Sequentially flooding an oil-bearing formation with a surfactant and hot aqueous fluid

Claim 2

A process for recovering oil from an oil-wet fractured subterranean oil-bearing formation having an ambient formation temperature and penetrated by at least two wells from the surface which are in fluid communication with said formation and with one another comprising: (a) injecting a first slug of a surfactant solution into said fractured formation via a first of said at least two wells, said surfactant solution capable of becoming the preferred wetting phase of an oil-wet matrix block in said fractured formation; (b) contacting a face of said oil-wet matrix block with said surfactant solution for a time sufficient for said surfactant solution to penetrate and become the preferred wetting phase of at least a portion of said matrix block thereby displacing oil from said portion of said matrix block toward said face of said matrix block; (c) injecting a second slug of a hot water having a temperature greater than said ambient formation temperature into said formation via a second of said at least two wells; (d) contacting said face of said matrix block with said hot water for a time sufficient for said hot water to penetrate and restore said portion of said matrix block to an oil-wet condition; (e) displacing said oil away from said face of said matrix block with said hot water toward said first well; (f) recovering said oil from said formation via said first well; and (g) repeating steps (a), (b), (c), (d), (e), and (f).

Claim 3

The process of claim 1 wherein said first well is shut in for a soak time during step (b).

Claim 4

The process of claim 1 further comprising heating said first slug of said surfactant solution to a temperature greater than said ambient formation temperature prior to step (a).

Claim 5

The process of claim 1 wherein the mobility of said first and second slugs are substantially about equal.

Claim 6

The process of claim 1 wherein said temperature of said hot water is greater than about 21° C.

Claim 7

The process of claim 1 wherein said hot water of said second slug is steam.

Claim 8

The process of claim 1 wherein the formation pressure at said first well does not substantially increase during steps (a) and (c).

Claim 9

A process for recovering oil from an oil-wet fractured subterranean oil-bearing formation having an ambient formation temperature and penetrated by at least two wells from the surface which are in fluid communication with said formation and with one another comprising: (a) injecting a first slug of a surfactant solution into said fractured formation via a first well of said at least two wells, said surfactant solution capable of becoming the preferred wetting phase of an oil-wet matrix block in said fractured formation; (b) contacting a face of said oil-wet matrix block with said surfactant solution for a time sufficient for said surfactant solution to penetrate and become the preferred wetting phase of at least a portion of said matrix block thereby displacing oil from said portion of said matrix block toward said face of said matrix block; (c) injecting a second slug of a hot water having a temperature greater than said ambient formation temperature into said formation via said first well; (d) contacting said face of said matrix block with said hot water for a time sufficient for said hot water to penetrate and restore said portion of said matrix block to an oil-wet condition; (e) displacing said oil away from said face of said matrix block with said hot water toward a second well of said at least two wells; (f) recovering said oil from said formation via said second well; and (g) repeating steps (a), (b), (c), (d), (e), and (f).

Claim 10

A process for recovering oil from an oil-wet fractured subterranean oil-bearing formation having an ambient formation temperature and penetrated by at least two wells from the surface which are in fluid communication with said formation and with one another comprising: (a) injecting a first slug of a surfactant solution into said fractured formation via a first well of said at least two wells, said surfactant solution capable of becoming the preferred wetting phase of an oil-wet matrix block in said fractured formation; (b) contacting a face of said oil-wet matrix block with said surfactant solution for a time sufficient for said surfactant solution to penetrate and become the preferred wetting phase of at least a portion of said matrix block thereby displacing oil from said portion of said matrix block toward said face of said matrix block; (c) injecting a second slug of a hot water having a temperature greater than said ambient formation temperature into said formation via said first well; (d) contacting said face of said matrix block with said hot water for a time sufficient for said hot water to penetrate and restore said portion of said matrix block to an oil-wet condition; (e) displacing said oil away from said face of said matrix block with said hot water toward a second well of said at least two wells; (f) recovering said oil from said formation via said second well; and (g) repeating steps (a), (b), (c), (d), (e), and (f).

Claim 11

The process of claim 8 wherein said first well is shut in for a soak time during step (b).

Claim 12

The process of claim 8 further comprises heating said first slug of said surfactant solution to a temperature greater than said ambient formation temperature prior to step (a).

Claim 13

The process of claim 8 wherein the mobility of said first and second slugs are substantially about equal.

Claim 14

The process of claim 8 wherein the formation pressure at said second well does not substantially increase during steps (a) and (c).

Claim 15

The process of claim 8 wherein said temperature of said hot water is greater than about 21° C.

Claim 16

The process of claim 8 wherein said hot water of said second slug is steam.

Claim 17

A process for recovering oil from an oil-wet fractured subterranean oil-bearing formation having an ambient formation temperature and penetrated by at least three wells from the surface which are in fluid communication with said formation and with one another comprising: (a) injecting a first slug of a surfactant solution into said fractured formation via a first well of said at least three wells, said surfactant solution capable of becoming the preferred wetting phase of an oil-wet matrix block in said fractured formation; (b) contacting a face of said oil-wet matrix block with said surfactant solution for a time sufficient for said surfactant solution to penetrate and become the preferred wetting phase of at least a portion of said matrix block thereby displacing oil from said portion of said matrix block toward said face of said matrix block; (c) injecting a second slug of a hot water having a temperature greater than said ambient formation temperature into said formation via a second well of said at least three wells; (d) contacting said face of said matrix block with said hot water for a time sufficient for said hot water to penetrate and restore said portion of said matrix block to an oil-wet condition; (e) displacing said oil away from said face of said matrix block with said hot water toward a third well of said at least three wells; (f) recovering said oil from said formation via said third well; and (g) repeating steps (a), (b), (c), (d), (e), and (f).

Claim 18

A process for recovering oil from an oil-wet fractured subterranean oil-bearing formation having an ambient formation temperature and penetrated by at least three wells from the surface which are in fluid communication with said formation and with one another comprising: (a) injecting a first slug of a surfactant solution into said fractured formation via a first well of said at least three wells, said surfactant solution capable of becoming the preferred wetting phase of an oil-wet matrix block in said fractured formation; (b) contacting a face of said oil-wet matrix block with said surfactant solution for a time sufficient for said surfactant solution to penetrate and become the preferred wetting phase of at least a portion of said matrix block thereby displacing oil from said portion of said matrix block toward said face of said matrix block; (c) injecting a second slug of a hot water having a temperature greater than said ambient formation temperature into said formation via a second well of said at least three wells; (d) contacting said face of said matrix block with said hot water for a time sufficient for said hot water to penetrate and restore said portion of said matrix block to an oil-wet condition; (e) displacing said oil away from said face of said matrix block with said hot water toward a third well of said at least three wells; (f) recovering said oil from said formation via said third well; and (g) repeating steps (a), (b), (c), (d), (e), and (f).

Claim 19

The process of claim 15 wherein steps (c), (d), (e) and (f) are performed continuously.

Claim 20

The process of claim 15 wherein the mobility of said first and second slugs is substantially about equal.

Claim 21

The process of claim 15 further comprises heating said first slug of said surfactant solution to a temperature greater than said ambient formation temperature prior to step (a).

Claim 22

The process of claim 15 wherein the formation pressure at said third well does not substantially increase during steps (a) and (c).

Claim 23

The process of claim 15 wherein said hot water of said second slug is steam.

Claim 24

The process of claim 15 wherein said temperature of said hot water is greater than about 21° C.