System and method for complex fracture generation

Abstract

A system includes a first fluid comprising a viscosified fluid composed to generate an initial fracture geometry, a first spacer fluid, a second fluid being a high solids content fluid (HSCF) having a fine particle formulation, a third fluid being an HSCF having a coarse particle formulation, a second spacer fluid, a conventional proppant slurry fluid, and a flush fluid. The system includes a positive displacement pump fluidly coupled to a wellbore, the wellbore intersecting a formation of interest, and a controller that executes functions to perform complex fracture generation in the formation of interest. The controller provides pump commands to deliver a number of stage groupings to the formation of interest, each stage grouping including the first fluid, the first spacer fluid, the second fluid, the third fluid, and the second spacer fluid.

We claim: 
     
         1 . A method, comprising:
 treating a formation with, in order, a first fluid comprising a viscosified fluid, a second fluid comprising a high solids content fluid (HSCF) comprising a fine particle formulation, a third fluid comprising an HSCF comprising a coarse particle formulation, and a conventional proppant slurry fluid; and   wherein each HSCF fluid comprises a fluid having a plurality of particle size modalities, and a packed volume fraction (PVF) of greater than 0.65.   
     
     
         2 . The method of  claim 1 , further comprising repeating the treating the formation with the first fluid, second fluid, and third fluids before the treating the formation with the conventional proppant slurry fluid. 
     
     
         3 . The method of  claim 2 , further comprising repeating the treating the formation with the first fluid, second fluid, and third fluids a third time before the treating the formation with the conventional proppant slurry fluid. 
     
     
         4 . The method of  claim 1 , further comprising providing the second fluid in a volume ratio to the first fluid of second fluid:first fluid of between 1 and 5 inclusive. 
     
     
         5 . The method of  claim 4 , further comprising providing the third fluid in a volume ratio to the second fluid of third fluid:second fluid of between 1 and ⅓ rd  inclusive. 
     
     
         6 . The method of  claim 1 , further comprising treating the formation with a spacer fluid after the first fluid and before the second fluid. 
     
     
         7 . The method of  claim 1 , further comprising treating the formation with a spacer fluid after the third fluid and before the conventional proppant slurry fluid. 
     
     
         8 . A method, comprising:
 treating a formation with a plurality of stage groupings, each stage grouping comprising, in order:
 a first fluid comprising a viscosified fluid structured to generate an initial fracture geometry; 
 a first spacer fluid structured to maintain separation between the first fluid and a second fluid; 
 a second fluid comprising a high solids content fluid (HSCF) comprising a fine particle formulation; 
 a third fluid comprising an HSCF comprising a coarse particle formulation; and 
 a second spacer fluid structured to maintain separation between the third fluid and the first fluid for a subsequent stage grouping and a conventional proppant slurry fluid; and 
   wherein a last stage grouping further comprises the conventional proppant slurry fluid after the second spacer fluid, and a flush after the conventional proppant slurry fluid.   
     
     
         9 . The method of  claim 8 , wherein the conventional proppant slurry fluid comprises a proppant concentration of at least 6 pounds proppant added (PPA). 
     
     
         10 . The method of  claim 8 , wherein the coarse particle formulation comprises a largest particle size modality having an average size between 150 microns and 1,500 microns. 
     
     
         11 . The method of  claim 10 , wherein the fine particle formulation comprises a largest particle size modality having an average size ratio value to the largest particle size modality of the coarse particle formulation, the average size ratio value comprising between 1:3 and 1:100 for fine:coarse. 
     
     
         12 . The method of  claim 8 , wherein the coarse particle formulation and the fine particle formulation each comprise a packed volume fraction (PVF) exceeding a value selected from the values consisting of: 0.65, 0.75, 0.80, 0.85, 0.90, 0.93, and 0.96. 
     
     
         13 . The method of  claim 8 , further comprising generating a net pressure exceeding a maximum horizontal stress in the formation during the treating. 
     
