| Sanhu depression of Qaidam Basin is both the Quaternary Center of the Qaidam Basin also China's largest bio-gas field.Well Qijia 1 located in the north slope of Sanhu area structure of the north slope is a all coring exploratory well.Reservoir is the key factor to control the production capacity of oil field.It is significant to carry out reservoir evaluation for well Qijia 1,which can provide a scientific basis for accurate selection of the exploration direction,but also for the further exploration and development of natural gas in Salt Lake to lay a good foundation.In this thesis,the Saline Lake structure in Qaidam Basin of the Neogene Shizigou and the Quaternary Qigequan formation in QJ1 are taken as the object of the study.On the basis of theory and method of disciplines such as sedimentary petrography,petroleum geology and combined with previous research results,Firstly,the sedimentary facies of this area were analyzed.Then a series of studies of the reservoir characterization are carried out in respect of its petrography,digenesis,pore types,pore structure,physical property.Meanwhile,based on well logging data and core analysis data,a model for the interpretation of porosity and permeability is established.According to the standard of fluid interpretation in Saline Lake area,the log interpretation of QJ1 is carried out,and the relationship between reservoir and four character is also carried out.At last,based on the above research results,using the gray theory to classify the target well reservoir.The study shows that the depositional system of the delta and shore shallow lake are broadly spreaded in the research area,which consist of microfacies like distributary channel,flood plain,underwater distributary channel,crevasse splay,marsh and underwater distributary channel,interdistributary bay,mouth bar,shore shallow lake sand bar,mixed beaches,mudflats and aeolian sand and other major microfacies.Reservoir lithology is mainly lithic feldspar sandstone and feldspar lithic sandstone,composition maturity and structure maturity of medium-low,among them the Shizigou formation maturity compared to Qigequan Formation was a little low.The sandstone reservoir in the study area has undergone compaction,cementation,dissolution and dissolution.Shizigou formation is mainly in the middle diagenesis phase A,and the Qigequan formation mainly in the early diagenesis phase.Reservoir in the study area is of primary pore based,with the buried depth increase primary pores began to reduce the amount,is relatively developed secondary pores,main pore types have intergranular pore,intragranular dissolution pore,occasionally fracture pore.A total of 189 water layers were explained by well Qijia 1,which is total 373.45 m and 35 dry layers total 54.05 m.while no hydrocarbon is found.Shizigou formation,Qigequan formation reservoir can be divided into class I,class II,III class.The class I of the Aeolian sand,distributary channel,shore shallow lake sand bar mainly;class II underwater diversion channel,mouth bar;class III mainly concentrated in shore shallow lake of mud and sand beach and mortar sand dam. |
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