Method of storing hydrogen gas in a subsurface formation using nitrogen, methane, and carbon dioxide blend as a cushion gas

A method of storing hydrogen (H2) gas in a subsurface formation having at least one injection well, at least one production well and at least one heat well penetrating the subsurface formation, comprising:

• 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;
• wherein the injecting increases wettability of the solid matrix by contact with the gas-phase mixture and the liquid-phase mixture, and reduces surface tension of the gas-phase mixture and the liquid-phase mixture;
• wherein the gas-phase mixture of the first composition comprises:
• 10 to 60% of H2;
• 40 to 80% of nitrogen (N2);
• 1 to 5% of methane (CH4);
• and
• 1 to 10% of carbon dioxide (CO2), and each % is based on a total volume of the gas phase mixture;
• wherein the liquid-phase mixture of the first composition comprises water and at least one water-soluble mineral;
• wherein the solid matrix of the first composition comprises clay, shale, slate, and minerals;
• and
• 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;
• wherein the H2-containing gas stream comprises at least 50% of H2 based on a total volume of the H2-containing gas stream;
• 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.