RESERVOIR COMPARTMENT ASSESSMENT: A CASE STUDY OF BANGKO AND BEKASAP FORMATION, CENTRAL SUMATRA BASIN INDONESIA

Abstract

The reservoir compartment assessment for a case study of the Agur field, Central Sumatra Basin
has been successfully carried out by using fault seal analysis (FSA). The objective of this paper is to asses
subsurface fault properties in term of the fault sealing that was defining the hydrocarbon reservoir compartment.
In this work, the FSA was performed by integrating juxtaposition, shale gouge ratio (SGR) and transmissibility
analysis over fault plane that was identified within reservoir layers on the Bangko and Bekasap formation. The
juxtaposition seal is intended to assess how the reservoir layer is juxtaposed across the fault plane over either
reservoir or non-reservoir layer. The SGR analysis is applied to estimate the shale content in the fault plane,
which is caused by the fault movement of sequence stratigraphy. The last analysis of transmissibility is carried
out to calculate the capacity of a reservoir to drain the hydrocarbon through a fault plane. Faults architecture
(throw, heave, and orientation) and the reservoir layer target were identified based on 3D seismic and well log
data interpretation. The FSA is applied to nine faults that formed nine reservoir compartments within three
reservoir layers, which are obtained from 3D seismic and well log interpretation. The fault characteristics were
classified and the fault seal distribution map was produced to identify the reservoir connectivity among the faults.
The FSA results show that nine identified compartments in the first reservoir layer are clustered into five
compartments. In addition, the FSA clustered nine identified compartments in the second reservoir layer into
four compartments. In contrast, nine compartments in the third reservoir layer were connected each other that
are clustered into one compartment. These results are useful not only for evaluating future hydrocarbon traps but
also for future field development.