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An embodiment consistent with the present invention is a high strength proppant comprising an electrofused pellet. In another embodiment, a high strength proppant comprises a substantially solid and substantially spherical pellet produced by electrofusion of at least one metal oxide. A method of mak

An embodiment consistent with the present invention is a high strength proppant comprising an electrofused pellet. In another embodiment, a high strength proppant comprises a substantially solid and substantially spherical pellet produced by electrofusion of at least one metal oxide. A method of making a proppant is also provided, with that method comprising melting at least one metal oxide in an electrical arc furnace, pouring the molten metal oxide to create a pour stream, and separating the pour stream to form at least one electrofused pellet. A method of fracturing subterranean formations is also provided, with that method comprising injecting a fluid containing at least one electrofused pellet.

대표청구항 ▼

We claim: 1. A high strength proppant comprising an electrofused pellet, wherein the proppant has an apparent specific gravity less than about 3.9, and wherein the proppant has a bulk density of between about 1.7 g/cm3 and about 2.7g/cm3. 2. The proppant of claim 1, wherein the electrofused pelle

We claim: 1. A high strength proppant comprising an electrofused pellet, wherein the proppant has an apparent specific gravity less than about 3.9, and wherein the proppant has a bulk density of between about 1.7 g/cm3 and about 2.7g/cm3. 2. The proppant of claim 1, wherein the electrofused pellet is substantially solid. 3. The proppant of claim 1, wherein the electrofused pellet has a substantially spherical shape. 4. The proppant of claim 3, wherein the electrofused pellet has a sphericity of at least 0.8 on the Krumbein scale. 5. The proppant of claim 4, wherein the electrofused pellet has a sphericity of greater than about 0.9 on the Krumbein scale. 6. The proppant of claim 5, wherein the electrofused pellet has a sphericity of greater than about 0.95 on the Krumbein scale. 7. The proppant of claim 1, wherein the electrofused pellet comprises a metal oxide. 8. The proppant of claim 7, wherein the metal oxide comprises alumina. 9. The proppant of claim 7, wherein the metal oxide is contributed by at least one of pure alumina, bauxite, or zircon mullite. 10. The proppant of claim 7, wherein the metal oxide is contributed by at least about 50% pure alumina by weight. 11. The proppant of claim 7, wherein the metal oxide is contributed by at least about 90% bauxite by weight. 12. The proppant of claim 1, wherein the electrofused pellet has an average diameter of about 0.1 mm to about 3 mm. 13. The proppant of claim 12, wherein the electrofused pellet has an average diameter of about 0.2 mm to about 2 mm. 14. The proppant of claim 13, wherein the electrofused pellet has an average diameter of about 0.25 mm to about 1.7 mm. 15. The proppant of claim 1, wherein the electrofused pellet has an average mesh size of about 6 mesh to about 140 mesh. 16. The proppant of claim 15, wherein the electrofused pellet has an average mesh size of about 10 mesh to about 80 mesh. 17. The proppant of claim 16, wherein the electrofused pellet has an average mesh size of about 12 mesh to about 80 mesh. 18. The proppant of claim 1 wherein the proppant has a compressive strength of up to about 50,000 psi. 19. The proppant of claim 1 wherein the proppant has a conductivity of at least about 4,000 md-ft at a closing pressure of about 5,000 psi. 20. The proppant of claim 1 wherein the proppant has a permeability of at least about 200 Darcies at a closing pressure of about 5,000 psi. 21. The proppant of claim 1 wherein the proppant has an apparent specific gravity of between about 3.0 and about 3.9. 22. The proppant of claim 21 wherein the proppant has an apparent specific gravity of between about 3.4 and about 3.7 g/cm3. 23. The proppant of claim 1 wherein the proppant has a bulk density of between about 1.9 g/cm3 and about 2.5 g/cm3. 