川西北地区超高压含硫气井安全地面集输工艺

四川盆地西北部地区超高压气藏富含硫化氢和二氧化碳,对地面集输工艺的安全性要求极高,其中双探1井为川西北地区典型的超高压含硫气井,是目前国内投入试采井口压力最高(104 MPa)的气井,其安全试采的关键是节流降压和防止天然气水合物形成。为此,以该井为先导,创新建立了超高压含硫气井的地面集输工艺流程:(1)考虑冲蚀腐蚀的影响,按照等压设计思路,设计了高压多级节流橇;(2)提出了地面一级加热+天然气水合物抑制剂+移动蒸汽加热的天然气水合物防治技术;(3)形成了地面安全控制技术,建立了安全等级最高的超高压井口安全系统,保障了气井的安全生产;(4)针对气田产水和高含硫化氢的特点,提出了气液分离+脱硫+缓蚀剂+清管的防腐措施。该配套技术工艺对超高压含硫气井地面集输工艺的研究和试验具有典型性和示范性,对其他同类气田具有一定的借鉴意义。

The surface gathering and transportation technology suitable for ultrahigh pressure sulfur gas wells in the northwestern Sichuan Basin

The ultrahigh pressure gas reservoirs in the NW Sichuan Basin contain high content of hydrogen sulfide and carbon dioxide, so their surface gathering and transportation technology shall meet high requirements. Well Shuangtan 1 is a typical ultrahigh pressure sulfur gas well in the NW Sichuan Basin and its wellhead pressure (104 MPa) is the highest of all production gas wells in China. The key to its safe production testing is to reduce the pressure through throttling and prevent the formation of natural gas hydrate. In this paper, this well was taken as a pilot well to set up the surface gathering and transportation system of ultrahigh pressure sulfur gas well. First, the effect of erosion and corrosion was taken into consideration to design the high pressure multi-stage throttle skid according to the isobaric design concept. Second, a gas hydrate prevention and treatment technology was put forward, i.e., first-stage surface heating + gas hydrate inhibitor + movable steam heating. Third, the surface safety control technology was established, and the ultrahigh pressure wellhead safety system with the highest safety level was set up, so that the safe production of gas wells can be guaranteed. In view of the water production and the high hydrogen sulfide content, pipeline anti-corrosion measures of gas liquid separation + desulfurization + corrosion inhibitor + pigging were presented. This set of technology is typical and demonstrative for the study and experiment of surface gathering and transportation technologies of ultrahigh pressure sulfur gas wells, and it can be used as a reference for the development of similar gas fields.