Patent NZ-736480-A (NZ)
Title: Use of superabsorbent polymers for pressure control and diversion applications
Inventor: BRANNON HAROLD DEAN
IPC: E21B43/267
Filed: 2016-03-30
Abstract: There is a continuing need for an improved method of diverting fluids during hydraulic fracturing operations. Disclosed herein is a method of hydraulically fracturing a subterranean formation penetrated by a wellbore, the method comprising: providing a diverting fluid comprising a carrier fluid, a first superabsorbent polymer and a second superabsorbent polymer, the second superabsorbent polymer having a shape, or a composition, or a combination thereof different from that of the first superabsorbent polymer; injecting the diverting fluid into the subterranean formation; and injecting a fracturing fluid into the formation after injecting the diverting fluid, wherein the flow of the fracturing fluid is impeded by the first and second superabsorbent polymers, the diverting fluid comprises about 1 to about 200 pounds (about 0.45kg to about 90.72kg) of the combined first and second superabsorbent polymers per one thousand gallons (3785L) of the diversion fluid, the weight ratio of the first superabsorbent polymer relative to the second superabsorbent polymer is about 1:10 to about 10:1, and one or more of the following conditions apply: (i) the first superabsorbent polymer is an uncoated superabsorbent polymer, and the second superabsorbent polymer is a coated superabsorbent polymer, or (ii) the first superabsorbent polymer comprises an interpenetrated network, and the second superabsorbent polymer is free of an interpenetrated network. Also disclosed herein is a method of hydraulically fracturing a subterranean formation penetrated by a wellbore, the method comprising: providing a diverting fluid comprising a carrier fluid, a first superabsorbent polymer and a second superabsorbent polymer, the second superabsorbent polymer having a shape, or a composition, or a combination thereof different from that of the first superabsorbent polymer; injecting the diverting fluid in the subterranean formation; and injecting a fracturing fluid into the formation after injecting the diverting fluid, wherein the flow of the fracturing fluid is impeded by the first and second superabsorbent polymers the diverting fluid comprises about 1 to about 200 pounds of the combined first and second superabsorbent polymers per one thousand gallons of the diversion fluid, the weight ratio of the first superabsorbent polymer relative to the second superabsorbent polymer is about 1:10 to about 10:1; wherein the first superabsorbent polymer is a particulate material and the second superabsorbent polymer is a fiber; and at least one of the first superabsorbent polymer and the second superabsorbent polymer comprise a copolymer of acrylic acid and sodium acrylate with crosslinks derived from polyethylene glycol diacrylate. Further disclosed herein is a method of hydraulically fracturing a subterranean formation penetrated by a wellbore, the method characterized by: providing a diverting fluid comprising a carrier fluid, a superabsorbent polymer, and a viscosity modifying agent effective to increase the viscosity of the diverting fluid at a shear rate of 100s-1; injecting the diverting fluid into the subterranean formation; injecting a fracturing fluid into the formation after injecting the diverting fluid, wherein the superabsorbent polymer comprises a polyacrylamide having crosslinks derived from polyethylene glycol diacrylate, a polyacrylic acid homopolymer or copolymer having crosslinks of a vinyl ester oligomer, a copolymer of acrylic acid and sodium arylate with crosslinks derived from polyethylene glycol diacrylate, or a combination comprising at least one of the foregoing, and the flow of the fracturing fluid is impeded by the superabsorbent polymer. Diverting fluids used in the methods disclosed herein can reduce or eliminate fluid leak off and/or have improved diversion efficiencies, such as at low shear conditions.