The Talang Akar Formation is one of the hydrocarbon-producing reservoirs of the South Sumatra Basin. This basin is filled from two different sources in the Eastern part and Western part paleo-high. The bottom Talang Akar consists of coarse-grained sandstone, and the upper part constrains intercalation of sandstone and shale, known as low resistivity low contrast zone (LRLC). The Talang Akar Formation from Air Batu and Sukomoro confers an excellent probability to observe and define LRLC zones over systematic approaches. This paper will provide an analogue of the LRLC reservoir zone by analyzing the relation between facies distribution and reservoir properties, including detailed shale structure. Facies distribution was obtained from the outcrop stratigraphic profile. The reservoir properties are identified by the Thomas Stieber plot and the petrographic section. Seven facies of Talang Akar Formation had been identified, which are: 1) planar cross-bedded sandstone (PCBS), 2) trough cross-bedded sandstone (TCBSS), 3) laminated sandstone (LSS), 4) heterolytic sandstone (HSS), 5) clay-rich sandstone (CSS), 6) mudstone (MS), 7) scour conglomeratic sandstone (SCSS). There are several types of shale distribution: structural shale, dispersed shale, and laminar shale. The laminar and dispersed shale consists of most of the reservoir and fills the pore. The clay structure deduces the disparity in the facies-porosity correlation. The finding of this study revealed that the LRLC zones are caused by lamination structures, thin intercalation layers, heterolytic and clay minerals.
3D geology and reservoir modeling in oil industry: Geologic model construction by integration of sedimentology, sequence stratigraphy, seismic geomorphology, exploration geophysics and geostatistics
