渤海稠油热采井井口抬升距离预测研究

Prediction and Research of Wellhead Growth in Bohai Offshore Heavy Oil Thermal Recovery Wells

我国渤海油田具有丰富的稠油资源,稠油储量占总储量65%以上。海上稠油开发受到平台面积、作业环境的限制,一般采用蒸汽吞吐方式进行开发。实际生产中,随着多轮次的蒸汽注入容易导致井口抬升或者损坏,严重威胁平台井口装置及管线安全。目前关于热采井井口抬升的研究大部分针对自由套管受热后的轴向伸长,当固井水泥环返至井口时不再适用。本文考虑全井固井条件下,井口附近套管-水泥环胶结失效后水泥环对套管的摩阻约束,分析了套管-水泥环接触压力及水泥环摩擦阻力变化规律,建立了井口抬升距离预测模型。根据该模型对渤海油田南堡区块A井注汽作业时井口抬升距离进行了15轮次的预测分析,预测结果表明:15轮次内的井口最大抬升距离为15.28 cm,现场实测抬升距离为14.99 cm,误差仅为1.93%,其余各轮次预测误差均小于5%,满足工程需要。该研究对于现场合理选择热采井井口装置具有重要意义。

The Bohai oil field in China has abundant heavy oil resource, which is about more than 65% of the total reserves. Offshore heavy oil exploration is limited by platform area and operating environment, so cyclic steam injection is often adopted. In actual production, many rounds of steam injection can lead to wellhead growth and damage easily. It seriously threatens the safety of wellhead equipment and the pipeline. At present, most studies of thermal recovery wellhead growth are about the axial extension of free casing when heated, it’s not applied to casing which is cemented. In this paper, by considering the well cementing to the wellhead and casing constrained by cement friction after cementing failure, the casing and cement contact pressure and cement sheath friction change law are analyzed and a wellhead growth prediction model is established. The wellhead growth during 15 rounds of steam in.jection of the well A in Nanpu blocks in Bohai oilfield is predicted and analyzed with this model. The results showed that the maximum wellhead growth in 15 rounds steam injection is 15.28 cm, the measured growth is 14.99 cm, the error is only 1.93%. The prediction error in all other rounds is less than 5%, which meet the needs in engineering. This research has great significance for selecting wellhead equipment rationally in thermal recovery wells.