Stratigraphic-lithologic reservoir type and hydrocarbon accumulation main controlling factors of Shijiutuo swell in Bohai Sea

Based on the analysis of structure,sedimentary reservoir and hydrocarbon source rock,the forming conditions,types and main control factors of stratigraphic lithologic reservoirs of Shijiutuo formation have been deeply analyzed.It is believed that hydrocarbon source rocks of Sha-3 member,Sha-1,sha-2 members and lower Dongying were de-veloped in Bozhong and Qinnan sag beside north and south of Shijiutuo swell.With good hydrocarbon source conditions,affected by tectonic movement,ramp slope break,single fault type steep slope break and slow slope fold have been formed.In Dong-3 member and Sha-1,Sha-2 members,braided river delta and fan delta reservoirs have been deposited,which provided good conditions for stratigraphic-lithologic reservoirs.Stratigraphic lithologic reservoir types are mainly of slope stratigraphic reservoirs,deep thick broken nearshore fan lithologic reservoirs and delta updip pinchout lithologic reservoirs.It is pointed out that in the Bozhong and Qinnan sag,these two rich hydrocarbon generation depression are the basis of stratigraphic lithologic reservoir formation,the stable distribution of dongying group of huge thick mudstone and one section,east three sections of the extensive development of high quality reservoirs is the guarantee of stratigraphic lithologic reservoir formation and the key.