水平井试油过程裂缝性储层失稳机理  

A mechanism study on the fractured reservoir instability during well testing of horizontal wells

作　　者：金衍[1] 齐自立[1] 陈勉[1] 张福祥[2] 卢运虎[1] 侯冰[1] 

机构地区：[1]中国石油大学石油工程学院,北京102249 [2]中国石油塔里木油田公司,新疆库尔勒834000

出　　处：《石油学报》2011年第2期295-298,共4页Acta Petrolei Sinica

基　　金：国家重点基础研究发展规划(973)项目(2010CBN226700);教育部新世纪优秀人才支持计划项目(NCET-08-0840)联合资助

摘　　要：针对水平井裂缝性储层试油过程中井底压力选择不当会引起井壁坍塌问题,开展了天然裂缝性储层水平井井壁稳定问题研究。从井壁稳定的力学机理出发,建立了水平井井周应力状态,选用弱面破坏准则,建立了水平井段测试过程维持井壁稳定的井底最小压力模型,模型考虑了天然裂缝产状、井斜方位、地应力、地层强度与孔隙压力的联合影响。在此基础上定量分析了各因素对维持井壁稳定的最小井底压力的影响。结果表明:天然裂缝面倾角小于45°时,井壁岩石发生弱面破坏,倾角大于45°时,在某些井眼方位井壁岩石会发生本体破坏;天然裂缝走向对井壁的破坏形式也有显著的影响,在最小水平地应力方位附近,井壁最易坍塌;随着地应力非均质性的增强、孔隙压力的升高,维持井壁稳定的井底最小压力逐渐增大。The improper selection of the bottomhole pressure may cause borehole collapse during well testing of horizontal wells in fractured reservoirs.For this reason,the present paper carried out a study on the borehole stability of horizontal wells in naturally fractured reservoirs.A circumferential stress state of horizontal wells was presumed based on the mechanics of borehole stability.According to weakplane failure criteria,a model for the minimum bottomhole pressure to maintain borehole stability during testing of horizontal wells was established,and it gave attention to various composite effects of natural fracture occurrences,hole deviation azimuth,in-situ stress,formation strength and pore pressure and etc..Based on these,the paper quantitatively analyzed effects of various factors on the minimum bottomhole pressure for maintaining borehole stability,indicating that for a natural fracture surface with DIP45°,a weak-plane damage occurred in sidewall rocks,while if DIP45°,a sidewall rock itself might destroy.Strike of natural fractures could apparently also impact the damage form of sidewall rocks,and a sidewall adjacent to the minimum horizontal stress orientation was most readily to collapse.With the increase of stress heterogeneity and pore pressure,the minimum bottomhole pressure for maintaining borehole stability increased gradually.

关 键 词：试油 裂缝性储层 水平井 弱面破坏 井壁失稳 

分 类 号：TE273[石油与天然气工程—油气井工程]