Zingg Warren M, Grassman Delbert D: Well fracturing method using liquefied gas as fracturing fluid. The Dow Chemical Company, Clausen V Dean, Jowanovitz Lloyd S, October 22, 1974: US3842910 (44 worldwide citation)

An improved method is disclosed for fracturing an oil well or gas well with a mixture of liquid carbon dioxide and liquid petroleum gas. The objective is to be able to inject the liquid into the wellbore at a relatively high pumping rate without causing the liquid to boil. Prior to injection, both t ...