Abstract:

Based on exploration achievements of lithological reservoirs in Erlian Basin, the hydrocarbon enrichment factors are analysed in four primary sags. Lithological hydrocarbon enrichment factors include luxuriant oil-source, high quality sand-body trap and confluence pathway. The luxuriant oil resources are substantial base of hydrocarbon enrichment, because there are two sets of source rocks with huge thickness, widespread distribution, large resource extent and several relationships to sandbodies in Erlain Basin. The high quality sand-body trap is characteristic of a large-scale trap, having furthersome types of reservoir facies and favorable reservoir, which are key factors for hydrocarbon enrichment. The analysis of the high quality sandbody trap's characteristics suggests that large-scale traps include single large-sized sand-body trap and several overlaying small-sized lithological traps; furthersome reservoir facies involve fan delta, braided river delta and sublacustrine fan; the hydrocarbon enrichment usually forms in favorable reservoirs. Furthermore, abundant hydrocarbon enriches in high quality sand-body traps by lateral confluence pathway in digitiform sand and fault vertical confluence pathway.

Key words: hydrocarbon enrichment, factor, lithological reservoir, Erlian Basin