6000m以上超深井套损因素分析及治理对策

The Results Analysis and Countermeasures on Casing Wear in the Ultra-deep Well of Tahe Oilfield

塔河油田属于碳酸盐岩缝洞型油藏,开发难度大。在开发过程中,套管的变形、损坏时有发生,直接影响着油井的正常运转和生产。为找到套管损坏的规律和根本原因,对塔河油田440口高含H2S(95%井H2S超过20mg/L,平均1500mg/L)的掺稀超深生产井(5500~7100m)10年来的套管损坏情况进行了分析。分析结论认为塔河油田超深井套损的发生主要受井超深应力变化、裸眼上段的泥质岩、完井套管材质适应性差、地层改造强度高、生产压差大、套管悬挂器和套管接箍等因素影响。由于受井深限制,出现套损后,套管补贴难度大,普通的挤堵修套有效期短,因此超深井的套管损坏应以预防为主。预防套管损环的主要措施应以提高钻井技术、固井质量为基础,以取准地应力变化趋势、制定合理的注水、生产压差为手段,以研制抗高温、高H2S、高矿物质及超高强度抗挤毁的非API套管为攻克点,全面提高套管抗损坏能力。

Tahe oilfield belongs to carbonate fractured-vuggy reservoirs with great difficulty on production.During the development,deformation and wear of the casing occurred sometime,which effected normal operation and production of the oil wells.In order to find rule and basic reasons of the casing wear,casing failure of 440 bare foot ultra-deep wells(5500-7100m) in the carbonate reservoirs with high concentration of H2S(more than 20mg/L in 95% of the wells,and 1500mg/L of the average value) in Tahe oilfield was analyzed for the last ten years.We find the reasons of the casing failure: variation of well stress in the ultra-deep well,distribution of complex argillaceous shale at the top of barefoot interval,poor adaptability of well completion string material,high stress of formation reconstruction,high drawdown pressure,and quality of casing hanger and casing collar.Once casing failure happened,affected by well depth,casing patch will be very difficult and the useful life of normal cement squeeze will be limited.Prevention should be the first important.Major preventive measures for the casing wear should be focused on improving its integral anti-failure ability based on improving drilling technology and cement quality.Non API casing with anti high temperature,anti high concentration of H2S and mineral substance,anti compress should be developed.Tendency of crustal stress variation should be got accurately,and reasonable injection pressure and producing pressure should be made.