Method for carbon dioxide or hydrogen sulfide sequestration in a subterranean reservoir via pumping using sorbent particles in a carrier gas

Methods are provided for sequestering a pollutant gas of carbon dioxide (CO2) gas and/or hydrogen sulfide (H2S) gas in a subterranean reservoir. In one method, a carrier gas containing pollutant-sorbent particles (e.g., nanoparticles) is pumped into the subterranean reservoir, the pollutant-sorbent particles attach to the subterranean reservoir, the pollutant gas is pumped into the subterranean reservoir, and the pollutant-sorbent particles attached to the subterranean reservoir adsorb the pollutant gas. In another method, pollutant gas is introduced into a carrier liquid containing pollutant-sorbent particles to produce a pollutant-rich carrier liquid, the pollutant-rich carrier liquid is pumped into the subterranean reservoir, and the pollutant-rich carrier liquid is allowed to remain in the subterranean reservoir. A modifier gas or modifier liquid may be injected into the subterranean reservoir to modify a condition in the subterranean reservoir and thereby cause the pollutant-sorbent particles to release the sequestered pollutant gas.