Although electrical techniques have been used in the search for hydrocarbons since the pioneering work of the Schlumberger organization in the early 1920s, advances in seismic exploration quickly surpassed the structural mapping capabilities of surface electrical methods. Since that time, a variety of electrical techniques have remained in use, but impressive claims, even including direct detection of hydrocarbons, have remained largely unsubstantiated.

Certain basic electrical methods continued to be used successfully in minerals exploration during the past 3 decades, however, and recent advances (both theoretical and technological) in these well-substantiated methods have generated new interest in electrical methods as a useful tool in oil exploration.

Extensive research since 1977, including more than 350 line-mi (525 line-km) across 36 fields and prospects in a variety of both structural and stratigraphic traps has yielded several interesting results, some of which are inconsistent with past research. It does appear, however, that geochemical alterations above hydrocarbon accumulations are frequently detectable by conventional electrical techniques, and recent advances in these techniques are proving to be even more successful. In a parallel to seismic techniques, proper processing of the data appears to be the key to successfully detecting alterations associated with oil and gas reservoirs.

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