中文摘要：

针对密闭环空压力威胁深水油气井安全生产的问题,建立了密闭环空压力计算模型,研究了井筒内流体特性对环空压力的影响规律,并分析了各可控因素的敏感性和工程可行性。建立了基于相容性原则的体积平衡方程组和基于井筒-地层耦合传热的井筒温度计算模型,实现多层次含液密闭环空压力计算。环空压力随着环空液体的膨胀压缩比减小而降低;降低环空饱和度能从根本上消除环空压力,提出了极限环空饱和度计算公式;产出液比热容和流量的增加使环空压力上升;环空压力与产出液井底温度呈线性关系,产出液井口温度能够反映环空压力大小;含水率上升使环空压力动态增长。环空饱和度的调控敏感性远高于其他因素,降低环空液体导热系数具有较高的工程可行性。研发可释放环空液体的水下井口设备、高可压缩性材料和井下隔热液体可有效控制环空压力。

英文摘要：

To reduce the threat of trapped annular pressure on deepwater wells safe production,this study established a model of calculating trapped annular pressure,examined the influence of wellbore fluid properties on trapped annular pressure,and analyzed the sensitivities and engineering feasibilities of controllable factors.To realize the calculation of trapped annular pressure under multiple annuli with liquid,a volume balance matrix was built according to compatibility principle and a wellbore temperature computing model was built based on wellbore-formation coupled heat transfer.Annular pressure decreases as the expansion-compression ratio of annular fluid reduces.Decreasing annular saturation can eliminate annular pressure radically and then a formula was proposed to give extreme annular saturation.The increase of production fluid specific heat capacity and flow rate leads to enhancement of annular pressure.Annular pressure keeps a linear relation to production fluid hole bottom temperature and the wellhead temperature can reflect the value of annular pressure.The water ratio increase of production fluid causes dynamic increase of annular pressure.The sensitivity of annular saturation is much higher than other factors.Decreasing annular liquid thermal conductivity has relatively higher engineering feasibility.The annular pressure can be controlled effectively by developing subsea wellheads with the ability to release annular fluid,highly compressible materials and downhole thermal-insulated fluids.