海相碳酸盐岩干酪根热解成气过程及其碳同位素演化特征

应用高压封闭体系,对海相碳酸盐岩干酪根进行了热裂解模拟实验,并从气态烃、非气态烃产率及碳同位素演化特征等方面,探讨了海相碳酸盐岩烃源岩干酪根作为气源的生气机理。在模拟实验基础上,结合专用Kinetics软件求取碳酸盐岩烃源岩干酪根裂解产气动力学参数(活化能和指前因子),并将模拟实验结果外推至地质条件下,探讨其动力学模型的实际应用。结果表明,在该地质条件下,甲烷在EasyRo为0.9%时进入主生气期(转化率为10%),2.9%时主生气期结束(转化率为90%)。乙烷至戊烷在EasyRo为1.1%时进入主生气期(转化率10%),2.7%时主生气期结束(转化率90%)。该研究成果为我国海相碳酸盐岩裂解气的判识、资源评价提供了可靠的实验依据。

Gaseous Hydrocarbon Generation and Carbon Isotope Evolution of Pyrolytic Kerogan in Marine Carbonate Source Rock

The kerogen separated from a sample of carbonate source rock was pyrolyzed under a constant high pressure(50MPa) for kinetic simulating experiment to probe into the genetic mechanism of gas generation from kerogen in marine carbonate source rocks according to the percentages of generating gaseous and non-gaseous hydrocarbons and the analysis of carbon isotope.By means of the Kinetics software,the kinetic parameters(activation energy and frequency factor) of generating methane(C1),ethane(C2) to pentane(C5) from kerogen are determined and the result is used in nature via extrapolation of laboratory kinetic data to very low heating rates in geological condition.It is indicated that methane(C1) is pyrolyzed from the source rock at EasyRo=0.9%～2.9%(the conversion rate in the range of 10%～90%) and the other gaseous hydrocarbons(C2,C3,C4 and C5) generate at EasyRo=1.1%～2.7%(the conversion rate being 10%～90%).This experimental result means that it can be a reliable model for effectively quantitative evaluation of marine carbonate source rocks.