【摘要】 井壁的稳定性问题是一项急需解决的世界级难题，井壁失稳在世界范围内的各个油田中普遍存在。A-1井是一口位于东海某区块的直井，根据相邻已钻井复杂情况统计可知，该区块遇阻、掉块、卡钻等问题频发。将理论分析与数值模拟相结合，通过收集大量的地质、地震、钻井和测井资料，选择合适的理论模型，预测计算了A-1井的地应力、孔隙压力、破裂压力、坍塌压力等，绘制出了地层七压力剖面图，进而得到该井的安全钻井液密度窗口。经与实测点比对，孔隙压力和破裂压力的预测误差均小于5%。基于弹塑性力学理论，分析井壁围岩的应力状态，并利用ABAQUS软件对井壁稳定性进行数值模拟，分析钻井液密度对井筒稳定性的影响。结果表明：在低钻井液密度条件下，井周应变不均匀性明显，最小主应力方向上的井周应变远大于最大主应力方向上的井周应变；而在高钻井液密度下，井周应变较为均匀，没有明显的差异性。研究成果为了解目标区块井壁稳定机理提供了有力工具。更多还原

【Abstract】 The problem of wellbore stability is a world-class problem that needs to be solved urgently, and wellbore instability is widespread in various oilfields around the world. Well A-1 is a vertical well located in a block in the East China Sea. According to the statistics of the complexity of adjacent drilled wells, the block is blocked, broken and stuck frequently. Combining theoretical analysis with numerical simulation, through collecting a large number of geological, seismic, drilling and logging data, selecting an appropriate theoretical model, predicting and calculating the ground stress, pore pressure, fracture pressure, collapse pressure, etc. of well A-1, drawing a seven pressure profile of the formation, and then obtaining the safe drilling fluid density window of the well. Compared with the measured points, the prediction errors of pore pressure and fracture pressure are less than 5%. Based on the theory of elastic-plastic mechanics, the stress state of the surrounding rock of the shaft lining was analyzed, and ABAQUS software was used to conduct numerical simulation of the stability of the shaft lining, the influence of drilling fluid density on the stability of the shaft was analyzed. The results show that under the condition of low drilling fluid density, the strain around the shaft is obviously uneven, and the strain around the shaft in the direction of the minimum principal stress is far greater than the strain around the shaft in the direction of the maximum principal stress. However, under the condition of high drilling fluid density, the strain around the well is relatively uniform without obvious difference. The research results provide a powerful tool for understanding the wellbore stability mechanism of the target block.更多还原