Doubled Production in Mature Sandy and Multilayers Reservoir Using Screenless and Overdesigned ESP System

Abstract

Abstract The fifty-two sandy and multilayer reservoir from depth 500 – 1750 m in Mamburungan field became more challenging when electric submersible pumps (ESP) were used. The average 2 – 7 m range net pay height in each layer contrasts with sand production for screen implementation in reducing productivity index. Multilayer reservoirs result requires various types of ESP design based on depth. As a result, a reliable method is needed to produce the well effectively and economically. The production method was divided into two basic concerns. Firstly, determining reservoir analysis with loose sand reservoir at 500 – 1000 m depth, and consolidated sand reservoir at 1000 -1750 m depth, Secondly, designing ESP which could accommodate all layers, which are divided into two main zones, i.e. the optimum design zone at 1200 – 1750 m depth and the overdesigned zone at 500 – 1200 m depth. In an overdesigned zone attention must be paid to choke installation to limit production rate, the safety factor for motor temperature specifications based on reservoir temperature, and also the safety factor for power specifications in variable speed drive (VSD) and transformer. Currently, all ESP wells in Mamburungan field are producing without failure and the ESP operation is running smoothly by implementing the aforementioned production method. In the optimum design zone, no ESP performance issues have been raised. Meanwhile in the overdesigned zone, potential performance issues might not be arise by adhering to certain rules: application of choke to control the production rate within up thrust and down thrust area; implementation of additional 40 percent safety factor in motor temperature specification refer to the deepest layer temperature; design of VSD and transformer to provide sufficient power consumption based on motor requirement at the deepest layer. Applying the overdesigned method delivers an optimum trade-off between lifetime, cumulative production, economic value with ESP system efficiency to produce the well in Mamburungan field.