1.2 — OCS EXPLORATION AND PRODUCTION METHODOLOGY 

 Exploration 



The exploration segment of the oil and gas industry can 



be identified as three distinct phases: 



Regional surveys to identify promising geological 



formations; 



Detailed surveys upon which to base the evaluation 



of specific tracts; and 



Exploratory drilling -to determine whether oil or 



gas are actually present (Kash et al . , 1973: 26). 



Phase 1 is generally passive in nature and includes: 

 looking for natural oil seeps, observing local variations in 

 the earth's gravity, and various methods of detecting changes 

 in the earth's magnetic field, all of which may indicate the 

 presence of oil. Salt domes, a prime location for oil deposits 

 along the Gulf Coast, are located primarily by detecting 

 variations of gravity readings (Kash et al . , 1973: 27). 



Phase 2 involves a more detailed analysis of specific tracts of 

 land, primarily by two techniques: seismic or geophysical surveying, 



and direct hydrocarbon detection. Basically, seismic detection, 



4 

 as shown in Figure 1.1, involves the transmission of pulses 



Adapted from Mumphrey et al . , 1976: 57-94. 



4 

 Until a few years ago, dynamite or some other explosive was 



used as the source of energy for the pulses. However, since 



the explosives caused ecological damage and killed marine life, 



other energy sources have been developed. Currently, almost 



all seismic work is done with these new energy sources of which 



there are two principal types. The first type detonates propane 



and oxygen inside a rubber sleeve, which transmits wave energy 



directly to the water. The second type is a high-powered 



ocillator whose frequency changes continuously over a period of 



a few seconds. Neither of these new energy sources appears to 



have any significantly adverse environmental effects (Kash 



et al . , 1973: 30). 



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