PHOTO GEOLOGY
The hydrocarbons you're looking for may be trapped by structure (anticlines, folds, reefs, salt domes, wrench faulting, basement faulting, fractures, etc.) and marked at the surface by tonal anomalies, (nothing new to photogeology) which can result from the multifarious effects of hydrocarbons as they (micro)seep from buried reservoirs at depth. Hydrocarbons affect the near-surface soils in ways we can detect as they're expressed in various ways: soil staining, bleaching, erosional differences, moisture content variation, and by vegetation as a result of stunted growth, cell structure changes, photosynthesis alterations, and population density variation; or because fewer soil-building microbes (they don’t like to live in areas where they’re gassed) live there. Conversely, there may be an increased presence of anaerobic bacteria, whose populations bloom in the presence of the reducing environment brought on by the hydrocarbons and sometimes leave a residue of iron oxide staining.