Method of treating oil and gas wells

• US 20050230117A1
• Filed: 04/16/2004
• Published: 10/20/2005
• Est. Priority Date: 04/16/2004
• Status: Active Grant

• Current Assignee: Universal Pressure Pumping, Inc. (Patterson-Uti Energy Incorporated)
• Original Assignee: Key Energy Services Incorporated
• Inventors: Wilkinson, Jeffrey M.
• Granted Patent: US 7,066,266 B2
• Time in Patent Office: Days
• US Class Current: 166/308.100
• CPC Class Codes: E21B 33/138 Plastering the borehole wall; Injecting into the formation
• CPC Class Codes: E21B 43/261 Separate steps of (1) cementing, plugging or consolidating and (2) fracturing or attacking the formation

Abstract

An improved process for optimizing the stimulation of an entire target formation of an oil or gas well during fluid treatment is obtained by dividing the target formation into intermediate zones and initiating stimulation in each intermediate zone. Once stimulation is initiated in each intermediate zone, ball sealers are used to block the casing perforations at the intermediate zone and divert fluids to another intermediate zone. After stimulation has been initiated in all intermediate zones, the ball sealers are removed from the perforations and treatment of the entire target formation is conducted.

Claims

1. A method of stimulating an earth formation, the formation having a plurality of intermediate zones and a casing through the zones, the intermediate zones having Fracture Gradients, the casing having perforations, the method comprising the steps of:

(a) pumping fluid into the casing to initiate hydraulic treatment of a first intermediate zone having a first Fracture Gradient;

(b) using a first instant shut-in pressure to determine the first Fracture Gradient of the first intermediate zone;

(c) diverting the pumped fluid into a second intermediate zone by using a diverter to block the pumped fluid from the first intermediate zone;

(d) pumping fluid into the casing to initiate hydraulic treatment of the second intermediate zone having a second Fracture Gradient;

(e) using a second instant shut-in pressure to determine the second Fracture Gradient of the second intermediate zone;

(f) dislodging the diverter from the first intermediate zone; and

(g) hydraulically stimulating all of the intermediate zones of the formation.

2. The method of claim 1, further comprising the step of determining if the pumped fluid is diverted from the first intermediate zone to the second intermediate zone before step (f) by verifying that the second fracture gradient is greater than the first fracture gradient by a predetermined amount.

3. The method of claim 2, further comprising the step of repeating the steps (c) through (e) for an additional intermediate zone of the formation before proceeding to steps (f) and (g) if the second fracture gradient is greater than the first fracture gradient.

4. The method of claim 1, wherein diverting the pumped fluid into the second intermediate zone by using the diverter to block the pumped fluid from the first intermediate zone comprises inserting the diverter into the casing and blocking the perforations adjacent the first intermediate zone with the diverter.

5. The method of claim 1, wherein the diverter is selected from the group consisting of ball sealers, rock salt, wax beads, proppant, benzoic acid flakes, foam-based fluid, gelled aqueous-based fluids, and ungelled aqueous-based fluids.

6. The method of claim 1, wherein dislodging the diverter from the first intermediate zone comprises unseating ball sealers from the perforations in the casing.

7. The method of claim 1, wherein the fluid includes water, treated water, a water-based fluid, a hydrocarbon-based fluid, an energized fluid, an acid, proppant, sand, sand slugs, or a combination thereof.

12. The method of claim 11, wherein determining the fracture gradient of the portion after treating the portion comprises the steps of measuring an instant shut-in pressure after treating the portion and calculating the fracture gradient of the portion from the instant shut-in pressure.

8. A method of treating a formation with fluid, the formation having a plurality of portions and having a casing positioned through the plurality of portions, the portions defining fracture gradients, the casing defining a plurality of perforations, the method comprising the steps of:

(a) treating at least a first portion of the formation regardless of the location of the first portion in the formation by pumping fluid into the casing;

(b) treating at least a second portion of the formation regardless of the location of the second portion in the formation by pumping fluid into the casing and diverting the pumped fluid from the first portion;

(c) determining if fluid is substantially diverted from the first portion to the second portion; and

(f) if fluid is substantially diverted from the first portion to the second portion, treating at least a successive portion of the formation regardless of the location of the successive portion in the formation by pumping fluid into the casing and diverting the pumped fluid from the first and second portions.

9. The method of claim 8, wherein the fluid includes water, treated water, a water-based fluid, a hydrocarbon-based fluid, an energized fluid, an acid, proppant, sand, sand slugs, or a combination thereof.

10. The method of claim 8, wherein the first portion has substantially the least fracture gradient of the formation.

11. The method of claim 8, wherein determining if fluid is substantially diverted from the first portion to the second portion comprises the steps of:

determining a first fracture gradient of the first portion after treating the first portion,

determining a second fracture gradient of the second portion after treating the second portion, and

determining if the second fracture gradient is greater than the first fracture gradient by a predetermined amount.

