Publications

Tunu is a mature and giant gas field in Mahakam Delta with enormous multilayer sand-shale series deposited within a deltaic environment. This field has been produced more than 9847 Bscf of cumulative gas production and 1300 drilled wells. It consists of stacked fluvial-deltaic sand bodies deposited as channel fill or mouth bars between the surface and 5000 mTVDss. The series is divided into Tunu Shallow Zone (SZ) and and Tunu Main Zone (MZ). Since the field is going matured and production decline is inevitable, continuous massive activities of drilling and well intervention become critical to the sustainability of Tunu field production.

Reservoir operation is essential to ensure the delivery of reservoir management programs on-track with short term field production forecasts. It is a back-bone of Tunu reservoir management activities by implementing massive, rapid and optimization-based well intervention program. Since the field is going mature and create field development paradox where at the marginal reserves thus the required effort becomes more complex and costly, reservoir operation best practice should be adaptive to deal with this condition. This paper presents a best practice of reservoir operation by implementing closed-loop reservoir operation in order to optimize reservoir management program. It delivers iterated-closed loop process of workflow based on fundamental reservoir management which consists of job planning, surveillance, diagnosis, evaluation and reserves portfolio management. It covers well & reservoir surveillance, well diagnosis, data acquisition, remedial action, multilayer reservoir perforation, dynamic synthesis, reserves portfolio management and well revival plan. Reservoir engineers have been actively implemented this closed-loop workflow and a case study from the last three years of production showed a contribution by supporting production realization in average 11% above field production target. The best practice could be applied for typical characteristics of mature gas field in order to achieve production target with appropriate reservoir management.