Print this pageModel for Hydrocarbon Microseepage and Related Alterations
SAUNDERS, DONALD F., K. RAY BURSON, and KEITH C. THOMPSON
Evidence indicates that hydrocarbon microseepage from reservoirs most probably involves buoyant colloidal-size "microbubbles" of light hydrocarbons (principally methane through the butanes) ascending relatively rapidly through a water-filled network of fractures, joints and bedding planes.
Consumption of these hydrocarbons by bacteria creates carbon dioxide and hydrogen sulfide which may alter sediments, producing detectable geomorphic, seismic, magnetic and radiometric anomalies.
Methods used successfully by the authors include geomorphology, airborne and near-surface hydrocarbon detection, aerial and surface gamma-ray spectrometry, high-sensitivity aeromagnetic surveys and magnetic susceptibility measurements of soils. The authors have found that combinations of these methods can substantially increase the probability of wildcat success and minimize finding costs. However, this type of surface evidence of subsurface hydrocarbons cannot reveal depth or quality of reservoirs, or economics of petroleum recovery.