Research On Characteristics Of Chang 6 Reservoir In Huanxian Area,Ordos Basin

Huanxian area is located in the southwest edge of Ordos Basin,and Chang 6 reservoir is its new development area.Guided by the theories of sedimentary petrology,petroleum geology and other disciplines,this paper uses core observation,casting thin sections,scanning electron microscopy,particle size analysis,high pressure mercury injection and other experimental methods,combined with digital logging and rock sample analysis data,to analyze the geological conditions of Huanxian area.The Chang 6 formation in the study area was divided and compared.The sedimentary facies,petrology,pore structure,physical properties,diagenesis and other characteristics of the Chang 6 reservoir were systematically studied.And the main controlling factors affecting the development of the reservoir were analyzed.This paper construct a parameter of oil storage capacity above the research result.The reservoir parameters are integrated to realize the classification evaluation of the reservoir.The Chang 6 reservoir in the study area belongs to lacustrine sedimentary system,which mainly develops half-deep lake and deep lake subfacies,and contains microfacies such as sandy debris flows,turbidity currents and so on.The rock particles are mainly gray and gray black ultrafine-fine lithic arkose,and the main interstitial materials are illite and ankerite.The pore types are mainly residual intergranular pores and feldspar dissolved pores.The nano pore throat radius is generally small.Pore structure is divided into three categories by using Fisher discrimination.The finer pore throat also affects the physical properties of the reservoir.The average porosity of Chang 6 reservoir is 8.69% and the average permeability is 0.129 m D.Compaction is the main reason for reservoir densification.According to the division specification of diagenetic stages and the Chang 6 reservoir conditions of Huanxian area,it is considered that the target layer has entered medium diagenetic A-B stage.According to the classification standard of reservoir evaluation,Chang 6 reservoir in Huanxian area can be divided into type I,II and III.Different reservoir types have great differences in reservoir and seepage capacity.