Maturating Organic-Rich Source Rocks Using Superheated Gases Injection: Heat Transfer Analysis

Understanding unconventional formations is very important in order to improve the hydrocarbon production from these reservoirs. Different methods are used to increase the hydrocarbon recovery utilizing chemical injections. This study proposes a method for maturating unconventional shale formations using gases injection approach. The suggested method focuses on generating and improving gas production from immature and early mature organic-rich source rocks. The method comprises injecting superheated gases into the subsurface formation. The injected gases can maturate the organic matter due to the heat transfer between the high-temperature gases and kerogen. In this study, different superheated gases were examined including hydrogen, carbon dioxide, nitrogen, methane, steam, and air. Heat transfer analysis was carried out to investigate the impact of the injected gas on increasing the temperature of shale rock. Parameters such as injection velocity, rock density, and injection time were examined. Also, experimental measurements were carried out to capture the changes in organic and inorganic contents due to artificial maturation. The obtained results showed that the organic content can be reduced by around 8 to 33%, depending on the maturation conditions. The performance of the maturation treatment can be affected significantly by the temperatures of injected gases, treatment time, heating rate, gas type, and shale density. Among all examined gases, hydrogen and methane gases showed the highest maturation performance due to the fastest heat transfer. Also, increasing the kerogen density showed a negative impact on the maturation process by reducing heat transfer efficiency. Overall, injecting superheated hydrogen and methane gases at the maximum injection rate into shale formations of lower density would provide the best maturation performance.