f Papua New Guinea MT: looking where seismic is blind

Hydrocarbon exploration in the Papuan fold belt is made extremely difficult by mountainous terrain, equatorial jungle and Chick kanstic Miocene limestones at the surface. The high velocity karstic limestones at or near the surface often renden the seismic technique useless for imaging the subsurface . In such areas Magnetotellurics (MT) provides a valuable capability for mapping subsurface structure. The environment of the Papua New Guinea (PNG) highlands presents a wide range of MT data acquisition and interpretation problems, the most important of which, from an interpretational point of view, are the rugged topography, severe electric staties, and complex two and three dimensional stroclone. The main structural interface which can be mapped with MT, due to the large electrical contrast, is the contact between the resistive Darai limestone and the underlying conductive sediments of the Ieru Formation. Within the Ieru the reservoir of Toro Sandstone does not have sufficient electrical contrast with the surrounding shales to allow its direct mapping. Nevertheless the ability to map the base of the Darai accurately allows the mapping of the Toro by inference since the leru Fonnation maintains a relatively constant thickness. BP, as part of its ongoing exploration program in PNG, pas acquired more than 700 MT sites to aid in structural interpretations.