Quantifying a reservoir volume and pump pressure limit

Abstract

Methods for computer modelling of a pressure transient behavior after shut-in and during fall-off of an injection event are provided to provide estimates of stimulated reservoir volume, formation permeability, stress contrast across the target and adjacent zones, fracture dimensions, fracture beyond the target zone, and pump pressure limits for maintaining fractures within the target zone, especially in fractured tight reservoirs.

It is claimed: 
     
       1. A method of operating an injection well having a wellbore extending through a subterranean zone, the subterranean zone bounded by an adjacent upper confinement containment zone and an adjacent lower containment zone, the method comprising:
 pumping fluids having a first set of fluid properties into the subterranean zone at a first pressure above fracture pressure; 
 hydraulically fracturing the subterranean zone; 
 shutting-in the injection well and allowing pressure fall-off; 
 measuring pressure transient data after shutting-in the injection well and during pressure fall-off; 
 pumping fluids having a second set of fluid properties at a second pressure above fracture pressure, wherein at least one of the second set of fluid properties or the second pressure is different than the first set of fluid properties or first pressure, and the second set of fluid properties or second pressure determined by a computer-implemented method comprising:
 inputting to a computer program stored in a non-transitory memory and executed by a computer, pressure and time data from the pressure transient data measured after shut-in and during fall-off; 
 calculating, using the computer program, type curves based on the input pressure transient data, the type curves having associated curve parameters; 
 iteratively performing at least one curve-fitting algorithm using the computer program, the computer program determining a mathematically-described, calculated type curve which estimates the type curve to a pre-selected accuracy; 
 calculating, using the computer program, a stimulated reservoir volume; 
 determining, using the computer program, stress contrasts between the subterranean zone and at least one of an the adjacent upper and adjacent lower containment zones; and 
 conducting, using the computer program, iterative, computer-modelled fracture simulations and calculating a maximum injection pressure at which a corresponding maximum computer-modelled fracture does not breach at least one of the adjacent upper and adjacent lower containment zones. 
 
 
     
     
       2. The method of  claim 1 , wherein the second set of fluid properties or second pressure is determined by the computer-implemented method further comprising calculating a waterflood design or a maximizing fracture extent using the stress contrast contrasts. 
     
     
       3. The method of  claim 2 , wherein the second set of fluid properties or second pressure above fracture pressure are determined by the waterflood design or maximizing fracture extent. 
     
     
       4. The method of  claim 1 , wherein the second pressure is determined by using the calculated maximum injection pressure at which a corresponding maximum computer-modelled fracture does not breach at least one of the adjacent upper and adjacent lower containment zones. 
     
     
       5. The method of  claim 1 , wherein the second set of fluid properties or second pressure is determined by the computer-implemented method further comprising isolating, using the computer program, a water hammer effect from the pressure transient data. 
     
     
       6. The method of  claim 1 , wherein the second set of fluid properties or second pressure is determined by the computer-implemented method further comprising calculating a maximum contained volume in the subterranean zone, and maximum pressure limits and injection fluid properties which will not exceed the maximum contained volume. 
     
     
       7. A method of operating an injection well having a wellbore extending through a subterranean injection zone, the subterranean injection zone bounded by an adjacent upper containment zone and an adjacent lower containment zone, the method comprising:
 in an injection operation, pumping fluids having a first set of fluid properties into the subterranean injection zone at a first pressure above fracture pressure;   hydraulically fracturing the subterranean injection zone;   shutting-in the injection well and allowing pressure fall-off;   measuring pressure transient data after shutting-in the injection well and during pressure fall-off;   inputting to a computer program stored in a non-transitory memory and executed by a computer, pressure and time data from the pressure transient data measured after shut-in and during fall-off; and   determining, using the pressure transient data and computer program, a maximum injection pressure limit, for the fluids having the first set of fluid properties, to assure containment of the fluids in the subterranean injection zone.    
     
     
       8. The method of  claim 7 , further comprising determining a maximum injection pressure to create a maximum fracture without breach of the adjacent upper containment zone or adjacent lower containment zone.  
     
     
       9. The method of  claim 7 , further comprising applying the maximum injection pressure limit before resumption of the injection operation.  
     
     
       10. The method of  claim 7 , further comprising determining, using the computer program, stress contrasts between the subterranean injection zone and the adjacent upper and adjacent lower containment zones, and utilizing the stress contrasts to determine the maximum injection pressure limit.  
     
     
       11. The method of  claim 7 , further comprising determining an additional injection pressure, above the first pressure, the subterranean injection zone can sustain before fracturing either of the adjacent upper or adjacent lower containment zones.  
     
     
       12. The method of  claim 7 , wherein inputting the pressure transient data is performed in real time.  
     
     
       13. The method of  claim 7 , further comprising calculating, using the computer program, type curves based on the input pressure transient data, the type curves having associated curve parameters.  
     
