Proppants and anti-flowback additives including kaolin clay

Abstract

A method of making a sintered ceramic proppant may include providing a kaolin clay. The kaolin clay may include an Al.sub.2O.sub.3 content no greater than about 46% by weight, and a K.sub.2O content no greater than 0.1% by weight. The kaolin clay may have a particle size distribution such that greater than 70% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, and a shape factor less than about 18. The method may further include blunging the kaolin clay, agglomerating the kaolin clay, and sintering the agglomerated kaolin clay to produce a sintered ceramic proppant. The kaolin clay may have an A-bob Hercules viscosity of at least about 3,300 rpm at 18 kilodyne-cm and 70% solids.

Claims

1. A method of making a sintered ceramic proppant, the method comprising: providing a kaolin clay comprising an Al.sub.2O.sub.3 content of not greater than about 46% by weight, and a K.sub.2O content no greater than 0.1% by weight, and having a particle size distribution of particles of the kaolin clay such that greater than 70% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, and a shape factor less than about 18; blunging the kaolin clay; agglomerating the kaolin clay; and sintering the agglomerated kaolin clay to produce a sintered ceramic proppant, wherein the kaolin clay comprises a blend of a first kaolin clay comprising less than about 0.1% by weight K.sub.2O and a second kaolin clay comprising greater than about 0.1% by weight K.sub.2O, and wherein the blend comprises at least about 10% by weight of the first kaolin clay.

2. The method of claim 1, wherein the kaolin clay has an Al.sub.2O.sub.3 content ranging from about 42% by weight to about 46% by weight.

3. The method of claim 2, wherein the kaolin clay has an Al.sub.2O.sub.3 content ranging from about 43% by weight to about 45% by weight.

4. The method of claim 1, wherein the blend comprises at least about 25% by weight of the first kaolin clay.

5. The method of claim 1, wherein the particle size distribution of the kaolin clay is such that greater than 93% of the particles have an equivalent spherical diameter of less than 2 microns as measured by Sedigraph.

6. The method of claim 1, wherein the particle size distribution of the kaolin clay is such that greater than 85% of the particles have an equivalent spherical diameter of less than 1 micron as measured by Sedigraph.

7. The method of claim 1, wherein the particle size distribution of the kaolin clay is such that greater than 40% of the particles have an equivalent spherical diameter of less than 0.25 microns as measured by Sedigraph.

8. The method of claim 1, wherein the kaolin clay comprises a K.sub.2O content ranging from about 0.005% by weight to about 0.08% by weight.

9. The method of claim 1, wherein the kaolin clay comprises a K.sub.2O content ranging from about 0.01% by weight to about 0.06% by weight.

10. The method of claim 1, wherein the shape factor is less than about 15.

11. The method of claim 1, wherein the shape factor ranges from about 2 to about 15.

12. The method of claim 1, wherein the shape factor ranges from about 5 to about 8.

13. The method of claim 1, wherein the kaolin clay particles have a BET surface area of greater than about 15 m.sup.2/g.

14. The method of claim 1, wherein the kaolin clay particles have a BET surface area of greater than about 35 m.sup.2/g.

15. The method of claim 1, wherein the kaolin clay particles have a BET surface area ranging from about 15 m.sup.2/g to about 35 m.sup.2/g.

16. The method of claim 1, wherein the sintered ceramic proppant has a specific gravity greater than about 2.65.

17. The method of claim 1, wherein the sintered ceramic proppant has a bulk density greater than about 1.44 g/cm.sup.3.

18. The method of claim 1, wherein the sintered ceramic proppant has a bulk density ranging from about 1.45 g/cm.sup.3 to about 1.50 g/cm.sup.3.

19. The method of claim 1, wherein the crush strength measured under ISO 13503-2 of the sintered ceramic proppant at 10,000 psi is less than about 6% fines by weight.

20. The method of claim 1, wherein the kaolin clay has an A-bob Hercules viscosity of at least about 3,300 rpm at 18 kilodyne-cm and 70% solids.

