问答题 翻译：These reservoirs can be classified according to rock types, depending on variations in source rock, transport distance, and depositional environment.

问答题 翻译：Classification of traps logically falls into three broad general groups: (1) structural, (2)stratigraphic, and (3)combination.

问答题 翻译：The retort method has several disadvantages as far as commercial work is concerned.