂的作用，延长了稠化时间。这些改善有助于提高水泥环的完整性和井筒稳定性，突出了高岭土作为高密度水泥有效添加剂的潜力。
