Abstract A slug drive to recover medium- to high-gravity petroleum from underground formations is carried out by injecting CO2 into the petroliferous formation. A typical amount used is of the order of 5 percent to 20 percent, say, 10 percent of the pore volume of the hydrocarbons present in the portion of the reservoir being treated. This CO2 is immediately followed by approximately an equal volume of air or flue gas, and then by water. Flue gas may be injected after or with the water. The gas immediately following the CO2 (flue gas or air) very effectively displaces the CO2 which is miscible with the petroleum of the reservoir. The following gas is both cheaper than the CO2 and serves as a protective bank, since the gas immediately ahead of the waterflood is to a degree trapped in passing through the reservoir. An additional benefit obtained by driving the CO2 bank with a gas (air or flue gas) less soluble in water is an improvement in mobility ratio, hence in sweep efficiency.
Inventors
👤 David R Parrish
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-02 10:34
CPC Classifications
E; E21; E21B; E21B43/00; E21B43/16
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
40 words
A process according to claim 1 in which said petroleum is crude oil having an API gravity of at least about 30* and in which the pressure in said formation on said carbon dioxide is at least about 1,200 p.s.i.
Claim 2
Dependent Claim
23 words
A process according to claim 2 including the step of injecting water simultaneously with the injection of the last part of said gas.
Claim 3
Dependent Claim
41 words
A process according to claim 2 including the step of injecting a minor amount of said water before the injection of the last part of said gas, the remainder of said water being injected following the final injection of said gas.
Claim 4
Dependent Claim
42 words
A process according to claim 2 including the step of injecting a volume of water amounting to about 0.1 percent to 1 percent of the hydrocarbon pore volume of that part of the formation being processed before said injection of carbon dioxide.
Claim 5
Dependent Claim
25 words
A process according to claim 2 including the step of injecting part of said water before the injection of the last part of said gas.