Irradiation caused gas generation from organic matter: evidence from the neutron irradiation experiment

Abstract

The effects of U natural decay on the oil and gas generation are still controversial. We implemented a simulation experiment of neutron irradiation on immature organic matter, confirmed its benefit on oil generation. Here we report the generated gases and their composition and isotope characteristics. H2 was the most abundant gas, with a maximum yield of 1145.3 ml/g TOC, followed by N2, CO2, then CH4 and C2H6. All of the gases were depleted in D or 13C, indicating their organic source. H2 was suggested to be directly from kerogen, through a dehydrogenation and abstraction pathway. However, the specific generation mechanisms of N2, CO2, and CH4 were still unclear. Gas generation from kerogen will increase the gas-to-oil ratio of the hydrocarbon products, and make the oil much easier to discharge. It is of great importance to consider the artificial irradiation or U natural decay caused gas generation in the exploration and development of low-mature and immature shale oil.