深部甲烷气的演化和二氧化碳的成因

EVOLUTION OF METHANE FROM DEEP SOURCE AND ORIGIN OF CARBON DIOXIDE

刘斌

LIU Bin

地矿部石油地质中心实验室

Central Laboratory of Petroleum Geology, Ministry of Geology and Mineral Resources

本文以CH4-H2O-CO2为平衡体系,用统计热力学的观点,研究了平衡体系的反应条件和方向,甲烷转换成二氧化碳需大于1050K才易进行,而二氧化碳与水中游离氢还原生成甲烷所需温压较低,故以甲烷为主的天然气藏不可能转化成高含量的二氧化碳气藏。

Considering the equilibrium system of CH4-H2O-CO2 and the reaction of methane with CaSO4(gypsum)in water for example,with the viewpoint of statistical thermodynamics and chemical thermodynamic equilibrium,the conditions and direction of the reaction are studied,as a result,the rela-tion of equilibrium constant and temperature-pressure are inferred.Besides,the neccessary conditions for the preservation and destruction of methane gas under different burial depths and for the generation of carbon dioxide are discussed.It is proposed that the acidity of sedimentary environment,or the pH value,is an important factor which acts in conjunction with temperature in the hydrolysis of carbonate rocks.

https://doi.org/10.11781/sysydz198902167