Optimization and effect analysis of drainage gas recovery technology in Kela 2 gas field

The Kela 2 gas field is the main gas field for the West-East natural gas transmission project. Due to geological reasons, some gas wells in Kela 2 gas field have already produced water, which seriously affects the productivity and ultimate recovery of the gas wells. It is urgent to take drainage gas recovery measures to maintain the stable production of gas wells and the uniform advancement of edge and bottom water. The adaptability of the commonly used drainage gas recovery technologies was analyzed, and found that the most suitable drainage gas recovery technology in the Kela 2 gas field was wellhead pressurization and pipe string optimization, then the application effect of which was evaluated. The results show that: the pipe string optimization and wellhead pressurization can be used as the drainage gas recovery process in Kela 2 gas field; for water-producing gas wells, the optimal size of the running tubing is 62 mm, which can effectively carry liquid and prolong natural flow production. The wellhead pressurization process can effectively reduce the wellhead pressure and release the formation energy. When the wellhead pressure was reduced by 6 MPa, the corresponding formation pressure can be reduced by about 10 MPa after natural flow production, which greatly prolongs the gas well flowing production period. The research results show that wellhead pressurization can be used as the preferred drainage gas recovery process in the Kela 2 gas field, and the pipe string optimization process can be used as an alternative one.