流-固-化-热耦合的陆相页岩井壁稳定力学模型及应用  

Fluid-Solid-Chemical-Thermal Coupling Mechanical Model of Wellbore Stability for Continental Shale and Its Application

作　　者：张宇[1] 赵林[1] 王炳红[1] 张娜[1] 程万 Zhang Yu;Zhao Lin;Wang Binghong;Zhang Na;Cheng Wan(Sinopec Henan Oilfield Company, Nanyang, Henan 473000, China;China University of Geosciences ( Wuhan), Wuhan, Hubei 430074, China)

机构地区：[1]中国石化河南油田分公司,河南南阳473000 [2]中国地质大学(武汉),湖北武汉430074

出　　处：《特种油气藏》2019年第3期163-168,共6页Special Oil & Gas Reservoirs

基　　金：国家科技重大专项“中国典型盆地陆相页岩油勘探开发选区与目标评价”(2017ZX05049)

摘　　要：由于钻井液浸泡,陆相页岩中的黏土矿物发生水化膨胀,页岩力学强度会发生弱化,诱发井壁坍塌现象。为探讨陆相页岩井壁稳定机理,假设井壁页岩为多孔弹性介质,考虑页岩基质和层理随着钻井液浸泡时间的水化过程,构建了流-固-化-热耦合的井壁应力场模型,再结合剪切破坏准则,形成了陆相页岩井壁坍塌压力评价模型。以泌阳凹陷陆相页岩油藏A水平井基础参数为例进行计算,揭示了 A井井壁失稳原因,并优选了钻井液密度结果表明:水平井若沿着最小水平主地应力方向布置,则井壁坍塌风险最小;在井斜角为45 - 70。的造斜段内,可采用水基钻井液,但其密度应高于1.35 g/cm',在井斜角为70-90。的高造斜段内,应采用油基钻井液;研究结果与A井钻井情况吻合。该研究结果可应用于指导陆相页岩井壁坍塌压力预测和钻井设计。The drilling fluid immersion usually leads to the hydration and swelling of the clay minerals in the continental shale,which will reduce the mechanical strength of shale and induce wellbore collapse. In order to explore the wellbore stability mechanism of continental shale,it is assumed that the shale of borehole wall is a porous elastic medium. The fluid-solid-chemical-thermal coupling wellbore stress field model was established by considering the hydration process of shale matrix and bedding with drilling fluid immersion. A collapse pressure evaluation model for continental shale was provided by combining with the shear failure criterion. The basis parameters of horizontal well A in the continental shale reservoir of Biyang Depression was taken as a calculation case to reveal the causes of wellbore instability and optimize the drilling fluid density. Research indicates that the wellbore collapse risk can be greatly reduced by deploying the horizontal wellbore along the minimum horizontal principle geo-stress. Water-based drilling fluid can be adopted in the section with an inclination angle of 45 ~ 70°,and its density should be higher than 1.35 g/cm^3. Oil-based drilling fluid should be adopted in the high-inclination section with an inclination angle of 70 ~ 90°. The prediction shows a favorable agreement with actual drilling data of Well A. This research can be applied to guide the wellbore collapse pressure prediction and drilling design in the continental shale.

关 键 词：井壁稳定 多孔介质 坍塌压力 页岩 

分 类 号：TE21[石油与天然气工程—油气井工程]