21. A method of making a sintered ceramic proppant, the method comprising: providing a kaolin clay comprising an Al.sub.2O.sub.3 content not greater than about 46% by weight, and a K.sub.2O content no greater than 0.1% by weight, and having a particle size distribution of particles of the kaolin clay such that greater than 70% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, and an A-bob Hercules viscosity of at least about 3,300 rpm at 18 kilodyne-cm and 70% solids; blunging the kaolin clay; agglomerating the kaolin clay; and sintering the agglomerated kaolin clay to produce a sintered ceramic proppant, wherein the kaolin clay comprises a blend of a first kaolin clay comprising less than about 0.1% by weight K.sub.2O and a second kaolin clay comprising greater than about 0.1% by weight K.sub.7O, and wherein the blend comprises at least about 10% by weight of the first kaolin clay.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1 is a schematic diagram of an exemplary process for making exemplary sintered ceramic proppants consistent with exemplary methods disclosed herein.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(2) Reference will now be made to exemplary embodiments.

(3) Applicant has surprisingly found that relatively fine kaolin clay having a relatively low shape factor may be used as a feed material for producing proppants and anti-flowback additives that may exhibit one or more desirable proppant properties, such as, for example, relatively high crush resistance, relatively high conductivity, relatively high permeability, a desirable bulk density, and/or a desirable specific gravity. This fine, blocky kaolin clay may be used as a feed material that is processed, including sintering, to form a sintered ceramic proppant.

(4) For example, according to some embodiments, a method of making a sintered ceramic proppant may include providing a kaolin clay, wherein the kaolin clay may include an Al.sub.2O.sub.3 content no greater than about 46% by weight, and a K.sub.2O content no greater than 0.1% by weight. The kaolin clay may have a particle size distribution such that greater than 70% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, and a shape factor less than about 18. The method may further include blunging the kaolin clay, agglomerating the kaolin clay, and sintering the agglomerated kaolin clay to produce a sintered ceramic proppant.

(5) According to some embodiments, the kaolin clay may have an Al.sub.2O.sub.3 content ranging from about 42% by weight to about 46% by weight, for example, an Al.sub.2O.sub.3 content ranging from about 43% by weight to about 45% by weight.

(6) According to some embodiments, the kaolin clay may include a blend of a first kaolin clay including less than about 0.1% by weight K.sub.2O and a second kaolin clay including greater than about 0.1% by weight K.sub.2O. The blend may include at least about 10% by weight of the first kaolin clay, for example, at least about 25% by weight of the first kaolin clay.

(7) According to some embodiments, the kaolin clay may include a blend of a first kaolin clay including not greater than about 46% by weight Al.sub.2O.sub.3 and a second kaolin clay including greater than about 47% by weight Al.sub.2O.sub.3. For example, the second kaolin clay may have an Al.sub.2O.sub.3 content ranging from about 49% to about 55% by weight, or from about 50% to about 53% by weight. The blend may include at least about 10% by weight of the first kaolin clay, for example, at least about 25% by weight of the first kaolin clay.

(8) According to some embodiments, the particle size distribution of the kaolin clay may be such that greater than 75% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, such as, for example, greater than about 77%, or even greater than about 81%. For example, the particle size distribution of the kaolin clay may be such that about 70% to about 85% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, such as, for example, from about 75% to about 82%.

(9) According to some embodiments, the particle size distribution of the kaolin clay may be such that greater than about 90% of the particles have an equivalent spherical diameter of less than 2 microns as measured by Sedigraph, such as, for example, greater than about 93%, greater than about 94%, greater than about 95%, or even greater than about 96%. For example, the particle size distribution of the kaolin clay may be such that greater than about 85% of the particles have an equivalent spherical diameter of less than 1 micron as measured by Sedigraph, such as, for example, greater than about 87%, greater than about 89%, greater than about 90%, or even greater than about 92%. For example, the particle size distribution of the kaolin clay may be such that greater than about 40% of the particles have an equivalent spherical diameter of less than 0.25 microns as measured by Sedigraph, such as, for example, greater than about 45%, greater than about 50%, or even greater than about 55%.

