Sintered spherical pellets

Abstract

Sintered, spherical composite pellets or particles comprising alumina fines, at least one of clay and bauxite and optionally a sintering aid, are described, along with a process for their manufacture. The use of such pellets in hydraulic fracturing of subterranean formations and in grinding is also described.

1 . A gas and oil well proppant comprising a plurality of sintered, spherical pellets, said pellets being prepared from a composition comprising alumina fines and at least one of clay and bauxite.  
   
   
       2 . The proppant of  claim 1  wherein the composition further comprises at least one sintering aid.  
   
   
       3 . The proppant of  claim 2 , wherein the at least one sintering aid is selected from the group consisting of iron oxide, zinc oxide, bentonite clay, feldspar, nepheline syenite, talc, titanium oxide, lithium carbonate, sodium oxide, sodium carbonate, sodium silicates, magnesium oxide, magnesium carbonate, calcium oxide, calcium carbonate, manganese oxide, boric acid, boron carbide, aluminum diboride, boron nitride and boron phosphide.  
   
   
       4 . The proppant of  claim 2 , wherein the composition comprises from about 10 to about 75 percent by weight of alumina fines, from about 20 to about 90 percent by weight of at least one of clay and bauxite, and from about 0.1 to about 15 percent by weight of the at least one sintering aid.  
   
   
       5 . The proppant of  claim 4 , wherein the composition comprises from about 40 to about 75 percent by weight of alumina fines, from about 20 to about 60 percent by weight clay and from about 0.1 to about 15 percent by weight of at least one sintering aid.  
   
   
       6 . The proppant of  claim 5 , wherein the composition comprises kaolin clay.  
   
   
       7 . The proppant of  claim 6 , wherein the composition comprises calcined kaolin clay.  
   
   
       8 . The proppant of  claim 4 , wherein the composition comprises from about 10 to about 75 percent by weight of alumina fines, from about 20 to about 90 percent by weight of bauxite, and from about 0.1 to about 15 percent by weight of the at least one sintering aid.  
   
   
       9 . The proppant of  claim 1 , wherein the composition comprises 58 percent by weight of alumina fines and 42 percent by weight of clay.  
   
   
       10 . The proppant of  claim 2 , wherein the composition comprises 64 percent by weight of alumina fines, 28 percent by weight of clay and 8 percent by weight of the at least one sintering aid.  
   
   
       11 . The proppant of  claim 10 , wherein the at least one sintering aid comprises iron oxide.  
   
   
       12 . The proppant of  claim 2 , wherein the composition comprises 36 percent by weight of alumina fines, 63 percent by weight of bauxite and 1 percent by weight of the at least one sintering aid.  
   
   
       13 . The proppant of  claim 12 , wherein the at least one sintering aid comprises zinc oxide.  
   
   
       14 . The proppant of  claim 1 , wherein the composition comprises 20 percent by weight of alumina fines and 80 percent by weight of bauxite.  
   
   
       15 . The proppant of  claim 1 , wherein the composition comprises kaolin clay.  
   
   
       16 . The proppant of  claim 15 , wherein the composition comprises calcined kaolin clay.  
   
   
       17 . The proppant of  claim 1 , wherein the pellets have an apparent specific gravity of from about 2.70 to about 3.75.  
   
   
       18 . The proppant of  claim 1 , wherein the pellets have a bulk density of from about 1.35 to about 2.15 g/cm 3 .  
   
   
       19 . A method of fracturing a subterranean formation located at a depth of up to about 20,000 feet, comprising: 
 injecting a hydraulic fluid into the formation at a rate and pressure sufficient to open a fracture therein, and    injecting into the fracture a fluid containing sintered, spherical pellets, the pellets being prepared from a composition comprising alumina fines and at least one of clay and bauxite.    
   
   
       20 . The method of  claim 19  wherein the composition further comprises at least one sintering aid.  
   
   
       21 . The method of  claim 20 , wherein the at least one sintering aid is selected from the group consisting of iron oxide, zinc oxide, bentonite clay, feldspar, nepheline syenite, talc, titanium oxide, lithium carbonate, sodium oxide, sodium carbonate, sodium silicates, magnesium oxide, magnesium carbonate, calcium oxide, calcium carbonate, manganese oxide, boric acid, boron carbide, aluminum diboride, boron nitride and boron phosphide  
   
   
       22 . The method of  claim 20 , wherein the composition comprises from about 10 to about 75 percent by weight of alumina fines, from about 20 to about 90 percent by weight of at least one of clay and bauxite, and from about 0.1 to about 15 percent by weight of the at least one sintering aid.  
   
   
       23 . The method of  claim 22 , wherein the composition comprises from about 40 to about 75 percent by weight of alumina fines, from about 20 to about 60 percent by weight clay and from about 0.1 to about 15 percent by weight of at least one sintering aid.  
   
   
       24 . The method of  claim 23 , wherein the composition comprises kaolin clay.  
   
   
       25 . The method of  claim 24 , wherein the composition comprises calcined kaolin clay.  
   
   
       26 . The method of  claim 22 , wherein the composition comprises from about 10 to about 75 percent by weight of alumina fines, from about 20 to about 90 percent by weight of bauxite, and from about 0.1 to about 15 percent by weight of the at least one sintering aid.  
   
   
       27 . The method of  claim 19 , wherein the composition comprises 58 percent by weight of alumina fines and 42 percent by weight of clay.  
   
   
       28 . The method of  claim 20 , wherein the composition comprises 64 percent by weight of alumina fines, 28 percent by weight of clay and 8 percent by weight of the at least one sintering aid.  
   
   
       29 . The method of  claim 28 , wherein the at least one sintering aid comprises iron oxide.  
   
   
       30 . The method of  claim 20 , wherein the composition comprises 36 percent by weight of alumina fines, 63 percent by weight of bauxite and 1 percent by weight of the at least one sintering aid.  
   
   
       31 . The method of  claim 30 , wherein the at least one sintering aid comprises zinc oxide.  
   
   
       32 . The method of  claim 19 , wherein the composition comprises 20 percent by weight of alumina fines and 80 percent by weight of bauxite.  
   
   
       33 . The method of  claim 19 , wherein the composition comprises kaolin clay.  
   
   
       34 . The method of  claim 33 , wherein the composition comprises calcined kaolin clay.  
   
   
       35 . The method of  claim 19 , wherein the pellets have an apparent specific gravity of from about 2.70 to about 3.75.  
   
   
       36 . The method of  claim 19 , wherein the pellets have a bulk density of from about 1.35 to about 2.15 g/cm 3 .