     
       14. The method of  claim 7 , further comprising conducting, using the computer program, iterative, computer-modelled fracture simulations and calculating the maximum injection pressure limit at which a corresponding maximum computer-modelled fracture does not breach at least one of the adjacent upper and adjacent lower containment zones.  
     
     
       15. A method of operating an injection well having a wellbore extending through a subterranean injection zone, the subterranean injection zone bounded by an adjacent upper containment zone and an adjacent lower containment zone, the method comprising:
 an injection operation, pumping fluids having a first set of fluid properties into the subterranean injection zone at a first pressure above fracture pressure;   hydraulically fracturing the subterranean injection zone;   shutting-in the injection well and allowing pressure fall-off;   measuring pressure transient data after shutting-in the injection well and during pressure fall-off;   inputting to a computer program stored in a non-transitory memory and executed by a computer, pressure and time data from the pressure transient data measured after shut-in and during fall-off;   determining, using the pressure transient data and computer program, stress contrasts between the subterranean injection zone and the adjacent upper containment zone and adjacent lower containment zone.    
     
     
       16. The method of  claim 15 , further comprising, utilizing the stress contrasts, determining a maximum injection pressure limit to assure containment of the fluids in the subterranean injection zone.  
     
     
       17. The method of  claim 16 , further comprising applying the maximum injection pressure limit before resumption of the injection operation.  
     
     
       18. The method of  claim 17 , further comprising determining an additional injection pressure, above the first pressure, the subterranean injection zone can sustain before fracturing either of the adjacent upper or adjacent lower containment zones, and applying the additional injection pressure upon resumption of the injection operation.  
     
     
       19. A method of operating an injection well having a wellbore extending through a subterranean injection zone, the subterranean injection zone bounded by an adjacent upper containment zone and an adjacent lower containment zone, the method comprising:
 in an injection operation, pumping fluids having a first set of fluid properties into the subterranean injection zone at a first pressure above fracture pressure;   hydraulically fracturing the subterranean injection zone;   shutting-in the injection well and allowing pressure fall-off;   measuring pressure transient data after shutting-in the injection well and during pressure fall-off;   inputting to a computer program stored in a non-transitory memory and executed by a computer, pressure and time data from the pressure transient data measured after shut-in and during fall-off;   determining, using the pressure transient data and computer program, fracture penetration into one of the adjacent upper or adjacent lower containment zones.    
     
     
       20. The method of  claim 19 , further comprising determining a maximum injection pressure limit, for the fluids having the first set of fluid properties, to assure containment of the fluids in the subterranean injection zone.  
     
     
       21. The method of  claim 20 , further comprising applying the maximum injection pressure limit upon resumption of the injection operation.  
     
     
       22. A method of operating an injection well having a wellbore extending through a subterranean injection zone, the subterranean injection zone bounded by an adjacent upper containment zone and an adjacent lower containment zone, the method comprising:
 in an injection operation, pumping fluids having a first set of fluid properties into the subterranean injection zone at a first pressure above fracture pressure;   hydraulically fracturing the subterranean injection zone;   shutting-in the injection well and allowing pressure fall-off;   measuring pressure transient data after shutting-in the injection well and during pressure fall-off;   inputting to a computer program stored in a non-transitory memory and executed by a computer, pressure and time data from the pressure transient data measured after shut-in and during fall-off;   determining, using the pressure transient data and computer program, a maximum contained volume in the subterranean injection zone, and determining injection pressure limits and fluid properties to reach the maximum contained volume upon resumption of the injection operation.    
     
     
       23. The method of  claim 22 , further comprising applying the injection pressure limits and fluid properties upon resumption of the injection operation.  
     
     
       24. A method of operating an injection well having a wellbore extending through a subterranean injection zone, the subterranean injection zone bounded by an adjacent upper containment zone and an adjacent lower containment zone, the method comprising:
 in an injection operation, pumping fluids having a first set of fluid properties into the subterranean injection zone at a first pressure above fracture pressure;   hydraulically fracturing the subterranean injection zone, an inner mobility zone and an outer mobility zone defined radially around the wellbore, the inner and outer mobility zones having differing relative permeabilities;   shutting-in the injection well and allowing pressure fall-off;   measuring pressure transient data after shutting-in the injection well and during pressure fall-off;   inputting to a computer program stored in a non-transitory memory and executed by a computer, pressure and time data from the pressure transient data measured after shut-in and during fall-off;   determining, using the pressure transient data and computer program, a transition from the inner mobility zone to the outer mobility zone.    
     
     
       25. The method of  claim 24 , further comprising determining a stimulated reservoir volume.  
     
     
       26. The method of  claim 24 , further comprising determining fracture penetration into the adjacent upper or adjacent lower containment zone.  
     
     
       27. The method of  claim 24 , further comprising determining the length and height of the hydraulic fractures.  
     
     
       28. The method of  claim 24 , further comprising determining the shrinkage of the hydraulic fractures in height, length or both.  
     
     
       29. The method of  claim 28 , further comprising determining the shrinkage rate of the hydraulic fractures.