(10) According to some embodiments, the kaolin clay may include a K.sub.2O content ranging from about 0.005% by weight to about 0.08% by weight. For example, the kaolin clay may include a K.sub.2O content ranging from about 0.01% by weight to about 0.06% by weight. Although not wishing to be bound by theory, it is believed that K.sub.2O provides an indicator of the presence of mica in the kaolin clay. Mica is generally associated with a high shape factor, which leads to a high viscosity of a kaolin clay slurry.

(11) According to some embodiments, the kaolin clay may have a shape factor less than about 15, or less than about 10. For example, the shape factor may range from about 2 to about 15, from about 2 to about 10, or from about 5 to about 8.

(12) According to some embodiments, the kaolin clay particles may have a BET surface area of greater than about 15 m.sup.2/g. For example, the kaolin clay particles may have a BET surface area of greater than about 20 m.sup.2/g, or greater than about 35 m.sup.2/g. According to another aspect, the kaolin clay particles may have a BET surface area ranging from about 15 m.sup.2/g to about 35 m.sup.2/g.

(13) According to some embodiments, the sintered ceramic proppant may have a specific gravity greater than about 2.65, or a specific gravity greater than about 2.68. For example, the specific gravity may be greater than about 2.7.

(14) According to some embodiments, the sintered ceramic proppant may have a bulk density greater than about 1.44 g/cm.sup.3. For example, the sintered ceramic proppant may have a bulk density greater than about 1.45 g/cm.sup.3, greater than about 1.46 g/cm.sup.3, greater than about 1.47 g/cm.sup.3, or greater than about 1.48 g/cm.sup.3. For example, the sintered ceramic proppant may have a bulk density ranging from about 1.45 g/cm.sup.3 to about 1.50 g/cm.sup.3.

(15) According to some embodiments, the crush strength measured under ISO 13503-2 of a 30/50 mesh sintered ceramic proppant at 10,000 psi may be less than about 6% fines by weight. For example, the crush strength measured under ISO 13503-2 of a 30/50 mesh sintered ceramic proppant at 10,000 psi may be less than about 5% fines by weight, or less than about 4% fines by weight.

(16) According to some embodiments, the kaolin clay may have an A-bob Hercules viscosity of at least about 3,300 rpm at 18 kilodyne-cm and 70% solids. For example, the kaolin clay may have an A-bob Hercules viscosity of at least about 3,700 rpm at 18 kilodyne-cm and 70% solids, at least about 4,000 rpm at 18 kilodyne-cm and 70% solids, or at least about 4,400 rpm at 18 kilodyne-cm and 70% solids.

(17) According to some embodiments, a method of making a sintered ceramic proppant may include providing a kaolin clay, wherein the kaolin clay may include an Al.sub.2O.sub.3 content no greater than about 46% by weight, and a K.sub.2O content no greater than 0.1% by weight. The kaolin clay may have a particle size distribution of particles of the kaolin clay such that greater than 70% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, and an “A-bob” Hercules viscosity of at least about 3,300 rpm at 18 kilodyne-cm and 70% solids. The method may further include blunging the kaolin clay, agglomerating the kaolin clay, and sintering the agglomerated kaolin clay to produce a sintered ceramic proppant. According to some embodiments, the kaolin clay may have a shape factor less than about 18. For example, the kaolin clay may have a shape factor less than about 15, less than about 10, for example, a shape factor ranging from about 2 to about 10, or from about 5 to about 8.

