Abstract

This study was undertaken in an attempt to define the attitude and control mechanism of the gas water contact in the Arun Field by inter-relating and coordinating the geologic and engineering approaches.

The study confirms several apparent anomalies about the gas-water contact previously noted in the Arun Field. Logs and test data generally suggest an apparent southward tilt of the gas-water contact, although some data are contradictory. These anomalies may be due to more than one cause. No unique explanation of the control mechanism is as yet available, although the work to date suggest it may be related to a difference in rock properties.

A review of the geology setting indicates that diagenesis has affected the lowermost interval of the Arun limestone differently in the northern and southern areas. Attempts to explain the gas-water contact anomalies by detailed comparison of reservoir properties in the two areas, including porosity, permeability, scanning election microsopy, capillary pressure and microporosity have so far been inconclusive.

Further study of reservoir parameters below the top of the gas-water transition zone, including pore throat geometry, is ongoing.