Co-Development Plan Optimization of Complex Multiple Reservoirs for Giant Offshore Middle East Oil Field

Abstract

An extensive study was conducted to revise the field development plan (FDP) of a giant offshore Middle East oil field. The subject field contains several stacked reservoirs with light oil and has a long production life extending beyond 100 years. Primary recovery began in 1968. The field has been under water flooding with pattern injection since 1982. In the subject reservoir, most of injector wells are located in a concentric ring along the crest. This reservoir is currently undergoing further redevelopment with a line drive injection pattern utilizing long horizontal wells. Currently, a revised field redevelopment plan is being evaluated to assess increasing the production target of the reservoir while maintaining the production plateau. In order to sustain target oil production and improve recovery, the revised field redevelopment consists of different innovations including maximum reservoir contact (MRC) wells with line drive pattern, gas lift, infill drilling and co-development of multiple reservoirs with single lateral or dual lateral wells with different tubing strings and appropriate EOR technology. This paper describes the current work to optimize the combined development plan of three vertically adjacent reservoirs by using multiple strings in a given well to access them. The focus was to revise the development plan of the larger reservoir and use the future development wells of this reservoir to access other smaller vertically adjacent reservoirs that are within the drilling reach from different artificial islands. The study addresses optimized well spacing, vertical well placement, well drill sequence and infill well placement. This study also includes assessment of the value of infill wells, dual-lateral and single-lateral wells to target more than one reservoir. An optimized field development plan is formulated with new MRC wells which include both single and dual-lateral wells accessing one, two or three reservoirs depending upon location and applicability.