High-Resolution Aeromagnetics: Cost-Effective Reconnaissance Tool for Mature Provinces

Bailey Rascoe, William J. Czimer

Petroleum exploration in a mature province must be continually monitored in terms of the risk-reward ratio (finding costs versus potential field size). Over much of the Mid-Continent where lower Paleozoic reservoirs have provided prolific reserves in structural traps for 75 years, the search for an ever-shrinking number of these accumulations seems to require deploying expensive seismic grids.

High-resolution aeromagnetic surveys provide a low-cost means of identifying anomalies in the basement complex of the type associated with productive, basement-controlled structural features. High-resolution aeromagnetics uses the Vacquier method to identify the edges of magnetic bodies on flight-line profiles. Through this method, the interpreter recognizes signatures on the profile that indicate faults in the basement complex and their sense of throw. Structural anomalies are generally less than 10^ggr; compositional changes commonly differ by a greater order of magnitude.

The successful use of a high-resolution aeromagnetic survey depends on the evaluation of the basement anomalies through geologic analysis of associated structural and thickness patterns. The final step is a seismic program to confirm the existence of the aeromag-subsurface prospects and to select drill sites.

At current prices, the cost of a high-resolution aeromagnetic survey over a township area (36 mi² or 93 km²) is approximately equivalent to the cost of 2 mi of proprietary seismic data. Thus, in terms not only of use, but more importantly cost, high-resolution aeromagnetics is a reconnaissance tool that can significantly lower finding costs in a mature productive province.

AAPG Search and Discovery Article #91039©1987 AAPG Mid-Continent Section Meeting, Tulsa, Oklahoma, September 27-29, 1987.