Study On The Technology Of Drainage And Gas Recovery From Qiongxi Neiqi Gas

T3X2gas reservoir of Qiongxi area located in Longmen Mountains Fault Zone of Mesozoic-Cenozoic sedimentary depression belt is in the west of the Sichuan basin, which is a typically porous water-bearing gas reservoir with low permeability. With the exploitation of the gas reservoir, water gradually invades and liquid loading problem is increasingly serious which leads to the decrease of gas production. At the present, technologies of water drainage and gas production applied like foam drainage and other technologies are unable to stabilize the gas production effectively, and the results of water drainage in most of wells in the area aren’t ideal. Therefore, based on the current situation of water production of the gas reservoirs and implementation plan of the water drainage and gas production, research of suitable water drainage and gas production by gas lift is of great significance.In this thesis, liquid loading and water production are analyzed based on geological characteristics and current water production situation of T3X2gas reservoir. Using the basic theory of the gas lift, the optimization design method and computer programming language, this thesis completes the research and design of gas-lift drainage gas recovery and implements field calculation and analysis. The main results obtained are as followed:(l)According to the actual situation of the gas reservoir, the status of water drainage and gas production for the gas reservoir is analyzed, meanwhile, the thesis classifies the water production gas well on the basis of the gas well bottom hole fluid and water production situation;(2)Aimed at the characteristics of low permeability gas reservoir, the inflow performance model of the gas-water two-phase flow is derived considering the actuating pressure. For gas well deliverability analysis. Based on the field test data of7Wells, gas-water two-phase flow models commonly used are evaluated, the Hagedorn-Brown model is elected as the most suitable model for T3X2gas reservoir of Qiongxi area;(3)In the research of the optimization theory for gas lift, the thesis analyzes the rules for the optimization of gas lift string and gas injection mode and uses the sensitivity analysis technique to study the efficiency of gas-lift in different influence factors. Then the study about the design theory and design methods of gas lift are completed, what’s more, gas injection method with fixed ground pressure is chosen for T3X2gas reservoir of Qiongxi area;(4)Based on the previous basic theories and design methods of gas lift, the thesis applies C#language to design the computer program. Actual design using field data and parameters optimization are completed by the program, and the previous theories and designing program are verified by practical field data. The results of the design accord with actual conditions of the field preferably.