考虑磨损的弯曲套管抗挤强度研究及应用  

Research on Collapse Strength of Casing in Buildup Section

作　　者：贾宗文 Jia Zongwen(Drilling and Production Research Institute,CNOOC Research Institute Co.,Ltd;State Key Laboratory of Offshore Oil Exploitation,CNOOC Research Institute Co.,Ltd)

机构地区：[1]中海油研究总院有限责任公司钻采研究院 [2]中海油研究总院有限责任公司海洋石油高效开发国家重点实验室,北京市朝阳区100028

出　　处：《石油机械》2018年第12期1-7,共7页China Petroleum Machinery

基　　金：国家科技重大专项“海外重点油气田开发钻采关键技术”(2017ZX05032-004);国家自然科学基金项目“深水高温高压井钻采过程中密闭环空压力预测和套管柱力学研究”(51504284);国家重点基础研究发展计划(973计划)项目“深水海底井口-隔水管-平台动力学耦合机理与安全控制”(2015CB251203).

摘　　要：为避免异常高压造斜井段套管挤毁和变形等复杂情况,针对该井段套管抗挤强度开展了研究,建立了弯曲套管抗挤受力模型及套管磨损量化理论模型,研究了套管抗挤强度随井眼曲率、轴向载荷及磨损深度变化的规律。研究结果表明:套管抗挤强度随井眼曲率、轴向载荷的增加逐渐下降,且服从良好的二次函数关系;综合考虑轴向载荷及弯曲作用下,套管抗挤强与磨损深度服从良好的线性下降关系。针对目标井所用的244. 5 mm技术套管,在设计的每100 m井段10°造斜率下校核了不同磅级与不同钢级下的套管抗挤强度,推荐了满足强度要求的套管规格。综合考虑轴向载荷及磨损,在设计的10°造斜率下,计算得到剩余套管抗挤强度最低为54. 106 MPa,较套管API名义抗挤强度降低约7. 194 MPa,降幅11. 74%,剩余抗挤安全系数为1. 312(>1. 125),满足标准设计要求,同时计算了推荐套管所能承受的最大曲率范围。指出弯曲载荷下的套管抗挤强度受弯曲率及磨损深度影响较大。研究结果对于造斜井段的套管抗挤强度设计具有一定的借鉴意义。To avoid the complex conditions such as casing collapse and deformation in abnormal high-pressure inclined well section, the casing collapse strength is studied. The model of bending casing and the model of casing wear are established. The effects of wellbore curvature, axial load and wear depth on casing collapse strength are studied. The results show that the casing collapse strength decreases with the increase of the wellbore curvature and the axial load, and in a good quadratic function relationship. Under the axial and bending load, the casing collapse strength is in a good linear decline relationship with wear depth. For the Ф244. 5 mm intermediate casing in the case well, the collapse strength of different casings with different weights and grades are checked under the wellbore cur- vature of 10°/100 m. The casings met the strength requirements are recommended. The maximum curvatures the recommended casings can withstand are also calculated. The casing collapse strength under bending load is greatly affected by the bending rate and the wear depth. The research results could provide references for the casing design in the inclined well section.

关 键 词：异常高压 造斜井段 弯曲套管 抗挤强度 井眼曲率 轴向载荷 磨损深度 

分 类 号：TE925[石油与天然气工程—石油机械设备]