Method of manufacturing and using rod-shaped proppants and anti-flowback additives
A sintered rod-shaped proppant and anti-flowback agent possesses high strength and high conductivity. The sintered rods comprise between about 0.2% by weight and about 4% by weight aluminum titanate. In some embodiments, the sintered rods are made by mixing bauxitic and non-bauxitic sources of alumina that may also contain several so-called impurities (such as TiO 2 ), extruding the mixture, and sintering it. The starting material may optionally be milled to achieve better compacity and crush resistance in the final sintered rod. A fracturing fluid may comprise the sintered rods alone or in combination with a proppant, preferably a proppant of a different shape.
1. A method for making a proppant or antiflowback additive, the method comprising:
mixing a ceramic precursor and at least one binding agent to form an extrudable mixture;
extruding the extrudable mixture to form a plurality of extruded rods;
reducing the length of the extruded rods by at least partially drying the rods in a manner that results in breakage of the extruded rods to form dried extruded rods of reduced length; and
sintering the dried extruded rods of reduced length to obtain the proppant or antiflowback additive.
2. The method of claim 1 , wherein the length of the extruded rods is not reduced by cutting.
3. The method of claim 1 , further comprising fractionating the proppant or antiflowback additive to obtain a subset of rods having a desired range of lengths.
4. The method of claim 3 , wherein the fractionating comprises sieving.
5. The method of claim 1 , wherein the proppant or antiflowback additive has an average length to width ratio ranging from about 1.5:1 to about 7:1.
6. The method of claim 1 , wherein the proppant or antiflowback additive has a packed void volume of greater than 40%.
7. The method of claim 1 , wherein the proppant or antiflowback additive has a specific gravity ranging from 3.0 to 3.98 and a conductivity of greater than 3,000 mD-ft at 10,000 psi as measured under API Recommended Practice 61.
8. The method of claim 1 , wherein said at least one binding agent is selected from the group consisting of methyl cellulose, polyvinyl butyrals, emulsified acrylates, polyvinyl alcohols, polyvinyl pyrrolidones, polyacrylics, starch, silicon binders, polyacrylates, silicates, polyethylene imine, lignosulfonates, and alginates.
9. The method of claim 1 , further comprising adding at least one solvent during the mixing.
10. The method of claim 9 , wherein the at least one solvent is selected from water, alcohols, ketones, aromatic compounds, and hydrocarbons.
11. The method of claim 1 , wherein the ceramic precursor comprises at least 80% alumina and 0.15% to 3.5% TiO 2 .
12. The method of claim 1 , wherein the proppant or antiflowback additive comprises between about 0.2% by weight and about 4% by weight aluminum titanate.
13. The method of claim 1 , wherein from about 7% by weight and about 13% by weight of the proppant or antiflowback additive is crushed at 15,000 psi.
14. The method of claim 1 , wherein from about 9% by weight to about 19% by weight of the proppant or antiflowback additive is crushed at 15,000 psi.
15. The method of claim 1 , wherein the extruded rods are sintered at a temperature ranging from about 1,300° C. to about 1,700° C.
16. The method of claim 1 , wherein the extruded rods have an average length ranging from about 1 mm to about 5 mm.
17. The method of claim 1 , wherein the extruded rods have an average length ranging from about 2 mm to about 4 mm.
18. The method of claim 1 , further comprising coating the sintered rods with a coating agent selected from natural rubber, butyl rubber, polyurethane rubber, starches, petroleum pitch, tar, asphalt, organic semisolid silicon polymers such as dimethyl and methylphenyl silicones, polyhydrocarbons such as polyethylene, polyproplylene, polyisobutylene, cellulose and nitrocellulose lacquers, vinyl resins such as polyvinylacetate, phenolformaldehyde resins, urea formaldehyde resins, acrylic ester resins such as polymerized esters resins of methyl, ethyl and butyl esters of acrylic and alpha-methylacrylic acids, epoxy resins, melamine resins, drying oils, and mineral and petroleum waxes.
19. The method of claim 1 , further comprising cutting or mechanically breaking the extruded rods to achieve a narrower length distribution.