Publications

Benar Field (Central Sumatra Basin, Indonesia) is a pop-up anticlinal structure related to Miocene to Pleistocene tectonism involving a major transpressional strike-slip fault located 10km to the west of the Field. New wells drilled in flank areas indicate high oil saturation with multiple current oil water contacts. Seismic interpretation shows no evidence of faulting within Benar closures, therefore, stratigraphic compartmentalization alone is suspected. The current study of the Sand A (Early to Middle Miocene) focuses on facies analysis and high-resolution sequence stratigraphy of these tide-influenced clastics with emphasis on reservoir distribution and stratigraphic compartmentalization. The objective of the study is to increase oil recovery from the Sand A at Benar field. Fifty wells (four wells with conventional core) provide insight and constraints for the depositional system of the Sand A reservoir. In addition, high-resolution 3D seismic aids the prediction of reservoir geometry of this tide-influenced clastic system. Production and RFT pressure data are used to predict the current oil water contact (COWC) and to validate the compartmentalization analysis. Reservoir thickness variation and dissimilar gamma-ray log responses indicate reservoir heterogeneity which is one of the hypotheses in inquiring the different COWC. Heterolithic bedding, bioturbated very fine- to fine-grained sandstones, and massive to crossbedded fine- to coarse-grained sandstones highlight tide-influenced sedimentation. In analyzing reservoir geometry and distribution, seismic stratigraphy analysis is conducted using seismic attribute complex and waveform classification. These conclusions are validated against integration of wireline log and conventional core data. Data integration reveals an 800-1700m wide tidal channel with flanking sand-rich and mud-rich tidal flats. The tidal channel has a NE-SW orientation which broadens to the southwest. Two sweet spots with bypassed hydrocarbons in the northwest and southeast flanks at Benar Field were identified.