井壁稳定技术在涠洲11-1油田的应用

涠洲11-1油田地处南海西部北部湾盆地,该油田在钻井过程中极易发生井壁失稳问题,给钻井工程带来很大的风险,因此针对该油田进行井壁稳定机理研究显得十分必要。借助涠西南油田群井壁稳定性研究的成果,系统综述了与涠洲11-1油田有关的井壁稳定性机理及一些具体结论,包括微裂缝状况、地应力大小和方向、沿井眼轨迹的地层坍塌压力剖面,并提出了相应的实用技术对策,主要有确定合理的安全钻井液密度、强力防塌油基钻井液的应用、优化井眼轨迹及降低裸眼井段暴露时间等。将这些技术应用于涠洲11-1油田复杂地层的钻进过程中,实践证明取得了较好效果,涠洲11-1油田未出现因井壁失稳问题导致井下复杂情况或事故。

Application of sidewall stability technology in Weizhou11-1 oilfield

Weizhou11-1 oilfield,lying in Beibu Gulf Basin in west area of South China Sea,where sidewall instability problem is easier to appear in drilling process,bringing very big risk for drilling process.Therefore,research on sidewall stability mechanism for this oilfield is very necessary.With the results of research on sidewall stability in Weixinan oilfield group,this paper systematically summarizes sidewall stability mechanism and some specific conclusions on WZ11-1 oilfield,including micro-crack status,the size and direction of Earth stress,formation collapse pressure profile following borehole trajectory.Then it proposes corresponding practical technique strategies,mainly including confirming reasonable drilling fluid density,applying high strength anti-collapse oil-base drilling fluid,optimizing borehole trajectory,decreasing the exposure time of open-hole interval and so on.It made good results by applying the said techniques in drilling process of complex formation in Weizhou11-1 oilfield,no complicated cases and accidents caused by sidewall instability happening during the drilling progress in WZ11-1 oilfield.