Research On Sedimentary Facies And Reservoir Characteristics Of Yan 10 And Yan 9 Formation In T-29 Well Area Of Wuqi Oilfield

Ordos basin is an important energy base in China.The basin contains abundant fossil energy,of which the oil and gas resources are one of the important resources.The major strata of Petroleum are Triassic Yanchang Formation and the Jurassic Yan’an Formation in Ordos Basin,This paper mainly studies the sedimentary facies and reservoir characteristics of layer Yan 10 and Yan 9 in Yan’an Formation in area of T29well.On the basis of previous literature research and data collection,a stratigraphic division scheme suitable for the study area was used to conduct detailed stratigraphic division of the target stratum and establish a stratigraphic profile skeleton.On the basis of stratigraphic classification,combined with the characteristics of core observation and logging curves,the sedimentary microfacies and sand body development characteristics of the study area are depicted from the section to the plane,from the single well to the well tie.Using core test data,X-diffraction,splat particle size analysis,porosity and permeability under overburden pressure,and casting thin slice to study reservoir characteristics.Using heterogeneous evaluation parameters,determine how strong reservoir heterogeneity.Finally,Finally,the reservoir favorable area is preliminarily predicted.It can provide some help for further exploration and development.The layer Yan 10 is divided into Yan 10~1 and Yan 10~2,and the layer Yan 9 is divided into Yan 91 and Yan 92.The strata of the study area are relatively flat,showing that high in the east and low in the west.Braided River sedimentary subfacies were developed at Yan 10 Group.of Yan’an Formation in the study area,and the main sedimentary microfacies are braided channel deposition and flood plain.The sedimentary body is channel deposition at Yan 10~2 single layer,and the average thickness of sand body is 9.13 meters.The sedimentary body is flood plain at Yan 10~1single layer,and the average thickness of sand body is 3.48 meters.Delta plain subfacies were developed at Yan 9 layer.of Yan’an Formation in the study area,and the main sedimentary microfacies are distributary channel,river swamp and natual levee.The average thickness of sand body at Yan 9~2 single layer is 5.17 meters,and the average thickness of sand body at Yan 9~1 single layer is 2.56 meters.The reservoir sandstones is mainly consisted by lithic feldspar sandstone.The reservoir pore types are mainly dissolution pores and residual intergranular pores,intergranular pores are rarely.The main diagenesis has compaction,cementation and dissolution.Related heterogeneity parameters show that the reservoir belongs to strong heterogeneity.The reservoir’s main controls are sedimentary and diagenetic.The sedimentary sand body of the stream channel has better reservoir property than the sedimentary sand body of the interchannel.Space of reservoir is increase in the dissolution,the compaction and cemention reduce the reservoir space.The reservoir types in the study area areⅡandⅢ_a,belongs to low permeability reservoirs.The reservoirs in the northwest and southeast of the study area are favorable exploration areas.