The Study On The Sedimentary Facies And Reservoir Characteristics Of The Chang 2 Oil-bearing Strata Of The Triassic Yanchang Formation In The Maning Oilfield, Jingbian Oilfield

Based on the theory of sequence stratigraphy,tectonic geology,sedimentary petrology,petroleum geology and reservoir geology as well as various data,the paper divided and contrasted the stratigraphic strata of the group of Chang 2 oil layer in Maning Oilfield,and analyzed the top interface structure of the single layer in the study area,studied the core facies,profile facies and plane facies successively,then summarized the distribution of sand bodies.And the debris composition,interstitial composition,structural characteristics,pore type,throat type and physical properties of the reservoir were studied.The paper analyzed the interlayer heterogeneity and intraformational inhomogeneity,and finally classified and evaluated the reservoirs layers of the study area comprehensively.The following results were obtained:The main research objectives of this paper are these two single layers named Chang 21-1 and Chang 21-2,Chang 21-1 has a higher oil content.The superface structure of Chang 21 is a westward tilted monocline with several low amplitude nose structure and there is a small depression in the East.The top structure is placid and wide.The top interface structure of Chang 21-1 has inheritance.The sedimentary facies of Chang 21 are mainly branch channels and interchannels,then the natural levees and crevasse splay deposits.The provenance comes from the Northeast.The branch channels are from northeast to southwest.There are more branch channels in the southern part of the study area.The sand body of Chang 21-1 is thinner than Chang 21-1.The rocks in the study area are mainly arcose with low componential maturity and high.The interstitial content is less.The rocks are mainly fine sandstone.The grinding is sub-angular and the sorting is good.The textural maturity is medium-high.Primary intergranular pores and feldspar dissolution pores are the main reservoir spaces.The throat is mainly lamellar or curved,bundle.Chang 21 reservoir is low porosity and extra low permeability reservoir with strong correlation between porosity and permeability.The distribution direction of porosity and permeability is basically the same as that of the sand body.High porosity and high permeability zone are located in the central part of channel sand body and they are approximately superposition.The southern part of the study area has more high value areas.The sand body of Chang 21-1 has higher porosity and permeability than Chang 21-2.Chang 21 reservoir has strong interlayer heterogeneity and intraformational inhomogeneity.Chang 21-1 has the strongest heterogeneity in three single layers.The exploration target area in the study area is mainly class ? reservoir.Reservoir distribution is affected by sedimentation.The reservoir quality of the central part of the channel sand body is better.The type of Chang 21-1 reservoir is better than Chang 21-2.There are more high-quality reservoirs in the south of the study area.