LOW BULK DENSITY PROPPANT AND METHODS FOR PRODUCING THE SAME

• US 20080058228A1
• Filed: 08/30/2007
• Published: 03/06/2008
• Est. Priority Date: 08/30/2006
• Status: Active Grant

• Current Assignee: Carbo Ceramics Incorporated
• Original Assignee: Carbo Ceramics Incorporated
• Inventors: Wilson, Brett
• Granted Patent: US 8,063,000 B2
• Time in Patent Office: Days
• US Class Current: 507/140
• CPC Class Codes: C04B 2235/3201 Alkali metal oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3206 Magnesium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3232 Titanium oxides or titanates, e.g. rutile or anatase
• CPC Class Codes: C04B 2235/3272 Iron oxides or oxide forming salts thereof, e.g. hematite, magnetite
• CPC Class Codes: C04B 2235/3418 Silicon oxide, silicic acids, or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint glass constituents C04B2235/36
• CPC Class Codes: C04B 2235/528 Spheres
• CPC Class Codes: C04B 2235/5427 millimeter or submillimeter sized, i.e. larger than 0,1 mm
• CPC Class Codes: C04B 2235/5436 micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/656 characterised by specific heating conditions during heat treatment
• CPC Class Codes: C04B 2235/6562 Heating rate
• CPC Class Codes: C04B 2235/6567 Treatment time
• CPC Class Codes: C04B 2235/72 Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
• CPC Class Codes: C04B 2235/77 Density
• CPC Class Codes: C04B 2235/80 Phases present in the sintered or melt-cast ceramic products other than the main phase
• CPC Class Codes: C04B 2235/96 Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
• CPC Class Codes: C04B 33/04 Clay; Kaolin
• CPC Class Codes: C04B 35/185 Mullite 3Al2O3-2SiO2
• CPC Class Codes: C04B 35/6263 characterised by their solids loadings, i.e. the percentage of solids
• CPC Class Codes: C04B 35/62635 Mixing details
• CPC Class Codes: C04B 35/62655 : Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 35/62695 : Granulation or pelletising devices for shaping artificial aggregates from ceramic mixtures B28B1/004
• CPC Class Codes: C04B 35/63416 : Polyvinylalcohols [PVA]; Polyvinylacetates
• 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 8/805 : Coated proppants

Abstract

Materials and Methods for making low bulk density proppant capable of providing permeability at subterranean pressures. The low bulk density proppant is made from kaolin clay and at least one of calcined diatomaceous earth and burned kaolin clay.

Claims

1. A method for forming a low bulk density proppant comprising:

forming substantially round and spherical green pellets from raw materials comprising water;

calcined, partially calcined, or uncalcined kaolin clay; and

at least one material selected from the group consisting of calcined diatomaceous earth and burned kaolin clay; and

sintering the pellets to form a proppant having a bulk density of less than about 1.60 g/cc;

wherein the proppant has a short term permeability greater than that of a proppant having a bulk density of less than about 1.60 g/cc made from pellets consisting of water and calcined, partially calcined or uncalcined kaolin clay.

2. The method of claim 1 further comprising:

coating the proppant with a material to create a coated proppant having an apparent specific gravity lower than the apparent specific gravity of the proppant without a coating.

3. The method of claim 1 further comprising:

co-milling the kaolin clay and the at least one material selected from the group consisting of calcined diatomaceous earth and burned kaolin clay.

4. The method of claim 1 wherein the short term permeability of the proppant is 10% to 50% greater than the short term permeability of a proppant having a bulk density less than about 1.60 g/cc made from pellets consisting of water and calcined, partially calcined or uncalcined kaolin.

5. A method for producing a low bulk density proppant comprising:

heating kaolin clay sufficient to produce a burned kaolin clay comprising at least 5 weight percent of mullite;

co-milling calcined, partially calcined, or uncalcined kaolin clay and the burned kaolin clay to form a co-milled mixture;

forming substantially round and spherical green pellets from the co-milled mixture and water; and

sintering the pellets to form a proppant having a bulk density of less than about 1.60 g/cc;

wherein the proppant has a short term permeability greater than that of proppant having a bulk density of less than about 1.60 g/cc made from pellets consisting of water and calcined, partially calcined or uncalcined kaolin clay.

