Spherical pellets containing common clay particulate material useful as a proppant in hydraulic fracturing of oil and gas wells

Abstract

Ceramic propping agents include a plastic clay, aluminosilicate network modifier, strength enhancing agent, and binder. Usable strength enhancing agents can include nepheline materials having 0.1 to 5 percent iron oxide by weight. A resin coating can be used to encapsulate particles of the ceramic propping agent. The propping agent can be produced by grinding the components to the same approximate particle size, nucleating the particles by adding water, growing the resulting spherical pellets by adding additional particles that adhere to the surface of the spherical pellets, and vitrifying the pellets to form the propping agent.

What is claimed is: 
     
         1 . A method for producing a ceramic propping agent, the method comprising:
 grinding a mineral particulate, an aluminosilicate network modifier, a strength enhancer, and a binder to form particles having a same approximate particle size;   mixing said particles of mineral particulate, aluminosilicate network modifier, strength enhancer, and binder;   nucleating said particles by adding water thereto to form spherical pellets;   growing said spherical pellets by adding additional particles comprising said mineral particulate, said aluminosilicate network modifier, said strength enhancer, and said binder, wherein said additional particles adhere to a surface of said spherical pellets;   drying said spherical pellets; and   vitrifying said spherical pellets to form the ceramic propping agent.   
     
     
         2 . The method of  claim 1 , wherein mixing said particles comprises mixing at a high speed using a mixer. 
     
     
         3 . The method of  claim 2 , wherein using said mixer comprises processing said mineral particulate, said aluminosilicate network modifier, said strength enhancers, and said binder into spheroids having a high Krumbein roundness. 
     
     
         4 . The method of  claim 1 , wherein nucleating said particles comprises adding said water proximate to an impeller of a mix pelletizer to be dispersed into droplets, thereby aiding in formation of the spherical pellets. 
     
     
         5 . The method of  claim 1 , further comprising polishing the surface of said spherical pellets, smoothing the surface of said spherical pellets, or combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein vitrifying said spherical pellets comprises feeding said spherical pellets into a kiln. 
     
     
         7 . The method of  claim 1 , further comprising screening said ceramic propping agent to obtain a desired particulate ceramic size fraction. 
     
     
         8 . The method of  claim 1 , wherein drying said spherical pellets comprises applying a temperature ranging from 120 degrees Centigrade to 180 degrees Centigrade thereto. 
     
     
         9 . A ceramic propping agent comprising:
 a plastic clay;   an aluminosilicate network modifier;   a strength enhancing agent comprising nepheline materials, wherein the nepheline materials comprise from 0.1 percent to 5 percent iron oxide by weight; and   a binder.   
     
     
         10 . The ceramic propping agent of  claim 9 , wherein said plastic clay comprises from 38% to 90% of the ceramic propping agent by weight. 
     
     
         11 . The ceramic propping agent of  claim 10 , wherein said aluminosilicate network modifier comprises from 30% to 70% of the ceramic propping agent by weight, wherein said strength enhancing and flux agent comprises from 0.25% to 20% of the ceramic propping agent by weight, and wherein said binder comprises 10% or less of the ceramic propping agent by weight. 
     
     
         12 . The ceramic propping agent of  claim 9 , wherein said plastic clay comprises a plurality of layers having a thickness of five feet or less. 
     
     
         13 . The ceramic propping agent of  claim 9 , wherein said plastic clay comprises from 7% to 25% alumina by weight, from 60% to 90% silica by weight, and 45% or less quartz by weight. 
     
     
         14 . The ceramic propping agent of  claim 9 , wherein said aluminosilicate network modifier is selected from the group consisting of: kaolin, metakaolin, bauxite, bauxitic clays, aluminum oxide, metal oxides, and combinations thereof. 
     
     
         15 . The ceramic propping agent of  claim 9 , wherein said binder is selected from the group consisting of: cornstarch, polyvinyl alcohol, cellulose gum, bentonite, sodium silicate, vegetable starches, sodium lignosulphonate, and combinations thereof. 
     
     
         16 . The ceramic propping agent of  claim 9 , further comprising a resin coating adapted to encapsulate particles of the ceramic propping agent. 
     
     
         17 . A ceramic propping agent comprising:
 a plastic clay;   an aluminosilicate network modifier;   a strength enhancing agent;   a binder; and   a resin coating adapted to encapsulate particles of the ceramic propping agent.   
     
     
         18 . The ceramic propping agent of  claim 17 , wherein the strength enhancing agent comprises nepheline materials, and wherein the nepheline materials comprise from 0.1 percent to 5 percent iron oxide by weight. 
     
     
         19 . The ceramic propping agent of  claim 17 , wherein said plastic clay comprises from 38% to 90% of the ceramic propping agent by weight. 
     
     
         20 . The ceramic propping agent of  claim 17 , wherein said plastic clay comprises from 7% to 25% alumina by weight, from 60% to 90% silica by weight, and 45% or less quartz by weight.