Today's explorationist is generally unfamiliar with the potential and success of surface-based electrical resistivity methods as geophysical tools useful in reducing exploration and reserve-areas definition costs, as well as drilling costs. Two major reasons for this are: (1) the promise of direct detection of hydrocarbons where surface-based electrical methods have been used to delineate shallow subsurface anomalies; and (2) the geophysical data from electrical methods are more complex than simple anomaly profiles and require a specifically educated and costly consultant to do the interpretation.

In spite of the above, the electrical methods may be used directly as a resistivity-defining tool which not only delineates structure but also provides information necessary to resolve lithologic and stratigraphic problems, such as rock type, fluid content, and porosity. In areas where seismic data quality is poor because of adverse conditions, such as volcanics, electrical techniques are unaffected and, in many instances, the data quality is actually improved.

To help meet the challenge of today's petroleum exploration problems, a multi-methodology electrical resistivity system has been developed. This system is used to great advantage in exploring reef, overthrust, and pre-volcanic sediment prospects. Case histories in Nevada and west Texas show resolution of these problems by electrical methods.

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