Logging Evaluation On Chang 6 Reservoir Of Yanchang Formation Of B Well Area In Ordos Basin

The Ordos basin,which locates in the mid-west of China,is the second largest sedimentary craton basin.It is a multicycle-sendimentary petroleum-bearing basin and is well-known for its rich oil and gas bearing.B oil region is located in the basin of Shan Bei slope of the Middle West,Chang6 reservoir is a lithological reservoir which has the characteristics of complex lithology,lowporosity,low permeability,complicated pore types and structure,and the response characteristics of oil and gas on the conventional logging curve is not clear.Logging evaluation is difficult.In this paper,on the basis of predecessors' study of ordos basin,using the collected geological data,drilling data,analysis of test data,test data,core and logging data from the lithology and pore structure types,sedimentary microfacies,the relationship between the“four character”,and heterogeneity are studied.on the basis of the above research,porosity,permeation,expulsion pressure and median pressure,maximum,median radius of pore throat radius and average combination classification,sorting coefficient is selected as classsify parameter in gap four evaluation level of C6 reservoir evaluation.Accomplishing the study of Stratigraphic correlation and classification of B region,Chang 6 subgroups is divided into three groups,respectively:Chang61,Chang62,Chang63.In the study of lithology and pore structure research,this area reservoir lithology is mainly feldspar sandstone,intergranular pores and secondary dissolution pore is main pore in the Chang 6 reservoir.After the petrology and logging microfacies analysis was conducted,to determine the sedimentary facies in B well area:turbidite fan deposit.Micro phase:turbidite channel facies and turbidite thallus facies,overflow facies and semi deep lake mud microfacies.On the basis of above,the main parameters affecting porosity and oil saturation are optimized to set up the logging interpretation model of porosity and oil saturation by using the method of multivariate regression analysis.According to the practical application,the two models can be used for reservoir evaluation because of their high precision and good adaptability.Compared with Ansai and other adjacent area,the effective thickness minimum standards of chang 6 reservoir is similar to them.At last,based on the ordos basin Mesozoic sandstone reservoir classification rating standard,the chang 6 reservoir is divided into four types of reservoir.