Downhole fluid injection systems are provided that can include a first well extending into a geological formation, and a fluid injector assembly located within the well. The fluid injector assembly can be configured to inject a liquid CO.sub.2/H.sub.2O-emulsion into the surrounding geological formation. CO.sub.2 sequestration methods are provided that can include exposing a geological formation to a liquid CO.sub.2/H.sub.2O-emulsion to sequester at least a portion of the CO.sub.2 from the emulsion within the formation. Hydrocarbon material recovery methods are provided that can include exposing a liquid CO.sub.2/H.sub.2O-emulsion to a geological formation having the hydrocarbon material therein. The methods can include recovering at least a portion of the hydrocarbon material from the formation.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
This invention was made with Government support under Contract DE-AC0576RL01830 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.