Log-Interpreted Modeling Of Lacustrine Carbonate Rocks Restricted By Sedimentary Facies

Microscopic feature of lacustrine carbonate reservoir of the Fourth member of Shahejie Formation?Es₄?of Shaojia Sag is well studied by utilizing core,thin sections,logging data,measured property and producing test data.Meanwhile,a log interpret model was established which restricted by sedimentary facies.Further,physical property difference from petrophysics was analyzed and finally an integrated classification and evaluation criterion was built to predict the favorable reservoir distribution and made good prediction.Research indicates that there are several kinds of rock types in research area,in which reef dolomite,oolitic limestone,biolithite limestone,calcarenite,micrite,packstone,marlstone and gypsum are the domain types.On the other hand,reef,offshore beach and nearshore beach were the main sedimentary facies.The diagenesis here is very complex,which contains dissolution,cementation,dolomization,compaction,et al.There are various porosity developed in the reservoir,which can be classified into three types,primary porosity,secondary porosity and fracture.The type and content of carbonate rocks in different facies are quite diverse.In addition,sedimentary facies'effect on rock characteristics may influence the log response for lithology.Bayes discriminate method played important role in establishing logging interpretation model of different sedimentary facies,by which we found out two or three rock types precisely from homogeneous logging records,and the results compares well to thin section.The information of the pore structure was digged with the help of thin section and digital image analysis.As is shown,different pore structure parameter has different influence on physical property and compress velocity.By discussing the relationship of those,we set up the fitting formula of property and compress velocity with various pore structure parameters.At last,research demonstrates that roundness,form factor and equivalent diameter have more conspicuous relation with compress velocity.Given by the relationship of those,we may find it difficult to predict physical properties from acoustic well logs.Based on reservoir research,classification and evaluation criterias of carbonate reservoir in the area were established by taking sedimentary facies,rock types,main structure and diagenesis into consideration comprehensively and make prediction of favorable reservoir in the area by well logs.