Untrapped petroleum naturally escapes reservoirs through seepage and undergoes active biodegradation over time by specialized microbial communities in marine and aquatic sediments.
The retrieved papers consistently provide evidence that natural petroleum seeps occur and that the hydrocarbons involved undergo extensive microbial degradation over time. Papers 0, 1, 3, and 6 (among others) detail how diverse microbial taxa metabolize these petroleum compounds in marine and lacustrine environments. There is no evidence in the provided literature refuting natural seepage or biodegradation.