The Research On Sedimenttary Facies And Reservoir Characteristics Of Chang 2 Oil-bearing Formation In Dong-bai Area,Qingpingchuan Oilfield

Qingpngchuan Oilfield is located in Country Guanzhuang,Yanchuan County of Shaanxi province,and Dongyibai District is in the middle of the Oilfield.The ares size is 23.36 square kilometer.Its development effect in the beginning is pretty good since exploited,however,the degree of further exploitation is restricted greatly owing to the shortage of geology and oil-gas distribution.The chang2 reservoir layer which is the main oil-bearing strata is divided in detail,and sedimentary facies,sand distribution as well as the integrated characteristic of reservoir layer are fully researched.So there are 3 benefits from the above research:further understand the geological situation,further develop the productivity and provide a reasonable basis for the next comprehensive treatment.Taking the disciplines and theories of petroleum geology,sedimentology,petrology and reservoir geology as the guideline,and on the basis of abundant data and materials from drilling,logging,core,testing,producing analysis and research report,and widely gathering related data of neighboring region,this paper has all studied sedimentary,tectonic,sedimentary facies,reservoir comprehensive feature,etc.The research results show that the target area is a broad gental west-dip monocline,with nose like structure locally.The deposition system of Chang 2 member is the delta-plain facies.The distributary channel is the advantage facies in target area,it distributes nearly N-S banded,crevasse splay never develop basically.Rock types of Chang 2 reservoirs are mainly dust colour argilliferous fine-medium lithic arkose.The main diagenesis of reservoir sandstone are compaction and denudation,etc,the pore types are mainly intergranular and dissoluted ones,which belongs to very low permeability layer.The studies have shown that Dong-Bai area reservoirs in Qingpingchuan Oilfield are mainly gray-brown fine,clay fine-grained lithic feldspathic sandstone,whose pore type are mainly intergranular pore and feldspar dissolved pore,whose pore throat combination are maily intergranular pore type,dissolved pore-intergranular and grain hole between the passpass the main solvent.Heterogeneity of reservoir sand bodies is at the intermediate level,,even above it.Chang 212 and Chang 221 that are the main reservoir of Chang2 both have big heterogeneity.Oil-Water distribution is mainly affected by sedimentary facies,reservoir properties and diagenesis.Channel sand dam is a major site for oil and gas migration and accumulation.