Depositional Environment of the Basal Pratu Tao Formation Thap Raet Field, Phitsanulok Basin, Thailand

Abstract

This study was conducted to better understand the depositional environment of the Basal Pratu Tao Formation in the Thap Raet Field, Phitsanulok Basin in order to improve the prediction of reservoir distribution and properties. Two conventional cores and 11 well logs were integrated were used to interpret the depositional environment and establish paleogeographic models of the third order event. The depositional environment of the Basal Pratu Tao Formation was identified as a river-dominated lake delta consisting of: 1) a delta front to pro-delta, 2) a delta plain environment, and 3) a delta plain to proximal delta front facies. In addition, this study interprets the rivers in the lake delta system as distributaries of one river as opposed to multiple rivers. It also indicates that the delta had a NE-SW orientation, with distributaries coming in from the north and northwest. Stacked channels and mouth bar sands are good reservoirs in the field and apparently extend across the study area. Consequently, there is no concern about reservoir
distribution for field development.