Dump-Flooding Electrical Submersible Pump (ESP) Approach and Lessons Learned in Sustaining Production Cycle

Abstract

Water injection for pressure maintenance is common in the oil and gas field to ensure a reservoir’s energy does not drop beyond the limit which will jeopardize production over time. Most of the major oil companies utilize the produced water on surface for injection or treated seawater either as pressure support or as a sweeping catalyst to recover as much hydrocarbon possible. Water dump-flooding is one of the less common methods of pressure maintenance as compared to surface injection. This method utilizes the shallower aquifer sand as the inflow to feed the deeper reservoir. As a mature field of water-flooding, downhole injection does fit the purpose in theory but there are many considerations which need to be addressed before embarking on this route. Even though well intervention technology has advanced in recent years, most companies would rather keep well intervention as simple and quick to avoid increasing Operating Expenditure (OPEX) which will push further the job priority. This is due to the well's accessibility, especially for offshore settings with limited space and operating window duration, especially when weather is known to be the main showstopper. Subsurface issues such as sand migration, gas handling, reservoir souring and scaling may also contribute to the system's inefficiency, which may result in system failure. Installing an ESP especially with an inverted pump does need an extensive monitoring capability be it downhole or on surface. Lack of essential data handling will often lead to malfunction which results in an expensive operation of pulling and total workover. The dump-flooding method was chosen as the field has an existing aquifer with no serious compatibility issues across different reservoirs. The idea was deployed considering the existing platform capability with minimum modification on surface whilst ensuring the reservoir is being supported continuously. Downhole sand control for the water source zone was necessary in the designing stage to mitigate formation failure based on its lithology that would interrupt the ESP efficiency. The supported reservoir requires constant pressure charging to sustain its production and realizing some of the future development plans. This paper will talk through the process and challenges faced during the planning, designing, commissioning, and maintenance of the dump-flood ESP. The lessons learned are crucial to ensure the project is a success for supporting the reservoir with minimal operational obstacles during execution.