Electrically-conductive proppant and methods for detecting, locating and characterizing the electrically-conductive proppant

Abstract

Electrically-conductive sintered, substantially round and spherical particles and methods for producing such electrically-conductive sintered, substantially round and spherical particles from an alumina-containing raw material. Methods for using such electrically-conductive sintered, substantially round and spherical particles in hydraulic fracturing operations.

What is claimed is: 
     
         1 . A method of making electrically-conductive proppant particles, comprising:
 contacting a plurality of particles with an alkaline plating solution comprising one or more electrically-conductive metals selected from the group consisting of nickel, copper, and a combination thereof to provide electrically-conductive particles comprising a coating of an alloy comprising nickel and copper formed on the outer surface of each said particle, wherein the coating has a thickness of about 100 nm to about 3,500 nm.   
     
     
         2 . The method of  claim 1 , wherein the particles are selected from the group consisting of ceramic proppant, resin-coated ceramic proppant, sand, and resin-coated sand. 
     
     
         3 . The method of  claim 1 , wherein a pack of the electrically-conductive particles has an electrical conductivity of at least about 5 S/m and a long-term fluid conductivity of at least about 100 mD-ft under a closure pressure of about 7,500 psi. 
     
     
         4 . The method of  claim 1 , further comprising contacting the plurality of particles with an activation solution comprising a palladium salt prior to the contacting of the plurality of particles with the alkaline plating solution, wherein the activation solution has a palladium salt concentration of about 0.1 mg/l to about 30 mg/l. 
     
     
         5 . The method of  claim 4 , wherein the palladium salt comprises palladium chloride or palladium ammonium or a combination thereof. 
     
     
         6 . The method of  claim 1 , wherein the alkaline plating solution is an aqueous solution comprising a salt of nickel and a salt of copper. 
     
     
         7 . The method of  claim 1 , wherein the alkaline plating solution further comprises a phosphorous-containing reducing agent. 
     
     
         8 . A method of making electrically-conductive proppant particles, comprising:
 subjecting a plurality of particles comprising oxidized iron to a reducing environment to provide activated particles comprising reduced iron, wherein each of the activated particles has a specific gravity of less than 4 and a size of about 100 mesh to about 10 mesh; and   contacting the activated particles with one or more alkaline plating solutions comprising copper and nickel to provide electrically-conductive proppant particles comprising a coating of an alloy comprising copper and nickel formed on the outer surface of each said particle, wherein the coating has a thickness of about 100 nm to about 3,500 nm.   
     
     
         9 . The method of  claim 8 , wherein the particles are green pellets. 
     
     
         10 . The method of  claim 8 , wherein a pack of the electrically-conductive proppant particles has an electrical conductivity of at least about 5 S/m and a long-term fluid conductivity of at least about 100 mD-ft under a closure pressure of about 7,500 psi. 
     
     
         11 . The method of  claim 8 , wherein subjecting comprises sintering at a temperature of about 1,000° C. to about 1,600° C. 
     
     
         12 . The method of  claim 11 , wherein the sintering occurs in a reducing environment comprising carbon monoxide or hydrogen. 
     
     
         13 . The method of  claim 8 , wherein the reduced iron comprises elemental iron, iron (II) or a combination thereof. 
     
     
         14 . The method of  claim 8 , wherein the alkaline plating solution is an aqueous solution comprising a salt of nickel and a salt of copper. 
     
     
         15 . A method of making electrically-conductive proppant particles, comprising:
 contacting a plurality of sintered, substantially round and spherical particles with an activation solution comprising a catalytically active material to provide activated particles; and   contacting the activated particles with an aqueous plating solution comprising a salt of nickel and a salt of copper to provide electrically-conductive proppant particles comprising an alloy coating comprising nickel and copper formed on the outer surface of each said particle, wherein the coating has a thickness of about 100 nm to about 3,500 nm.   
     
     
         16 . The method of  claim 15 , wherein the plating solution has a pH from about 2 to about 6.5. 
     
     
         17 . The method of  claim 15 , wherein the catalytically active material comprises a palladium salt, a silver salt, or a combination thereof. 
     
     
         18 . The method of  claim 15 , wherein a pack of the electrically-conductive proppant particles has an electrical conductivity of at least about 5 S/m and a long-term fluid conductivity of at least about 100 mD-ft under a closure pressure of about 7,500 psi. 
     
     
         19 . The method of  claim 15 , wherein the activation solution has a palladium salt concentration of about 0.1 mg/l to about 30 mg/l. 
     
     
         20 . The method of  claim 17 , wherein the palladium salt comprises palladium chloride or palladium ammonium or a combination thereof and the silver salt comprises silver nitrate.