Microcapsule well treatment

• US 20040043906A1
• Filed: 08/21/2003
• Published: 03/04/2004
• Est. Priority Date: 06/06/2000
• Status: Active Grant

• Current Assignee: T R Oil Services Limited
• Original Assignee: T R Oil Services Limited
• Inventors: Bourne, Hugh Malcolm, Heath, Stephen Mark
• Granted Patent: US 7,196,040 B2
• Time in Patent Office: Days
• US Class Current: 507/200
• CPC Class Codes: C09K 8/536 characterised by their form or by the form of their components, e.g. encapsulated material
• CPC Class Codes: C09K 8/80 Compositions for reinforcing fractures, e.g. compositions of proppants used to keep the fractures open
• CPC Class Codes: C09K 8/92 characterised by their form or by the form of their components, e.g. encapsulated material C09K8/70 takes precedence
• CPC Class Codes: Y10S 507/902 Controlled release agent
• CPC Class Codes: Y10S 507/939 Corrosion inhibitor

Abstract

A material and a device for releasing chemicals in a fluid environment is disclosed, and a method for releasing substances into downhole fluid environments. The invention also relates to materials for sand control and hydraulic fracturing. The substance release device typically comprises a polymeric material for releasing a substance into a downhole fluid environment in a well, and in preferred embodiments the material comprises a spherical, plastic chemical release capsule which is hard, permeable and may encapsulate a range of solids and/or liquids for subsequent release. These solids or liquids can include inhibitors such as scale inhibitors and other oilfield production chemicals for release into the wellbore of an oil or gas producing well or a water injection well.

Claims

1. A substance release device comprising a polymeric material for releasing a substance into a downhole fluid environment in a well.

2. A device according to claim 1, wherein the substance comprises one or more selected from the group comprising scale inhibitors, hydrate and halite inhibitors, corrosion inhibitors, biocides, wax and asphaltene control substances, demulsifiers, gel breakers, tracers, drag reducers and well clean up substances including enzymes;

organic molecules, acids, esters, and aliphatic substances.

3. A device as claimed in any preceding claim wherein the polymeric material is permeable.

4. A device as claimed in any preceding claim, wherein the material is one or more selected from the group comprising polypropylene, polyethylene, high density polyethylene, high density polypropylene, polyethylene terephthalates, polyamides (both aliphatic and aromatic), liquid crystal polymers, liquid engineered resins, starch and polyhydroxy alkanoates or mixtures of these.

5. A device as claimed in any preceding claim, wherein the material comprises a matrix that provides the material with structural support, and which contains the substance to be released.

6. A device as claimed in claim 5, wherein the material also contains one or more of the group of substances comprising acrylic, polybutylene, polycarbonate, polyester, polystyrene, polyurethane, polyvinyl chloride, polycaprolactone, polybutylene terephthalate, polyvinyl alcohol, polylactic acid, polyglycolide, polyester amide, polyimides, acrylonitrile-butadiene-styrene, acrylonitrile-styrene-acrylate, polyoxymethylene, polybutylene, polyisobutylene, polyvinylbutyral, epichlorohydrin elastomer, nitrile elastomer, nitrile rubber, polyetherketone, polyetheretherketone, polyetherketoneketone, polymethylmethacrylate, polyethylene oxide, polyphenylene oxide, polysulphones, polyethersulphone, polyurea, chlorinated polyethylene, ethylene-chlorofluoroethylene, tetrafluoroethylene-perfluoropropylene, Perfluoroalkoxy, silicon rubbers and other polymeric materials consisting of mixtures of these, copolymers, terpolymers and hydrophobically/hydrophilically modified and crosslinked derivatives of these.

7. A device as claimed in any preceding claim, wherein the material contains one or more of the group of substances comprising waxes, calcium stearate, metallocene, thermoplastic rubber, resins, hot melt adhesives, fibreglass, silicones, fluorosilicones e.g. Ryton, polysiloxanes, fluoroelastomers e.g. Viton, Aflas, fluorocarbons e.g. PTFE, PVDF, halogenated polymers, cellulose, polysaccharides, lignin, chitin, gums and mixtures and derivatives of the above.

8. A device as claimed in any preceding claim, comprising a generally spherical capsule.

9. A device as claimed in any preceding claim, manufactured using an underwater pelletising system using an extrusion and either a spheronisation or granulation process.

10. A device as claimed in any preceding claim, wherein the material contains a high active content of substance to be released.