(18) FIG. 1 is a schematic diagram of an exemplary process for making sintered ceramic proppants consistent with exemplary methods disclosed herein. As shown in FIG. 1, a kaolin clay, for example, a fine, blocky feed kaolin clay, is transferred from storage to a blunger for blunging in a conventional manner known to those skilled in the art with inorganic or organic dispersant (e.g., TSPP, SHMP, Na-polyacrylate, and/or similar dispersants). Thereafter, the blunged feed kaolin clay is wet-screened and degritted, after which the degritted feed kaolin clay is fluidized for agglomeration. According to some embodiments, agglomeration may be performed using a spray fluidizer such as, for example, a fluidizer marketed by NIRO. Following agglomeration, the feed kaolin clay is green-screened, and undersized material is recirculated to the fluidizer to serve as seeds. According to some embodiments, 35 mesh screen may be used. Thereafter, the feed kaolin clay may be sintered in a kiln. For example, the feed may be heated in a kiln with the temperature being increased at a rate of, for example, 10° C. per minute until it reaches a temperature of, for example, 1,450° C. According to some embodiments, this temperature may be maintained for, for example, about an hour, and thereafter, the temperature may be reduced at a rate of, for example, about 5° C. per minute. Thereafter, the sintered and cooled material may be fed to a screening tower to classify the sintered material into different grades (e.g., oversized, undersized, and dust). Thereafter, the final sintered ceramic proppant may be obtained.

EXAMPLES

(19) The following examples include five samples: three samples and two comparative samples of feed kaolin clays used to form sintered ceramic proppants of the five proppant samples tested. Table 1 below shows the chemical content in weight percent of the five feed kaolin clay samples.

(20) TABLE-US-00001 TABLE 1 Fired Basis Total Total Fe2O3 MgO Al2O3 SiO2 TiO2 CaO Na2O K2O Alkali Sample (%) (%) (%) (%) (%) (%) (%) (%) (%) (%) Sample 1 100.5 1.11 0.07 44.52 52.14 2.53 0.05 0.01 0.03 0.16 Sample 2 100.5 1.08 0.05 43.80 51.84 3.59 0.06 0.00 0.05 0.16 Sample 3 100.6 1.57 0.07 43.88 52.68 2.14 0.06 0.07 0.09 0.29 Comparative 100.2 1.53 0.08 43.77 52.40 2.02 0.09 0.01 0.17 0.36 Sample 1 Comparative 101.1 0.44 0.06 52.16 46.43 2.01 0.04 0.00 0.09 0.19 Sample 2

(21) Table 2 below shows material characteristics of the five feed kaolin clay samples listed in the same order as Table 1. Note that for Samples 1 and 2, the Hercules viscosity is shown in units of kilodyne-cm @ 4,400 rpm rather than rpm because for more fluid slurries, the Hercules viscosity is reported as a function of the force in kilodyne-cm required to spin the bob at its maximum speed of 4,400 rpm.

(22) TABLE-US-00002 TABLE 2 Shape BET Factor w/SHMP Hercules SA (NSF) 2 um 1 um 0.5 um 0.25 um Solids(%) Poly (#/t) rpm pH m.sup.2/g 6 94.5 91.4 83.0 59.6 70 — 6.1 6.9 24.0 8 92.6 88.6 79.0 53.0 70 — 5.4 6.9 11.3 92.9 88.3 78.2 57.5 70 17 3718 6.7 18 94.8 90.5 81.0 58.4 69.7 11 2384 25.6 5 61.3 45.3 27.5 15.7 70 8 770 7.2

(23) Table 3 below shows the corresponding fired real density, fired bulk density, and crush resistance at 10,000 psi according ISO 13503-2 of five 30/50 mesh proppant samples prepared according to methods consistent with the exemplary methods disclosed previously herein, as follows: Samples 1-3 correspond to the feed kaolin clay Samples 1-3 shown in Tables 1 and 2; Comparative Sample 1 corresponds to Comparative Sample 1 of the feed kaolin clay; and the remaining sample is a blend of the feed kaolin clays of 50% by weight of Sample 3, 40% by weight of Comparative Sample 1, and 10% of a high-alumina content kaolin clay. All the proppant samples tested were screened to 325 mesh using 035 mesh plant seed. The proppant samples were obtained by being passed through a 30 mesh but retained on 50 mesh (i.e., “30/50”).