6. The method of claim 5 wherein the burned kaolin clay comprises at least 50 weight percent of mullite.

7. The method of claim 5 wherein the burned kaolin clay comprises at least 65 weight percent of mullite and at least 15 weight percent of cristobalite.

8. A method for producing a low bulk density proppant comprising:

co-milling calcined, partially calcined, or uncalcined kaolin clay and calcined diatomaceous earth to form a co-milled mixture;

forming substantially round and spherical green pellets from the co-milled mixture and water; and

sintering the pellets to form a proppant having a bulk density of less than about 1.60 g/cc;

wherein the proppant has a short term permeability greater than that of a proppant having a bulk density of less than about 1.60 g/cc made from pellets consisting of water and calcined, partially calcined or uncalcined kaolin.

9. A method for propping fractures in subterranean formations comprising:

mixing a fluid and a proppant comprising a plurality of sintered substantially round and spherical particles made from calcined, partially calcined, or uncalcined kaolin clay and at least one material selected from the group consisting of calcined diatomaceous earth and burned kaolin clay, and having a bulk density of less than about 1.60 g/cc and a 4 Kpsi short term permeability greater than 187 Darcies; and

introducing the mixture into a fracture in a subterranean formation.

10. The method of claim 9 wherein substantially all of the surface porosity of the proppant is coated to form a coated proppant, wherein the coated proppant has an apparent specific gravity lower than the apparent specific gravity of the proppant without a coating.

11. A proppant comprising:

calcined, partially calcined, or uncalcined kaolin clay and at least one material selected from the group consisting of calcined diatomaceous earth and burned kaolin clay, wherein the proppant comprises a sintered substantially round and spherical particle having a bulk density of less than about 1.60 g/cc and a 4 Kpsi short term permeability greater than 187 Darcies.

12. The proppant of claim 11 further comprising:

a coating covering substantially all of the surface porosity of the proppant to form a coated proppant, wherein the coated proppant has an apparent specific gravity lower than the apparent specific gravity of the proppant without a coating.

13. A plurality of pellets made from a mixture comprising:

calcined, partially calcined, or uncalcined kaolin clay and at least one material selected from the group consisting of calcined diatomaceous earth and burned kaolin clay,

wherein a proppant produced from the pellets has a bulk density of less than about 1.60 g/cc.

14. The pellets of claim 13 wherein the mixture comprises calcined, partially calcined, or uncalcined kaolin clay and burned kaolin clay and the mixture comprises from about 70 to about 90 weight percent of kaolin clay and about 10 to about 30 weight percent of burned kaolin clay.

15. The pellets of claim 13 wherein the mixture comprises calcined, partially calcined, or uncalcined kaolin clay and burned kaolin clay and the mixture comprises from about 80 to about 85 weight percent of kaolin clay and about 15 to about 20 weight percent of burned kaolin clay.

16. The pellets of claim 13 wherein the burned kaolin clay comprises at least 5 weight percent of mullite.

17. The pellets of claim 13 wherein the burned kaolin clay comprises at least 50 weight percent of mullite.

18. The pellets of claim 13 wherein the burned kaolin clay comprises at least 65 weight percent of mullite and at least 15 weight percent of cristobalite.

19. The pellets of claim 13 wherein the mixture comprises calcined, partially calcined, or uncalcined kaolin clay and calcined diatomaceous earth and the mixture comprises from about 70 to about 92.5 weight percent of kaolin clay and about 7.5 to about 30 weight percent of calcined diatomaceous earth.

20. The pellets of claim 13 wherein the mixture comprises calcined, partially calcined, or uncalcined kaolin clay and calcined diatomaceous earth and the mixture comprises from about 80 to about 90 weight percent of kaolin clay and about 10 to about 20 weight percent of calcined diatomaceous earth.

21. The pellets of claim 13 wherein the mixture comprises calcined, partially calcined, or uncalcined kaolin clay;

calcined diatomaceous earth; and

burned kaolin clay and the mixture comprises from about 75 to about 90 weight of kaolin clay, about 5 to about 10 weight percent of calcined diatomaceous earth, and about 5 to about 15 weight percent of burned kaolin clay.