Overpressure Characterization in Baram Delta: Rock Properties to Seismic Velocities Evaluation

Subsurface geopressure analyses studies in Baram delta were done by many researchers (Schaar, 1976; Mantaring et al., 1994; Wee, 2000, Hoesni, 2004). They tried to predict overpressured areas and evaluated the hydrocarbon expulsion, migration pathway and hydrocarbon entrapment in the Baram Delta region. The information required by drilling engineers for well design were onset of overpressure, maximum pressure with depth and thickness of zone of overpressure In this regional study, we analyzed rock/fluid properties e.g. Poisson Ratio, Vp/Vs and impedances (P-Impedance (IP) and S-Impedance (IS)), Pressure-Temperature (P-T) gradient and seismic wave propagation behaviour under normal and overpressured conditions. This was to determine the origin and mechanism of overpressure as well as to predict and quantify the amount of pore pressure. The objective was to use these information in determining the origin and the mechanism of overpressure as well as to improve prediction and quantification of pore pressure.