Multi Mineral Petrophysic and Reservoir Modelling of Sawahtambang Formation in Sinamar Field, Ombilin Basin

Abstract

Sinamar Field is an field location in Ombilin Basin, West Sumatra. Based on the physiography of Sumatra Island, the Ombilin Basin was classified as a Tertiary intermontane basin (Koesoemadinata and Matasak, 1981). The basin is situated within the continental crust along the Sumatra Fault Zone (SFZ), surrounded by a more recent magmatic arc.

The objective of this study is to identify reservoir property (Volume shale, porosity, and water saturation) on the productive zone as well as reservoir property distribution using petrophysic analysis with multimin (Multi Mineral) method and facies modelling. The productive zone are from eo-oligocene sandstone of Sawahtambang Formation. Several well logging and well test data were performed in Sawahtambang Formation through 3 exploration wells. Facies analysis on Sawahtambang Formation is performed using electrofacies concept and driven by sidewall core and conventional core data. Depositional environment interpretation on Sawahtambang Formation shows braided river and meandering environment. Geomodeling analysis method using structural & property modelling which was derived by facies modelling.

Petrophysical analysis resume that porosity range between 6.1%-8.5%, Vshale range between 7.6%-26.9%, Water Saturation (Sw) range between 10.9%-38.9%. Base on well test data, the reservoir thickness range between 51 ft - 142 ft. The reservoir property were going better to South and South West of the central deep of the basin.