Light Weight Proppant With Improved Strength And Methods Of Making Same

Abstract

Methods are described to make strong, tough, and lightweight whisker-reinforced glass-ceramic composites through a self-toughening structure generated by viscous reaction sintering of a complex mixture of oxides. The invention further relates to strong, tough, and lightweight glass-ceramic composites that can be used as proppants and for other uses.

1 . A method for producing a proppant comprising
 a. forming a green body from a green body material comprising
 i. at least one metal oxide or precursor thereof that is capable of forming whiskers in said proppant and as part of said proppant, 
 ii. at least one amorphous material containing at least one entrapped vaporizable material, 
 iii. preformed whiskers, and 
 iv. at least one whisker promoter, optionally in the absence of fluorine or fluorine compounds; 
   b. reactive sintering said green body under reactive sintering conditions to form a sintered body comprising whiskers and at least one amorphous phase.   
     
     
         2 - 4 . (canceled) 
     
     
         5 . The method of  claim 1 , wherein said at least one metal oxide comprises a first metal oxide and a second metal oxide, wherein said first metal oxide and said second metal oxide are different from each other. 
     
     
         6 . (canceled) 
     
     
         7 . The method of  claim 1 , wherein said amorphous material comprises perlite, stober silica, pumice, andesite, scoria, volcanic glasses, or any combination thereof. 
     
     
         8 . The method of  claim 7 , wherein said vaporizable material comprises water (H 2 O) carbon dioxide (CO 2 ), sulfur dioxide (SO 2 ), hydrogen sulfide (H 2 S), nitrogen, argon, helium, neon, methane, carbon monoxide (CO), hydrogen, oxygen, hydrogen chloride (HCl), hydrogen fluoride (HF), hydrogen bromide (HBr), nitrogen oxide (NOx), sulfur hexafluoride (SF 6 ), carbonyl sulfide (COS), volcanic gases, or any combination thereof. 
     
     
         9 . The method of  claim 1 , wherein said amorphous material has a lower specific gravity than other said green body materials. 
     
     
         10 . (canceled) 
     
     
         11 . The method of  claim 1 , wherein said method further comprises forming said green body around a template so as to encapsulate said template. 
     
     
         12 - 16 . (canceled) 
     
     
         17 . The method of  claim 11 , wherein said reactive sintering at least partially converts said template to a template comprising in-situ whiskers and at least one amorphous phase. 
     
     
         18 - 19 . (canceled) 
     
     
         20 . A proppant comprising a sintered body, wherein said sintered body comprises whiskers and at least one amorphous phase, wherein said whiskers comprise in-situ whiskers. 
     
     
         21 - 25 . (canceled) 
     
     
         26 . The proppant of  claim 20 , wherein said whiskers have a phase connectivity of 3. 
     
     
         27 - 28 . (canceled) 
     
     
         29 . The proppant of  claim 20 , further comprising a template. 
     
     
         30 - 34 . (canceled) 
     
     
         35 . The proppant of  claim 29 , wherein said template comprises whiskers and at least one amorphous phase wherein concentration of whiskers in said template is different from concentration of whiskers in said sintered body that is on said template. 
     
     
         36 - 38 . (canceled) 
     
     
         39 . A method to prop open subterranean formation fractures comprising introducing a proppant formulation comprising the proppant of  claim 20  into a subterranean formation. 
     
     
         40 - 42 . (canceled) 
     
     
         43 . The method of  claim 1 ,
 said green body material comprising
 i. alumina and/or at least one alumina precursor and a siliceous material in a ratio to form whiskers in to a glass-ceramic composite, and 
 ii. at least one amorphous material containing at least one entrapped vaporizable material, and 
 iii. whiskers, and 
 iv. at least one whisker promoter in the absence of fluorine or fluorine compounds; 
   sintering said green body under sintering conditions to form in situ said glass-ceramic composite comprising at least one mullite whisker phase and at least one amorphous phase.   
     
     
         44 - 45 . (canceled) 
     
     
         46 . The method of  claim 43 , wherein said alumina or alumina precursor has a particle size distribution, d as , from about 0.5 to about 15, wherein, d as ={(d a90 −d a10 )/d a50 } wherein d a10  is a particle size wherein 10% of the particles have a smaller particle size, d 50  is a median particle size wherein 50% of the particles have a smaller particle size, and d a90  is a particle size wherein 90% of the particle volume has a smaller particle size. 
     
     
         47 . (canceled) 
     
     
         48 . The method of  claim 43 , wherein the median particle size, d a50 , of said alumina or alumina precursor is from about 0.01 μm to about 100 μm, wherein d 50  is a median particle size where 50% of the particles of the distribution have a smaller particle size. 
     
