BZ25-1油田井壁稳定性分析

ANALYSIS OF WELL BORE STABILITY IN BZ25-1 OILFIELD

介绍了BZ25-1油田井壁失稳的现状。综合利用测井资料、井史和理论分析,采用"关键层位"法确定明化镇组和馆陶组为井壁失稳的关键层位;利用等效深度法计算了孔隙压力,与实测孔隙压力吻合较好;利用密度测井资料计算了垂向地应力;利用改进的黄氏模型计算了水平地应力。利用上述计算的结果和岩石强度参数,计算了坍塌压力和破裂压力剖面。结合井眼波动压力分析结果,给出了钻井液的安全密度窗口。现场应用表明,推荐的钻井液密度应用较好,且低于设计密度。

In this paper,using well logging and well history data and the key layer analytical method,the layers of Minghuazhen and Guantao were confirmed as easiest instable layers.The pore pressure was calculated by using equivalent depth method,and the calculated pore pressure coincided with that of tested.The vertical earth stress was calculated by using density logging data,and horizontal earth stress was also calculated using improved Huang's modulus.Using the research results above mentioned and rock strength parameters,the caving pressure and fracture pressure were calculated.Combined with surge pressure,the safe density window of drilling fluid was given.The application results showed that the recommended mud density meets the need of wellbore stability,and which is lower than that of design.