Water and miscible fluid flooding method having good vertical conformance for recovering oil

Claim 1

A method of recovering oil from a subterranean oil reservoir by injection of water and fluid miscible with said oil comprising: (a) drilling a plurality of wells in communication for injection and production, defining a recovery zone within the reservoir, while spacing said wells sufficiently close and then injecting said water with said miscible fluid in said wells for injection at sufficient rate such that a value between 0.3 and 1.5 is obtained over said recovery zone for the following dimensionless parameter: ##EQU3## where, I t is the total injection rate of both the water and the miscible fluid injected into an injection well, Δρ is the difference in density between the water and the miscible fluid, k v is the average vertical permeability of the reservoir, a is the horizontal area of the reservoir to be flooded by the injection well, and ##EQU4## is the sum of the mobilities of the water and the miscible fluid at steady state around the injection well; (b) producing said oil from said reservoir from said production wells.

Claim 2

A method of recovering oil from a subterranean oil reservoir by injection of water and fluid miscible with said oil comprising: (a) drilling a plurality of wells in communication for injection and production, defining a recovery zone within the reservoir, while spacing said wells sufficiently close and then injecting said water with said miscible fluid in said wells for injection at sufficient rate such that a value between 0.3 and 1.5 is obtained over said recovery zone for the following dimensionless parameter: ##EQU3## where, I t is the total injection rate of both the water and the miscible fluid injected into an injection well, Δρ is the difference in density between the water and the miscible fluid, k v is the average vertical permeability of the reservoir, a is the horizontal area of the reservoir to be flooded by the injection well, and ##EQU4## is the sum of the mobilities of the water and the miscible fluid at steady state around the injection well; (b) producing said oil from said reservoir from said production wells.

Claim 10

A method of recovering oil from a subterranean oil reservoir by alternate injection of water and fluid miscible with said oil, said reservoir being penetrated by a plurality of wells for injection and production, comprising: (a) defining a pattern of wells for injection of said water and miscible fluid and production of said oil wherein the spacing of the wells in said pattern and the rate of injection of said water and miscible fluid is such that a value between 0.3 and 1.5 is obtained for the following dimensionless parameter for any given injection well in said pattern: ##EQU5## where, I t is the total injection rate of both the water and the miscible fluid injected into said given injection well, Δρ is the difference in density between the water and the miscible fluid, K v is the average vertical permeability of the reservoir, a is the area of the reservoir to be flooded by said given injection well, and ##EQU6## is the sum of the mobilities of the water and the miscible fluid at steady state around said given injection well; (b) alternately injecting said water and said miscible fluid in said injection wells in said pattern of wells and producing from the production wells in said pattern of wells to recover oil.

Claim 11

A method of recovering oil from a subterranean oil reservoir by alternate injection of water and fluid miscible with said oil, said reservoir being penetrated by a plurality of wells for injection and production, comprising: (a) defining a pattern of wells for injection of said water and miscible fluid and production of said oil wherein the spacing of the wells in said pattern and the rate of injection of said water and miscible fluid is such that a value between 0.3 and 1.5 is obtained for the following dimensionless parameter for any given injection well in said pattern: ##EQU5## where, I t is the total injection rate of both the water and the miscible fluid injected into said given injection well, Δρ is the difference in density between the water and the miscible fluid, K v is the average vertical permeability of the reservoir, a is the area of the reservoir to be flooded by said given injection well, and ##EQU6## is the sum of the mobilities of the water and the miscible fluid at steady state around said given injection well; (b) alternately injecting said water and said miscible fluid in said injection wells in said pattern of wells and producing from the production wells in said pattern of wells to recover oil.