Publications

Prabumulih Barat Field is located in the South Sumatera Basin and the reservoir rocks belong to deltaic deposits of the Miocene, Talang Akar Formation. The development drilling phase, of the Prabumulih Barat Field, started on the northwest of Prabumulih Barat Field and is currently in an outstepping drilling campaign towards the southeast end of the field. The objective of this paper is to understand the depositional system of the reservoir, their relationship to the reservoir quality and predict reservoir distribution between the Northwest and Southeast portions of the field. This field has six wells that acquired borehole image logs. In two of those wells, conventional cores were retrieved, and core analysis were performed on those core samples. Integration of rock textures interpretation from borehole image logs together with lithology information from mud and conventional logs were used to infer the lithofacies in each well. Finally, the field depositional environment interpretation was performed based on its lithofacies association. To understand the significance of sedimentological processes to the reservoir quality, a comparison between the lithofacies and their permeability was performed. Furthermore, palaeocurrent indicators from cross-bedding dip data were extracted and corrected to predict the field's reservoir distribution. The primary production reservoir in Prabumulih Barat Field was characterized into several lithofacies based on borehole image logs analysis and can be distinguished into delta plain, distal delta plain and delta front. The lithofacies and sortation index from borehole image logs revealed a good correlation to the core permeability data. Finally, the cross-bedding dips were extracted and corrected from the structural tilts in every well and these demonstrated a unidirectional palaeocurrent toward the south-southeast. The integrated sedimentological analysis, described in this paper, successfully reduced uncertainty associated with a deltaic reservoir within the Talang Akar Formation where conventional logs failed to provide sufficient information regarding the depositional system and the reservoir distribution.