Research On Reservoir Characteristics Of Yan10 Member In Longdong ZH250 Well Area

The ZH250 well area is located in the east of Zhenbei Oilfield in Longdong,the main reservoir is the Yan 10 member of the Lower Jurassic Yan’an Formation.With the deepening of development and the increasing degree of recovery,the understanding of sediment and reservoir can no longer provide important support for the fine reservoir description in this area.This paper mainly studies the sedimentary facies and reservoir characteristics of the Yan 10member in the study area,in order to provide reliable geological basis for the next development.Pay attention to the auxiliary marker layer,and finely divide and compare the Yan 10reservoir group in the study area,based on the systematic analysis of the sedimentary facies,the types of sedimentary microfacies and the distribution characteristics of sand bodies in each sand layer group are studied,the focus is on the study of reservoir characteristics.Multiple reservoir geological parameters are obtained through the study of reservoir characteristics,and comprehensive evaluation of the reservoir is performed.The main recognition is:The Yan 10 member in the study area belongs to the sandy braided river sedimentary facies,including Channel subfacies,interchannel subfacies and river spreading subfacies,and develops micro-facies such as central bar,channel sand,channel edge,channel mud,floodplain,etc,central bar and channel sand are the dominant sand-control microfacies.On the plane,the central bar microfacies are isolated and irregularly surrounded by the channel sand microfacies.The two microfacies form an embedded configuration pattern,resulting in good sand body continuity.Yan 10 member in the study area is mainly composed of medium sandstone and fine sandstone,and siltstone is seen,and feldspar debris sandstone is the most developed;Yan 10₂ reservoir in the study area has an average porosity of 12.76%and an average permeability of 4.83×10^-3μm².The types of reservoir pores are mainly residual intergranular pores and feldspar dissolved pores;Mercury pressure curves are mainly of typeⅡandⅢ.In general,it belongs to the sand control reservoirs with central bar and channel sand,low porosity,low permeability,and medium heterogeneous sandstone reservoirs.Research on the"Four characteristics"Characteristics and Relationship of Sand Control Microfacies:the electrical cobweb patterns of the central bar microfacies are mainly unimodal“approximately irregular pentagons”,while the channel sand microfacies are mostly bimodal“regular hexagons”;Both central bar and channel sand are the main reservoir microfacies of the sand formations in this area.However,the lithology and physical properties of central bar body is better than those of channel sand,and their oil-bearing properties are also better than those of channel sand.Based on the comprehensive parameters of lithology,physical properties and pore structure,Yan10 reservoir in the study area is divided into 4 types,Yan10₂ reservoirs are mainly of type II and III,and the reservoir quality is better than Yan 10₁ and Yan 10₃ reservoirs.