Hybrid System of ESP and Gas Lift Application from Conceptual Design Pilot Test to System Analysis

Abstract

Abstract Artificial lift technology application in heavy oil production has been a far-reaching development in the industry over past decades guided by persistent efforts to improve the ultimate recovery of this "difficult" hydrocarbon. Heavy oil discovery in a marginal field, Cuu Long Basin, Offshore Vietnam is relatively aberrant and pose challenges to full field development. A series of systematic technical studies has been purposely planned from the first discovery of heavy oil in the wildcat well to the modeling study and facility design to accommodate the viscous fluid over the field life. Apart from the thermal method, pumping technology makes remarkable advance by enlarging the drawdown created over the conventional gas lift in several heavy oil projects. After due consideration, the Electrical Submersible Pump (ESP) was finally decided as the key driver to reinforce well production performance. Moreover, the gas lift has been brought in as a backup in case of pump failure which is not only to prolong well life, save workover expenditure but also boost production if operating in hybrid mode. This paper presents sequential events from the conceptual study to pilot test hybrid ESP/Gas lift system and ultimately the inflow/outflow curves analysis. A proper system analysis of the inflow/outflow curves is indispensable to model the outflow curve above the pump where the aid of gas lift complicated the upward flow and to generate the lift curves used in reservoir simulation. The pilot test of this electro-gas system to Well A has shown about 30% liquid production increment with lesser pump energy consumed and flexibility in control operating point. The early results promise further extension to the remaining ESP wells to enhance field production.