(24) TABLE-US-00003 TABLE 3 Fired real Fired Bulk 10K density density Crush Feed Sample (g/cc) (g/cc) 30/50 Sample 1 2.69 1.49 3.6 Sample 2 2.66 1.49 3.3 Sample 3 2.66 1.46 5.8 Comparative Sample 1 2.57 1.42 7.3 50% Sample 3/40% 2.65 1.47 4 Comparative Sample 1/10% High Alumina Kaolin

(25) As shown in Table 3, the sintered ceramic proppant Samples 1-3 exhibit a better crush resistance (i.e., a lower percentage of fines) than Comparative Sample 1. In addition, the blended Sample also exhibits a better crush resistance than Comparative Sample 1, but an inferior crush resistance relative to Samples 1 and 2.

(26) For the avoidance of doubt, the present application is directed to the subject matter described in the following numbered options (i.e., numbered options 1-62).

(27) Option 1. A method of making a sintered ceramic proppant, the method comprising: providing a kaolin clay comprising an Al.sub.2O.sub.3 content of not greater than about 46% by weight, and a K.sub.2O content no greater than 0.1% by weight, and having a particle size distribution of particles of the kaolin clay such that greater than 70% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, and a shape factor less than about 18; blunging the kaolin clay; agglomerating the kaolin clay; and sintering the agglomerated kaolin clay to produce a sintered ceramic proppant.

(28) Option 2. The method according to numbered option 1, wherein the kaolin clay has an Al.sub.2O.sub.3 content ranging from about 42% by weight to about 46% by weight.

(29) Option 3. The method according to any preceding numbered option (i.e., options 1 and 2), wherein the kaolin clay has an Al.sub.2O.sub.3 content ranging from about 43% by weight to about 45% by weight.

(30) Option 4. The method according to any preceding numbered option, wherein the kaolin clay comprises a blend of a first kaolin clay comprising less than about 0.1% by weight K.sub.2O and a second kaolin clay comprising greater than about 0.1% by weight K.sub.2O, wherein the blend comprises at least about 10% by weight of the first kaolin clay.

(31) Option 5. The method according to any preceding numbered option, wherein the blend comprises at least about 25% by weight of the first kaolin clay.

(32) Option 6. The method according to any preceding numbered option, wherein the particle size distribution of the kaolin clay is such that greater than 93% of the particles have an equivalent spherical diameter of less than 2 microns as measured by Sedigraph.

(33) Option 7. The method according to any preceding numbered option, wherein the particle size distribution of the kaolin clay is such that greater than 85% of the particles have an equivalent spherical diameter of less than 1 micron as measured by Sedigraph.

(34) Option 8. The method according to any preceding numbered option, wherein the particle size distribution of the kaolin clay is such that greater than 40% of the particles have an equivalent spherical diameter of less than 0.25 microns as measured by Sedigraph.

(35) Option 9. The method of according to any preceding numbered option, wherein the kaolin clay comprises a K.sub.2O content ranging from about 0.005% by weight to about 0.08% by weight.

(36) Option 10. The method according to any preceding numbered option, wherein the kaolin clay comprises a K.sub.2O content ranging from about 0.01% by weight to about 0.06% by weight.

(37) Option 11. The method according to any preceding numbered option, wherein the shape factor is less than about 15.

(38) Option 12. The method according to any preceding numbered option, wherein the shape factor is less than about 10.

(39) Option 13. The method according to any preceding numbered option, wherein the shape factor ranges from about 2 to about 15.

(40) Option 14. The method according to any preceding numbered option, wherein the shape factor ranges from about 5 to about 8.

(41) Option 15. The method according to any preceding numbered option, wherein the kaolin clay particles have a BET surface area of greater than about 15 m.sup.2/g.

