Field Wide Gas Lift Optimization Method

Abstract

Gas Lift is one of the most widely use artificial lift. However, in a real field cases, there will always be a constraint in the system such as limited amount of lift-gas that can be utilized. These constraints will become a drawback in order to achieve the maximum total oil production rate. Hence, the system needs a gas lift distribution optimization in order to maximize the production oil rate. The ultimate objective for this project is to determine how the distribution of the gas lift available can be done in order to achieve the maximum total oil production rate. The second objective is to study on different parameters that affect the behavior of the gas lift optimization result. In order to run this project, Schlumberger PIPESIM© will be utilized to establish a gas lift performance curve for all wells. Visual Basic for Application (VBA) Macros and mathematical coding will be utilized to compute the calculation for the optimization. The result generated will be analyzed by running sensitivity analysis on certain parameters which are water cut, gas oil ratio, well productivity index, reservoir pressure, reservoir temperature and oil API gravity. Case study had been done of by optimizing 5 wells with a constraint of 5.5 mmscf/d total injection rate. The result shows that by redistributing the available gas lift in optimum mauner, the oil production manage to be increase by 21.03 bbl oil/day, or 0.36%. Optimizing using different case scenario had proved that the major factor that affects the result of the optimization is the gas oil ratio (GOR). Low GOR will make the well become more sensitive towards the changes of injection gas rate. Oil API gravity and reservoir temperature will not give significant impact towards the optimization results. The outcome from this project will benefit the oil and gas industry as the optimum distribution method can be used in order to increase total field oil production