煤层气多分支井成井失效分析及补救措施研究

Drilling Failure Analysis and Remedial Measures of Coalbed Methane Multiple Laterals Wells

煤层气多分支水平井是煤层气高效开发方式之一,钻井过程中易发生煤层垮塌、卡钻等复杂事故,其制约煤层气多分支水平井有效成井,影响开发效率。本文从煤岩特性、宏观地质构造、煤层力学环境和施工参数、工艺技术措施等方面对煤层气水平多分支井成井失效因素进行分析,通过优化设计和工艺措施参数等措施对煤层气多分支水平井成井失效后进行补救,来达到煤层气多分支井地质控制点的目的,扩大井眼的波及面积,提高单井产量。结果表明:(1)成井失效的地质因素主要是煤岩具有性脆、易水化、不稳定、强度低等地质特性,分布有破碎带、断层等复杂的宏观地质构造;(2)成井失效的工程因素主要是由钻压、转速、排量等钻井参数不当和频繁起下钻、划眼等作业施工工艺措施不到位引起的;(3)工程轨迹补救设计创新采用分支"两段扭方位"和"侧钻脉支"轨迹补救设计技术,优化分支井眼轨迹布局;(4)工艺措施参数优化主要是优化钻井参数,采用地质导向轨迹控制技术,确保井眼轨迹在煤层稳定区延伸。通过在山西沁水盆地现场推广应用,解决了多分支水平井成井失效的问题,取得了良好的效果。

The coal bed methane multiple laterals horizontal well is one of the high efficiency development methods, it is prone to collapse and occur complicated accidents during the drilling process, affect the development efficiency. This paper analyzed and researched the coal bed methane multiple laterals horizontal well drilling failure factors ftom the aspects of coal rock characteristics, macroscopic geological structure, coal seam mechanics environment and drill ing parameters and operation technical measures. Adopt trajectory remediation design and drilling parameters optimi zation and other measures to remedy, achieved the purpose of coal bed methane multiple laterals well geological con trol point. The research indicated that： （~）The geological factors of drilling failure are coal rock geological character istics, distribute broken belt, fault and other complex macro geological structure l （~）Drilling failure engineering fac tots are mainly improper drilling parameters ancl improper operation measures l （~）Well trajectory remediation design innovates using ~Two section twist Azimuth＂ and ~Sidetrack pulse branch＂ trajectory remediation design techniques, Optimize the laterals hole trajectory layout l （~）The operation parameters Optimization is mainly to optimize the drill ing parameters, adopt geological guidance trajectory control technology to ensure that the well trajectory extends in the coal seam stability zone. Through the application in Qinshui Basin in Shanxi Province, the coal bed methane mul tiple laterals horizontal well drilling fallure problem has solved, and it obtained good results.