Use of scale inhibitors in hydraulic fracture fluids to prevent scale build-up

• US 5,224,543 A
• Filed: 08/30/1991
• Issued: 07/06/1993
• Est. Priority Date: 08/30/1991
• Status: Expired due to Fees

• Current Assignee: Union Oil Company of California (Chevron Corp.)
• Original Assignee: Union Oil Company of California (Chevron Corp.)
• Inventors: Smith, John C., Watkins, David R., Edwards, Hetty G., Clemens, Joseph J., Sharma, Surinder N.
• Primary Examiner(s): Suchfield, George A.
• Application Number:
  US07/753,200
• Time in Patent Office: 676 Days
• Field of Search: 166/279, 166/300, 166/308, 166/312, 252/8.551, 252/8.552
• US Class Current: 166/279
• CPC Class Codes: C09K 8/528 inorganic depositions, e.g. sulfates or carbonates
• CPC Class Codes: C09K 8/685 containing cross-linking agents
• CPC Class Codes: E21B 37/06 using chemical means for preventing or limiting , e.g. eliminating, the deposition of paraffins or like substances
• CPC Class Codes: E21B 43/26 by forming crevices or fractures
• CPC Class Codes: Y10S 507/922 Fracture fluid

Abstract

Scale inhibitor is added to a cross-linked fracturing fluid as an integral part of the fracturing fluid. Preferred fracturing fluids are borate cross-linked and the preferred scale inhibitor is polyacrylate. In another embodiment of this invention, the fracturing fluid is prepared by adding a scale inhibitor to a fracturing fluid at a pH of between 8.5 and 10.5. In a third embodiment, the fracturing fluid prepared above is used to fracture subterranean formations. In a fourth embodiment, the fracturing fluid is used to pressurize a subterranean formation to break scale near the hydrocarbon wellbore.

Claims

1. A method of fracturing a hydrocarbon-bearing subterranean formation comprising:

a) pumping a borate cross-linked fracturing fluid gel having a pH between 8.5 and 10.5 including a polyacrylate scale inhibitor down hole;

b) pressurizing the fracturing fluid sufficiently to fracture a subterranean formation located down hole having a temperature less than 300°

F. and force the fracturing fluid and the scale inhibitor into the subterranean formation.

2. The method of claim 1 wherein the maximum fracturing fluid pressure down hole is less than 4,500 psia.

3. The method of claim 1 further comprising the step of breaking the gel down hole forming a lower viscosity liquid and removing resulting the lower viscosity liquid.

4. The method of claim 1 wherein the scale inhibitor substantially remains in the subterranean formation.

5. A method to remove scale, and inhibit its return, from the down hole perforations of the well casing of a hydrocarbon well in a subterranean formation comprising:

a) pumping a borate cross-linked fracturing fluid having a pH between 8.5 and 10.5 including a polyacrylate scale inhibitor down hole;

b) pressurizing the fluid to a pressure at least as high as that required to fracture a subterranean formation having a temperature less than 300°

F.;

c) forcing the fracturing fluid and the scale inhibitor past the perforations in the well casing; and

d) removing the pressure applied before a fracture propagates into the subterranean formation.

6. The method of claim 5 further comprising removing the fracturing fluid from the well.