Research On Oil-gas Distribution And Key Control Factors Of Es₂ Of Da 8 Block In Dawangzhuang Oil Field

Da 8 fault bolck is located in the southern Dawangzhuang gentle slope between Dawangbei Sag and Yihezhuang Arch, Chezhen Depression. Es2 with great exploration potential is the most important hydrocarbon reservoir assemblages in this area. But due to lack of research on fault distribution, character of oil distribution and key control factors in Da 8 area, exploration has stepped into stagnant period. Based on the precedent outcomes, the modern oil geology theories are utilized to study the faults, reservoirs, oil source and characters of oil distribution in this paper with the purpose of clarifying the law of oil distribution and key control factors in Da 8 fault block.Study suggests that the Es2 with angle disconformity contact on underlying Es3 can be divided into four sand groups from bottom to top. Based on stratigraphic classification and correlation to implement the distribution of faults in Da 8 area, result indicates that the normal faults with EW and NE are distributed in parallel type and en echelon type in the plane. A large-scale fault nose structure is developed in the south, which leads to the layout declines from north to south.There is only one depositional systems in Da 8 area, beach and bar depositional system belonging to littoral-shallow lake facies. Beach and bar reservoirs are distributed in entire region continuously in the plane, and superimposed each other vertically with good lateral connectivity. The types of sand body of beach and bar are mainly siltstones and fine sandstones with medium porosity and low permeability, distributed in the south and north of study area.The hydrocarbon reservoir type can be divided into three types, these are tectonic reservoir, composite reservoir and lithologic reservoir. The oil of the Es2 in the beach and bar reservoir are mainly distributed in southern fault nose structural zone. And the tectonic factors, the lithological and physical properties of reservoirs control the oil distribution. The Es2 2+3 sand groups are main hydrocarbon reservoir assemblages, which are consisted of numerous thin oil layers.Oil-source correlation reveals that the oil of the Es2 in the beach bar reservoir came from the upper Es4 source rock of the northern Dawangbei Sag. The faults and reservoirs control the formation and distribution of oil in the beach bar reservoir. The faults and reservoir sand bodies supply important migration pathway for hydrocarbon. In the meantime faults further control the oil accumulation stratigraphic position, the physical properties of reservoir control the distribution scope of oil in the plane.