Petroleum: The Geologist and the Geophysicist (OG-07)
The petroleum industrys use of geology, which became widespread about 1915, g and geophysics, which was introduced in the 1920s, has greatly reduced the ration of unsuccessful exploratory wells. This is due to being able to predict the occurrence of rock structures in which oil and gas may be found. In the early years, most oilfields were found by mapping surface geology or by random wildcat drilling. Later, after the electric log became generally available in the 1930s, geologists could explore more effectively for structures that might contain petroleum. Seismography also became important, first to identify anticlinal structures, and later to locate stratigraphic traps to depths exceeding the drilling capabilites of the time. Tools, such as the seismograph, gravimeter, magnetometer, torsion balance, electric well loggings, micropaleontology, and examination of cuttings and cores, have been important to oil discovery.

Our Hoosier State Beneath Us: Oil and Gas