Publications

Western Sundaland of Indonesia has been widely known as hydrocarbon producer, in one of which composed of alluvial-fluvial channels deposited within Paleogene rift system. The lack of information and limited data availability can cause uncertainty especially in the subsurface interpretation and reservoir characterization. The objective of this study is to provide geometrical information of a Paleogene syn-rift alluvial-fluvial channel system as an analogue to the subsurface. Our study utilizes quantitative approach to better understand spatial and temporal distribution of reservoir geobody using scaling relationship method on excellent outcrop Brani Formation exposure in the Harau Valley, Payakumbuh Basin, West Sumatra. Field measurements were documented, and Digital Outcrop Model (DOM) was developed to generate probabilistic parameters, such as width, thickness, width-thickness ratio, and net to gross ratio based on medial and distal channel facies. Medial braided channel shows medium to high degree of interconnections with probabilistic average width of 50.35 m, average thickness of 4.09 m, and high net to gross ratio. The geometrical relationship among them shows relatively medium values of the coefficient correlation and determination. In addition, distal channel (meandering system) showing probabilistic average width of 26.77 m, average thickness of 1.35 m and relatively lower net to gross ratio. The coefficient correlation and determination are relatively higher than medial channel suggesting relatively more connected facies compared to others. Our study results indicate that outcrop scaling relationship and morphometric analysis can significantly improve understanding on reservoir geometry, connectivity and heterogeneity especially in the area with sparse well data and poor seismic quality. Furthermore, our statistical results and equation revealed that parameters can be used as an input for variogram analysis of reservoir geobody, stratigraphic correlation, as well as reservoir modeling by predicting the lateral extent and lithological variation of fundamental reservoir flow units. This method can also be applied in assisting field development strategies and reserve estimation.