A petroleum system encompasses a pod of active [[source rock]] and all genetically related oil and gas accumulations. It includes all the geologic elements and processes that are essential if an oil and gas [[accumulation]] is to exist.
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A petroleum system encompasses a pod of active [[source rock]] and all genetically related oil and gas accumulations. It includes all the geologic elements and processes that are essential if an [[oil]] and [[Natural gas|gas]] [[accumulation]] is to exist.
'''Petroleum''' describes a compound that includes high concentrations of any of the following substances:
'''Petroleum''' describes a compound that includes high concentrations of any of the following substances:
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* Thermal and biological hydrocarbon gas found in conventional reservoirs as well as in [[gas hydrates]], tight reservoirs, [[fracture]]d shale, and coal
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* Thermal and biological hydrocarbon gas found in conventional reservoirs as well as in [[gas hydrates]], tight reservoirs, [[fracture]]d [[shale]], and [[coal]]