Production optimization of a network of multiple wells with each well using a combination of Electrical Submersible Pump and Gas lift

Abstract

Artificial lift methods such as ESP and GL are commonly used in oil wells around the world, especially in offshore wells. However, these two methods are normally used separately, and this paper therefore aimed to study the possible combination of ESP and GL by analyzing its effects on energy saving using equivalent depth method and on production rate as well as on ESP life cycle using nodal analysis. The paper also performed the production optimization for a network of wells using each well a combination of GL and ESP. The optimization process consists of selecting the appropriate operation frequency for the ESP system and the injection gas lift distributed to each well with the aim of maximizing the total production of the network. In addition, this optimization process was conducted in two cases: unlimited and limited volume of injection gas lift. In case the GL flow is limited, the BST (Binary Search Tree) algorithm was used to determine the suitable gas rates injected into each well to maximize the total network production. The optimization workflow proposed in this study was applied to the field X in Cuu Long basin of Vietnam and was calibrated from the real data of this field. The results demonstrated the advantage of the combination of ESP and GL in energy saving and in application for small diameter wells. In addition, the workflow and source code will allow engineers to replicate the results and to apply this method for future studies in order to determine optimum operating parameters of this hybrid artificial lift to achieve the highest production rate from a network of multiple wells.