Methods for in situ fluid gelation for far-field fracture control

Abstract

Described herein are methods for the control of fracture formation and propagation during fracturing operations performed on a subterranean formation. These methods can comprise injecting an aqueous composition comprising a gelling agent and a crosslinker into at least one fracture present in the subterranean formation via a wellbore in fluid communication with the subterranean formation; displacing the gelling agent and the crosslinker to a desired location within the at least one fracture present in the subterranean formation.

What is claimed is: 
     
         1 . A method comprising:
 injecting an aqueous composition comprising a gelling agent and an encapsulated crosslinker into at least one fracture present in a subterranean formation via a wellbore in fluid communication with the subterranean formation;   displacing the gelling agent and the encapsulated crosslinker to a desired location within the at least one fracture present in the subterranean formation; and   allowing for release of the crosslinker from its encapsulant, thereby crosslinking the gelling agent within the at least one fracture.   
     
     
         2 . The method of  claim 1 , wherein upon crosslinking of the gelling agent, the aqueous composition increases in viscosity by at least one order of magnitude, such as at least two orders of magnitude, or at least three orders of magnitude. 
     
     
         3 . The method of  claim 1 , wherein upon crosslinking of the gelling agent, the aqueous composition forms a gel within the at least one fracture. 
     
     
         4 . The method of  claim 1 , wherein the at least one fracture is formed during a hydraulic fracturing operation. 
     
     
         5 . The method of  claim 4 , wherein the gel at least partially controls growth of far-field fracture geometry during a fracturing operation performed via the wellbore. 
     
     
         6 . The method of  claim 1 , wherein prior to injection into the subterranean formation, the aqueous composition has an apparent viscosity of 20 cP or less at 25° C. measured at a shear rate of 170 sec −1 . 
     
     
         7 . The method of  claim 1 , wherein upon crosslinking of the gelling agent, the aqueous composition has an apparent viscosity of at least 50 cP at 25° C. measured at a shear rate of 170 sec −1 . 
     
     
         8 . The method of  claim 1 , wherein the encapsulated crosslinker comprises a crosslinker at least partially encapsulated within a dissolvable coating, a frangible coating, a meltable coating, a soft-gel coating, or a degradable coating. 
     
     
         9 . The method of  claim 8 , wherein when the encapsulated crosslinker comprises a dissolvable coating, the dissolvable coating comprises a dissolvable salt, a soluble polymer, or any combination thereof. 
     
     
         10 . The method of  claim 1 , wherein the crosslinker is chosen from organic crosslinkers, aluminates, borates, zirconates, chromates, titanates, and combinations thereof. 
     
     
         11 . The method of  claim 1 , wherein the gelling agent comprises a polymer. 
     
     
         12 . The method of  claim 1 , wherein the polymer is present in the aqueous composition at a concentration of at least 1 lbm/Mgal. 
     
     
         13 . The method of  claim 11 , wherein the polymer is present in the in the aqueous composition at a concentration of from 0.005% to 0.5% by weight of the aqueous composition. 
     
     
         14 . The method of  claim 1 , wherein after crosslinking of the gelling agent within the fracture, the method further comprises injecting the aqueous composition through the wellbore at a pressure and flow rate effective to form, continue to form, or extend a fracture in the subterranean formation. 
     
     
         15 . The method of  claim 14 , wherein the fracture is present in a first region of the subterranean formation; and
 wherein crosslinking of the gelling agent within the fracture inhibits fracture growth in the first region of the subterranean formation.   
     
     
         16 . The method of  claim 14 , wherein the fracture is present in a first region of the subterranean formation; and
 wherein crosslinking of the gelling agent within the fracture preferentially directs the growth of fractures in a different direction within the first region of the subterranean formation.   
     
     
         17 . The method of  claim 14 , wherein the fracture is present in a first region of the subterranean formation; and
 wherein crosslinking of the gelling agent within the fracture preferentially directs fracture formation into a second region of the subterranean formation.   
     
     
         18 . The method of  claim 1 , wherein the method further comprises producing fluids from the wellbore after crosslinking of the gelling agent within the fracture. 
     
     
         19 . The method of  claim 1 , wherein displacing the gelling agent and encapsulated crosslinker to a desired location within the subterranean formation comprises injecting a displacement fluid through the wellbore after injection of the aqueous composition so as to drive the aqueous composition further into the fracture. 
     
     
         20 . A method comprising:
 injecting an aqueous composition comprising a gelling agent and a crosslinker into at least one fracture present in a subterranean formation via a wellbore in fluid communication with the subterranean formation;   displacing the gelling agent and the crosslinker to a desired location within the at least one fracture present in the subterranean formation; and   optionally exposing the gelling agent and crosslinker to an external trigger, thereby crosslinking the gelling agent within the at least one fracture.