Surface Exploration for Oil and Gas: Experiences in the Amazon Rain Forest, Libyan Desert and the Semi-Arid Areas of Northeast Brazil

M. R. Mello, H. L. B. Penteado, F. T. T. Goncalves, N. A. Babinski, R. C. Santos, F. P. Miranda

The application of surface exploration using geochemical, microbiological and remote sensing methods, as an investigative technique to reduce exploration risk, is increasing in importance, since they are considered faster, more cost effective and, under the environmental point of view, cleaner than the other methods.

The aim of this paper is to show the successful use of these nonconventional methods in the discovery of significant oil-condensate accumulations in a tropical rain forest (Urucu area, Solimoes basin, Brazil), a typical desert environment (Ghadames basin, Libya) and a semi-arid area (Potiguar basin, northeast Brazil).

In these studies, more than 5,000 soil and sediment samples were collected at or near the surface along seismic lines. Maps were made using the analytical results aiming to locate the microseep anomalies for each gas, and to correlate them with structural traps present in the area.

In the previously mapped structural traps, samples were collected specifically for microbiological analyses. The results of the microbiological survey were compared to the light-gases anomalies in order to check the consistency of the results and to help ranking the more prospective areas.

An integration of all geochemical analyses with geological and geophysical data allowed the recognition of areas which are more likely to contain hydrocarbon accumulations in the subsurface. Further exploration proved the existence of several oil and oil/condensate accumulations. Therefore, the use of surface geochemistry, microbiological and remote sensing techniques proved to be very cost-effective and helpful to reduce exploration risk.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995