Methods of improving heavy oil production
The invention provides an improved method for extracting heavy oil or bitumen contained in a reservoir. The invention involves directing the formation of a solvent fluid chamber through the combination of directed solvent fluid injection and production at combinations of horizontal and/or vertical injection wells so as to increase the recovery of heavy oil or bitumen contained in a reservoir. The wells are preferably provided with flow control devices to achieve uniform production.
1. A method for extracting hydrocarbons from a reservoir containing said hydrocarbons and having disposed therein at least one first well and at least one second well, each of the first wells having a first completion string disposed therein, and each of the second wells having a second completion string disposed therein, the first wells being positioned in a lower portion of the reservoir and the second wells being positioned vertically above and laterally offset from the first wells, the method comprising:
(a) injecting a solvent fluid into the reservoir through at least one of the first completion strings to cause gravity induced counter-flow mixing of the solvent fluid and the hydrocarbons within the reservoir;
(b) extracting reservoir fluid from the reservoir through at least one of the second completion strings to create a solvent fluid chamber extending between the at least one first well and the at least one second well;
(c) injecting solvent fluid into the reservoir through at least one of the second completion strings;
(d) extracting reservoir fluid from the reservoir through at least one of the first completion strings;
wherein at least one of the first and second completion strings includes two or more flow control devices located on a portion thereof in the reservoir for uniform injection of the solvent fluid into the reservoir or uniform extraction of reservoir fluid from the reservoir.
2. The method of claim 1 , wherein the first and second wells are horizontal wells.
3. The method of claim 1 , wherein the solvent fluid chamber is delimited by vertically inclined upper and lower boundaries.
4. The method of claim 3 , wherein the upper and lower boundaries converge towards the at least one second well.
5. The method of claim 1 , wherein the solvent fluid is a liquid, gas or a mixture thereof and the liquid or gas is selected from the group consisting of steam, methane, butane, ethane, propane, pentanes, hexanes, heptanes, and CO 2 and mixtures thereof.
6. The method of claim 1 , wherein the hydrocarbons comprise heavy oil and/or bitumen.
7. The method of claim 1 , wherein the extracting of reservoir fluid in step (b) is done concurrently with the solvent fluid injection of step (a).
8. The method of claim 1 , wherein the extracting of reservoir fluid in step (d) is done concurrently with the solvent fluid injection of step (c).
9. The method of claim 1 , wherein the steps (a) to (d) are repeated at least once.
10. The method of claim 1 , wherein at least two of said second wells are provided for each first well, said second wells being horizontally spaced apart from each other, and wherein the solvent fluid chamber formed in step (b) extends from the first well to each of the second wells.
11. The method of claim 10 , wherein two second wells are provided for each first well whereby said solvent fluid chamber is bi-directional, extending from the first well to each of said second wells.
12. The method of claim 1 wherein step (c) is commenced upon solvent fluid breakthrough at the second well in step (b).
13. The method of claim 1 wherein at least one of the extracting steps (b) or (d) utilizes a production string provided in or adjacent to the respective completion string.
14. The method of claim 1 , wherein the solvent fluid chamber includes an upper “hydrocarbon over solvent fluid” surface and a lower “solvent fluid over hydrocarbon” surface.
15. A method for extracting hydrocarbons from a reservoir containing said hydrocarbons and having disposed therein at least one first well and at least one second well, each of the first wells having a first completion string disposed therein, and each of the second wells having a second completion string disposed therein, the first wells being positioned in a lower portion of the reservoir and the second wells being positioned vertically above and laterally offset from the first wells, the method comprising:
(a) injecting a solvent fluid into the reservoir through at least one of the first completion strings to cause gravity induced counter-flow mixing of the hydrocarbons and the solvent fluid within the reservoir;
(b) extracting reservoir fluid from the reservoir through at least one of the second completion strings to create a solvent fluid chamber extending between the at least one first well and the at least one second well;
(c) injecting solvent fluid into the reservoir through at least one of the second completion strings; and,
(d) extracting reservoir fluid from the reservoir through at least one of the first completion strings.
16. The method of claim 15 , wherein the first and second wells are horizontal wells.
17. The method of claim 15 , wherein the solvent fluid chamber is delimited by vertically inclined upper and lower boundaries.
18. The method of claim 17 , wherein the upper and lower boundaries converge towards the at least one second well.
19. The method of claim 15 , wherein the extracting of reservoir fluid in step (b) is done concurrently with the solvent fluid injection of step (a).
20. The method of claim 15 , wherein the extracting of reservoir fluid in step (d) is done concurrently with the solvent fluid injection of step (c).
21. The method of claim 15 , wherein at least two of said second wells are provided for each first well, said second wells being horizontally spaced apart from each other, and wherein the solvent fluid chamber formed in step (b) extends from the first well to each of the second wells.
22. The method of claim 21 , wherein two second wells are provided for each first well whereby said solvent fluid chamber is bi-directional, extending from the first well to each of said second wells.
23. The method of claim 15 wherein step (c) is commenced upon solvent fluid breakthrough at the second well in step (b).
24. The method of claim 15 wherein at least one of the extracting steps (b) or (d) utilizes a production string provided in or adjacent to the respective completion string.
25. The method of claim 15 , wherein the solvent fluid chamber includes an upper “hydrocarbon over solvent fluid” surface and a lower “solvent fluid over hydrocarbon” surface.