Enabling Hydrogen Production from Shale Oil Reservoirs: An Experimental Study Using Microwave-Assisted Catalytic Heating

Abstract Transforming hydrocarbon resources to a clean, low-cost hydrogen (H2) supplier is a promising, albeit technically difficult, pathway towards decarbonizing fossil fuels by petroleum industry. A novel approach recently proposed is the microwave/electromagnetic-assisted catalytic heating technology for in-situ hydrogen generation and extraction directly from petroleum reservoirs. Here we further evaluate the potential of shale oil for H2 generation in the presence of shale rocks under microwave irradiation. A series of lab-scale experiments are conducted for shale oil conversion to hydrogen in Mancos shale rock samples without artificial catalysts. The real-time variations of measured temperature of rock samples, gas flow rate, and concentration of hydrogen and other generated gases are monitored. We find that the pure shale rocks can be heated up to over 600 °C without any promoter at an input power of 1.5 kW during microwave heating. A sudden increase of measured temperature of the Mancos shale is monitored at a temperature below 300 °C during microwave irradiation, referred to as "temperature soaring" (TS) phenomenon. Once TS phenomenon happens, the shale rock can be easily heated at a much lower microwave power. Furthermore, minerals in shale rocks have a significant natural catalytic effect on shale oil conversion to H2. A concentration of 1% hydrogen starts to be monitored in generated gases from shale oil at a measured temperature of 253-421 °C in the presence of Mancos rocks, much lower than the sample with 100% quartz at 523 °C. The highest H2 production rate and H2 concentration are 178 sccm and 77 mol.% from the conversion of 0.4 g shale oil, respectively. Additionally, long-range well-ordered carbon is commonly found in the shale rocks after microwave heating experiments.