Abstract: A method is disclosed for determining the minimum miscibility pressure of a three (3) or more component fluid system consisting of an in-place fluid and an injected fluid, such as a mixture of liquid and gaseous hydrocarbons and another gas, such as CO.sub.2 or nitrogen. For a given pressure, the concentration of the first fluid is varied until a multiphase fluid state is indicated. The coexisting equilibrium phase compositions are calculated to determine a tieline which is translated geometrically retaining the direction of its slope to estimate a new tieline which attempts to be coincident with the second fluid's composition. The method above is repeated utilizing an increased pressure if the new tieline is coincident with a second fluid's composition and utilizing a decreased pressure if a coincident tieline does not exist, until a boundary pressure is achieved which represents the minimum miscibility pressure.

Abstract: Carbon dioxide is removed from CO.sub.2 and hydrocarbon containing gaseous streams. In the instance where the hydrocarbons and CO.sub.2 are such that hydrocarbons would condense out during CO.sub.2 removal, the gas stream is treated in one or more stages to accomplish hydrocarbon composition control.

Abstract: Carbon dioxide is removed from CO.sub.2 and hydrocarbon containing gaseous streams. In the instance where the hydrocarbons and CO.sub.2 are such that hydrocarbons would condense out during CO.sub.2 removal, the gas stream is treated in one or more stages to accomplish hydrocarbon composition control.