Method for hydraulic fracturing of a hydrocarbon formation

Abstract

A fracturing fluid is injected under a high pressure into a well drilled in a formation to create a hydraulic fracture. Then a suspension of the hydraulic fracturing fluid mixed with proppant particles is injected into the well and the created hydraulic fracture, the suspension having a consistency coefficient greater than 0.1 Pa s n at any flow index n and a yield stress higher than 5 Pa. Then, an overflush fluid having a consistency coefficient lower than 0.01 Pa·s n is injected into the well.

1 . A method for hydraulic fracturing of a hydrocarbon formation, comprising:
 injecting under a high pressure a hydraulic fracturing fluid into a well drilled in the formation to create a hydraulic fracture;   injecting a suspension of the hydraulic fracturing fluid mixed with proppant particles into the well and the created hydraulic fracture, the suspension having a consistency coefficient greater than 0.1 Pa·s n  at any flow index n and a yield stress higher than 5 Pa; and   injecting an overflush fluid with a consistency coefficient lower than 0.01 Pa·s n  into the well.   
     
     
         2 . The method of  claim 1 , wherein the overflush fluid comprises a chemical diluent capable of reacting with the suspension to transform the suspension into a power linear gel without yield stress. 
     
     
         3 . The method of  claim 1 , wherein optimal parameters of the suspension and the overflush fluid are determined based on numerical simulation of the overflush fluid injection operation. 
     
     
         4 . The method of  claim 1 , wherein a diameter of a proppant particles-free region created by the overflush fluid in a near-wellbore area within the fracture is adjusted by adjusting an injection rate of the overflush fluid. 
     
     
         5 . The method of  claim 4 , wherein the injection rate of the overflush fluid is higher than a threshold rate u c  at a suspension—overflush fluid interface when a behavior factor of the overflush fluid is greater than that of the hydraulic fracturing fluid, or the injection rate of the overflush fluid is lower than the threshold rate u c  at the suspension—overflush fluid interface when the behavior factor of the overflush fluid is lower than that of the hydraulic fracturing fluid.