The Main Controlling Factors Of Dessert Area In Ek₂ Of Cangdong Sag

In the North American tight oil has achieved breakthroughs in both theory and technology,China's tight oil exploration and development progress is also rapidly catching up.After years of technical research and in-depth exploration,it has been determined that the Bodong sag in the Bohai Bay Basin is consistent as Oil-rich area in China,Among them,each small layer of Kong 2 is rich in dense oil and gas resources,which has great potential for development.However,due to the unclear source-storage relationship of tight oil reservoirs in Kong 2,the type and regularity of hydrocarbon accumulation are insufficient,and the research area is dense.There are many types of reservoirs,and there is no classification study on the relationship between various tight reservoirs and adjacent source rocks,so that the main controlling factors of tight oil enrichment are unknown.It is necessary to systematically summarize the main controlling factors of tight oil enrichment in the study area.In the current situation,this paper summarizes the structure and sedimentary characteristics of the study area by observing cores,thin slices,combined with logging data,test oil data and geochemical indicators,and further analyzes the characteristics of source rocks by geochemical methods.It is combined with reservoir characteristics to determine the source-storage relationship,and finally the control factors for tight oil enrichment are determined,and the"dessert"zone is preferred.Research area is consented as evaporative inland lake basin,In all four layers Ek₂¹,Ek₂²,Ek₂³ and Ek₂⁴ contain effective source rock TOC averages around 3%,The kerogen type is mainly type I-II₁,and Ro is between 0.5 and 1.3%.There are three types of tight reservoirs in the interval,namely fine sandstone,dolomite and transitional rock.The main reservoir types are secondary dissolution pores and intercrystalline micropores.The pores of the reservoir pores with nano-scale pores are3.03%¹3.65%,with an average of 7.71%and a permeability of 0.04⁹.44 mD,with an average of 0.59 mD.The source-storage relationship in the study area is dominated by self-generated and self-storing,and the small amount is the sub-type after very short migration.In the self-generated self-storage category,the coupling configuration relationship is sandwich,inter-layer and layer-layer cake.Combining the above results and superimposing multiple potential master factors on the plane,the main controlling factors of tight oil enrichment are source rock with large area and large thickness distribution,TOC,Ro,tight reservoir permeability,and sweetness.The area is optimized,TOC is above 3%,the oil shale rock thickness is more than 50m,Ro is 0.5-1.0.The tight sandstone thickness is greater than 10m.The dolomite is relatively developed.The central part of the lake basin with a buried depth of less than3800m is a favorable area for the exploration of tight oil dessert area.