【摘要】 以伊朗西南部某油田Asmari组砂岩储集层为研究对象,研究其中一口垂直井的井筒稳定性,利用FLAC3D软件,根据钻遇地层地质力学特征建立井筒的有限体积模型,监测井壁岩石塑性状态的形成以确定砂岩层安全钻井液密度的上限值和下限值。评估了岩石强度特性、井筒周围主要地应力和孔隙压力对该井安全钻井液密度窗口的影响,敏感性分析结果表明,井壁岩石内聚力和内摩擦角的减小会导致安全钻井液密度窗口大幅变窄;孔隙压力和最大水平应力与最小水平应力之比的减小则会使安全钻井液密度窗口显著增大。此模型便于量化安全钻井液密度窗口的变化,可作为一种油气井钻井方案设计和监测工具。图11参50更多还原

【Abstract】 The wellbore stability of a vertical well through the sandstone reservoir layers of the Asmari oil-bearing formation in south-west Iran is investigated. The safe drilling-fluid density range for maintaining wellbore stability is determined and simulated using FLAC3D software and a finite volume model established with drilled strata geomechanical features. The initiation of plastic condition is used to determine the safe mud weight window(SMWW) in specific sandstone layers. The effects of rock strength parameters, major stresses around the wellbore and pore pressure on the SMWW are investigated for this wellbore. Sensitivity analysis reveals that a reduction in cohesion and internal friction angle values leads to a significant narrowing of the SMWW. On the other hand, the reduction of pore pressure and the ratio between maximum and minimum horizontal stresses causes the SMWW to widen significantly. The ability to readily quantify changes in SMWW indicates that the developed model is suitable as a well planning and monitoring tool.更多还原