Feasibility of Gas Lift to Increase Oil Production in an Iraqi Giant Oil Field

Abstract

Abstract Gas lift is one of the artificial lift techniques which it is frequently implemented to raise oil production. Conventionally, the oil wells produce depending on the energy of reservoir pressure and solution gas which declines due to continuous production. Therefore, many oil wells after a certain production time become unable to lift oil to the surface. Thus, the continuity of production requires implementation of gas lift which works to decrease the average fluid density in the tubing by injection gas through the annulus into the tubing. This paper aims to get maximum oil production of an Iraqi giant oil field at optimum injected gas rate. The field is located in south of Iraq and includes 67 wells. In this paper, new model is designed to matching PVT data, matching vertical pressure drop calculations, making sensitivity analysis of wellhead temperature variation, making sensitivity analysis of productivity index variation, achievement of optimum design of gas lift and finding optimum values of oil production and injected gas rate. The gas lift design is implemented within two cases. The first case aims to get the maximum oil production using flowing bottom hole pressure cut off as 50 psi above the bubble point pressure at certain depth. Whereas in the second plan, the same cut off value is maintained while keeping the injected gas oil ratio below or equals 350 SCF/STB. The two constraints are applied according to the policy of the operating company for the field under study. This results show the implementation of the gas lift technique can increase oil production from 64379 STB/D to 302712 STB/D in the first case and to 272359 STB/D in the second case. In addition, 45 ceased wells were brought to production by implementation of the gas lift. The model predicts that the required injected gas rates to produce the new production are 186.3 MMSCF/D and 74.606 MMSCF/D in the first and second cases respectively. The main conclusions lead to the application of gas lift technique for this reservoir can increase the oil production volume significantly.