System and methods to deliver energy downhole

Patent metadata

Field	Value
Publication number	US-9951265-B2
Application number	US-201514742246-A
Country	US
Kind code	B2
Filing date	Jun 17, 2015
Priority date	Jun 17, 2014
Publication date	Apr 24, 2018
Grant date	Apr 24, 2018

Abstract

A method is provided to deliver energy downhole with a heat and nitrogen generating reaction, wherein the heat and nitrogen generating reaction occurs in-situ with an acid-generating reaction. The heat and nitrogen generating reaction is initiated by injecting into a reservoir a) nitrogen gas-generating reactants which react to generate heat at a pH of less than 8.0; b) an acid precursor which is capable of hydrolyzing in-situ in the reservoir to generate a sufficient amount of acid to maintain the reactants at a pH of less than 8.0, for a reaction that generates at least 20 kcal of heat per mole of reactants.

First claim

The invention claimed is:

1. A method, comprising:
providing a subsurface reservoir containing hydrocarbons contained within;
providing a wellbore in fluid communications with the subsurface reservoir;
providing components for a heat generating reaction comprising: at least one compound which contains at least one nitrogen atom to which a hydrogen atom is attached and is capable of being oxidized at a pH of less than 8.0 to yield nitrogen gas; and at least an oxidizing agent capable of oxidizing the nitrogen-containing compound;
providing an acid precursor separate from and not in contact with the components for the heat generating reaction;
injecting the components for the heat generating reaction and the acid precursor into the subsurface reservoir wherein the components for the heat generating reaction do not contact the acid precursor until the components for the heat generating reaction and the acid precursor are in-situ in the reservoir at a subsurface temperature above a surface temperature;
allowing at least a portion of the acid precursor to hydrolyze in-situ in the reservoir to generate a sufficient amount of acid to maintain the components for the heat generating reaction at a pH of less than 8.0 such that a heat generating reaction takes place and at least 20 kcal of heat per mole of the nitrogen-containing compound and nitrogen gas are generated in-situ in the reservoir.

2. The method of claim 1 , wherein the acid precursor is selected from the group of: cyclic ester dimers of lactic acid; cyclic ester dimers of glycolic acid; homopolymers of lactic acid; homopolymers of glycolic acid; copolymers of lactic acid; copolymers of glycolic acid; a copolymer of at least one of glycolic acid and lactic acid combined with at least one moiety selected from the moieties consisting of a hydroxyl-containing moiety, carboxylic acid-containing moiety, and hydroxycarboxylic acid-containing moiety; and combinations thereof.

3. The method of claim 2 , wherein the acid precursor is polylactic acid.

4. The method of claim 3 , wherein the acid precursor is a solid acid precursor coated with a hydrolysis delaying material.

5. The method of claim 1 , wherein the nitrogen-containing compound is selected from the group consisting of ammonium chloride, ammonium nitrate, ammonium nitrite, ammonium acetate, ammonium formate, ethylene diamine, formamide, acetamide, urea, benzyl urea, butyl urea, hydrazine, phenylhydrazine, phenylhydrazine hydrochloride, and mixtures thereof and the oxidizing agent is selected from the group consisting of alkali metals, ammonium salts of nitrous acid, and mixtures thereof.

6. The method of claim 1 , wherein the acid precursor hydrolyzes in-situ in the reservoir to generate a sufficient amount of acid for maintaining the heat generating reaction at a pH in a range of 4.75 and 5.5.

7. The method of claim 6 , wherein the acid precursor hydrolyzes in-situ in the reservoir to generate a sufficient amount of acid for the heat generating reaction to generate 20 kcal to about 200 kcal per mole of the nitrogen-containing compound.

8. The method of claim 1 , wherein the acid precursor hydrolyzes in-situ in the reservoir to generate a sufficient amount of acid for the heat generating reaction to take place generating at least 40 kcal of heat per mole of the nitrogen-containing compound.

