THE HYDROCARBON GENERATION MECHANISM AND THE 3-STAGE TYPE MODEL OF HYDROCARBON GENERATION FOR CARBONATE SOURCE ROCKS

The diagenetic mechanism and process of carbonate rocks, which is diff erent to that of clastic rocks, decides the existence of different exi sting state organic matters in carbonate rocks. This has been verified by both the microscopic observation of organic petrology and the anal ysis of organic geochemistry of many samples. Based on the hydrous pyr olysis simulation experiment of the low-mature carbonate rocks, the co ntrasting study on the yield and their geochemistry characteristics of different existing state soluble organic matters of a series of vario us maturity samples shows that the different existing slate organic ma tters make different contributions to hydrocarbon generation during ev ery evolution state. So that, the hydrocarbon generation process of ca rbonate rocks can be summarized as the following three stages: the fir st is the direct degradation of biogenic bitumen macromolecules during the immature stage, the second is the thermal degradation of a large amount of kerogen at the mature stage, the last stage is the expulsion or release of inclusion organic matter owing to the increased thermal expansion pressure during the high evolution stage.