11. A device as claimed in any preceding claim, including a weighting agent to adjust the density of device.

12. A device as claimed in claim 11, wherein the weighting agent is selected from the group comprising barite, zirconium oxide, manganese oxide, titanium dioxide, tungsten and magnetite.

13. A device as claimed in any preceding claim, including a strengthening agent to adjust the hardness, compressive strength and/or elastic properties of the device.

14. A device as claimed in claim 13, wherein the strengthening agent is selected from the group comprising glass, sand, minerals, carbon fibres, boron fibres and impact modifiers.

15. A device as claimed in any preceding claim, wherein the material has a specific gravity between 0.9 and 2.0.

16. A device as claimed in any one of claims 1-14, wherein the device has a specific gravity up to 12.

17. A device as claimed in any preceding claim, wherein the device and/or the material is pliable.

18. A method of treating a well, the method comprising loading a substance into a polymeric material, inserting the material into the well, and allowing the substance to leach from the polymeric material into the well.

19. A method as claimed in claim 18, wherein the substance comprises one or more selected from the group comprising scale inhibitors, corrosion inhibitors, hydrate and halite inhibitors, biocides, wax and asphaltene control substances, demulsifiers, gel breakers, tracers, drag reducers and well clean up substances, enzymes, organic molecules, acids, esters, copolymers, ter-polymers, aliphatic compounds, polymeric species, and other oilfield production chemicals.

20. A method according to claim 18 or claim 19, wherein the material releases well cleanup substances.

21. A method as claimed in any one of claims 18-20, wherein the material is inserted into a fissure, fracture, screen area, gravel pack, fracture pack or a pre-packed screen.

22. A method as claimed in any one of claims 18-21, wherein the material is injected into the rathole or base of a well.

23. A method as claimed in any one of claims 18-22, wherein the material is used to support portions of the well, reservoir or formation in addition to releasing the substance.

24. A method according to any one of claims 18-23, wherein the material controls entry of particulate matter into the production stream of the well.

25. A method as claimed in any one of claims 18-24, wherein the material is loaded with a high active content of the substance to be released.

26. A method as claimed in any one of claims 18-25, wherein the solubility of the substance is selected to suit prevailing well conditions.

27. A method as claimed in any one of claims 18-26, wherein the hardness of the material is adjusted to suit prevailing well conditions.

28. A method as claimed in any one of claims 18-27, wherein the oil and/or acid tolerance of the material is adjusted to suit prevailing well conditions.

29. A method as claimed in any one of claims 18-28, wherein a number of the devices having a generally heterogeneous size distribution are delivered to the well.

30. A method as claimed in any one of claims 18-28, wherein a number of the devices having a generally homogeneous size distribution are delivered to the well.

31. A method as claimed in claim 30, wherein the size distribution of devices delivered to the well is ±

5% of the mean size.

32. A method as claimed in any one of claims 29-31, wherein the range of sizes of the devices delivered to the well is 250 μ

m-5 mm.

33. A method as claimed in any one of claims 18-32, wherein the material is adapted to degrade over a period of time, after which the well is retreated.

34. A method as claimed in claim 33, wherein the period of degradation is adjusted to suit the prevailing well conditions.

35. A method as claimed in any one of claims 18-34, wherein the rate and lifetime of release of the substance is adjusted to suit the degradation lifetime of the material.

36. A method as claimed in any one of claims 18-35, wherein the material is charged with one or more substances selected from the group comprising scale inhibitors, hydrate and halite inhibitors, corrosion inhibitors, biocides, wax and asphaltene control substances, demulsifiers, gel breakers, tracers, drag reducers and well clean up substances including enzymes;

organic molecules, acids, esters, and aliphatic substances.

37. A method of forming a substance-releasing particle for release of substances into a fluid environment in an well, the method comprising mixing the substance to be released with a matrix material forming the particle, and thereafter forming the particle from the mixture of the matrix and the substance, so that the substance is dispersed throughout the formed particle.

38. A polymeric downhole proppant.

39. A method of supporting a well or a portion thereof, comprising disposing a support material in the well or portion to be supported, wherein the support material comprises a polymeric material.

40. A polymeric material for use downhole for the control of particulate matter entering the production stream of the well.

41. A method of controlling the entry of particulate matter into the production stream of a well, the method comprising disposing a number of polymeric devices into the wellbore between the formation and the production fluids outlet of the well.