Electrical Prospecting for Oil Structure

Abstract

Electrical prospecting methods were originally developed for the purpose of finding ore. Only recently have electrical methods been applied to oil prospecting. Some investigators assert that oil can be located directly as an insulator by electrical methods, but this is believed to be possible only under extremely favorable conditions, which occur in very few places. Both potential and electromagnetic methods have recently been applied to structural studies. Electromagnetic methods, so far as developed at present, are believed to have broader applicability because of greater depth penetration. The Swedish electrical methods for structural studies are described, and the possible applications discussed. The conclusion is that these methods have broad application and that they are particularly suitable for detail work, especially in faulted regions. Results of electrical surveys in the salt-dome district of Texas and Louisiana, the Balcones fault zone in central Texas, and the West Texas Permian basin are presented and are compared with results of drilling. Most of the electrical pictures agree well with the geological. A party of two or three engineers and twelve or fifteen helpers can survey an area of 1-6 square kilometers a day. The depth reached generally ranges from 500 to 1,500 feet.