Well treatment

Abstract

A method and system for increasing fracture conductivity. A slurry, of a solid particulate freely dispersed in fluid spaces around macrostructures suspended in a carrier fluid, is injected into a fracture, the solid particulate is aggregated in the fracture to form clusters, and the pressure reduced to prop the fracture open on the clusters and form interconnected, hydraulically conductive channels between the clusters. The system comprises a subterranean formation, a treatment slurry stage disposed in a wellbore penetrating the formation, and a pump system to inject the treatment fluid stage into a fracture.

We claim: 
     
         1 . A method for treating a subterranean formation penetrated by a wellbore, comprising:
 injecting a treatment stage fluid, comprising a slurry of a solid particulate freely dispersed in fluid spaces around macrostructures suspended in a carrier fluid, into a fracture in the formation;   aggregating the solid particulate in the fracture to form clusters at respective interfaces with adjacent macrostructures;   reducing pressure in the fracture to prop the fracture open on the clusters and form interconnected, hydraulically conductive channels between the clusters.   
     
     
         2 . The method of  claim 1 , wherein the solid particulate comprises disaggregated proppant and the treatment fluid stage is a proppant-laden hydraulic fracturing fluid. 
     
     
         3 . The method of  claim 1 , wherein the carrier fluid comprises fiber present in the fluid spaces around the macrostructures to stabilize the treatment stage fluid for the injection into the fracture. 
     
     
         4 . The method of  claim 1 , further comprising viscosifying the carrier fluid for injection into the formation, and breaking the carrier fluid in the fracture to trigger the aggregation of the solid particulate. 
     
     
         5 . The method of  claim 1 , further comprising successively alternating concentration modes of the macrostructures in the treatment stage fluid between a relatively macrostructure-rich mode and a macrostructure-lean mode during the treatment stage fluid injection. 
     
     
         6 . The method of  claim 1 , wherein the macrostructures comprise viscous gel. 
     
     
         7 . The method of  claim 1 , wherein the macrostructures comprise viscous gel comprising crosslinked polymer. 
     
     
         8 . The method of  claim 1 , wherein the macrostructures comprise viscous gel comprising crosslinked polymer selected from polysaccharides, polyacrylates, alginates, polyacrylamides, and combinations thereof. 
     
     
         9 . The method of  claim 1 , wherein the macrostructures comprise viscous gel reinforced with proppant, subproppant, fiber or a combination thereof. 
     
     
         10 . The method of  claim 1 , further comprising degrading the macrostructures after the aggregation of the solid particulate in the fracture. 
     
     
         11 . The method of  claim 1 , further comprising elongating the macrostructures in the fracture. 
     
     
         12 . The method of  claim 1 , wherein the macrostructures comprise a gel relatively more viscous than the carrier fluid, and further comprising elongating the macrostructures in the fracture by restraining flow of the macrostructures in the fracture relative to the carrier fluid, by compression of the macrostructures during fracture closure, or by a combination thereof. 
     
     
         13 . The method of  claim 1 , wherein the macrostructures comprise viscous gel and further comprising compression and elongation of the macrostructures during fracture closure to form gel-filled channels comprising a plurality of the elongated macrostructures in contact with each other. 
     
     
         14 . The method of  claim 1 , wherein the macrostructures in the injection comprise a volume in the treatment fluid from 5 to 30 volume percent [e.g. 15 vol %] and the solid particulate comprises a volume in the treatment fluid from 95 to 70 volume percent [e.g., 85 vol %], based on the total volume of the macrostructures and solid particulate in the treatment fluid. 
     
     
         15 . The method of  claim 1 , wherein the macrostructures have a dimension at least 10 times larger than the solid particulate. 
     
     
         16 . The method of  claim 1 , wherein the macrostructures comprise long fibers having a length of at least about 0.75 cm. 
     
     
         17 . The method of  claim 1 , wherein the macrostructures comprise long fibers having a length of from about 1 cm to about 7.5 cm. 
     
     
         18 . The method of  claim 1 , wherein the injection into the fracture is at a continuous rate of the treatment fluid stage with a continuous concentration of the solid particulate; and further comprising, while maintaining the continuous rate and solid particulate concentration during injection of the treatment fluid stage, successively alternating concentration modes of the macrostructures in the treatment fluid stage between a plurality of relatively macrostructure-rich modes and a plurality of macrostructure-lean modes. 
     