     
         49 - 51 . (canceled) 
     
     
         52 . The method of  claim 43 , wherein said siliceous material has a particle size distribution, d ss , from about 0.5 to about 15, wherein, d ss ={(d s90 −d s10 )/d s50 } wherein d s10  is a particle size wherein 10% of the particles have a smaller particle size, d s50  is a median particle size wherein 50% of the particles have a smaller particle size, and d s90  is a particle size wherein 90% of the particle volume has a smaller particle size. 
     
     
         53 . (canceled) 
     
     
         54 . The method of  claim 43 , wherein the median particle size, d s50 , of said siliceous material is from about 0.01 μm to about 100 wherein d s50  is a median particle size where 50% of the particles of the distribution have a smaller particle size. 
     
     
         55 - 58 . (canceled) 
     
     
         59 . The method of  claim 43 , wherein the median particle size, d a50 , of said amorphous material containing at least one entrapped vaporizable material is from about 0.01 μm to about 100 μm, wherein d a50  is a median particle size where 50% of the particles of the distribution have a smaller particle size. 
     
     
         60 . (canceled) 
     
     
         61 . The method of  claim 43 , wherein said ratio to form whiskers in said glass-ceramic composite is from about 20% SiO 2  material/80% Al 2 O 3  or alumina precursor by weight to about 60% siliceous material/40% alumina or alumina precursor by weight. 
     
     
         62 - 66 . (canceled) 
     
     
         67 . The method of  claim 43 , wherein said sintering is performed in the presence of a gas. 
     
     
         68 . The method of  claim 67 , wherein said gas comprises from about 100 ppm to about 100% by weight oxygen. 
     
     
         69 - 87 . (canceled) 
     
     
         88 . The method of  claim 43 , wherein said green body material further comprises at least one fluxing agent. 
     
     
         89 . The method of  claim 88 , wherein said fluxing agent comprises nepheline syenite, feldspar, synthetic clay, natural clay or any combination thereof. 
     
     
         90 - 92 . (canceled) 
     
     
         93 . The method of  claim 43 , wherein the phases of said glass-ceramic composite comprises 3-3 connectivity for the mullite whisker phase and the amorphous phase. 
     
     
         94 . The method of  claim 43 , wherein the phases of said glass-ceramic composite comprises 3-3-0 connectivity for the mullite whisker phase, the amorphous phase and the unreacted alumina or alumna precursor. 
     
     
         95 . The method of  claim 43 , wherein the phases of said glass-ceramic composite comprises 3-3-0 connectivity for the mullite whisker phase, the amorphous phase and the unreacted siliceous material. 
     
     
         96 . The method of  claim 43 , wherein the phases of said glass-ceramic composite comprises 3-3-0 connectivity for the mullite whisker phase, the amorphous phase and the amorphous material containing at least one entrapped vaporizable material. 
     
     
         97 - 106 . (canceled) 
     
     
         107 . A glass-ceramic composite material comprising a sintered body having at least one whisker phase and an amorphous phase and optionally, at least one crystalline particulate phase. 
     
     
         108 . The glass-ceramic composite material of  claim 107 , wherein said whisker phase is a mullite whisker phase. 
     
     
         109 . The glass-ceramic composite material of  claim 107 , wherein said amorphous phase is a ceramics comprising alumina, silica and any combination thereof. 
     
     
         110 . The glass-ceramic composite material of  claim 107 , wherein said amorphous phase further comprises unreacted particles of alumina, alumina precursor, siliceous material, amorphous material containing at least one entrapped vaporizable material or any combination thereof. 
     
     
         111 . The glass-ceramic composite material of  claim 107 , further comprising a template. 
     
     
         112 - 116 . (canceled) 
     
     
         117 . The glass-ceramic composite material of  claim 107 , wherein the phases of said glass-ceramic composite comprises 3-3-0 connectivity for the whisker phase, the amorphous phase and the unreacted alumina or alumna precursor. 
     
     
         118 . The glass-ceramic composite material of  claim 107 , wherein the phases of said glass-ceramic composite comprises 3-3-0 connectivity among the whisker phase, the amorphous phase and the unreacted alumina or alumna precursor. 
     
     
         119 . The glass-ceramic composite material of  claim 107 , wherein the phases of said glass-ceramic composite comprises 3-3-0 connectivity among the whisker phase, the amorphous phase and the amorphous material containing at least one entrapped vaporizable material. 
     
     
         120 . The glass-ceramic composite material of  claim 107 , wherein the phases of said glass-ceramic composite comprises 3-3-0-0-0 connectivity for the whisker phase, the amorphous phase, the unreacted alumina material, the unreacted siliceous material, and the amorphous material containing at least one entrapped vaporizable material. 
     
