Method for providing multiple fractures in a formation

Abstract

The invention includes providing a propped hydraulic fractures in a subterranean formation including the steps of: injecting a fracturing fluid into the subterranean formation at a pressure sufficient to initiate and propagate at least one hydraulic fracture wherein the fracturing fluid comprises a proppant; when the at least one hydraulic fracture has reached a target size, adding to the fracturing fluid a predetermined amount of a diverter material wherein the diverter material comprises material having a specified size distribution, and comprising a material that degrades at conditions of the subterranean formation, the diverter material effective to essentially block flow of fracturing fluid into the at least one fracture; and continuing to inject fracturing fluid at a pressure effective to initiate at least one additional fracture within the subterranean formation.

We claim: 
     
         1 . A method to provide propped hydraulic fractures in a subterranean formation comprising:
 injecting a fracturing fluid into the subterranean formation at a pressure sufficient to initiate and propagate at least one hydraulic fracture wherein the fracturing fluid comprises a proppant;   adding to the fracturing fluid, when the at least one hydraulic fracture has reached a target size, a predetermined amount of a diverter material wherein the diverter material comprises between 10 to 30 weight percent of particles having a size larger than 2000 microns, between 1 and 15% by weight of particles between 1000 and 2000 microns, 10 to 40 percent by weight particles having a diameter in the range of 500 to 1000 microns, 40 to 70 percent by weight particles smaller than 500 microns, and comprising a material that degrades at conditions of the subterranean formation, the diverter material effective to essentially block flow of fracturing fluid into the at least one fracture; and   continuing to inject fracturing fluid at a pressure effective to initiate at least one additional fracture within the subterranean formation.   
     
     
         2 . The method of  claim 1  further comprising the step of providing a wellbore withink the subterranean formation and providing a casing within the wellbore 
     
     
         3 . The method of  claim 2  further comprising perforating the casing within the subterranean formation wherein the diverter material is sized to bridge the perforations 
     
     
         4 . The method of  claim 3  wherein the diverter material is sized to bridge the perforations. 
     
     
         5 . The method of  claim 1  wherein the time when the fracture has reached the target size is determined by the volume of fracturing fluid injected. 
     
     
         6 . The method of  claim 1  wherein the time when the fracture has reached the target size is determined by the rate at which fracture fluid can be injected into the formation at a pressure that is less than the fracture initiation pressure. 
     
     
         7 . The method of  claim 1  wherein the time when the fracture has reached the target size is determined by microseismic data. 
     
     
         8 . The method of  claim 1  wherein the material that degrades at conditions of the subterranean formation comprises polylactate, 
     
     
         9 . The method of  claim 1  wherein the material that degrades at conditions of the subterranean formation comprises polyglycolate. 
     
     
         10 . The method of  claim 1  wherein the material that degrades at conditions of the subterranean formation comprises oil soluble resins. 
     
     
         11 . The method of  claim 1  wherein the material that degrades at ambient conditions of the subterranean formation degrades within a time period in the range of six hours to ninety days. 
     
     
         12 . The method of  claim 1  wherein the steps are repeated a plurality of times. 
     
     
         13 . The method of  claim 1  further comprising the step of producing hydrocarbons from the subterranean formation through the fractures. 
     
     
         14 . The method of  claim 1  wherein the wellbore is essentially horizontal for at least a portion of the wellbore within the subterranean formation. 
     
     
         15 . The method of  claim 1  wherein the wellbore is slanted from horizontal for at least a portion of the wellbore within the subterranean formation. 
     
     
         16 . The method of  claim 1  wherein the wellbore is essentially vertical for at least a portion of the wellbore within the subterranean formation. 
     
     
         17 . The method of  claim 1  wherein the concentration of diverter in the fracturing fluid is between 25 and 200 grams per liter. 
     
     
         18 . A method to provide propped hydraulic fractures in a subterranean formation comprising:
 injecting a fracturing fluid into the subterranean formation at a pressure sufficient to initiate and propagate at least one hydraulic fracture wherein the fracturing fluid comprises a proppant;   when the at least one hydraulic fracture has reached a target size, adding to the fracturing fluid a predetermined amount of a diverter material wherein the diverter material comprises between 10 to 30 weight percent of particles having a size larger than 2000 microns, between 1 and 15% by weight of particles between 1000 and 2000 microns, 10 to 40 percent by weight particles having a diameter in the range of 500 to 1000 microns, 40 to 70 percent by weight particles smaller than 500 microns, and comprising a material that degrades at ambient conditions of the subterranean formation, the diverter material effective to essentially block flow of fracturing fluid into the at least one fracture; and   continuing to inject fracturing fluid at a pressure effective to initiate at least one additional fracture from the wellbore within the subterranean formation.   
     
     
         19 . A method to provide acid or reactive chemical etched fractures in a subterranean formation comprising:
 injecting a reactive chemical into the subterranean formation at a pressure sufficient to initiate and propagate at least one hydraulic fracture wherein the fracturing fluid comprises a reactive chemical that can etch the fracture surface;   when the at least one hydraulic fracture has reached a target size, adding to the fracturing fluid a predetermined amount of a diverter material wherein the diverter material comprises between 10 to 30 weight percent of particles having a size larger than 2000 microns, between 1 and 15% by weight of particles between 1000 and 2000 microns, 10 to 40 percent by weight particles having a diameter in the range of 500 to 1000 microns, 40 to 70 percent by weight particles smaller than 500 microns, and comprising a material that degrades at ambient conditions of the subterranean formation, the diverter material effective to essentially block flow of fracturing fluid into the at least one fracture; and   continuing to inject fracturing fluid at a pressure effective to initiate at least one additional fracture from the wellbore within the subterranean formation.