超深大斜度高破压井国产封隔器优化与改进

Optimization and improvement of domestic packer in ultra-deep,high-angle and highbreak wells

川西雷口坡组超深大斜度小井眼井储层破裂压力高达170~180 MPa,受高交变载荷、井眼轨迹等因素影响,储层改造施工过程中易出现封隔器密封失效、卡瓦落井等问题。分析失效原因,明确了胶筒密封不足、缸体强度不足、卡瓦结构缺陷是导致封隔器失效的主要因素。优化胶筒结构为MESH结构提高密封可靠性,改进缸体设计使得缸体绝对承压由75 MPa增加到125 MPa,满足泵压120 MPa下改造要求,同时调整卡瓦与锥体距离,避免解封上提时在喇叭口位置发生挂卡。改进后的127 mm高温高压测试封隔器在川西超深大斜度井累计试验3井次,成功率100%。该封隔器及配套工具能满足超深大斜度井高破压含硫地层70 MPa或更高压差下改造及试气需求。

In the Leikoupo formation of the western Sichuan Basin,the fracture pressure of ultra-deep highly deviated wells with slim borehole can reach as high as 170~180 MPa.Due to factors such as high alternating loads and well trajectory,issues such as sealing failures and slip falling into the wellbore are prone to occur during reservoir stimulation construction.Through analyzing the failure reasons,it was clarified that insufficient seal of the rubber cylinder,insufficient strength of the cylinder body,and defects in the slip structure are the main factors leading to slip failure.By optimizing the structure of the rubber cylinder to a MESH structure to improve sealing reliability,improving the design of cylinder body to increase the absolute pressure-bearing capacity from 75 MPa to 125 MPa,the stimulation requirement within a pump pressure of 120 MPa was met.Additionally,distance between the slip and the cone was adjusted to avoid hanging up at the bell mouth position during lifting.The improved 127 mm high-temperature and high-pressure test packer was tested in three ultra-deep highly deviated wells in the western Sichuan Basin,achieving a success rate of 100%.This packer and its supporting tools can meet the requirements of reservoir stimulation and gas testing in ultra-deep and highly deviated wells with high fracture pressure in sulfur-containing formations with pressure of 70 MPa or higher.