ORGANIC GEOCHEMISTRY RESEARCH INTO MULTI-PHASE PETROLEUM MIGRATION AND ACCUMULATION IN RIFT-SUBSIDENCE BASIN

The petroleum migration is not only an important theoretical problem but also a puzzle in petroleum geology. In this paper, the organic geochemical analytical results of the crude oil and source rocks, especially the biomarker compositions, are used to classify the petroleum types for the correlation between the petroleum sources, with some examples of oil fields within the Zhanhua sag, northeast of Jiyang depression. In this case, the features can be summarized of the multi-phase petroleum migration and accumulation in the rift-subsidence basin. The present research results support the correlation between the formation of the -phase petroleum migration and accumulation. The Kenxi oilfield in the marginal fault zone is a product of the alternation of petroleum migration directions: the lateral migration through the carrier beds and the vertical migration through the faults. The formation of the Gudao-type Guqianshan oilfield is related to the third petroleum migration from the lower Tertiary pool. The lateral migration and filling within the rift-subsidence basin often result in the formation single-source petroleum accumulation, but the vertical filling at the fault zone often results in the formation of the mixed-source petroleum accumulation. Therefore, the multi-phase petroleum migration is related to the duration and episodes of the fracturing activity within the basin.