Analysis Of Main Controlling Factors Of Chang 9 Reservoir Formation In Wuqi Area Of ??Ordos Basin

With the enhanced exploration and development of global oil and gas,The focus of oil and gas exploration is from the conventional oil and gas reservoirs to the low permeability reservoirs,and even the tight reservoirs.Yanchang formation of Ordos basin is an important low permeability and tight reservoir in China.Previous studies are mainly concentrated in the chang 7-chang l,but recently,with the development of the exploration of Chang 9,Chang 9 exploration has made great the breakthrough,a large number of industrial reservoirs have been found,it shows that the Chang 9 oil-bearing formation in Ordos basin has a good exploration prospect,Chang 9 is the new main force oil producing zones.For Chang 9 formation,diffirent regions of Chang 9 reservoir characteristic,oil and gas sources,main controlling factors of hydrocarbon accumulation and accumulation model are different.Based on sorting and summarizing predecessors' reserch data,with the geology theory guidance including the sedimentary petrology,petroleum geology,logging geology and petroleum geochemistry,using drilling,well logging,petrophysical and geochemistry data,this article is studying reservoir characteristics,oil and resource correlation,migration system,dynamics,hydrocarbon accumulation model and controlliong factors.Studies have shown that:Wuqi area Chang 9 Sand body are mainly developed in underwater distributary channel,mouth bar et al,the sand body's distribution is ne-sw,the rock types of Chang 9 reservoir are mainly debris-feldspar and feldspathic lithic sandstone.There are many kind of interstitial material,including hydromica,calcite,ferrocalcite,chlorite and siliceous.The particles is mainly fine-grained sandstone and siltstone,which have medium separation,sub-angular.The main reservoir spaces are intergranular pores and dissolution pore,throat type is microthroat.Wuqi area Chang 9 has poor reservoir property,porosity and permeability are 7.42%and 0.39mD,belongs to extra low porosity and ultra-low permeability reservoir.Compaction and cementation are the main diagenesis of the Chang 9 reservoir,while dissolution is the main constructive diagenesis.Wuqi area Chang 7,Chang 8,Chang 9 formation are developed with good source rock.However,the study of oil source correlation shown that,Oil mainly from Wuqi area Chang 8,Chang 9 source rocks,the reservoir of Chang 9 is the lithologic hydrocarbon reservoir,migration conductiong system for sand body connectivity and crack.Reservoir forming dynamics of this area is mainly from undercompaction of source rocks and abnormal high pressure from hydrocarbon generating pressurization.Chang 9 oil is mainly concentrated in the relatively high porosity and high permeability reservoir,belong to near source accumulation.Overall,Wuqi area Chang 9 reservoir formation is mainly controlled by source rock,hydrocarbon generation intensity scale,sand body connectivity,cracks and reservoir property.