耐超高温全金属桥塞研制与室内试验测试

Development and Laboratory Test of All-Metal Bridge Plug for Ultra-High Temperature Environments

针对目前可溶桥塞承压强度低、降解速率慢、无法适用于超高温环境的问题,创新性提出适用于超高温环境的全金属桥塞设计方案,同时开展可溶镁基合金的室温、高温下力学性能试验及高温溶解性能试验,并结合有限元分析结果完成桥塞关键部件材料优选,最终试制耐超高温全金属桥塞实物样机并开展室内试验测试,从室温承压性能、高温承压性能和溶解性能3个方面验证实际应用效果。研究结果表明:随着温度升高,相对于高伸长率可溶镁基合金,高强度可溶镁基合金抗拉强度和屈服强度下降幅度较小,伸长率变化幅度较大;在超高温环境中,可溶解镁基合金溶解速率呈现慢-快-慢现象,在溶解后48~72 h内溶解速率最快;研制的耐超高温全金属桥塞在205℃、质量分数2%的KCl水溶液中最高可承受压差70 MPa,并保持10 h有效密封;在模拟工况下的密闭容器中8 d可完全溶解,满足设计要求并具备入井条件。该研究可为开发适用于超高温环境的全金属桥塞提供技术支撑。

Soluble bridge plugs are deficient for low compressive strength,slow degradation rate,and inapplicability to ultra-high temperature environment.For these problems,an innovative design of all-metal bridge plug for ultra-high temperature environments was proposed.The room-temperature and high-temperature mechanical performance and high-temperature dissolution performance of soluble magnesium-based alloys were performed.Moreover,the materials for key bridge plug components were optimized through the finite element analysis.Finally,the prototype of all-metal bridge plug for ultra-high temperature environments was trial-manufactured and laboratory-tested.The application performance was verified with respect to pressure-bearing and dissolution capacities at room and high temperatures.The results show that with increasing temperature,high-strength soluble magnesium-based alloys present smaller reductions of tensile and yield strengths and yet considerable growth of the elongation rate,compared with high-elongation soluble magnesium-based alloys.At ultra-high temperatures,the dissolution rate of soluble magnesium-based alloys is found with a trend featuring slow-fast-slow variation,and the dissolution rate is the highest at 48~72 hours of dissolution.The developed all-metal bridge plug for ultra-high temperature environments can withstand a pressure difference of up to 70 MPa in 2%KCl aqueous solutions at 205℃,and maintain an effective seal for 10 hours.It can be completely dissolved in a closed container under simulated working conditions within 8 days,which meets the design and downhole service requirements.This study provides vital technical support for the development of all-metal bridge plugs suitable for ultra-high temperature environments.