Comprehensive Integrated Study on a Novel Completion Technology of Hybrid ESP-Gas Lift System for a Gas Lift Field in the GOS

Abstract

Abstract GS327 field is a small field located in the central of GOS with a relative heavier oil than the other neighboring fields which affects the sweeping efficiency. Started production in 1986 with a peak production in 2007. The field is being operated under gas lift artificial method, producing mainly from two reservoirs with high petro-physical parameters and very good sand quality in addition to be supported by a strong aquifer. One of our main responsibilities as petroleum engineers is to select the optimum artificial lift technology to maximize the field production. In an especially limited offshore field, not all methods are applicable due to the platform spaces, operating costs, and system reliability. Concern for alternative lifting methods has arisen since 2012, due to the limitation of gas lift injection capacity that is no longer adequate for the current and future development wells at that time. Moreover, the network system is suffering from bottleneck causing back pressure and losing more oil, this is mainly due to the gas effect in the production lines. 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. A comprehensive integrated study was carried on to evaluate the switching from Gas Lift operated field to the novel hybrid ESP Gas Lift system taking the advantage of the ESP wide range of outflow performance to increase the oil production and hence adding more reserve. Initializing the study first by using the reservoir analytical approaches to assess the added value of the ESP; WOR Exercise, analog performance, asset integrated modeling by GAP MBAL PROSPER was created which revealed we can add around 1.5 MMSTBO as an incremental reserve. Realizing the construction, layout and electricity power sources were critical points that took much effort to assess. In addition the risk of sand production due to the higher drawdown from the ESP was studied as well from the geomechanics team to mitigate it.Finally a complete reservoir simulation model was created to integrate all the inputs, assumptions, risks and uncertainties which revealed we have a very good room to increase the sweeping efficiency, drawing out more oil and increase the reserve. In this paper, we present sequential events from the conceptual study to the designed pilot test. It is a very good example of managing uncertainty by integrating different data to convert it into reality that can be translated ultimately into oil production and revenues