Study On Gas Production Technology Of Suction And Gas Lift Drainage

As the exploitation time goes on,the gas well effusion leads to the decrease of productivity.The effective period of single drainage methods,such as bubble drainage and gas lift,is short.Although the combined process drainage and gas production device has the advantages of continuous suction and gas injection,it still needs long-term field experiments to determine the reasonable process combination.In this paper,based on the drainage and gas production device which can realize pumping,gas lift,energy replenishment and other processes,two process selection processes are designed and relevant experimental verification is completed.(1)Based on the field production data of 25 wells in a block in China,this paper screens out the calculation formula of critical liquid carrying flow rate applicable to this block.In the laboratory,an experimental platform which can simulate the drainage and gas production of vertical wells and directional wells was set up,and the experimental research was carried out under three working conditions: normal gas production,suction gas lift and main pipe energy supplement.According to the drainage effect,a correction coefficient K=0.7 was added to Li Min model as the design flow rate,and a more reasonable design flow rate and drainage scheme were given according to different drainage working conditions.(2)According to the working performance,critical liquid-carrying flow rate formula and pipe flow pressure formula of the combined process drainage gas production device,the design and calculation of the gas extraction volume of the suction gas lift process and the design and calculation of the gas injection pressure of the oil casing under different gas-liquid ratios are completed.According to the casing pressure of gas well in normal production,the selection scheme of main pipe energy replenishing pressure and the parameter calculation scheme of combined process are given.(3)Through the conservation of pressure,volume and mass,the calculation formulas of liquid level height of gas wells under two operation modes are derived by using the method of oil casing pressure conversion by injection and deflation or liquid level balance by connecting oil casing at wellhead.Based on whether the two-phase flow is measurable or not,two process selection processes are designed,and process adjustments are made according to different criteria to ensure effective operation.(4)The 26-day field experiment of a well was completed,and the average daily gas production increased by 22690 N·m3,which verified the correctness of the process selection method: the pumping and re-injection operations were selected by the flow pressure as the criterion,and the single-machine and double-machine operations were started by the casing pressure as the criterion,which provided a reference for the further research of intelligent drainage gas recovery technology.