     
         121 - 126 . (canceled) 
     
     
         127 . A method for producing a proppant comprising
 a. forming a green body from a green body material comprising
 i. at least one metal oxide or precursor thereof that is capable of forming whiskers in said proppant and as part of said proppant, and 
 ii. at least one amorphous material containing at least one entrapped vaporizable material, and 
 iii. optionally preformed whiskers, and 
 iv. at least one whisker promoter, optionally in the absence of fluorine or fluorine compounds; and 
 v. at least one carbide or metal carbide, 
   b. reactive sintering said green body under reactive sintering conditions to form a sintered body comprising in-situ whiskers and at least one amorphous phase.   
     
     
         128 . (canceled) 
     
     
         129 . The proppant of  claim 20 , wherein said sintered body comprises whiskers, at least one glassy phase, and at least one amorphous phase. 
     
     
         130 . The proppant of  claim 129 , wherein said sintered body further comprises at least one carbide or metal carbide. 
     
     
         131 - 138 . (canceled) 
     
     
         139 . The proppant of  claim 20 , comprising a sintered sphere having a Krumbein sphericity of at least about 0.5 and a roundness of at least about 0.4, and wherein said sphere comprises a) a plurality of ceramic whiskers or oxides thereof and b) a glassy phase and c) optionally at least one non-whisker crystalline phase and d) optionally a plurality of microspheres, wherein said sintered sphere has a diameter of from about 90 microns to 2,500 microns, and said sintered sphere has a specific gravity of from 0.8 g/cc to about 3.8 g/cc, and said proppant has a crush strength of from about 1,000 psi or greater, and wherein said proppant includes one or more of the following characteristics:
 1) said glassy phase is present in an amount of at least 10% by weight, based on the weight of the proppant;   2) said ceramic whiskers have an average length of less than 3.2 microns;   3) said ceramic whisker have an an average width of less than 0.35 micron;   4) said ceramic whiskers have a whisker length distribution, d as , of about 8 or less, wherein, d as ={(d a90 −d a10 )/d a50 } wherein d a10  is a whisker length wherein 10% of the whiskers have a smaller length, d a50  is a median whisker length wherein 50% of the whiskers have a smaller whisker length, and d a90  is a whisker length wherein 90% of the whiskers have a smaller whisker length;   5) said proppant having a specific gravity of from 1.6 to 1.8 with a crush strength of at least 2000 psi;   6) said proppant having a specific gravity of from 1.8 to 2 with a crush strength of at least 3000 psi;   7) said proppant having a specific gravity of from 2 to 2.1 with a crush strength of at least 5,000 psi;   8) said proppant having a specific gravity of from 2.25 to 2.35 with a crush strength of at least 8,000 psi;   9) said proppant having a specific gravity of from 2.5 to 3.2 with a crush strength of at least 12,000 psi;   10) said proppant having a specific gravity of from 2.5 to 3.2 with a crush strength of at least 18,000 psi;   11) said proppant having a combined clay amount and cristobalite amount of less than 20% by weight of proppant;   12) said proppant having an free alpha-alumina content of at least 5% by weight of said proppant;   13) said proppant having an HF etching weight loss of less than 35% by weight of said proppant;   14) said proppant having said microspheres present as hollow glass microspheres having a particle size distribution, d as , of from about 0.5 to about 2.7, wherein, d as ={(d a90 −d a10 )/d a50 } wherein d a10  is a particle size wherein 10% of the particles have a smaller particle size, d a50  is a median particle size wherein 50% of the particles have a smaller particle size, and d a90  is a particle size wherein 90% of the particle volume has a smaller particle size;   15) said proppant having microspheres present wherein said microspheres are uniformly present in said proppant or in a layered region of said proppant;   16) said ceramic whiskers are present in an amount of from 5% to 60% by weight of said proppant.   17) said proppant has a combined clay amount and cristobalite amount of less than 20% by weight of proppant and said mullite whiskers are present in an amount of 60% or more by weight of said proppant;   18) said proppant has a high whisker distribution density based on individual whiskers present in the proppant (# of whiskers per mg of proppant);   19) said proppant has a unimodal whisker distribution;   20) said proppant has at least two layers that form a laminate structure;   21) said proppant has at least a first layer and a second layer that form a laminate structure wherein the average length of said whiskers in said first layer compared to said second layer is different;   22) said proppant has at least a first layer and a second layer that form a laminate structure wherein the average width of said whiskers in said first layer compared to said second layer is different;   23) said whiskers in said proppant are less euhedral and more anhedral;   24) said proppant has at least one radial region of first whiskers and at least one region of second whiskers, wherein the average whisker length is different by at least 10%;   25) said proppant has at least one radial region of first whiskers and at least one region of second whiskers, wherein the average whisker width is different by at least 10%;   26) said proppant has a major phase of whiskers of less than one micron and a secondary minor phase of whiskers of one micron or higher; and/or   27) said ceramic whiskers have a whisker length distribution having d a90 , which is a whisker length wherein 90% of the whiskers have a smaller whisker length, of less than 12 microns.   
     
     
         140 - 146 . (canceled)