9. The method of claim 1 , wherein the acid precursor hydrolyzes in-situ in the reservoir to generate a sufficient amount of acid for the heat generating reaction to take place generating at least 50 kcal of heat per mole of the nitrogen-containing compound.

10. The method of claim 1 , further comprising providing to the heat generating reaction at least an additive selected from corrosion inhibitors, surfactants, cross-linkers, polymers, biocides, oxygen and H 2 S scavengers, iron control agents, chelating agents, demulsifiers, gelling agents, foaming agents, fluid loss additives, intensifiers, acid retarders, solvents, diverting agents, mutual solvents, fracturing fluids, viscoelastic fluids, and combinations thereof.

11. The method of claim 1 , further comprising providing to the heat generating reaction at least an additive selected from solid acid precursors and acid reactive materials.

12. The method of claim 11 , wherein the additive is selected from water-insoluble solid acid-soluble materials.

13. The method of claim 11 , wherein the additive is selected from esters, diesters, anhydrides, lactones, amides and mixtures thereof.

14. The method of claim 11 , wherein the additive is selected from sodium hydroxide, potassium hydroxide, ammonium hydroxide, alkoxides, water-soluble carbonates, bicarbonates, alcohols, alkanol amines, organic amines and mixtures thereof.

15. The method of claim 1 , for use in any of mitigation of formation damage, pipeline transmission, dispersing wax built-up in exploration operations, and stimulation treatment for improved permeability in formation.

16. The method of claim 1 , for use to control gas hydrates in subsea production and injection wells.

17. The method of claim 1 , wherein the nitrogen gas generated sweeps oil in the reservoir toward a producer well.

18. The method of claim 1 , wherein no additional gas is injected into the reservoir.

19. The method of claim 1 , wherein the nitrogen gas generated extends a fracture in the reservoir.

20. The method of claim 1 , wherein the components for the heat generating reaction are maintained at a pH of at least 7 prior to the heat generating reaction.

21. A method to generate heat in reservoir formation, comprising:
providing a wellbore in fluid communications with a subsurface reservoir containing hydrocarbons;
providing components for a heat generating reaction comprising: at least one compound which contains at least one nitrogen atom to which a hydrogen atom is attached and is capable of being oxidized at a pH of less than 8.0 to yield nitrogen gas; at least an oxidizing agent capable of oxidizing the nitrogen-containing compound; and at least an additive selected from solid acid precursors and acid reactive materials;
providing an acid precursor separate from and not in contact with the components for the heat generating reaction;
injecting the components for the heat generating reaction and the acid precursor into the subsurface reservoir wherein the components for the heat generating reaction do not contact the acid precursor until the components for the heat generating reaction and the acid precursor are in-situ in the reservoir at a subsurface temperature above a surface temperature;
allowing at least a portion of the acid precursor to hydrolyze in-situ in the reservoir to generate a sufficient amount of acid to maintain the components for the heat generating reaction at a pH of less than 8.0 such that a heat generating reaction takes place and at least 20 kcal of heat per mole of the nitrogen-containing compound and nitrogen gas are generated in-situ in the reservoir.

22. The method of claim 21 , wherein the additive is selected from esters, diesters, anhydrides, lactones, amides and mixtures thereof.

23. The method of claim 21 , wherein the additive is selected from sodium hydroxide, potassium hydroxide, ammonium hydroxide, alkoxides, water-soluble carbonates, bicarbonates, alcohols, alkanol amines, organic amines and mixtures thereof.

24. The method of claim 21 , further comprising providing to the heat generating reaction at least an additive selected

Assignees

• Saudi Arabian Chevron Inc
• Chevron Usa Inc

Inventors

• Almutairi Saleh Haif

Classifications

• C09K2208/22

  Hydrates inhibition by using well treatment fluids containing inhibitors of hydrate formers · CPC title

• C09K2208/32

  Anticorrosion additives · CPC title

• E21B43/24

  using heat, e.g. steam injection · CPC title

• C09K8/592 Primary

  Compositions used in combination with generated heat, e.g. by steam injection · CPC title