Gamal Hany, Elkatatny Salaheldin, Abdulraheem Abdulazeez
College of Petroleum Engineering & Geosciences, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
ACS Omega. 2020 Dec 8;5(50):32677-32688. doi: 10.1021/acsomega.0c05067. eCollection 2020 Dec 22.
During drilling operations, the filtrate fluid of the drilling mud invades the drilled rock. The invading filtrate fluid will interact with the rock and therefore alter the rock internal topography, pore system, elastic moduli, and rock strength. The objective of this study is to evaluate the effect of the mud filtrate of barite-weighted water-based mud on the geomechanical properties of four types of sandstone rocks (Berea Buff, Berea Spider, Bandera Brown, and Parker). The mud filtrate was collected to provide mud filtrate-rock exposure at a pressure of 300 psi and 200 °F temperature for 10 days. The study assessed the alteration in the rock geomechanics employing an integrated laboratory analysis of X-ray diffraction (XRD), scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), and scratch testing. The ultrasonic results showed changes after exposure to the mud filtrate and an obvious reduction trend in the shear wave velocities due to the dissolution and mineralogical modifications in rock samples. The obtained results displayed a general strength reduction for the four sandstone types with different levels. The strength reduction ranged from 6% reduction for Berea Spider to a record 23% reduction for Parker. For all sandstone types, Young's modulus showed a general reduction ranging from 11 to 40%, while Poisson's ratio recorded an increase by 62-155% after the filtrate interaction. The study illustrated the role of pore-system alteration in controlling the rock strength and dynamic moduli.
在钻井作业过程中，钻井泥浆的滤液侵入已钻岩石。侵入的滤液会与岩石相互作用，从而改变岩石的内部形貌、孔隙系统、弹性模量和岩石强度。本研究的目的是评估重晶石加重水基泥浆的泥浆滤液对四种砂岩（贝雷亚米色砂岩、贝雷亚蜘蛛砂岩、班德拉棕色砂岩和帕克砂岩）地质力学性质的影响。收集泥浆滤液，使其在300 psi的压力和200°F的温度下与岩石接触10天。该研究采用X射线衍射（XRD）、扫描电子显微镜（SEM）、核磁共振（NMR）和划痕测试等综合实验室分析方法，评估岩石地质力学的变化。超声结果表明，在接触泥浆滤液后发生了变化，由于岩石样品的溶解和矿物学改变，剪切波速度出现明显下降趋势。所得结果显示，四种砂岩类型的强度普遍降低，降低幅度不同。强度降低幅度从贝雷亚蜘蛛砂岩的6%到帕克砂岩创纪录的23%不等。对于所有砂岩类型，杨氏模量普遍降低了11%至40%，而泊松比在滤液相互作用后增加了62%至155%。该研究说明了孔隙系统改变在控制岩石强度和动态模量方面的作用。
