The Kinetic Fractionation of Hydrogen Isotope for Methane—A Case Study in Xujiahe Gas Reservoir, Zhongba Gas Field

Abstract

A low mature coal sample from the Xujiahe Foramation in Sichuan Basin is selected to perform the thermal simulation experiment in gold tubes under pressure. Gas components and carbon and hydrogen isotopic values of the simulation products are analyzed. Kenetics software and kenetic fractionation model of the hydrogen isotope for methane are applied to calculate the kinetic parameters of hydrocarbon generation and hydrogen isotopes. Combined the geochemical characteristics of natural gas and the thermal history of the source rocks in the Xujiahe Formation in Zhongba gas field with the kinetic parameters calculated above, gas maturity, formation temperature and formation age of the gases are quantified. In particularly, hydrogen kinetic model is extrapolated to the geological conditions. The results show that gases from the Xujiahe Formation are generated at approximately 145 Ma (the end of the Late Jurassic, Early Cretaceous) with temperature of about 132 ˚C and the maturity of source rock (R o ) is 0.8% with the source rock transformation rate being only 5%. The results agree well with the actual geological conditions and confirm the reliability of the hydrogen isotope kinetic fractionation model.

Phase characteristics and geological significance of coal-generated hydrocarbon: Take the Minhe Basin as an example

“…The program of coal cracked to gas is always assumed that follows the first-order kinetics, which means that can be equal to a sum of a series of parallel first-order reactions(Cramer et al., 1998; He et al., 2018; Liao et al., 2014; Shuai et al., 2006; Wang et al., 2012; Xiong et al., 2004; Zhang et al., 2008). There is a compensation effect between the frequency factor (A) and the activation energies for hydrocarbon generation and destruction (Pepper and Dodd, 1995; Waples, 2000).…”