24. The proppant of claim 1 wherein the proppant has a BET specific surface area of between about 0.05 m2/g and about 0.5 m2/g. 25. The proppant of claim 1 wherein the proppant has a Vollstaedt grain crush resistance of greater than or equal to about 30 N. 26. The proppant of claim 25 wherein the proppant has a Vollstaedt grain crush resistance of greater than or equal to about 60 N. 27. The proppant of claim 1 wherein the proppant has a pore volume of less than about 50%, wherein the pore volume is determined by digital image analysis. 28. The proppant of claim 27 wherein the proppant has a pore volume of less than about 30%. 29. The proppant of claim 28 wherein the proppant has a pore volume of less than about 20%. 30. The proppant of claim 1 wherein the proppant has a substantially smooth surface. 31. A high strength proppant comprising a substantially solid and substantially spherical pellet produced by electrofusion of at least one metal oxide wherein the proppant has an apparent specific gravity less than about 3.9, and the proppant has a bulk density of between about 1.7 g/cm3 and about 2.7 g/cm3. 32. The proppant of claim 31, wherein the pellet has a sphericity of at least 0.8 on the Krumbein scale. 33. The proppant of claim 32, wherein the pellet has a sphericity of greater than about 0.9 on the Krumbein scale. 34. The proppant of claim 33, wherein the pellet has a sphericity of greater than about 0.95 on the Krumbein scale. 35. The proppant of claim 31, wherein the metal oxide comprises alumina. 36. The proppant of claim 35, wherein the metal oxide is contributed by at least one of pure alumina, bauxite, or zircon mullite. 37. The proppant of claim 35, wherein the metal oxide is contributed by at least about 50% pure alumina by weight. 38. The proppant of claim 35, wherein the metal oxide is contributed by at least about 90% bauxite by weight. 39. The proppant of claim 31, wherein the pellet has an average diameter of about 0.1 mm to about 3 mm. 40. The proppant of claim 39, wherein the pellet has an average diameter of about 0.2 mm to about 2 mm. 41. The proppant of claim 40, wherein the pellet has an average diameter of about 0.25 mm to about 1.7 mm. 42. The proppant of claim 31, wherein the pellet has an average mesh size of about 6 mesh to about 140 mesh. 43. The proppant of claim 42, wherein the pellet has an average mesh size of about 10 mesh to about 80 mesh. 44. The proppant of claim 43, wherein the pellet has an average mesh size of about 12 mesh to about 80 mesh. 45. The proppant of claim 31 wherein the pellet has a compressive strength of up to about 50,000 psi. 46. The proppant of claim 31 wherein the proppant has a conductivity of at least about 4,000 md-ft at a closing pressure of about 5,000 psi. 47. The proppant of claim 31 wherein the proppant has a permeability of at least about 200 Darcies at a closing pressure of about 5,000 psi. 48. The proppant of claim 31 wherein the proppant has an apparent specific gravity of between about 3.0 and about 3.9. 49. The proppant of claim 48 wherein the proppant has an apparent specific gravity of between about 3.4 and about 3.7. 50. The proppant of claim 31 wherein the proppant has a bulk density of between about 1.9 g/cm3 and about 2.5 g/cm3. 51. The proppant of claim 31 wherein the proppant has a BET specific surface area of between about 0.05 m2/g and about 0.5 m2/g. 52. The proppant of claim 31 wherein the proppant has a Vollstaedt grain crush resistance of greater than or equal to about 30 N. 53. The proppant of claim 52 wherein the proppant has a Vollstaedt grain crush resistance of greater than or equal to about 60 N. 54. The proppant of claim 31 wherein the proppant has a pore volume of less than about 50%, wherein the pore volume is determined by a digital image analysis. 55. The proppant of claim 54 wherein the proppant has a pore volume of less than about 30%. 56. The proppant of claim 55 wherein the proppant has a pore volume of less than about 29%. 57. The proppant of claim 31, wherein the proppant has a substantially smooth surface. 58. The proppant of claim 57, wherein the substantially smooth surface improves fluid conductivity and reduces abrasiveness. 