A Success Story of Unlocking Depleted Channel Reserves in Tunu Gas Field, Mahakam Delta, Indonesia

Crestal part of Tunu Main Zone has been heavily developed with infill wells mainly targeting the isolated bars, while channel reservoirs in western flank have been depleted and considered as upsides. A novel strategy in targeting depleted channel reservoirs is initiated to challenge the conventional gridding method. The workflow comprises of integration of channel geometry update with current static data, connected gas in place reconciliation, production history, pressure update, and water rise analysis. These become key points in geological mapping of the channel which helps to identify remaining potential channels in the field. The recent result of four wells that have been drilled targeting the depleted channels in Tunu Main Zone gave significant higher reserves and have been producing with more than 1 Bcf cumulative. The success story of those four wells leads the opportunity to propose new wells targeting proven depleted channels. Statistically, those channels have 6-8 meters of thickness, 14-16% of porosity, and 30-60 mD of permeability. A considerable amount of remaining potential in channel reservoirs was caused by commingled production strategy and relatively high flowing pressure in the past existing wells resulting in basket gas. Better production result than prognosis in depleted channel reservoirs is due to selective perforation strategy and lower back pressure due to lower production flowing pressure. Depleted channel reservoirs are still promising to be targeted for future wells candidate using more systematic approach. This paper endeavors to exhibit a systematical approach in converting undervalued potential of depleted channel reservoirs to compelling prospects as an incremental value creation process in a mature gas field.