Sedimentary And Reservoir Characteristics Of The Fourth Member Of Xishanyao Formation In Hongtai-gedatai Area,Tuha Basin

The tight sandstone of the fourth member of the West Jurassic Xishanyao Formation in the Hongtai-Gedatai area of the Turpan-Hami Basin is an important target for oil and gas exploration,but the research on sedimentary sources,sedimentary environment and reservoir development characteristics related to it is relatively weak Urgent research is needed.Based on this,the thesis takes the fourth member of the middle Jurassic Xishanyao Formation in the Hongtai-Gedatai area of the Tuha Basin as the research object.On the basis of previous studies,it closely combines the actual situation in exploration and production development.Guided by multi-disciplinary geological theories and technical methods such as reservoir geology and petroleum geology,on the basis of core well observation and description and log analysis and other test and analysis data analysis,combined with slices,scanning electron microscopy,logging and physical property analysis and other data,Systematically carried out provenance,sedimentary facies and reservoir characteristics analysis of the fourth member of the Xishanyao Formation in the Hongtai-Gedatai area;and based on this,on the premise of revealing the main controlling factors of high-quality reservoirs in the area Reservoir evaluation criteria to predict favorable reservoir distribution areas.Combining the characteristics of sandstone clastic components,heavy minerals and ZTR index of the fourth member of the Xishanyao Formation in the Hongtai-Gedatai area,it is believed that the source of sediments in the fourth member of the Xishanyao Formation in the area is mainly in the southern part of the study area,but in the Geda block,the Hongtai 2 and the Hongtai 23 have different source areas.Based on the comprehensive study of sedimentary facies markers,it is considered that braided river delta and lake sedimentary facies are mainly developed in the fourth member of the Xishanyao Formation in the Hongtai-Gedatai area.The braided river delta in the study area can be further divided into delta front and pre-delta subfacies,including sedimentary microfacies such as distributary channels,inter-distributary depressions,inter-distributary swamps,and distributary distributary channels.The sand bodies in the study area are mainly developed in the braided river delta front subfacies.It developed in the area of Well 3,and the sand bodies in Hongtai area were mainly enriched in Well 2 and Well 2301.The sandstones of the fourth member of Xishanyao Formation in the study area are mainly represented by feldspar detrital sandstone,followed by detrital sandstone.The sorting is moderate,mainly sub-circular-sub-angular,porous cementation is the main cement type,the support type is mainly particle support,and the contact method is mainly point-line contact.The hetero-base in the interstitial material is mainly muddy hetero-base,and the cement is mainly carbonate and kaolinite cement;in the same fashion,pyrite,clay minerals,and pseudocrystalline self-generated minerals can be seen after the stone salt is dissolved.The main pore types are remaining primary pores and secondary dissolution pores.The minimum porosity is 3.2%,the maximum is 17.7%,and the average value is 8.80%;the minimum permeability is 0.006 m D,the maximum value is 9.86 m D,and the average value is 0.54 m D,which belongs to low porosity-ultra-low permeability reservoirs.The sandstone reservoir of the fourth member of the west of the Xishanyao Formation in the study area developed compaction,pressure dissolution,cementation,alteration,and dissolution.Compaction is the main factor that leads to reservoir densification.Cementation leads to further densification of the reservoir.Calcite cementation is more common,with obvious pore reduction and a pore reduction rate of about 5%.The chlorite cement in the form of a clay film produced by the pore lining in the early stage played a certain role in improving the reservoir,and the chlorite aggregates filled in the pore in the later stage caused the destruction of the pore.The detrital components and other soluble components in the reservoir improve the physical properties of the reservoir after dissolution;the alteration also further improves the physical properties of the reservoir.According to the diagenetic evolution of the study area,the sandstone in the study area is basically in the stage A of mesodiagenesis.Through the analysis of the relationship between the lithology,physical properties,electrical properties and oil-bearing properties of the fourth member of the Xishanyao Formation in the study area,the reservoir characteristics and classification evaluation criteria of the study area were clarified: The lower limit of permeability is0.1,the lower limit of lithology is fine sandstone,the lower limit of oil and gas display is oil trace level,the lower limit of oil saturation is 40%,the lower limit of electrical property is acoustic wave time difference 207?s / m,and the deep resistivity is30?.m.On this basis,the reservoir classification evaluation criteria were established based on the parameters such as reservoir permeability and effective thickness of sandstone.The III1 reservoir developed in the vicinity of Ge 15,Hongtai 2,Hongtai2301 and Hongtai 304 wells.