复杂工况油套管柱失效控制与完整性技术研究进展及展望

随着对深层碳酸盐岩、新区、页岩等油气勘探开发力度的加大,油气田的地层条件和介质环境变得更为苛刻复杂,油套管柱变形、泄漏、腐蚀、挤毁、破裂等失效事故时有发生;加上特殊结构井和特殊工艺井、特殊增产改造措施等对油套管柱提出的新要求,油套管柱面临着一系列新的挑战和难题需要破解。为此,围绕我国石油天然气工业增储上产的迫切需求和深井超深井、特殊结构和特殊工艺井、强酸/大排量高压力反复酸化压裂增产改造等复杂工况油套管柱失效频发的技术难题,历经十余年攻关,取得了一系列试验研究进展与重要技术成果,主要包括:(1)形成了基于气井全生命周期的油套管腐蚀选材评价、腐蚀控制和油套管柱完整性技术;(2)形成了油套管柱螺纹连接结构和密封可靠性设计评价及配套技术;(3)研发并形成了低渗透致密气井经济高效开发“API长圆螺纹套管+CATTS101高级螺纹密封脂”套管柱技术;(4)建立了高温高压等复杂工况油套管柱结构和密封完整性试验平台和评价技术。进而根据当前国家大力提升油气勘探开发力度的新要求和面临的新问题,提出了继续深入开展深层、酸性环境、页岩气等复杂工况油套管柱失效控制与完整性研究攻关的若干建议。结论认为,上述技术成果有力地支撑了我国重点油气田的经济有效开发。

Failure control and integrity technologies of tubing/casing string under complicated working conditions: Research progress and prospect

As the exploration and development of deep carbonate reservoirs, new areas and shale oil and gas is strengthened, the stratigraphic conditions and the medium environments of oil and gas fields become more complex and demanding, and failure accidents happen from time to time, such as tubing/casing string deformation, connection leaking, collapse and fracturing. In addition, wells with special structure and special process and the special stimulation measures ask for new requirements on tubing/casing string. As a result, tubing/casing string is faced with a series of new challenges and difficulties. After over 10 years' research, a series of experimental research progresses and important technological achievements have been obtained to meet the urgent need of reserves and production increase of domestic oil and natural gas industry and solve the technological difficulties of frequent tubing/casing string failure under complicated working conditions, e.g. deep and ultra-deep wells, wells with special structure and special process, and repeated acidizing fracturing of strong acid/high displacement and high-pressure. And these achievements are mainly as follows. First, corrosion material selection and evaluation of tubing/casing pipe, corrosion control and integrity technology of casing/tubing string based on the whole life cycle of a gas well is formed. Second, reliability design & evaluation and supporting technologies for the threaded connection structure and seal of tubing and casing are developed. Third, the casing string technology of "API long round threaded casing + CATTS101 advanced thread compound" suitable for the cost-effective efficient development of low-permeability tight gas wells is researched and developed. Fourth, the test platform and evaluation technology for the structure and seal integrity of casing/tubing string under complicated working conditions (e.g. high temperature and high pressure) are established. Then, based on domestic new needs and new problems in strengthening the exploration and development of oil and gas, some suggestions were proposed on continuing to carry out the research on failure control and integrity of casing/tubing string under complicated working conditions (such as deep layer, acidic environment and shale gas). In conclusion, these technological achievements provide powerful support for the cost-effective development of important oil and gas fields in China.