Sedimentary Facies And Reservoir Characteristics Of Ch2&Ch6 Formation In Southeast Of Jingbian Area On Ordos Basin

Ordos Basin is rich in oil and gas.Dingbian-Hengshan area is in the north of Shanbei Slope,which has been explored and developed for more than a decade.The exploring of Mesozoic petroleum is made constantly progress,but the whole exploring extent is still low. This text had done some basic geological information analysis inferred with the region of interest,such as the outcrops and the cores.Simultaneity,this article comprehensively uses the theory and method of stratigraphy,sedimentology and reservoir geology.Besides,we made researches of stratigraphic classification and correlation,sedimentary facies identification,the analysis of sedimentary facies and sand body determination distribution, as well as,some studies about reserevoir features,so,we further reconiged the sedimentary system of Yanchang Formation in Jingbian area.We looked for regional stratigraphy correlation key beds,adopted cyclical control and depth reference methods,made stratigraphy correlation of the Yanchang Formation in Jingbian area,at the same time,obeying to practice,we subdivided the Chang2 and Chang6 Formations into Chang2~1,Chang 2~2,Chang 2~3 and Chang 6~1,Chang 6~2,Chang 6~3,Chang 6~4. At the above effort,we have established several connecting-well sections to make strata correlation.Through the sedimentary characteristics,fossils,rocks and other electrical characteristics, an analysis of sedimentary facies and depositional systems about Yanchang Formation in the south-eastern of Jingbian area has been made,the study shows that the Chang6 is mainly a delta sedimentary facies,it develops distributary channel of plain intrafacies,natural levee, interfluvial pit and crevasse splay.The Chang2 is a river sedimentary facies,Chang2~2 and Chang2~3 develop braided river channel sand dam and flood plain microfacies,Chang2~1 mainly develops meandering river channel sand dam and floodplain dam microfacies.Among this,distributary channel sand body and channel sand body are the main reservoir sand body. The development of sand body,controled by sedimentary,distributes in the direction of NE-WS.We researched the reservoir characteristics of Chang2 and Chang6 from the reservoir rock characteristics,physical characteristics and of pore structure,the results show that:the reservoir character of Yanchang Formation in the target area is with low compositional maturity and high structure maturity,and is apparently controlled by sedimentary facies. Chang2 oil unit is a reservoir bed belonging to mid-porosity and low permeability,even low porosity and low permeability.Correspondely,Chang6 is a part of low porosity and low even ultra low permeability reservoir bed.We Overally examine the sedimentary facies,sand body distribution,physical character of the reservoir and structure feature and other factors,and comprehensively inquire the oil/gas enrichment and distribution of the area.These above provide evidencies for further exploration and exploitation.