摘要
运用X射线衍射、微观扫描电镜实验,结合岩石三轴抗压实验,研究了清水及不同钻井液浸泡对鄂尔多斯盆地延长组页岩坍塌压力增量的影响,测试了不同钻井液浸泡前后的岩石强度,分析了地层坍塌压力变化情况,为钻井液的选择提供技术参考。研究表明:延长组页岩地层层理、裂隙发育,水相将沿裂缝或微裂缝侵入地层,一方面降低弱结构面间的摩擦力,进而削弱页岩的力学强度,导致井壁垮塌;另一方面,侵入的液相将产生水力劈裂作用,导致地层破碎,诱发井壁失稳。通过分析钻井液浸泡前后页岩应力应变曲线变化情况,能够更加详细了解页岩地层井壁不稳定机理,从钻井液密度、抑制性和黏结能力等方面为页岩气井防塌钻井液设计提供技术参考。
The X-ray diffraction, microscopic scanning electron microscopy and rock tri-axial compression tests are used to study the effects of fresh water and different drilling fluid soaking on the shale collapse pressure increment in Yanchang Formation of Ordos Basin. The rock strengths before and after different drilling fluid soaking are tested to analyze the variation of formation collapse pressure and provide certain technical reference for drilling fluid opti- mization. Research indicates that the water invades into formation along the fracture or micro-fracture due to the well-developed bedding and fissure. On the one hand, it reduces the friction between weak structural planes and weakens the mechanical strength of shale, which results in borehole collapse. On the other hand, the hydraulic frac- turing effect results from the invaded liquid leads to formation crush and borehole instability. The shale instability mechanism can be further explored by analyzing the stress and strain performances before and after drilling fluid soaking, which could provider certain technical reference for the anti-collapse drilling fluid design in shale gas well from the aspects of drilling fluid density, inhibition and bonding performance.
作者
王平全
邓嘉丁
白杨
王建龙
青胜兰
Wang Pingquan;Deng Jiading;Bai Yang;Wang Jianlong;Qing Shenglan(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu, Sichuan 610500, China;Southwest Petroleum University, Chengdu , Sichuan 610500, China;PetroChina Southwest Oil ＆Gas field Company, Guanghan , Sichuan 618300, China)
出处
《特种油气藏》
CAS
CSCD
北大核心
2018年第2期159-163,共5页
Special Oil & Gas Reservoirs
基金
国家自然科学基金"富有机质硬脆性页岩水化机理基础研究"(41772151)
陕西延长石油(集团)有限责任公司研究院科研项目"延长气田水平井钻井液关键技术研究及应用"(YJGCS17SFW0002)
关键词
页岩气
坍塌压力
防塌钻井液
井壁稳定
鄂尔多斯盆地
shale gas
collapse pressure
anti-collapse drilling fluid
borehole stability
Ordos Basin