(42) Option 16. The method according to any preceding numbered option, wherein the kaolin clay particles have a BET surface area of greater than about 20 m.sup.2/g.

(43) Option 17. The method according to any preceding numbered option, wherein the kaolin clay particles have a BET surface area of greater than about 35 m.sup.2/g.

(44) Option 18. The method according to any preceding numbered option, wherein the kaolin clay particles have a BET surface area ranging from about 15 m.sup.2/g to about 35 m.sup.2/g.

(45) Option 19. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a specific gravity greater than about 2.65.

(46) Option 20. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a specific gravity greater than about 2.68.

(47) Option 21. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a specific gravity greater than about 2.7.

(48) Option 22. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a bulk density greater than about 1.44 g/cm.sup.3.

(49) Option 23. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a bulk density greater than about 1.45 g/cm.sup.3.

(50) Option 24. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a bulk density ranging from about 1.45 g/cm.sup.3 to about 1.50 g/cm.sup.3.

(51) Option 25. The method according to any preceding numbered option, wherein the crush strength measured under ISO 13503-2 of the sintered ceramic proppant at 10,000 psi is less than about 6% fines by weight.

(52) Option 26. The method according to any preceding numbered option, wherein the crush strength measured under ISO 13503-2 of the sintered ceramic proppant at 10,000 psi is less than about 5% fines by weight.

(53) Option 27. The method according to any preceding numbered option, wherein the crush strength measured under ISO 13503-2 of the sintered ceramic proppant at 10,000 psi is less than about 4% fines by weight.

(54) Option 28. The method according to any preceding numbered option, wherein the kaolin clay has an A-bob Hercules viscosity of at least about 3,300 rpm at 18 kilodyne-cm and 70% solids.

(55) Option 29. The method according to any preceding numbered option, wherein the kaolin clay has an A-bob Hercules viscosity of at least about 3,700 rpm at 18 kilodyne-cm and 70% solids.

(56) Option 30. The method according to any preceding numbered option, wherein the kaolin clay has an A-bob Hercules viscosity of at least about 4,000 rpm at 18 kilodyne-cm and 70% solids.

(57) Option 31. The method according to any preceding numbered option, wherein the kaolin clay has an A-bob Hercules viscosity of at least about 4,400 rpm at 18 kilodyne-cm and 70% solids.

(58) Option 32. A method of making a sintered ceramic proppant, the method comprising: providing a kaolin clay comprising an Al.sub.2O.sub.3 content not greater than about 46% by weight, and a K.sub.2O content no greater than 0.1% by weight, and having a particle size distribution of particles of the kaolin clay such that greater than 70% of the particles have an equivalent spherical diameter of less than 0.5 microns as measured by Sedigraph, and an A-bob Hercules viscosity of at least about 3,300 rpm at 18 kilodyne-cm and 70% solids; blunging the kaolin clay; agglomerating the kaolin clay; and sintering the agglomerated kaolin clay to produce a sintered ceramic proppant.

(59) Option 33. The method according to any preceding numbered option, wherein the kaolin clay has an A-bob Hercules viscosity of at least about 3,700 rpm at 18 kilodyne-cm and 70% solids.

(60) Option 34. The method according to any preceding numbered option, wherein the kaolin clay has an A-bob Hercules viscosity of at least about 4,000 rpm at 18 kilodyne-cm and 70% solids.

(61) Option 35. The method according to any preceding numbered option, wherein the kaolin clay has an A-bob Hercules viscosity of at least about 4,400 rpm at 18 kilodyne-cm and 70% solids.

(62) Option 36. The method according to any preceding numbered option, wherein the kaolin clay has an Al.sub.2O.sub.3 content ranging from about 42% by weight to about 46% by weight.

(63) Option 37. The method according to any preceding numbered option, wherein the kaolin clay has an Al.sub.2O.sub.3 content ranging from about 43% by weight to about 45% by weight.

