Hydraulic fracture height growth control

Abstract

A method is given for creating a fracture, in a subterranean formation, that has a fluid flow barrier at the top, at the bottom, or at both the top and the bottom. The method is applied before or during a conventional hydraulic fracturing treatment and is used to limit undesired vertical growth of a fracture out of the productive zone. A lower-viscosity pad fluid is used to initiate the fracture; a higher-viscosity fluid containing barrier particles is then injected; a lower-viscosity particle-free fluid is then injected to promote settling (or rising) of the barrier particles and to finger through the slug of barrier particles and cut it into an upper and lower portion. If the barrier is to be at the bottom of the fracture, the barrier particles are denser than the fluids; if the barrier is to be at the top of the fracture, the barrier particles are less dense than the fluids. Optionally, between the barrier transport stage and the subsequent lower-viscosity stage, there may be a stage of a higher viscosity particle-free fluid that pushes the barrier particles farther into the fracture. To provide both upper and lower particles in one treatment, the pad stage may be of higher-viscosity, or the barrier particles may include particles less dense than, and more dense than, the fluid.

1 . A method for creating a fracture, in a subterranean formation, having a barrier, comprising particles, to fluid flow out of the top or bottom or both the top and bottom of the fracture comprising (a) injecting a pad fluid having a viscosity that allows settling or rising of barrier particles toward the top or bottom to form the barrier, (b) injecting a slurry of the barrier particles in a fluid of a viscosity higher than the pad fluid, said fluid capable of transporting the barrier particles, and (c) injecting a fluid having a lower viscosity than the fluid of step (b) through which the particles may settle or rise to form the barrier. 
     
     
         2 . The method of  claim 1  wherein the ratio of the particle density to the fluid density is in the range of from about 1.0 to about 5.0. 
     
     
         3 . The method of  claim 2  wherein the ratio of the particle density to the fluid density is in the range of from about 2.5 to about 5.0. 
     
     
         4 . The method of  claim 1  wherein the ratio of the particle density to the fluid density is in the range of from about 0.2 to about 1.0. 
     
     
         5 . The method of  claim 4  wherein the ratio of the particle density to the fluid density is in the range of from about 0.5 to about 1.0. 
     
     
         6 . The method of  claim 1  wherein the particles are a mixture of particles having a ratio of the particle density to the fluid density in the range of from about 0.2 to about 1.0 and particles having a ratio of the particle density to the fluid density in the range of from about 1.0 to about 5.0. 
     
     
         7 . The method of  claim 1  further comprising a step of injecting, between steps (b) and (c), a fluid capable of transporting the particles. 
     
     
         8 . The method of  claim 1  further comprising a step of injecting, after step (c), a fluid capable of transporting the particles. 
     
     
         9 . The method of  claim 1  wherein at least a portion of the particles adhere to one another after placement. 
     
     
         10 . The method of  claim 1  wherein at least a portion of the particles dissolve after the treatment. 
     
     
         11 . The method of  claim 1  wherein at least a portion of the particles release acid after the treatment. 
     
     
         12 . The method of  claim 1  wherein at least a portion of the particles release a breaker after the treatment. 
     
     
         13 . The method of  claim 1  wherein one or more of the fluids contains fibers. 
     
     
         14 . The method of  claim 1  wherein one or more of the fluids contains a fluid loss control additive. 
     
     
         15 . The method of  claim 1  followed by a shut in period. 
     
     
         16 . A method for creating a fracture, in a subterranean formation, having a barrier, comprising particles, to fluid flow out of both the top and bottom of the fracture comprising (a) injecting a pad fluid having a viscosity that does not allow settling or rising of barrier particles toward the top or bottom during the treatment, (b) injecting the barrier particles in a fluid capable of transporting the barrier particles, and (c) injecting a fluid having a lower viscosity than the fluid of step (b) through which the particles may settle or rise to form the barrier. 
     
     
         17 . The method of  claim 16  wherein the fluids of steps (a) and (b) have the same viscosity. 
     
     
         18 . The method of  claim 16  wherein all three fluids have the same viscosity. 
     
     
         19 . The method of  claim 16  wherein the ratio of the particle density to the fluid density is in the range of from about 1.0 to about 5.0. 
     
     
         20 . The method of  claim 19  wherein the ratio of the particle density to the fluid density is in the range of from about 2.5 to about 5.0. 
     
     
         21 . The method of  claim 16  wherein the ratio of the particle density to the fluid density is in the range of from about 0.2 to about 1.0. 
     
     
         22 . The method of  claim 21  wherein the ratio of the particle density to the fluid density is in the range of from about 0.5 to about 1.0. 
     
     
         23 . The method of  claim 16  wherein the particles are a mixture of particles having a ratio of the particle density to the fluid density in the range of from about 0.2 to about 1.0 and particles having a ratio of the particle density to the fluid density in the range of from about 1.0 to about 5.0. 
     
     
         24 . The method of  claim 16  further comprising a step of injecting, between steps (b) and (c), a fluid capable of transporting the particles. 
     
     
         25 . The method of  claim 16  further comprising a step of injecting, after step (c), a fluid capable of transporting the particles. 
     
     
         26 . The method of  claim 16  wherein at least a portion of the particles adhere to one another after placement. 
     
     
         27 . The method of  claim 16  wherein at least a portion of the particles dissolve after the treatment. 
     
     
         28 . The method of  claim 16  wherein at least a portion of the particles release acid after the treatment. 
     
     
         29 . The method of  claim 16  wherein at least a portion of the particles release a breaker after the treatment. 
     
     
         30 . The method of  claim 16  wherein one or more of the fluids contains fibers. 
     
     
         31 . The method of  claim 16  wherein one or more of the fluids contains a fluid loss control additive. 
     
     
         32 . The method of  claim 16  followed by a shut in period.