Evaluating Hydrocarbon Potential At Attic Position in Deltaic Multi Complex Reservoirs Case – A100 Reservoir, Semberah Field



VICO Indonesia is one of the Oil and Gas producers operating across the onshore part of the Mahakam delta, East Kalimantan, Indonesia. Semberah field is one of VICO’s fields, which is located in the most northern area of Sanga-Sanga Block. Geologically, the field is a part of ancient Mahakam deltaic environment with complexity of multi layer reservoirs. The paleo-environment is typical transition of fluvio-tidal delta, which is
dominated by delta plain and delta front sedimentation. Basically, the field is already mature, where total of 83 wells have been drilled and about 60 – 70 % of the reserves have been produced. There is a consideration amount of activities to search additional reserves beside implement current field development strategies in order to maintain and increase the field production. One approach to search additional reserves is by evaluating hydrocarbon potential at attic position of stratigraphy or structural trap reservoir. With the background complexity of deltaic environment, which is characterized by sand-shale interbedding, will cause a contrast facies change in short distance of lateral distribution, sometimes within tens meters radius. The method to evaluate those potentials is by combining petrophysical data and basic petroleum system. A review in petrophysical properties (Sw) will give an overview of petrophysical changing pattern corresponding to offset well position. Basic petroleum system such as trapping system, migration path, and hydrodynamic concept will help petrophysical result to see the hydrocarbon migration. By combining those analyses, it would help to seek opportunities of hydrocarbon potential at attic position from proved wet zone wells in downdip level. This method has been applied in proposing successful 1 development well in Semberah field, which encountered “A100” reservoir as secondary objectives. The result found 46 ft of gas reservoir with initial rate of 17 mmscf/d in first pass perforation.


Author : I Made A. Sutha N, Ratno Adi, Zainal Arifin S