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Abstract: Overpressures in the Baram Field, Offshore Sarawak, East Malaysia

Kho Siak Chung, Dave Hemmings, Ton Ten Have

ca. 9000'ss). Overpressures encountered at relatively shallower depth/stratigraphic levels were thought to be of inflationary origin.

A recent development well in the Baram B Field experienced two unexpected kicks at 8700'ss and 8900'ss with overpressures of some 1100 psi and 2800 psi above hydrostatic, respectively. Well results indicated that, close to and within the overpressured interval, reservoir units were encountered consistently shallower than expected. Lithologically, they become more shaly/silty, and poorly correlate with surrounding wells.

A review of available well data and newly acquired 3-D seismic data was conducted to explain the unexpected well results. This study has identified and delineated a distinctive seismic facies (characterized by discontinuous, chaotic, weak to no internal reflections of low amplitudes) in which overpressures have been confirmed by wells. Supported by geological analog models, this seismic facies is interpreted as an overpressured shale diapir.

The results demonstrate how 3-D seismic and well data have been successfully integrated to provide an alternative overpressure model in the Baram B field. The same model is also applicable to other fields in the Baram Delta Province, having similar geologic settings.

AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994