海上超深大位移气井生产管柱设计与应用

Design of Production String for Offshore Ultra-Deep Extended Reach Gas Well and Its Application

海上超深大位移气井生产管柱下入超深,压降摩阻损失和起下摩阻均远大于常规井,功能设计不同于常规井,设计难度大。以海上一口典型的超深大位移气井为例,通过管柱敏感性分析优选油管尺寸,通过下入能力分析优选88.9 mm与73.03 mm油管组合,推荐88.9 mm油管长度为3000 m,通过优化功能设计解决油管试压和封隔器坐封难题,形成一套超深大位移气井生产管柱设计方法,为海上大位移气井设计提供参考和借鉴。该井实际作业顺利,生产情况良好,井筒完整性良好,生产管柱下入反演摩阻系数为0.08~0.16,小于设计阶段取值0.12~0.27,证明在设计阶段摩阻系数取值保守,抗拉强度安全系数取值1.6合理,建议大位移井生产管柱抗拉强度安全系数的选择需综合考虑摩阻系数取值。

The offshore ultra-deep extended reach gas well is of ultra-large production string running depth,its tripping friction resis⁃tance and friction resistance pressure drop are far greater than those of conventional wells,which will cause that its function design is different from the conventional wells and difficult.Taking a representative offshore ultra-deep extended reach gas well as an example,the combination production string composed of 3 1/2″tubing and 2 7/8″tubing is selected through sensitivity analysis of production string.The recommended length of 3 1/2″tubing is 3000 m.By optimizing the function design,the problems of tubing pressure testing and packer setting are solved,and a set of production string design method of ultra deep extended reach gas well is formed,which provides a reference for the design of offshore extended reach gas wells.The actual operation of the well is smooth,and its production condition and wellbore integrity are good.The inverse friction coefficient of the production string running is 0.08~0.16,which is less than the value of 0.12~0.27 in the design stage,which proves that the value of friction coefficient in the design stage is conservative,and the value of tensile strength safety factor of 1.6 is reasonable.It is suggested that the selection of safety factor of tensile strength of produc⁃tion string in extended reach well should comprehensively consider the value of friction coefficient.