Applications and Limitations of Surface Exploration Techniques
J. Edward Tillman
All surface techniques for detecting subsurface accumulations of hydrocarbons have distinct limitations and specific applications where they work the best. This applies to seismic surveying as well as to geochemical surveying and less common geophysical techniques. To apply surface techniques successfully, workers must understand the generic limitations of surface detection and the specific limitations of the technique.
Geochemical procedures should be considered as a valuable addition to other data, or as a technique that directs an exploration program in areas where reservoirs are laterally discrete and production is from a limited number of producing intervals. Reservoirs are more difficult to interpret in areas of complex structure or multiple producing zones.
Variables that must be evaluated for specific geochemical techniques include: sampling depth, density, and method; soil type, moisture, chemistry, and age; and atmospheric conditions throughout the survey. The significance of these variables differs between techniques, but they must all be considered for each survey.
An evaluation of these variables and their effect on specific techniques helps select the optimum methods under certain geologic/climatic conditions. However, all the variables can rarely be addressed; therefore, more than one technique must be used to help "solve the equation." That is, integrating the information gathered from simultaneously acquired independent measurements can lead to a better understanding of the migration process and the nature of the underlying reservoirs.
AAPG Search and Discovery Article #91043©1986 AAPG Annual Convention, Atlanta, Georgia, June 15-18, 1986.