Forming mineral in fractures in a geological formation

Patent metadata

Field	Value
Publication number	US-10900339-B2
Application number	US-201916392420-A
Country	US
Kind code	B2
Filing date	Apr 23, 2019
Priority date	Apr 23, 2019
Publication date	Jan 26, 2021
Grant date	Jan 26, 2021

Abstract

A system and method for forming mineral or proppant in-situ in fractures in a geological formation via a fracturing fluid. The mineral or proppant is formed from rock in the geological formation.

First claim

What is claimed is:

1. A method of forming proppant in-situ in a geological formation, comprising:
injecting a fracturing fluid through a wellbore into the geological formation;
hydraulically fracturing the geological formation with the fracturing fluid to generate fractures in the geological formation; and
forming proppant in situ in the fractures via the fracturing fluid, wherein the proppant is formed from rock in the geological formation comprising leaching iron from the rock into the fracturing fluid and hydrothermally converting the iron in the fracturing fluid to a mineral.

2. The method of claim 1 , wherein forming the proppant comprises hydrothermally converting the iron and sulfur in the fracturing fluid to the mineral.

3. The method of claim 1 , comprising adjusting an amount of oxidizer in the fracturing fluid to alter a property of the mineral, wherein forming the proppant is contemporaneous with the hydraulic fracturing, and wherein the proppant comprises the mineral formed on the rock via the fracturing fluid.

4. The method of claim 3 , wherein the property comprises size of mineral grains of the mineral, and wherein the mineral comprises hematite, jarosite, lepidocrocite, or ferrihydrite, or any combinations thereof.

5. The method of claim 1 , wherein the proppant comprises the mineral, and wherein forming the proppant in situ in the fractures comprises depositing the mineral on the rock in the fractures via the fracturing fluid.

6. The method of claim 5 , wherein the proppant comprising the mineral comprises a particle size in a range of 200 nanometers (nm) to 2 micrometers (μm).

7. The method of claim 1 , wherein forming the proppant in situ in the fractures comprises oxidizing the rock via an oxidizer in the fracturing fluid, and wherein the oxidizing comprises the leaching the iron from the rock.

8. The method of claim 7 , wherein the oxidizing comprises oxidative leaching of the rock to give ions comprising the iron as iron ions into the fracturing fluid.

9. The method of claim 8 , wherein forming the proppant in situ in the fractures comprises growing the mineral on the rock in the fractures via the hydrothermally converting comprising hydrothermal synthesis of the ions, and wherein the proppant comprises the mineral.

10. The method of claim 9 , wherein the hydrothermal synthesis comprises precipitating the mineral as a crystalline material on the rock.

11. The method of claim 7 , wherein oxidizing the rock comprises oxidative leaching of the rock giving the iron comprising Fe3+ ions into the fracturing fluid.

12. The method of claim 1 , wherein the leaching is contemporaneous with the hydraulic fracturing, wherein the fractures comprise microfractures having a fracture width less than 100 microns (μm), wherein the proppant is formed in situ in the microfractures, and wherein the proppant comprises the mineral formed from the rock via the fracturing fluid.

13. The method of claim 1 , wherein the proppant comprises the mineral grown on the rock via the fracturing fluid, wherein the fractures comprise nanofractures having a fracture width less than 1 μm, and wherein the proppant is formed in situ in the nanofractures.

14. The method of claim 4 , wherein the mineral grains near-wellbore comprise a particle size of at least 150 micrometers (μm), wherein than the mineral grains far-field comprise a particle size less than 150 μm, wherein the fracturing fluid comprises an oxidizer comprising bromate, sodium bromate, persulfate, or ammonium persulfate, or any combinations thereof, and wherein forming the proppant comprises the leaching comprising oxidizing the rock via the oxidizer in the fracturing fluid to grow the proppant comprising the mineral on the rock in the fractures via the hydrothermally converting of the iron in the fracturing fluid to the mineral.

15. The method of claim 14 , wherein oxidizing the rock gives the iron comprising Fe3+ ions into the fracturing fluid, and wherein the proppant comprises the mineral comprising a mineral matrix.

16. A method of forming a mineral in a geological formation, comprising:
pumping a fracturing fluid through a wellbore into the geological formation;
hydraulically fracturing the geological formation with the fracturing fluid to generate fractures in the geological formation; and
forming the mineral on rock in the fractures, wherein the mineral is formed from the rock by tandem oxidative leach-hydrothermal synthesis via the fracturing fluid, and wherein the rock comprises siderite, pyrite, pyrrhotite, chlorite group minerals, chamosite, clays illite, marcasite, mica, or ankerite, or any combinations thereof.

17. The method of claim 16 , wherein forming the mineral on the rock comprises forming a layer of the mineral on faces of the fractures to protect against embedment by external proppant pumped and conveyed into the fractures.

18. The method of claim 17 , wherein forming the layer comprises precipitating the mineral on the faces of the fractures, wherein the mineral comprises a Fe(III)-based mineral, and wherein the layer comprises a thickness of less than 50 microns (μm).

19. The method of claim 16 , wherein the mineral formed acts as a proppant and comprises mineral grains grown on a surface of the rock by the tandem oxidative leach-hydrothermal synthesis via the fracturing fluid, and wherein the tandem oxidative leach-hydrothermal synthesis is contemporaneous with the hydraulic fracturing.

20. The method of claim 16 , wherein the rock comprises iron-containing shale, and wherein the mineral formed comprises an iron oxyhydroxide group mineral or a sulfate group mineral, or a combination thereof.

21. A method of forming proppant in-situ in a geological formation, comprising:
injecting a fracturing fluid through a wellbore into the geological formation;
hydraulically fracturing rock in the geological formation with the fracturing fluid to generate fractures in the geological formation;
leaching ions from the rock via the fracturing fluid contemporaneous with the hydraulic fracturing; and
forming the proppant from the ions.

22. The method of claim 21 , wherein the fracturing fluid comprises an oxidizer, wherein the leaching comprises oxidative leaching, and wherein forming the proppant comprises synthesizing the proppant from the ions.

23. The method of claim 21 , wherein forming the proppant comprises nucleating and growing a mineral on the rock, and wherein the proppant comprises the mineral.

24. The method of claim 21 , wherein forming the proppant from the ions comprises hydrothermal synthesis, and wherein the proppant comprises petrogenic proppant formed from the rock.

25. The method of claim 21 , wherein the proppant comprises a mineral, wherein forming the proppant comprises precipitating hydrothermally the mineral, and wherein the method comprises altering size of mineral grains of the mineral by adjusting an amount of oxidizer in the fracturing fluid or altering packing density of the mineral matrix by adjusting the amount of the oxidizer in the fracturing fluid, or a combination thereof.

26. A method of forming proppant in situ in a geological formation, comprising:
injecting a fracturing fluid through a wellbore into the geological formation;
hydraulically fracturing rock in the geological formation with the fracturing fluid to generate fractures in the geological formation;
forming proppant in situ in the fractures by

Assignees

• Saudi Arabian Oil Co

Inventors

• Schipper Desmond
• Hull Katherine Leigh
• Haque Mohammad Hamidul

Classifications

• C09K2208/10

  Nanoparticle-containing well treatment fluids · CPC title

• C21B13/00

  Making spongy iron or liquid steel, by direct processes · CPC title

• E21B43/267 Primary

  reinforcing fractures by propping · CPC title

• C09K8/665 Primary

  containing inorganic compounds (proppants C09K8/80) · CPC title

• C09K8/80

  Compositions for reinforcing fractures, e.g. compositions of proppants used to keep the fractures open · CPC title