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ABSTRACT: The Use of Magneto-Telluric Surveying as a Risk-Reduction Tool for Hydrocarbon Exploration in the Papuan Fold Belt

BENNETT, JOHN K., and MARCUS PARISH, BP Developments Australia Limited, Melbourne, Australia, and MICHAEL HOVERSTE, BP Exploration, Sunbury, United Kingdom

The inability to obtain usable seismic data in the Papuan fold belt due to the surface exposure of the Tertiary Darai Limestone causes significant uncertainty in defining subsurface geometry.

In the absence of the seismic tool and other conventional potential field methods, such as gravity and magnetic data, to provide adequate subsurface definition, prospect definition at Toro level relies on the construction of balanced cross sections based on surface geological measurements, limited well data, and regional knowledge of the stratigraphy. This methodology invariably leads to nonunique solutions and a range of outcomes, which may range from highly prospective to nonprospective for individual structures.

The magneto-telluric (MT) method has been applied to this problem in the Papuan fold belt in an attempt to constrain the structure at the base of the Darai Formation. In areas of broad structure, where the two-dimensional response of the MT soundings is not extreme, the application of two-dimensional forward and inverse modeling has enabled us to determine gross structure at the base of the Darai from field MT recordings.

In more structurally complex areas, a clear definition of the geological problem to be addressed by the MT technique is required, as well as modeling studies to determine the ability of MT to provide an answer to the problem. Despite the inherent problems in the MT soundings caused by extreme two-dimensional response and near-surface static effects, MT has been able to discriminate between different structural models, and, consequently, reduce exploration risk.


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