     
         19 . The method of  claim 1 , wherein the injection of the treatment fluid stage forms a homogenous region within the fracture of continuously uniform distribution of the first solid particulate, and wherein the alternation of the concentration modes of the macrostructures forms heterogeneous areas within the fracture comprising macrostructure-rich areas and macrostructure-lean areas. 
     
     
         20 . The method of  claim 1 , further comprising forming bridges with the macrostructures in the fracture to retain the clusters. 
     
     
         21 . The method of  claim 1 , wherein the macrostructures are selected from a fiber, a floc, a flake, a ribbon, a platelet, a rod, or a combination thereof. 
     
     
         22 . The method of  claim 1 , wherein the macrostructures are selected from the group consisting of polylactic acid (PLA), polyglycolic acid (PGA), polyethylene terephthalate (PET), polyester, polyamide, polycaprolactam and polylactone, poly(butylene succinate), polydioxanonepolylactic acid, polyester, polycaprolactam, polyamide, polyglycolic acid, polyterephthalate, or a combination thereof. 
     
     
         23 . The method of  claim 1 , wherein the macrostructures are long fibers selected from the group consisting of glass, ceramics, carbon (including carbon-based compounds), elements in metallic form, metal alloys, wool, basalt, acrylic, polyethylene, polypropylene, novoloid resin, polyphenylene sulfide, polyvinyl chloride, polyvinylidene chloride, polyurethane, polyvinyl alcohol, polybenzimidazole, polyhydroquinone-diimidazopyridine, poly(p-phenylene-2,6-benzobisoxazole), rayon, cotton, or other natural fibers, cellulose, wool, basalt, glass, rubber, acrylic, mica, and combinations thereof. 
     
     
         24 . The method of  claim 1 , wherein the macrostructures comprise sticky fiber. 
     
     
         25 . The method of  claim 1 , wherein the macrostructures are degradable and further comprising degrading the macrostructures after closure of the fracture. 
     
     
         26 . A system, comprising:
 a subterranean formation penetrated by a wellbore;   a treatment slurry stage disposed in the wellbore, the treatment slurry stage comprising a slurry of a solid particulate freely dispersed in fluid spaces around macrostructures suspended in a carrier fluid; and   a pump system to inject the treatment fluid stage from the wellbore to the formation at a pressure above fracturing pressure to inject the treatment fluid stage into a fracture in the formation.   
     
     
         27 . The system of  claim 26 , wherein the solid particulate comprises disaggregated proppant and the treatment fluid stage is a proppant-laden hydraulic fracturing fluid. 
     
     
         28 . The system of  claim 26 , wherein the carrier fluid comprises fiber present in the fluid spaces around the macrostructures to stabilize the treatment stage fluid for the injection into the fracture. 
     
     
         29 . The system of  claim 26 , wherein the treatment slurry stage further comprises a viscosifier in the carrier fluid and a breaker to break the carrier fluid in the fracture to trigger the aggregation of the solid particulate. 
     
     
         30 . The system of  claim 26 , wherein the treatment slurry stage further comprises successively alternating concentration modes of the macrostructures in the treatment slurry stage between a relatively macrostructure-rich mode and a macrostructure-lean mode during the treatment slurry stage injection. 
     
     
         31 . The system of  claim 26 , wherein the macrostructures comprise viscous gel. 
     
     
         32 . The system of  claim 26 , wherein the macrostructures comprise viscous gel comprising crosslinked polymer. 
     
     
         33 . The system of  claim 26 , wherein the macrostructures comprise viscous gel comprising crosslinked polymer selected from polysaccharides, polyacrylates, alginates, polyacrylamides, and combinations thereof. 
     
     
         34 . The system of  claim 26 , wherein the macrostructures comprise viscous gel reinforced with proppant, subproppant, fiber or a combination thereof. 
     
     
         35 . The system of  claim 26 , wherein the macrostructures comprise a gel relatively more viscous than the carrier fluid. 
     
     
         36 . The system of  claim 26 , wherein the macrostructures comprise a volume in the treatment slurry stage from 5 to 30 volume percent [e.g. 15 vol %] and the solid particulate comprises a volume in the treatment slurry stage from 95 to 70 volume percent [e.g., 85 vol %], based on the total volume of the macrostructures and solid particulate in the treatment slurry stage. 
     
     
         37 . The system of  claim 26 , wherein the macrostructures have a dimension at least 10 times larger than the solid particulate. 
     
     
         38 . The system of  claim 26 , wherein the macrostructures comprise long fibers having a length of at least about 0.75 cm. 
     
     
         39 . The system of  claim 26 , wherein the macrostructures comprise long fibers having a length of from about 1 cm to about 7.5 cm.