(64) Option 38. The method according to any preceding numbered option, wherein the kaolin clay comprises a blend of a first kaolin clay comprising less than about 0.1% by weight K.sub.2O and a second kaolin clay comprising greater than about 0.1% by weight K.sub.2O, wherein the blend comprises at least about 10% by weight of the first kaolin clay.

(65) Option 39. The method according to any preceding numbered option, wherein the blend comprises at least about 25% by weight of the first kaolin clay.

(66) Option 40. The method according to any preceding numbered option, wherein the particle size distribution of the kaolin clay is such that greater than 93% of the particles have an equivalent spherical diameter of less than 2 microns as measured by Sedigraph.

(67) Option 41. The method according to any preceding numbered option, wherein the particle size distribution of the kaolin clay is such that greater than 85% of the particles have an equivalent spherical diameter of less than 1 micron as measured by Sedigraph.

(68) Option 42. The method according to any preceding numbered option, wherein the particle size distribution of the kaolin clay is such that greater than 40% of the particles have an equivalent spherical diameter of less than 0.25 microns as measured by Sedigraph.

(69) Option 43. The method according to any preceding numbered option, wherein the kaolin clay comprises a K.sub.2O content ranging from about 0.005% by weight to about 0.08% by weight.

(70) Option 44. The method according to any preceding numbered option, wherein the kaolin clay comprises a K.sub.2O content ranging from about 0.01% by weight to about 0.06% by weight.

(71) Option 45. The method according to any preceding numbered option, wherein the kaolin clay has a shape factor less than about 18.

(72) Option 46. The method according to any preceding numbered option, wherein the kaolin clay has a shape factor less than about 15.

(73) Option 47. The method according to any preceding numbered option, wherein the kaolin clay has a shape factor less than about 10.

(74) Option 48. The method according to any preceding numbered option, wherein the kaolin clay has a shape factor ranging from about 2 to about 15.

(75) Option 49. The method according to any preceding numbered option, wherein the kaolin clay has a shape factor ranging from about 5 to about 8.

(76) Option 50. The method according to any preceding numbered option, wherein the kaolin clay particles have a BET surface area of greater than about 15 m.sup.2/g.

(77) Option 51. The method according to any preceding numbered option, wherein the kaolin clay particles have a BET surface area of greater than about 20 m.sup.2/g.

(78) Option 52. The method according to any preceding numbered option, wherein the kaolin clay particles have a BET surface area of greater than about 35 m.sup.2/g.

(79) Option 53. The method according to any preceding numbered option, wherein the kaolin clay particles have a BET surface area ranging from about 15 m.sup.2/g to about 35 m.sup.2/g.

(80) Option 54. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a specific gravity greater than about 2.65.

(81) Option 55. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a specific gravity greater than about 2.68.

(82) Option 56. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a specific gravity greater than about 2.7.

(83) Option 57. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a bulk density greater than about 1.44 g/cm.sup.3.

(84) Option 58. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a bulk density greater than about 1.45 g/cm.sup.3.

(85) Option 59. The method according to any preceding numbered option, wherein the sintered ceramic proppant has a bulk density ranging from about 1.45 g/cm.sup.3 to about 1.50 g/cm.sup.3.

(86) Option 60. The method according to any preceding numbered option, wherein the crush strength measured under ISO 13503-2 of the sintered ceramic proppant at 10,000 psi is less than about 6% fines by weight.

(87) Option 61. The method according to any preceding numbered option, wherein the crush strength measured under ISO 13503-2 of the sintered ceramic proppant at 10,000 psi is less than about 5% fines by weight.

(88) Option 62. The method according to any preceding numbered option, wherein the crush strength measured under ISO 13503-2 of the sintered ceramic proppant at 10,000 psi is less than about 4% fines by weight.

(89) Other embodiments may be apparent to those skilled in the art from consideration of the specification and practice of the exemplary embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only.