Some characteristics of the evolution of organic matter in carbonate formations

Abstract

Abstract Widespread in South China is a suite of well-developed and very thick carbonate formations (from Sinian to Triassic). In the present paper a brief discussion has been given to one of the characteristic features of the early evolution of organic matter in carbonate rocks—the great diagenetic loss of organic matter and its bearing on the evaluation of oil and gas prospects in carbonate rock-distributed areas. The author has also described the characteristic features of the evolution of organic matter, such as gaseous hydrocarbons, soluble organic matter and kerogen in carbonate rocks which have evidently reached the late stage of organic evolution, as well as the highest temperature range they once underwent during their evolution history. In terms of the vertical distribution patterns of oil and gas in the region of South Sichuan, the lowest limit has been preliminarily established for the commercial preservation of oil and gas in carbonate formations.