Publications

Gas lift is one of the most common artificial lift methods used in either single or multiple oil producing wells. Because of high gas prices and compressing costs, an optimum allocation for each well is needed to obtain maximum field oil production, particularly where there is limited gas supply. A new simple-effective-efficient model is constructed here which only needs 3 items of data: the number of gas lift wells, total gas injection rate and gas lift performance curve (GLPC). The developed model uses a fundamental allocation method for 2 gas lift wells. By applying first differential to total oil production as a function of allocation and total gas injection rate, optimum allocation as a function of total gas injection rate can be obtained. Then, for 3 wells, it will be same as for 2 wells. 1 well is 3rd well and another is the result of the previous calculation of 2 gas lift wells and so it goes on. By just inputting data of the number of gas lift wells, total gas injection rate availability and GLPC of each gas lift well, optimum gas injection allocation for all wells can be directly and simply obtained without doing any iteration or graphical method. Compared with Equal Slope which is a long procedure with lots of graphs and limited to a small number of wells, this model demonstrates more flexibility and faster performance but yields almost exactly the same results and can be applied to a large number of wells. Compared with the numerical method in commercial software, this model uses less gas injection rate but produces more oil production. This model has been also successfully tested on field data under both unlimited and limited gas supply. A macro-excel program is then developed by the author based on this analytical model to conduct a simulation test. Keywords: Gas Lift, Gas Lift Allocation, Gas Lift Performance Curves, Limited Gas Injection Rate