高压气井钻进过程中控制回压值研究

 Research on values of managed back pressure during drilling of high pressure gas well

 刘刚¹ 黄亮² 金业权¹ 常鑫¹

中国石油大学（华东）石油工程学院，山东　青岛　２６６５80 中海石油（中国）有限公司湛江分公司，广东 湛江 524057

 对于高压气井特别是含硫气井安全钻井的控制回压值确定，目前还没有明确结论。文中以漂移流动理论为基础，建立了高压气井带回压井筒气液两相流动计算模型，并结合算例采用数值方法分析了不同井口回压对气体膨胀抑制效果及井底压力的影响。在综合考虑抑制气体膨胀、控制井底压力降低幅度、井控装备工作安全和不同回压下井控人员心理压力等因素的前提下，给出了保持高压气井钻井安全宜施加2～5 MPa井口回压的建议。

 No accurate conclusion has been reached so far for the determination of wellhead back pressure values during the drilling of high pressure gas well, especially for the sulphur gas well. Based on the theory of drift flow, the computational models of gas-liquid flow are established under the condition of drilling with back pressure in high pressure gas well zone and computed by using finite difference approach. Combined with the examples, the effects of different back pressure on gas expansion and bottom-hole pressure have been analyzed. The results show that values of wellhead back pressure is suitable to be controlled under 2-5 MPa during drilling. This can not only inhibit the invasion of gas expansion and effectively control the bottom-hole pressure reduction, but also can ensure the safety of well control equipment and relieve the psychological burden of operation personnel.

10.6056/dkyqt201203023