Study On Sedimentary Facies Of The Ek₂⁴ In Zaoyuan Region,Cangdong Seg

The Cangdong Seg is located in the southern part of the Huanghua Depression.It is a complex oil and gas accumulation area with the Kongdian Formation as the main source rock and reservoir.The Kongdian Formation developed a complete sedimentary cycle,which was characterized by an independent basin-forming process.It was divided into three segments,Ek1,Ek2 and Ek3.It is an important hydrocarbon-bearing strata.The Zaoyuan area is located in the northern part of the Cangdong Seg,it is the most important oil and gas exploration target area in the Cangdong Depression.In the production practice,a lot of work has been done on the deposition system and sequence stratigraphy of the Kongdian component layer system?Ek1,Ek2,Ek3?.Ek₂⁴ is the low-level system of the Kongdian Formation.The source of supply is sufficient and the sand body develops.It is one of the main exploration strata in the Zaoyuan area,but the research on the provenance,sedimentary facies and sand body distribution of this reservoir group is weak,which affects the oil and gas exploration and development of the Ek₂⁴ in this area.In view of the above problems,this paper selects the Zaoyuan area as the study area,applying sedimentology and continental sequence stratigraphy theory to study the sedimentary facies,sedimentary subfacies,sedimentary microfacies characteristics of the Ek₂⁴.and the spatial distribution law of sedimentary microfacies of the Ek₂⁴ is revealed.On this basis,the study of spatial distribution of favorable reservoir sand body was carried out by combining physical data.The following four points are mainly obtained:?1?Through the comprehensive analysis of the core,well logging,logging and seismic data of the Ek₂⁴ in the Zaoyuan area,it is considered that two sedimentary facies,braided river delta and lake,are developed during the Ek₂⁴ deposition period in Zaoyuan area,three sedimentary subfacies in the braided river delta plain,the leading edge and the shore shallow lake;six sedimentary microfacies in the diversion channel,the diversion channel,the underwater distributary channel,the underwater distributary channel,the estuary dam and the mat sand.?2?According to heavy mineral composition,skeleton sandstone composition,the types of cuttings,dispersed system,the seismic facies sand body,and the comprehensive analysis of regional gravity anomaly,it is believed that there are seven provenances in the Zaoyuan area during the Ek₂⁴ sedimentary period in the Cangdong Depression,the Kongdian bulge in the north is the main source supply area for detrital materials.?3?Through the comprehensive analysis of the combined well sand body comparison,associated well sedimentary facies profile,seismic facies spread,percentage content of sandstone,sand body thickness and seismic attribute of Ek₂⁴ in the Zaoyuan area of the Cangdong Depression,it is considered that the microfacies of the subaqueous distributary channel in the front of the braided river delta of the Ek₂⁴in Zaoyuan area are most developed.which is located in the middle and the front edge of each flower body,and shows a zonal distribution with a large range,mainly distributed in the area of the Junma station-Zaoyuan-Dongguan and the south of Shenjiapu.The microfacies of the estuary dam of the braided river delta are mainly developed at the front end of the body of Kongdian,which is distributed in point.?4?Through the analysis of sandstone porosity and permeability characteristics of the Ek₂⁴ in Zaoyuan area of Cangdong Seg,it is considered that the reservoir performance of the underwater distributary channel and the estuarine dam sand body of the Ek₂⁴ in Zaoyuan area is the best,followed by the estuarine dam sand.