准噶尔南缘膏泥岩地层井壁失稳机理  

Borehole Instability Mechanism of Plaster Mudstone Formation in Southern Margin of Junggar Basin

作　　者：徐生江[1] 刘颖彪[1] 戎克生[1] 叶成[1] 马超 苏超 

机构地区：[1]中国石油天然气股份有限公司新疆油田公司工程技术研究院,克拉玛依834000 [2]长江大学石油工程学院,油气钻采工程湖北省重点实验室,武汉430100

出　　处：《科学技术与工程》2017年第28期194-199,共6页Science Technology and Engineering

基　　金：中国石油新疆油田公司项目(XJYT-gcjsyjy-2016-JS-223)资助

摘　　要：准噶尔盆地南缘山前安集海河组和紫泥泉子组地层钻井过程中易发生遇阻、卡钻、井漏等井下复杂事故。为研究这两组地层井壁失稳的原因,从岩心的黏土矿物组分、微观结构、力学性能、分散膨胀性能的角度,同时结合典型井的测井等数据,研究地层的坍塌压力和破裂压力的当量密度,综合分析井壁失稳机理。研究认为:安集海河组和紫泥泉子组地层均具有黏土含量高(30%)、伊/蒙混层含量高(57%)且混层比高(55%)的特点,电镜扫描显示岩心表面含有大量伊/蒙混结构,因此,钻井液滤液依靠压差和毛细管作用侵入地层是造成地层非均匀水化膨胀是地层失稳的主要原因;岩屑的回收率和膨胀率结果可见地层具有高分散高膨胀的特点,极易造成井壁坍塌及钻井液性能恶化;岩心实验显示岩心抗压强度较低,经水基钻井液浸泡后破碎或者产生裂纹,油基钻井液浸泡抗压强度下降,说明岩心本身的抗压强度低也是地层不稳定的本质原因;另外,地层孔隙压力高,钻井液安全密度窗口窄,钻井液密度控制不当也是导致地层失稳(漏失和坍塌)的重要原因。There are serious accidents such as obstruction, stuck drilling and well leakage during the drillingprocess of the Anjihaihe Formation and the Zuiquanquzi Formation in the Piedmont of the study the causes of thie instability of thie two strata, T h e instability m e c h a n i s m of thie borehole wall is analyzed syn-thetically from the angle of thie clay mineral composition, microstructure, mechanical properties, disjDersion expan-sion performance, collapse pressure and the equivalent density of fracture pressure. tent （30% ） and high content （5 7 % ） and mixed layer ratio （5 5 % ） were found in the Anjiiiaiiie Formation and thepurple mudstone subgroup, the electron microscopic scanning of the core shows that the core surface contains alarge number of I /S, therefore, the drilling fluid filtrate relies on the pressure difference and the capillary action topenetrate the strata is caused by the formation of non-uniform hydration expansion is the mai n reason for formationinstability. The recovery rte and the expansion rate of the cuttings showthat the stdispersion and high expansion, which can easily lead to the collapse of the borehodrilling fluid. The strength test shows that the compressive strength of the core is l o w, and of the oil-based drilling fluid decreases after the soaking of the water-based drilling fluid, which indicates that thecompressive strengtii of tiie core itself is also the essential reason of tiie formation instability. In addition, the forma-tion of high pore pressure, drilling fluid safety density w i n d o w is n a r o w, improper drilling fluid density control isalso leading to instability （loss and collapse） of tiie important reasons.

关 键 词：准噶尔盆地 黏土矿物 伊蒙混层 电镜扫描 X射线衍射 井壁失稳 

分 类 号：TE39[石油与天然气工程—油气田开发工程]