Analysis On Main Controling Factors Of Mesozoic Hydrocarbon Accumulation In Chepaizi Area Of West Junggar Basin

The exploration degree of Mesozoic in Chepaizi area ofwest Junggar Basin is relatively low,and the study of the source of oil and the hydrocarbon accumulation process in Chepaiziarea is weak,result in the hydrocarbon accumulation control factors is not clear.In accordance with these problems exist in the study area,under the guidance of the theory of petroleum geology,petroleum geochemistry,sedimentologyand the hydrocarbon accumulation theory,we fully use thefield outcrops,cores,logging,seismics and analysis assay data,and use technical means and research methods of geological statistics and geochemicalanalysis,focusing on the research of reservoir characteristics and the source of oil,to discuss the hydrocarbon accumulation characteristics and clear the accumulation controlling factors for building hydrocarbon accumulation model.Based on the research above,we come up with the exploration direction and target next.Through core observation,analysis of grain size and the microscopic observationof rock chips,distinguish the sedimentary facies types of single well,determined the sedimentary facies types,establish the sedimentary facies model.Using the method of distribution function curve,the physical property lower limit of effective reservoir inJurassic and cretaceous of west Junggar Basin is explicated.The burial depth of Cretaceous reservoir within 1000 meters,the physical property lower limit of effective reservoir is 14%,the Jurassic is 10%.Reservoir lithology is mainly feldspathic lithic sandstone and lithic feldspar sandstone,the type of reservoir space are mainly fracture and solution pore,comprehensive evaluated as medium porosity and permeability.Oil source correlation determined crude oil in the east wing of Chepaizi area is from the middle Permian series in Shawan sag,crude oil in the middle wing of Chepaizi area belongs to the mixed oil of Permian and Jurassic,crude oil in the west wing of Chepaizi area is from early Jurassic of Sikeshu sag.On the basis of the accumulation process research and the accumulation characteristics of oil and gas in Mesozoic of Chepaizi area,hydrocarbon accumulation is mainly controlled by two aspects: the conducting efficiency of fault and sand body and the reservoir quality.Fault,blanket sand control distribution layerof oil and gas,the reservoir qualityof sand body controlsthe stand or fall of oil and gas.The accumulation characteristics of Mesozoic in Chepaizi bump are twosource for hydrocarbon,two stage filling(J2,K,E-N),buoyancy driven,fault-blanket sand conducting,accumulated in the carpet edge.In the process of accumulation,the conducting system of fault-sand body plays a crucial role in controlling oil and gas accumulation and distribution,thereservoir quality of sand body controlsenrichment of oil and gas.In this foundation,we build the hydrocarbon accumulation model of Chepaizi area: long distance for hydrocarbon,fauty-blanket sand conducting,reservoir quality of sand body controls the hydrocarbon enrichment.