Standard Related to TOC Classification Evaluation of Carbonate Oil Source Rocks

The study of evaluation criterion of carbonate oil source is a basic research subject which has significant influences on exploratory decision and has important theoretical and practical value.In this paper,calculations have been performed about amount of oil generation,remained oil of unit area carbonate at different geologic conditions by the parameters(strata,geohistory,and thermal history) in Tarim basin,Bohai Bay basin,and Ordos basin.According to the material balance principle,oil-expulsion amount has been worked out(oil-expulsion amount = amount of oil-generation-amount of remained oil).We regard it as an index to present the classification evaluation of oil source rocks,figure out the corresponding organic enrichment,and establish the classification evaluation tables of carbonate oil source in Tarim basin,Bohai Bay basin,and Ordos basin.Based on the simulating calculation,find that TOC industrial threshold value(TOCgy) decreases with the increasing source thickness;decreases at first and then increases with the increasing maturity and decreases with the better type of organic matter.Investigations indicate that the evaluation Standard of carbonate oil source have great variance with the differences of geologic conditions.Based on the analysis,we induce the threshold values,TOC are 0.25,0.5,0.8,1.5,which correspond with the classes,non,ineffective,poor,moderate and good source rocks of mature carbonate oil source whose organic matter type is Ⅱ.