复合盐层多元协同稳定井壁钻井液技术  

Drilling fluid for stabilizing the wellbore in compound-salt formation based on multiple-synergism-method

作　　者：赵欣[1] 孙昊 邱正松[1] 黄维安[1] 徐加放[1] 钟汉毅[1] ZHAO Xin;SUN Hao;QIU Zhengsong;HUANG Weian;XU Jiafang;ZHONG Hanyi(School of Petroleum Engineering,China University of Petroleum(East China),Qingdao 266580,Shandong Province,P.R.China)

机构地区：[1]中国石油大学(华东)石油工程学院,山东青岛266580

出　　处：《深圳大学学报（理工版）》2022年第6期668-674,共7页Journal of Shenzhen University(Science and Engineering)

基　　金：国家科技重大专项资助项目(2011ZX05030-005-07);国家自然科学基金资助项目(51974354)。

摘　　要：复合盐层性质复杂,钻井过程中易发生井壁失稳.通过分析多个地区复合盐层的矿物组成、微观结构、理化性质及界面力学特性,探讨了井壁失稳机理.结果表明,地层孔隙和微裂缝发育、盐岩蠕变及溶解、膏泥岩水化是造成复合盐层井壁失稳的关键原因.提出了强化钻井液封固井壁作用-抑制盐膏溶解与膏泥水化-水活度平衡-有效应力支撑“多元协同”稳定井壁钻井液技术对策.依据水活度对泥岩水化膨胀和分散的影响规律,明确了钻井液水活度安全窗口的设计依据.针对中东地区M油田、乌兹别克斯坦H-S油田以及中国新疆地区复合盐层井壁失稳问题,采用“多元协同”稳定井壁技术对策,设计了相应的防塌钻井液体系.现场应用表明,该技术可有效提高复合盐层井壁稳定性,大幅减少井下复杂事故,提高钻井作业效率.The complex features of the compound-salt formation result in wellbore instability during drilling operations. The mechanism of wellbore instability in compound-salt formation is studied by the analysis of mineral compositions, microstructures, physical-chemical properties, and interface mechanical properties of compound salts from different areas. The results show that the existing micro-scale pores and fractures, creep and dissolution of salt,hydration of gypsum-mudstones are the key causes of wellbore instability in compound-salt formation. In order to stabilize the wellbore in compound-salt, we propose the drilling strategies based on the synergism of multiple methods of strengthening the wellbore by the sealing and consolidating effect of drilling fluid, inhibiting the dissolution of salt and the hydration of gypsum-mudstones, balancing the water activity between rocks and drilling fluid, providing effective stress to support the wellbore. Based on the effect of water activity on the shale hydration swelling and dispersion properties, the design basis of the safe window of water activity for drilling fluids is determined. According to the wellbore instability problems when drilling in compound-salt formations in M Oil Field in the Middle East, H-S Oil Field of Uzbekistan, and Xinjiang Uygur Autonomous Region of China, the drilling fluids are designed respectively based on the proposed wellbore stabilizing technology. The field applications show that the drilling fluid technology greatly improves the wellbore stability in compound salt formations and reduces downhole problems, thereby improving drilling efficiency.

关 键 词：油气井工程 油田开发 复合盐层 井壁失稳机理 多元协同 稳定井壁 水活度窗口 钻井液 

分 类 号：TE254[石油与天然气工程—油气井工程]