川东地区二迭系梁山组地层井壁不稳定机理及对策

川东地区属高陡构造，二迭系梁山组地层破碎松散，断层多，钻井过程常遇到掉块、坍塌、泥页岩水化膨胀缩径等严重井下复杂情况，已成为该地区深井钻控的严重障碍，在分析地层岩石矿物组成微观结构和理化特性的基础上，从地质、水化、物理和工程等方面分析井壁失稳机理，提出梁山组地层防塌技术对策：（1）严格控制当量钻井液浓度；（2）钻井液应具有良好的封堵性和抑制性；（3）严格控制失水小于10ml；（4）钻井液pH值控制在8～9；（5）尽量缩短浸泡时间。

The borehole instability mechanism and countermeasure to Permian Liangshan formation in east of Sichuan

East of Sichuan area is belong to high and steep structure. For Permian Liangshan formation is broken formarion and has many fault, wall sloughing, shale hydrate expansion and hole diameter reduction etc. downhole complex accident are often encountered during drilling. These cases have become serious obstruct to drill deep well in east of Sichuan. On the basis of analysis of structure and physicochemical characteristic of formation rock mineral, this paper analyzes the sidewall instability mechanism in geology, shale hydration, physics and engineering aspects. The technique countermeasures for hole sloughing prevention are proposed, including suitable mud density, good seal and inhibition for drilling fluid, water loss less than 1Oml and shorten soak time etc..