Derek J. Fairhead¹, William G. Dickson², Al Danforth³
(1) University of Leeds, Leeds LS2 9JT, United Kingdom
(2) Dickson International Geosciences (DIGs), Houston, TX
(3) Consulting Exploration Geologist, Houston, TX

Abstract: How Satellite Gravity is Providing Cost Effective Exploration Solutions for the Deep Water Areas of West Africa

Exploration costs in the deep water regions of the continental margin can be controlled in significant ways by careful use of existing geophysical data. Satellite derived gravity data, when coupled with good bathymetry, can delineate and define:

_The continent - ocean boundary(COB).

_Internal basement and basinal structure of the thinned continental margin.

_Segmentation of the margin and consequent controls on sediment entry points and reservoir distribution.

_Hydrocarbon prospectivity as a function of heat flow related to crustal type and total sediment thickness plus gross structural framework, all of which can be inferred from gravity.

These delineated and defined attributes in turn allow oil companies to design seismic acquisition, focus seismic purchases and guide interpretation, making best use of scarce staff resources and budget.

Free Air, Bouguer and Isostatic gravity and their total horizontal and vertical derivatives are playing an ever increasing role in delineating and defining the above features. Innovative use of filtering and map display techniques like Dip_azimuth (for the dedicated 3D seismologist) also enables the interpreter to better visualize structural relationships.

Plate Tectonic reconstruction across the South Atlantic region between Angola and Brazil using specially constructed dynamic visualization (moving Plate diagrams) helps to further constrain the COB geometry, extensional margin processes, segmentation and later volcanic events.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana