Abstract: A method of storing hydrogen (H2) gas in a subsurface formation having an injection well, a production well and a heat well. The method includes injecting a first fluid stream into the subsurface formation via the at least one injection well to form a first composition containing a gas-phase mixture, a liquid-phase mixture and a solid matrix; injecting a H2-containing gas stream into the subsurface formation via the at least one injection well to form a gas mixture containing H2 gas; and heating and pressurizing the subsurface formation containing the gas mixture via the at least one heat well thereby achieving a storage condition and maintaining the storage condition to store the H2 in the subsurface formation.

Abstract: A method of storing hydrogen (H2) gas in a subsurface formation having an injection well, a production well and a heat well. The method includes injecting a H2-containing fluid stream into the subsurface formation via the injection well to form a storage composition containing a gas-phase mixture, a liquid-phase mixture and a solid matrix; and heating the subsurface formation containing the storage composition via the heat well thereby achieving a storage condition and maintaining the storage condition. The gas-phase mixture includes 10 to 90% of H2, 5 to 80% of methane (CH4), 1 to 10% of carbon dioxide (CO2), and 1 to 10% of nitrogen (N2). Each % is based on a total volume of the gas-phase mixture. The liquid-phase mixture includes a water-soluble mineral; and the solid matrix includes clay, shale, slate, and minerals.

Abstract: A method of recovering a hydrocarbon from a reservoir, whereby an oil recovery formulation containing carboxylic acid functionalized-pyrolyzed date leaf particles is injected into the reservoir, and the hydrocarbon is collected from the reservoir. The carboxylic acid functionalized-pyrolyzed date leaf particles are obtained sequentially from date leaves by cutting the date leaves and drying, pulverizing in the presence of a metal bicarbonate, pyrolyzing at 700 to 1,000° C., and treating the product thus obtained with an acid solution that includes nitric acid to introduce carboxylic acid functional groups.