川东北地区陆相地层井眼失稳原因分析

川东北地区的勘探规模正在不断扩大,但施工时因陆相地层的失稳常造成重大经济损失,并延缓了勘探进度。室内试验结果表明,该地区陆相地层基本以泥岩为主,粘土矿物以伊利石为主,具有一定的膨胀能力,但表面水化作用非常显著,遇水后很短时间内即可达到最大水化程度,这有别于一般意义上的泥页岩地层。对该地区陆相地层基本资料进行了综合分析,并在此基础上归纳了陆相地层常见的失稳形式,分析总结了井壁失稳原因,以期对正确制定陆相地层井壁稳定技术方案提供参考。由于最终的分析结论均基于川东北地区近年来的相关技术资料,针对性强,与现场情况结合紧密,因此具有较好的可借鉴性。

Analysis of Wellbore Collapse in Continental Strata in Northeastern Sichuan Basin

Exploration scale in northeastern Sichuan basin is continuously expanding,while wellbore collapse in continental strata resulted in significant economic losses and delayed the progress of exploration.Laboratory experiment shows that continental strata consist mainly of mud shale which mainly comprise illite with a certain swelling capacity.While the surface hydration is very severe,the greatest degree of hydration can be obtained within a very short period of time after meeting the water which is different with conventional mud shale.Based on the comprehensive analysis of basic information of the continental strata,the reasons for well collapse were summarized for the purpose of providing the reference to solve the well collapse correctly.Since the analysis is based on the data of northeastern Sichuan basin which combined with the field condition closely,so it provides better reference.