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。
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.
出处
《石油勘探与开发》
SCIE
EI
CAS
CSCD
北大核心
2016年第5期799-805,共7页
Petroleum Exploration and Development
基金
国家自然科学基金"隔水管内气液两相流声传播特性与深水钻井气侵检测方法"(51574275)
教育部长江学者创新团队项目"海洋油气钻完井理论与工程"(IRT1086)
中国石油大学研究生自主创新工程(YCXJ2016011)
关键词
深水油气井
环空压力
流体特性
环空流体
极限环空饱和度
deepwater wells
annular pressure
fluid properties
annular fluid
extreme annular saturation
