Study of characteristics of hydrocarbon migration and accumulation in Xinzhuang oilfield in Biyang depression

A series of fault - nose and fault - block pools and several unconformity pools occur in Xinzhuang oilfield where faults are well developed and structures are fragmented. In respect of reservoir distribution, this oilfield has the following characteristics. The burial depth of reservoirs is shallow, barrier beds are relatively thin and oil - bearing intervals in a single well are concentrated; the number of pools is large, while their sizes are relatively small and the major reservoirs are not predominant; the distribution of reservoirs are obviously controlled by faults, and reservoirs are overlapped to some extent though the oil - bearing area of single layer is relatively small. In respect of the control factors of hydrocarbons, on one hand, the inherited structural noses would have controlled the direction of accumulation and the degree of enrichment of hydrocarbons, with hydrocarbons mainly accumulated in the positive traps such as the inside of arcuate faults and the inverse ridge fault blocks in a nose structural setting. On the other hand, the faults would have played an important role in migration and accumulation of hydrocarbons, acting as both migration pathways and seals. The oil-bearing area and oil column were mainly controlled by the sealing capacity of faults. The distribution patterns of hydrocarbons were controlled by structural styles of various fault block groups accompanying extensional structures.