无限级压裂固井滑套及关闭工具的研制

分段压裂技术已成为低渗致密油气藏提高产量的有效技术手段,尤其是液压式分段压裂技术能实现无限级层段压裂施工改造,改造后可保持原套管通径。为了解决现有固井滑套只能采用液压开启,后期无法关闭,且现有的关闭工具不具备强制脱手功能而无法满足油气藏安全开发的技术问题,研制了无限级压裂固井滑套及其配套的关闭工具,并对固井滑套和关闭工具的关键部件进行了有限元分析,验证了工具结构的合理性。测试结果表明,该固井滑套可承受60 MPa压差,液压开启压力约为16 MPa,结构简单,性能可靠;关闭工具在不低于1 MPa的压差下开关块完全突出,可有效进行固井滑套的关闭动作,其强制脱手拉力约为4 kN。研制的无限级压裂固井滑套可实现液控开启和机械关闭,关闭工具具备强制脱手功能,可有效避免在固井滑套关闭过程中因拉力过大造成的连续管拉断风险。

Development of Cased Hole Sliding Sleeve and Closing Tool for Infinite Stage Fracturing

The staged fracturing technology has become an effective technical means to enhance production in low-permeability tight oil and gas reservoirs.Especially,the hydraulic staged fracturing technology can realize infinite stage fracturing,and provide full bore after the stimulation.To address the technical problem that the existing cased hole sliding sleeve can only be opened by hydraulic pressure and cannot be closed,and the existing closing tools do not have a forced release function that cannot meet the requirement of oil and gas reservoirs safety development,a cased hole sliding sleeve and supporting closing tool for infinite stage fracturing is developed.Finite element analyses on the key components are conducted to verify the rationality of the tool structure.The test results show that the cased hole sliding sleeve can withstand a pressure difference of 60 MPa.The opening pressure is about 16 MPa.The structure is simple,and the performance is reliable.The shifting block is completely protruded under the pressure difference of no less than 1 MPa,which can effectively close the cased hole sliding sleeve.The forced release pull force is about 4 kN.The developed cased hole sliding sleeve for infinite stage fracturing can realize hydraulic opening and mechanical closing.The closing tool has a forced release function,which can effectively avoid the risk of coiled tubing breakage caused by excessive tension during closing of the cased hole sliding sleeve.