Revealing Hidden Potentials to Maintain Production by Using IntegratedPetrophysical Interpretation Techniques in Mahakam Mature Fields

摘要

Hydrocarbon identification in mature fields located in Mahakam area is very challenging due to thin andmulti layers of reservoir geometry,wide range of water salinity in deltaic environment,depletion and water-rise phenomena in highly producing zones.There are numerous possible gas reservoirs which were dubiousand not included in perforation targets due to poor quality sand or risk of water production which couldjeopardize the entire well potential.These possible gas reservoirs need to be re-evaluated in order to addperforation targets portfolio in maintaining field production when less new wells drilled.An integrated methodology has been continuously developed and calibrated to reduce uncertainty,henceelevate confidence level of fluid interpretation by combining the existing and recently developed techniquesin Mahakam fields.The existing techniques are (1)Conventional Qualitative interpretation,(2)True-WetResistivity separation,and (3)Gas-Oil Volumes from simultaneous solution.The new developed techniquesare (4)Swirr-SWT comparison,(5)Water Saturation Array Gradient with salinity,(6)AutoFluid resistivityspecific cut-off,(7)Dual logs sliding average analysis,(8)Neutron Count Rate,(9)RT-GR cut-off,and (10)Gas Chromatograph dynamic baseline.In collaboration between petrophysicist,development geologist & reservoir engineering,this newintegrated fluid interpretation methodology has been applied to re-evaluate more than 11,000 possiblegas reservoirs in Mahakam fields.This effort has revealed around 32% of them as hydrocarbon potentialreservoirs with total thickness of 4,195 meters.Those reservoirs are then convincingly re-interpreted as gasbearing reservoirs and included as additional perforation candidates.Some of those reservoirs have beenperforated and giving additional gain in maintaining gas production of Mahakam fields.By capitalizing the existing data,with no additional data acquisition,hence no additional cost,thisintegrated fluid interpretation methodology,could be implemented in other fields outside Mahakam to findhidden potentials which not identified yet.