Published 1996 as part of Memoir 66
Copyright © 1996 The American Association of Petroleum Geologists. All Rights Reserved.
 

Near-surface exploration for petroleum is based on the detection and interpretation of a great variety of natural phenomena occurring at or near the land surface or sea floor and attributed, directly or indirectly, to hydrocarbons migrating vertically upward from leaky reservoirs at depth. Development of surface exploration methods began in the early 1930s with the chemical analysis of gaseous hydrocarbons in soil air. It has since expanded to include a wide range of geochemical, geophysical, mineralogic, microbiological, and other types of anomalies. The great advances in the observational and analytical techniques, however, have not been matched with similar improvements in the method's efficiency and effectiveness in terms of new field discoveries. From a hydrogeologic perspective, the inconsistency of the results can be explained, at least in part, by a disregard for the possible effects that groundwater flow may have on the nature and intensity of the anomalies as well as on their positions relative to subsurface sources and accumulations. Since the principles and investigative techniques of regional groundwater flow are well established, introducing a hydrogeologic component of near-surface petroleum exploration should be technically easy and economically feasible. The expected improvement in the results should serve as a strong incentive for purposeful collaboration between near-surface explorationists and hydrogeologists.