     
         14 . The method of  claim 8 , wherein the coarse particle formulation comprises a plurality of particle size modalities, the method further comprising degrading at least one of the particle size modalities after the treating. 
     
     
         15 . A system, comprising:
 a first fluid comprising a viscosified fluid structured to generate an initial fracture geometry;   a first spacer fluid structured to maintain separation between the first fluid and a second fluid;   a second fluid comprising a high solids content fluid (HSCF) comprising a fine particle formulation;   a third fluid comprising an HSCF comprising a coarse particle formulation;   a second spacer fluid structured to maintain separation between the third fluid and one of the first fluid and a conventional proppant slurry fluid;   a flush fluid; and   a positive displacement pump fluidly coupled to a wellbore, the wellbore intersecting a formation of interest;   a controller structured to provide pumping commands to deliver a plurality of stage groupings to the formation of interest, each stage grouping comprising, in order, the first fluid, the first spacer fluid, the second fluid, the third fluid, and the second spacer fluid; and   wherein the pump is responsive to the pumping commands.   
     
     
         16 . The system of  claim 15 , wherein the controller is further structured to provide the pumping commands such that a last one of the stage groupings comprises a conventional proppant slurry fluid after the second spacer fluid, and a flush after the conventional proppant slurry fluid. 
     
     
         17 . The system of  claim 15 , wherein each HSCF fluid comprises a fluid having a plurality of particle size modalities, and a packed volume fraction (PVF) of greater than 0.65. 
     
     
         18 . The system of  claim 17 , wherein the coarse particle formulation and the fine particle formulation each comprise a PVF exceeding a value selected from the values consisting of: 0.75, 0.80, 0.85, 0.90, 0.93, and 0.96. 
     
     
         19 . The system of  claim 17 , wherein the fine particle formulation comprises a largest particle size modality having an average size between 0.5 microns and 100 microns. 
     
     
         20 . The method of  claim 17 , wherein the coarse particle formulation comprises a largest particle size modality having an average size between 150 microns and 1,500 microns. 
     
     
         21 . The system of  claim 15 , wherein the controller is further structured to provide the pump commands such that the second fluid is pumped in a volume ratio to the first fluid of second fluid:first fluid between 1 and 5 inclusive. 
     
     
         22 . The system of  claim 21 , wherein the controller is further structured to provide the pump commands such that the third fluid is pumped in a volume ratio to the second fluid of third fluid:second fluid between 1 and ⅓ rd  inclusive. 
     
     
         23 . The system of  claim 15 , wherein each of the second fluid and the third fluid have a liquid phase weight fraction of the fluid between 5% and 20% of a total fluid weight, inclusive. 
     
     
         24 . A method, comprising:
 treating a formation with a plurality of stage groupings, each stage grouping comprising, in order:
 a first fluid comprising a viscosified fluid structured to generate an initial fracture geometry; 
 a second fluid comprising a high solids content fluid (HSCF) comprising a fine particle formulation; 
 a third fluid comprising an HSCF comprising a coarse particle formulation; and 
   wherein a last stage grouping further comprises a conventional proppant slurry.   
     
     
         25 . A system, comprising:
 a first fluid comprising a viscosified fluid structured to generate an initial fracture geometry;   a second fluid comprising a high solids content fluid (HSCF) comprising a fine particle formulation;   a third fluid comprising an HSCF comprising a coarse particle formulation;   a second spacer fluid structured to maintain separation between the third fluid and one of the first fluid and a conventional proppant slurry fluid;   a flush fluid; and   a positive displacement pump fluidly coupled to a wellbore, the wellbore intersecting a formation of interest;   a controller structured to provide pumping commands to deliver a plurality of stage groupings to the formation of interest, each stage grouping comprising, in order, the first fluid, the second fluid, the third fluid; and   wherein the pump is responsive to the pumping commands.