ABSTRACT: Formation Pressure Measurements and Their Use in Papua New Guinea Exploration

DANIELS, MICHAEL C., Chevron Niugini Pty Ltd, Port Moresby, Papua New Guinea

The use of formation pressure testing via wireline tools has proven exceptionally valuable in the determination of not only hydrocarbon type but reservoir continuity for oil exploration in the Highlands of Papua New Guinea (PNG). As drill-stem testing in these remote locations can be prohibitively expensive, a different method of formation evaluation that would accurately differentiate reservoir fluids and define gas-oil-water contacts was needed. Wireline formation pressure measurement (e.g., with Schlumberger's RFT tool) has become the method of choice. Traditional wireline log based formation evaluation methods are made difficult by the light API gravity of the PNG oil, neutron-density cross-over in the oil column, and hydrodynamic reservoir conditions.

Use of relative formation pressure gradients and their intersections has allowed successful delineation of both gas-oil and oil-water contacts present in PNG reservoirs even when not encountered by well bores. Absolute pressures have aided in deciphering the complex structure and in answering questions about reservoir continuity. In addition, formation pressure measurements when evaluated and compared areally can be shown to delineate hydrodynamic reservoir conditions that are present in at least one of the oilfields. Anomalous formation pressure data sets do exist however which appear to be valid but fit no model of reservoir dynamics, indicating that our current reservoir models are not totally adequate.

AAPG Search and Discovery Article #91015©1992 AAPG International Conference, Sydney, N.S.W., Australia, August 2-5, 1992 (2009)