Major Controlling Factors of Overpressure Generation in West Baram Delta, Offshore Sarawak Basin: An Overview on Disequlibirum Compaction and Thermal Analysis Causing Overpressure Interval

Abstract

Pore pressure data at well location is one of the requirements for exploitation of oil and gas resources. The accurate pore pressure can be determined optimally when the overpressure mechanisms are well established. In general this paper is focusing on the determining of overpressure mechanisms and also characterizing the pore pressure. The origin of overpressure in the study area was firstly determined by using wireline log responses. In general, there were two prominent types of overpressure mechanisms, the disequilibrium compaction and fluid expansion in the study area. Overpressure mechanism typing was enhanced by integrating thermophysical parameters in the analysis. The relationship between pressure-temperature gradient with depth enable to discriminate the overpressure mechanisms. The high heat flow anomalies are unique to the fluid expansion zone and hence could be used as an indicator for the fluid expansion mechanism. A new workflow has been established and designed for overpressure mechanism determination which complements the existing technique with incorporating the thermophysical analysis.