摘要
长庆马岭油田水力压裂过程中套管变形问题频繁发生。针对该问题,考虑直井段地层力学特性变化、直井段套管内压变化,建立了水泥环环状缺失套管应力计算模型,分析了缺失位置套管应力以及安全系数随井深变化规律,研究了套管内压对于套管安全系数的影响规律,计算了不同钢级、壁厚套管的极限井深。研究结果表明:水泥环环状缺失导致套管应力显著增加,最大应力处出现在水泥环完整和缺失界面位置;随着井口压力的不断增加或井深的不断增加,缺失处套管应力不断增加,安全系数不断降低。提升套管钢级和降低径厚比都有利于套管安全系数的提升,保持合理的内压是防控水泥环缺失段套管变形的有效防范措施,最终形成了一种水泥环环状缺失时套管规格优选方法。研究结果可为马岭油田套管钢级和壁厚的优选提供依据。
In the Maling Oilfield,Changqing,casing frequently deform during the hydraulic fracturing process.In order to solve this problem,considering the change in mechanical behavior of strata and internal pressure of casing in vertical hole section,a stress calculation model of casing with a missing of cement sheath was built.The variation of casing stress and safety factor with well depth at cement sheath missing place was analyzed.The influence of internal pressure of casing on the casing safety factor was identified.The ultimate well depth of casing with different steel grades and wall thicknesses was calculated.The study results show that the missing of cement sheath leads to a significant increase in casing stress,and the maximum stress occurs at the complete and missing interface of cement sheath.With the increase of wellhead pressure or well depth,the casing stress at the cement sheath missing place increases and the safety factor decreases.Increasing the steel grade of casing and reducing the radius-thickness ratio are all beneficial to the improvement of the safety factor of casing.Maintaining a reasonable internal pressure is an effective preventive measure to prevent and control the deformation of casing in the cement sheath missing section.A casing specification optimization method at the time of missing of cement sheath is finally formed.The study results provide a basis for the optimization of steel grade and wall thickness of casing in the Maling oilfield.
作者
丁建新
席岩
王海涛
温欣
李辉
郭雪利
Ding Jianxin;Xi Yan;Wang Haitao;Wen Xin;Li Hui;Guo Xueli(Kunlun Digital Intelligence Technology Co.,Ltd.;Faculty of Architecture,Civil and Transportation Engineering,Beijing University of Technology;CNPC Engineering Technology R&D Company Limited)
出处
《石油机械》
北大核心
2023年第4期112-118,共7页
China Petroleum Machinery
基金
国家自然科学基金青年基金项目“基于压裂过程中四维地质力学的套管变形机理及控制方法研究”(52004013)
中国石油天然气集团公司科技项目“钻完井及井下作业智能优化系统研发-基于智能计算理论的多场耦合作用下井筒完整性评价与控制参数优化技术研究(2021DJ7401)”。
关键词
水力压裂
水泥环缺失
套管变形
安全系数
壁厚
应力变化
hydraulic fracturing
missing of cement sheath
casing deformation
safety coefficient
wall thickness
stress change
