超高压气井井口安全系统及其应用

Wellhead safety system of ultrahigh pressure gas wells and its application technologies

国内外采气树井口安全阀控制目前主要采用液动控制技术和气动控制技术,气动安全阀控制技术停留在低压、常温、低产、非腐蚀气质条件范围及压力等级34.5 MPa、69.0 MPa以下阶段,压力等级103.5 MPa、138.0 MPa及以上的超高压气井采用气动井口安全阀的控制至今尚无经验可循。为了解决目前国内超高压气井井口安全阀在高压、高温、高产、高腐蚀气质等恶劣工况下的使用难题,保证井口安全阀功能的有效性,确保采气树井口装置安全可靠,通过对井口安全系统一体化优化设计,从气动安全阀应用叠式气动执行器成套组装技术、气动安全阀在工艺管道上串联冗余安装方式、高低压压力传感器采用103.5 MPa等级保护技术、节流阀后加装防低温冻结的加温技术和控制系统采用逻辑关联控制技术等多方面、多角度对超高压气井的井口安全系统的应用技术进行分析,并在我国超高压气井双探1井井口安全控制系统进行了首次应用,取得了圆满成功,解决了超高压气井井口安全系统在国内使用的难题,为超高压气井气动安全阀控制技术推广应用奠定了基础。

Hydraulic control technology and pneumatic control technology are the principal control technologies for wellhead safety valve of Christmas tree around the world. The pneumatic control technology is still suitable for low pressure, normal temperature, low yield, non-corrosive medium and pressure rating lower than 34.5 MPa or 69.0 MPa. There is no experience available for the con- trol of pneumatic wellhead safety valve in ultrahigh pressure gas wells with pressure rating of 103.5 MPa, 138.0 MPa and above. In this paper, integrated optimization design was performed on wellhead safety system to solve the problems in application of wellhead safety valve in ultrahigh pressure gas wells where severe conditions exist （e.g. high pressure, high temperature, high yield and highly corrosive gas）, so as to ensure the functional effectiveness of wellhead safety valves and the safety and reliability of wellhead devices of Christmas trees. The application technologies for wellhead safety system of ultrahigh pressure gas wells were analyzed from multi- ple aspects, including complete assembly technology for stack type pneumatic actuator, tandem redundancy installation of pneumatic safety valve on process pipeline, protection technology of 103.5 MPa rating for high and low pressure sensors, heating technology for low-temperature anti-freezing behind the throttle valve, and logic association control technology for control system. These application technologies were, for the first time, successfully used for wellhead safety control system of Well Shuangtan 1, an ultrahigh pressure gas well in China. They help to solve the problems in application of wellhead safety system in ultrahigh pressure gas wells in China, and provide the basis for the popularization and application of pneumatic safety valve control technologies for ultrahigh pressure gas wells.