Irradiation Caused Gas Generation From Organic Matter: Evidence From The Neutron Irradiation Experiment

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. H-2 was the most abundant gas, with a maximum yield of 1145.3 ml/g TOC, followed by N-2, CO2, then CH4 and C2H6. All of the gases were depleted in D or C-13, indicating their organic source. H-2 was suggested to be directly from kerogen, through a dehydrogenation and abstraction pathway. However, the specific generation mechanisms of N-2, 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.