59. A method of making a proppant, comprising: melting at least one metal oxide in an electrical arc furnace; pouring the molten metal oxide to create a pour stream; and separating the pour stream to form at least one electrofused pellet, wherein the proppant has an apparent specific gravity less than about 3.9, and wherein the electrofused pellet has a bulk density of between about 1.7 g/cm3and about 2.7 g/cm3. 60. The method of claim 59, wherein separating the pour stream comprises bessemerizing the pour stream with compressed air to form the at least one electrofused pellet. 61. The method of claim 60, wherein the compressed air has an air pressure of between about 3 bars to about 10 bars. 62. The method of claim 59, wherein separating the pour stream comprises separating the pour stream to form the at least one electrofused pellet using centrifugal forces. 63. The method of claim 59, further comprising melting the at least one metal oxide in the electrical arc furnace under oxidizing conditions. 64. The method of claim 59, further comprising including about 0.1% to about 1% SiO2 by weight in the molten metal oxide mixture. 65. The method of claim 64, wherein the molten metal oxide mixture includes about 0.3% to about 0.6% SiO2 by weight. 66. The method of claim 59, wherein the molten metal oxide mixture is poured at a rate of less than about 100 kilograms per minute to create the pour stream. 67. The method of claim 59, wherein the electric arc furnace has a power of about 1.2 MW. 68. The method of claim 59, wherein the electric arc furnace is operated with a voltage of about 172 volts. 69. The method of claim 59, wherein the electrofused pellet is substantially solid. 70. The method of claim 59, wherein the electrofused pellet has a spherical shape. 71. The method of claim 70, wherein the electrofused pellet has a sphericity of at least 0.8 on the Krumbein scale. 72. The method of claim 71, wherein the electrofused pellet has a sphericity of greater than about 0.9 on the Krumbein scale. 73. The method of claim 72, wherein the electrofused pellet has a sphericity of greater than about 0.95 on the Krumbein scale. 74. The method of claim 59, wherein the at least one metal oxide comprises alumina. 75. The method of claim 74, wherein the at least one metal oxide is contributed by at least one of pure alumina, bauxite, or mullite. 76. The method of claim 59, wherein the at least one metal is contributed by at least about 50% alumina by weight. 77. The method of claim 59, wherein the at least one metal oxide is contributed by at least about 90% bauxite by weight. 78. The method of claim 59, wherein the electrofused pellet has an average diameter of about 0.1 mm to about 3 mm. 79. The method of claim 78, wherein the electrofused pellet has an average diameter of about 0.2 mm to about 2 mm. 80. The method of claim 79, wherein the electrofused pellet has an average diameter of about 0.25 mm to about 1.7 mm. 81. The method of claim 59, wherein the electrofused pellet has an average mesh size of about 6 mesh to about 140 mesh. 82. The method of claim 81, wherein the electrofused pellet has an average mesh size of about 10 mesh to about 80 mesh. 83. The method of claim 82, wherein the electrofused pellet has an average mesh size of about 12 mesh to about 80 mesh. 84. The method of claim 59, wherein the electrofused pellet has a compressive strength of up to about 50,000 psi. 85. The method of claim 59, wherein the proppant has a conductivity of at least about 4,000 md-ft at a closing pressure of about 5,000 psi. 86. The method of claim 59, wherein the proppant has a permeability of at least about 200 Darcies at a closing pressure of about 5,000 psi. 87. The method of claim 59, wherein the electrofused pellet has an apparent specific gravity of between about 3.0 and about 3.9. 88. The method of claim 87, wherein the electrofused pellet has an apparent specific gravity of between about 3.4 and about 3.7. 89. The method of claim 59, wherein the electrofused pellet has a bulk density of between about 1.9 g/cm3 and about 2.5 g/cm3. 90. The method of claim 59, wherein the electrofused pellet has a BET specific surface area of between about 0.05 m2/g and about 0.5 m2/g. 91. The method of claim 59, wherein the electrofused pellet has a Vollstaedt grain crush resistance of greater than or equal to about 30 N. 92. The method of claim 91, wherein the electrofused pellet has a Vollstaedt grain crush resistance of greater than or equal to about 60 N. 93. The method of claim 59, wherein the electrofused pellet has a pore volume of less than about 50%, wherein the pore volume is determined by a digital image analysis. 