Evolutionary characteristics of hydrocarbon generation in carbonate hydrocarbon source rocks

Abstract

Abstract Carbonate reservoirs, as the most important hydrocarbon reservoirs, have more than 50% of the total global hydrocarbon resources. By evaluating the hydrocarbon source rock development and hydrocarbon generation evolution characteristics, it is of great significance for the exploration and development of hydrocarbon reservoirs in carbonate reservoirs. This paper takes carbonate reservoirs in Sichuan Basin as the largest proven oil and gas reserves in China. By investigating the geological and tectonic characteristics of the study area, analyzing the maturation evolution history and hydrocarbon generation and discharge periods of hydrocarbon source rocks, and using stratigraphic thermal evolution hydrocarbon generation and discharge simulation experiments to simulate hydrocarbon generation in carbonate rock samples of limestone and dolomite, we analyze the evolution characteristics of liquid products of rock samples and evaluate the hydrocarbon generation potential of the reservoirs. and characteristics of the reservoir. The results show that the Sichuan basin is divided into northwestern depressional zone, central uplift zone, southern low steep tectonic zone and eastern high steep tectonic zone according to the tectonic characteristics, and mainly experienced the tectonic movements of Garidonian, Haixi, Indo-Chinese, Yanshan and Xishan phases. The hydrocarbon generation and discharge mainly occurred in the Garidonian, Indochinese and Yanshan phases; through the hydrocarbon generation and discharge simulation experiment of the thermal evolution of carbonate strata, it is concluded that with the increasing temperature, the total oil yield and total hydrocarbon yield of limestone and dolomite show a trend of slow increase - rapid increase - decrease, and the hydrocarbon gas mass yield shows a slow increase - rapid increase, and the residual oil and discharge oil of the experiment are mainly non-hydrocarbon asphaltene, saturated hydrocarbon and aromatic hydrocarbon, meanwhile The total oil yield, maximum hydrocarbon gas mass yield and maximum total hydrocarbon yield of limestone are greater than that of limestone, which is an effective hydrocarbon source rock with obvious hydrocarbon generation and a favorable reservoir. The research results provide theoretical data to support the hydrocarbon generation and evolution characteristics of carbonate hydrocarbon source rocks.