Apply Compound Gas-lift Drainage Gas Recovery to North China Oilfield

In buried-hill gas reservoirs of North China Oilfield,more severe activities of both edge and bottom water result in a well production with water or even a shutdown.Several drainage gas recovery technologies were analyzed according to a research on the geological setting,water-produced feature and gas source capability in limestone buried hill;and then the compound drainage gas recovery technology,with continuous gas liftas the soul and assisted by plunger lift and liquid-carrying capabil-ity of foam,was optimized.Case study illustrates that the applica-tion of plunger lift and continuous gas lift may not only reducethe slippage loss of wellbore fluid,but also increase the fluid-car-rying capability and save a certain gas injection rate whereas theapplication of plunger lift and liquid-carrying capability of foammay not only change downhole fluid to light foam,but also decrease the flowing pressure gradient in wellbore fluid and increase the fluid-carrying capability and gas lift efficiency.This compound technology can effectively solve a difficulty of drainage gas recovery in deep and extra-deep wells of limestone buried-hill reservoirs.