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Geochemical
Exploration in Deserts of
Schumacher,
Dietmar, Luis Clavijo, Daniel Hitzman, Geo-Microbial Technologies, Inc,
Surface geochemical exploration for petroleum is the search for
surface or near-surface occurrences of hydrocarbons and their alteration
products. It has been well documented that most oil and gas accumulations leak,
that this leakage is predominantly vertical, that it is dynamic, and that this
leakage can be detected and mapped using any of several direct and indirect
methods. 
Hydrocarbon
microseepage surveys in deserts require careful planning
and implementation. Microseepage data are inherently noisy and require adequate
sample density to distinguish between anomalous and background areas. To
optimize the recognition of a seepage anomaly, the sampling pattern and sample
density must reflect survey objectives, expected size and shape of the target,
and expected variation in surface measurements. Defining background values
adequately is an essential part of anomaly recognition and delineation.
Undersampling and/or the use of improper analytical techniques is a major
cause of ambiguity and interpretation failures.
Results of
microbial and soil gas surveys in the deserts of hydrocarbon microseepage data for high-grading basins,
plays, and prospects. Surveys in hydrocarbon microseepage to the
surface in spite of the presence of 200400 meters of halite above Triassic
reservoirs, and the composition of the migrating hydrocarbons correctly
predicted the composition of the reservoired hydrocarbons. Results from surveys
in hydrocarbon
charge. Geochemical exploration surveys such as these
require close sample spacing and are most effective when results are
integrated with subsurface data.