Publications

Hydrocarbon identification in mature giant Tunu Field located in Mahakam Delta is very challenging due to relatively thin shaly sand reservoirs, wide range of formation water salinity (variation from 1 up to 35 kppm in vertical and lateral), and water-rise phenomena observed in many reservoirs. There are a lot of possible gas reservoirs in Tunu Field which are not included in perforation target due to low quality sand and risk of water production which could jeopardize the wells potentials. An integrated fluid interpretation methodology has been developed in Mahakam fields to elevate confidence level of fluid interpretation by combining the existing and recently developed techniques. The existing techniques are quicklook interpretation, separation of True and Wet Resistivity (RT-R0), comparison of gas and oil volumes from simultaneous solution, comparison between maximum irreducible water saturation from core and water saturation from e-log, and taking into account geological correlation and production data of surrounding wells. The new techniques recently developed in Mahakam are AutoFluid module based on resistivity dynamic baseline, water rise log type’s classification, and gradient of water saturation with salinity. This new integrated fluid interpretation methodology has been applied in giant Tunu Field to re-evaluate the possible gas reservoirs. This effort has revealed hydrocarbon potential on more than 400 reservoirs which were previously defined as non-potential reservoirs. Those reservoirs are then convincingly interpreted as gas bearing reservoirs and proposed as additional perforation candidates. Some of those reservoirs have been perforated and giving additional gas production gain to help in maintaining gas production in mature Tunu Field despite having less new wells drilled recently.