ANTI-CAKING OR BLOCKING AGENT FOR TREATING SOLID ACID PRECURSOR ADDITIVES USED IN TREATING SUBTERRANEAN FORMATIONS

Abstract

Degradable material for treatment fluids for use in fluid loss control, diversion, and plugging operations, methods of preparing the degradable material, and methods of using the degradable material in treatment fluids are disclosed. The degradable materials are polymer-based solid acid precursor particles that have been partially or fully coated with an anti-caking agent to prevent agglomeration of the polymer-based solid acid precursor particles during storage and transport. These coated polymer-based solid acid precursor particles can then be added to a variety of treatment fluids to temporarily create a physical barrier to fluid flow before degrading and generating acids that can be used in other treatment operations. This degradable coated polymer-based solid acid precursor additive can be combined with other traditional downhole additives such surfactants, viscosifiers, and biocides, allowing for a wide variety of applications in hydrocarbon reservoirs.

Claims

1. A composition comprising at least one polymer-based solid acid precursor coated with an anti-caking agent.

2. The composition of claim 1, wherein said anti-caking agent has a particle size between about 1 to about 100 microns.

3. The composition of claim 2, wherein said anti-caking agent has a particle size between about 10 to about 30 microns.

4. The composition of claim 1, wherein said anti-caking agent is a solid acid precursor.

5. The composition of claim 4, wherein the solid acid precursor comprises gluconolactone.

6. The composition of claim 1, wherein said at least one polymer-based solid acid precursor has a particle size between about 100 microns to about 0.5 inches.

7. The composition of claim 1, wherein said at least one polymer-based solid acid precursor is shaped as platelets, shavings, flakes, ribbons, rods, strips, spheroids, toroids, pellets, tablets, or any combinations thereof.

8. The composition of claim 1, wherein said at least one polymer-based solid acid precursor is an aliphatic ester.

9. The composition of claim 8, wherein said aliphatic ester is selected from a group consisting of poly(lactic acid) (PLA), polyglycolide (PGA), poly(ε-caprolactone) (PCL), poly(γ-valerolactone) (PVL), polyhydroxyalkanoate (PHA), polyhydroxybutyrate (PHB), and copolymers thereof.

10. The composition of claim 1, wherein the anti-caking agent is present in an amount of about 1 wt % to about 15 wt % of the composition.

11. The composition of claim 1, wherein the anti-caking agent coats at least 10% of the outer surface of the at least one polymer-based solid acid precursor.

12. The composition of claim 1, wherein the at least one polymer-based solid acid precursor is poly(lactic acid) and the anti-caking agent is gluconolactone.

13. A treatment fluid for treating a reservoir, said treatment fluid comprising: a) a carrier fluid; and b) at least one polymer-based solid acid precursor coated with an anti-caking agent.

14. The treatment fluid of claim 13, further comprising at least one additive selected from a group comprising salts, viscosifying agents, pH control additives, surfactants, breakers, biocides, crosslinkers, additional fluid loss control agents, stabilizers, chelating agents, scale inhibitors, gases, mutual solvents, particulates, corrosion inhibitors, oxidizers, reducers, friction reducer, and any combination thereof.

15. The treatment fluid of claim 13, wherein said at least one polymer-based solid acid precursor coated with an anti-caking agent is present in an amount between about 5 pounds per thousand gallons (pptg) and about 2000 pptg.

16. The treatment fluid of claim 13, wherein the at least one polymer-based solid acid precursor is poly(lactic acid) and the anti-caking agent is gluconolactone.

17. A method of using the treatment fluid of claim 13, comprising a) injecting the treatment fluid of claim 13, into a subterranean formation; b) blocking at least one opening in said subterranean formation with the at least one polymer-based solid acid precursor coated with an anti-caking agent; and c) allowing the anti-caking agent and the at least one polymer-based solid acid precursor to degrade and generate acids; and, d) flowing a fluid through the at least one opening.

18. The method of claim 17, further comprising the step of etching surfaces of the formation with the generated acids.

19. The method of claim 17, further comprising the step of degrading acid soluble components in the formation with the generated acids.

20. The method of claim 17, further comprising the step of injecting an aqueous fluid to selectively degrade the anti-caking agent and the at least one polymer-based solid acid precursor.

Description

EXAMPLES

[0119] The caking of a polymer-based solid acid precursor additive coated with particulate gluconolactone under various storage conditions was measured. The polymer-based solid acid precursor additive was amorphous PLA particles with a particle size between about 2350 to about 3350 microns (6/8 mesh on the U.S. Sieve Series Scale).

[0120] In each example, an amorphous PLA particles with a glass transition temperature of less than 110° F. (˜38° C.) was admixed with gluconolactone particulates. Example 1 utilized unground gluconolactone having an average particle size of about 100 to 800 microns. Examples 2-6 utilized gluconolactone that was ground to a particle size of between 1 and 100 microns. For each example, a rotating blender was used to thoroughly coat the amorphous PLA particles with the gluconolactone.

[0121] For each example, the coated material was placed in a test cell under a positive pressure of 1 PSI to simulate the pressure that would be exerted on the polymer-based solid acid precursor additive if it was in the bottom bag of a pallet of bags of the additive. The test cell was then placed in an autoclave maintained at the test temperature for predetermined amounts of time. A ‘pass/fail’ determination regarding caking was then made after removal of the test cell from the autoclave. The results are shown in Table 1

TABLE-US-00002 TABLE 1 Caking of the amorphous polylactic acid at various temperatures Test Temperature Test Time Material (° F.) (hr) Pass/Fail Example 1 110 24 Failed - caking Example 2 110 24 Passed - no caking Example 3 110 66 Passed - no caking Example 4 116 24 Passed - no caking Example 5 135 24 Passed - no caking Example 6 140 24 Passed - no caking

[0122] The results shown in Table 1 demonstrate the effectiveness of gluconolactone with particle sizes between 1 and 100 microns in preventing caking of the solid acid precursor additive when exposed to storage conditions that exceed the glass transition temperature of the PLA particles. Thus, the present compositions will be storage stable while awaiting use in subterranean formation treatments. This allows the coated solid acid precursor additives to be transported around the world regardless of climate temperatures and immediately available for a variety of operations downhole, including fracturing, acidizing, fluid loss control, diversion, and plugging operations.