Method for reducing permeability restriction near wellbore

• US 20040157749A1
• Filed: 02/11/2003
• Published: 08/12/2004
• Est. Priority Date: 02/11/2003
• Status: Active Grant

• Current Assignee: ELY and Associates Incorporated
• Original Assignee: ELY and Associates Incorporated
• Inventors: Ely, John W., McCain, William D., Wolters, Bradley C.
• Granted Patent: US 6,945,327 B2
• Time in Patent Office: Days
• US Class Current: 507/200
• CPC Class Codes: C09K 8/575 containing organic compounds

Abstract

Method is provided for increasing the productivity of gas wells producing from reservoirs where retrograde condensation occurs around the wells. An oil-wetting surfactant is injected in a solvent to oil wet the formation for a selected distance around a well or a hydraulic fracture intersecting the well. A pre-flush liquid, such as carbon dioxide, alcohol or similar products and mixtures thereof, may be used to reduce water saturation before injection of the surfactant. The method may also be applied to increase the productivity of oil wells producing from reservoirs where breakout of solution gas occurs near the well.

Claims

1. A method for increasing the productivity of a well producing from a gas reservoir in a formation in which retrograde condensation occurs near the well, comprising:

(a) injecting a solution of an oil-wetting surfactant in a solvent into the well; and

(b) producing the solvent from the well.

2. The method of claim 1 additionally comprising before step (a) the step of injecting a pre-flush liquid to decrease the water saturation in the formation near the well.

3. The method of claim 1 wherein the formation is sandstone and the surfactant is cationic.

4. The method of claim 1 wherein the formation is carbonate and the surfactant is anionic.

5. The method of claim 1 further comprising the step of hydraulically fracturing the well before step (a).

6. The method of claim 1 wherein in step (a) the oil-wetting surfactant comprises a plurality of oil-wetting surfactants having a range of molecular weights or a range of solubilities in the solvent or a range of molecular weight and structure of the side chains of the oil-wetting surfactant.

7. The method of claim 6 wherein the plurality of oil-wetting surfactants are injected sequentially.

8. The method of claim 2 wherein the pre-flush liquid comprises carbon dioxide, alcohol or mixtures thereof.

9. The method of claim 1 further comprising the step of injecting a post-flush liquid after step (a).

10. The method of claim 1 wherein the concentration of the surfactant in the solvent is in the range of 0.05% to 5.0% by volume.

11. The method of claim 1 wherein concentration of the surfactant in the solvent is in the range of 0.1% to 3.0% by volume.

12. The method of claim 1 wherein the concentration of the surfactant in the solvent is in the range of 0.1% to 1.0% by volume.

13. The method of claim 1 wherein the solvent comprises alcohol, water, or mixtures thereof.

14. A method for increasing the productivity of a well producing from an oil reservoir in a formation in which breakout of solution gas occurs near the well, comprising:

(a) injecting a solution of an oil-wetting surfactant in a solvent into the well; and

(b) producing the solvent from the well.

15. The method of claim 14 additionally comprising before step (a) the step of injecting a pre-flush liquid to decrease the water saturation in the formation near the well.

16. The method of claim 14 wherein the formation is sandstone and the surfactant is cationic.

17. The method of claim 14 wherein the formation is carbonate and the surfactant is anionic.

18. The method of claim 14 further comprising the step of hydraulically fracturing the well before step (a).

19. The method of claim 14 wherein in step (a) the oil-wetting surfactant comprises a plurality of oil-wetting surfactants having a range of molecular weights or a range of solubilities in the solvent or a range of molecular weight and structure of the side chains of the oil-wetting surfactant.

20. The method of claim 15 wherein the pre-flush liquid comprises carbon dioxide, alcohol or mixtures thereof.

21. The method of claim 14 further comprising the step of injecting a post-flush liquid after step (a).