Integrated Management of Water, Lean Gas, and Air Injection: The SuccessfulIngredients to EOR Projects on the Mature Handil Field

摘要

The future of large very mature oilfields relies upon thesuccessful application of EOR techniques. This paperdiscusses from the Handil field case, the more useful conceptand practices that are applicable to optimize oil recovery in amulti-layer, multi reservoir waterflooded field.The Handil field, discovered in 1974, is a giant matureoilfield located in the Mahakam Delta, Indonesia. The fieldwas developed using conventional oil recovery methods:natural depletion and peripheral water injection and produceda maximum of 200,000 BOPD in the late seventies. Currently,the oil recovery is around 50% with a 15,000 BOPDproduction at high watercut.The Handil EOR lean gas injection project was started inNovember 1995 on five reservoirs and following its positiveresult was extended with six reservoirs in 2000. In 2003, anintegrated study on the largest EOR reservoir was performedto assess the projects’ performance. This included 3Dgeomodeling, reservoir simulation and chemical tracerinjection. The study permitted to track the main effects of thegas injection, to identify “bypassed oil” areas and to definereservoir management guidelines for the other lean gasinjection reservoirs.As field scale application of the gas injection technique isnot sustainable since the gas is exportable, two othertechniques are currently being evaluated as an alternative.Second Contact Water Displacement (SCWD) is plannedto be introduced on the maturest lean gas injection reservoirs.Simulation studies forecast potential for this technique whichalso allows decreasing the volumes of injected gas.An Air injection pilot on a waterflooded reservoir wasstarted in 2001. First results are encouraging but the injectionwas temporary suspended due to injector well problems after 6months of injection. The project was comprehensively studiedby compositional and thermal simulation and intends to restartearly 2005.Integrated studies of the Handil reservoirs provided indepthunderstanding of EOR mechanisms. This resulted in theability to better model field performance and to forecasttertiary oil production more accurately.