13. The method of claim 8, wherein diverting the pumped fluid from the first portion comprises inserting a diverter into the casing to block the perforations in the casing adjacent the first portion with the diverter.

14. The method of claim 13, wherein inserting the diverter into the casing to block the perforations in the casing adjacent the first portion with the diverter comprises determining a number of perforations in the casing adjacent the first portion and determining a quantity of the diverter for blocking the number of perforations adjacent the first portion.

15. The method of claim 13, wherein the diverter is selected from the group consisting of ball sealers, rock salt, wax beads, proppant, benzoic acid flakes, foam-based fluid, gelled aqueous-based fluids, and ungelled aqueous-based fluids.

16. The method of claim 8, further comprising the step of:

(g) if fluid is not substantially diverted from the first portion to the second portion, stimulating the formation by undiverting fluid from the first portion and pumping fluid into the casing.

17. The method of claim 8, further comprising the step of:

(h) determining if fluid is substantially diverted from the first and second portions to the successive portion.

18. The method of claim 17, further comprising the step of:

(i) if fluid is substantially diverted from the first and second portions to the successive portion, treating at least another successive portion of the formation regardless of the location of the other successive portion in the formation by pumping fluid into the casing and diverting the pumped fluid from the previously treated portions.

19. The method of claim 17, further comprising the step of:

(j) if fluid is not substantially diverted from the first and second portions to the successive portion, stimulating the formation by undiverting fluid from the previously treated portions and pumping fluid into the casing.

20. A method of treating a formation with fluid, the formation having a plurality of portions and having a casing positioned through the plurality of portions, the portions defining fracture gradients, the casing defining a plurality of perforations, the method comprising the steps of:

(a) treating at least a first portion of the formation by pumping fluid into the casing;

(b) determining a first fracture gradient of the first portion;

(c) treating at least a second portion of the formation by pumping fluid into the casing and diverting pumped fluid from the first portion;

(d) determining a second fracture gradient of the first portion;

(e) determining if the second fracture gradient is greater than the first fracture gradient;

(f) if the second fracture gradient is not greater than the first fracture gradient, stimulating the formation by undiverting fluid from the first portion and pumping fluid into the casing; and

(g) if the second fracture gradient is greater than the first fracture gradient, treating a successive portion of the formation by pumping fluid into the casing and diverting the pumped fluid from the first and second portions.

21. The method of claim 20, wherein the fluid includes water, treated water, a water-based fluid, a hydrocarbon-based fluid, an energized fluid, an acid, proppant, sand, sand slugs, or a combination thereof.

22. The method of claim 20, wherein treating at least the first portion of the formation by pumping fluid into the casing comprises pumping a first amount of fluid into the casing at a first rate.

23. The method of claim 22, wherein treating at least the second portion of the formation by pumping fluid into the casing and diverting pumped fluid from the first portion comprises:

inserting a diverter into the casing to block the perforations adjacent the first portion,

pumping a second amount of fluid into the casing at a second rate, and

diverting pumped fluid from the first portion with the diverter.

24. The method of claim 23, wherein the second amount of fluid is greater than the first amount of fluid.

25. The method of claim 23, wherein the second rate of fluid is substantially equal to the first rate of fluid.

26. The method of claim 20, wherein determining the fracture gradient of the portion after treating the portion comprises the steps of measuring an instant shut-in pressure after treating the portion and calculating the fracture gradient of the portion from the instant shut-in pressure.

27. The method of claim 20, wherein diverting the pumped fluid from the first portion comprises inserting a diverter into the casing to block the perforations in the casing adjacent the first portion with the diverter.

28. The method of claim 27, wherein inserting the diverter into the casing to block the perforations in the casing adjacent the first portion with the diverter comprises determining a number of perforations in the casing adjacent the first portion and determining a quantity of the diverter for blocking the number of perforations adjacent the first portion.

29. The method of claim 27, wherein the diverter is selected from the group consisting of ball sealers, rock salt, wax beads, proppant, benzoic acid flakes, foam-based fluid, gelled aqueous-based fluids, and ungelled aqueous-based fluids.

30. The method of claim 20, further comprising the step of:

(h) determining if fluid is substantially diverted from the first and second portions to the successive portion after treating the successive portion.

31. The method of claim 30, further comprising the step of:

(i) if fluid is substantially diverted from the first and second portions to the successive portion, treating at least another successive portion of the formation regardless of the location of the other successive portion in the formation by pumping fluid into the casing and diverting the pumped fluid from the previously treated portions.

32. The method of claim 30, further comprising the step of:

(j) if fluid is not substantially diverted from the first and second portions to the successive portion, stimulating the formation by undiverting fluid from the previously treated portions and pumping fluid into the casing.