Abstract:

Hydrocarbon third migratgion is a periodic flow process. When faults are in dormantstage,large faults are sealed and hydrocarbons could accumulate to the fault traps within abnormal high pressure source sets to form primary pools lwhen faults are active,large faultsare open,hydrocarbons in the primary pools would migrate upward along the large faults toform secondary hydrocarbon pools in shallow traps. As the third migration is quick and concentrated,it did not result in evident chromatographic effect but did result in obvious differentiae between the primary and secondary pools since most of the hydrocarbons overflowedfrom the primary pools are light components. The hydrocarbons overflowed continuouslyfrom the primary pools, and were flushed by water-flow, then entered different reservoirswith water-flow,thus resulting in random distribution of secondary pools vertically.