94. The method of claim 93, wherein the electrofused pellet has a pore volume of less than about 30%. 95. The method of claim 59, wherein the electrofused pellet has a substantially smooth surface. 96. A method of fracturing subterranean formations comprising injecting a fluid containing at least one electrofused pellet wherein the electrofused pellet has an apparent specific gravity less than about 3.9, and wherein the electrofused pellet has a bulk density of between about 1.7 g/cm3 and about 2.7 g/cm3. 97. The method of claim 96, wherein the electrofused pellet is substantially solid. 98. The method of claim 96, wherein the electrofused pellet has a substantially spherical shape. 99. The method of claim 98, wherein the electrofused pellet has a sphericity of at least 0.8 on the Krumbein scale. 100. The method of claim 99, wherein the electrofused pellet has a sphericity of greater than about 0.9 on the Krumbein scale. 101. The method of claim 100, wherein the electrofused pellet has a sphericity of greater than about 0.95 on the Krumbein scale. 102. The method of claim 96, wherein the electrofused pellet comprises a metal oxide. 103. The method of claim 102, wherein the metal oxide comprises alumina. 104. The method of claim 102, wherein the metal oxide is contributed by at least one of pure alumina, bauxite, or zircon mullite. 105. The method of claim 102, wherein the metal oxide is contributed by at least about 50% pure alumina by weight. 106. The method of claim 102, wherein the metal oxide is contributed by at least about 90% bauxite by weight. 107. The method of claim 96, wherein the electrofused pellet has an average diameter of about 0.1 mm to about 3 mm. 108. The method of claim 107, wherein the electrofused pellet has an average diameter of about 0.2 mm to about 2 mm. 109. The method of claim 108, wherein the electrofused pellet has an average diameter of about 0.25 mm to about 1.7 mm. 110. The method of claim 96, wherein the electrofused pellet has an average mesh size of about 6 mesh to about 140 mesh. 111. The method of claim 110, wherein the electrofused pellet has an average mesh size of about 10 mesh to about 80 mesh. 112. The method of claim 111, wherein the electrofused pellet has an average mesh size of about 12 mesh to about 80 mesh. 113. The method of claim 96 wherein the electrofused pellet has a compressive strength of up to about 50,000 psi. 114. The method of claim 96 wherein the electrofused pellet has a conductivity of at least about 4,000 md-ft at a closing pressure of about 5,000 psi. 115. The method of claim 96 wherein the electrofused pellet has a permeability of at least about 200 Darcies at a closing pressure of about 5,000 psi. 116. The method of claim 96 wherein the electrofused pellet has an apparent specific gravity of between about 3.0 and about 3.9. 117. The method of claim 116 wherein the electrofused pellet has an apparent specific gravity of between about 3.4 and about 3.7 g/cm3. 118. The method of claim 96 wherein the electrofused pellet has a bulk density of between about 1.9 g/cm3 and about 2.5 g/cm3. 119. The method of claim 96 wherein the electrofused pellet has a BET specific surface area of between about 0.05 m2/g and about 0.5 m2/g. 120. The method of claim 96 wherein the electrofused pellet has a Vollstaedt grain crush resistance of greater than or equal to about 30 N. 121. The method of claim 120 wherein the electrofused pellet has a vollstaedt grain crush resistance of greater than or equal to about 60 N. 122. The method of claim 96 wherein the electrofused pellet has a pore volume of less than about 50%, wherein the pore volume is determined by digital image analysis. 123. The method of claim 122 wherein the electrofused pellet has a pore volume of less than about 30%. 124. The method of claim 123 wherein the electrofused pellet has a pore volume of less than about 20%. 125. The method of claim 96 wherein the electrofused pellet has a substantially smooth surface.