Shale geomechanics for multi-stage hydraulic fracturing optimization in resource shale and tight plays

Abstract

Systems and methods for improving production from wellbores include providing optimal fracture design parameters based on geomechanical analyses combined with geological, geophysical, and/or petrophysical knowledge. In at least one embodiment, the systems and methods include defining a well direction, defining a fracture spacing, selecting a fracturing fluid system and optimizing a fracture design, such as a complex multi-stage hydraulic fracture design. Such systems and methods can help minimize a learning curve associated with a wellbore or subterranean formation and optimize the hydraulic fracturing operation for a hydrocarbon reservoir.

What is claimed is: 
     
         1 . A computer-implemented method of designing a hydraulic fracturing operation for a hydrocarbon reservoir, comprising:
 defining an anisotropy of a formation material in the reservoir;   defining a heterogeneity of a formation material in the reservoir;   creating, in computer readable storage, an electronically stored geomechanical model of at least a portion of the reservoir based on at least the anisotropy and the heterogeneity, wherein the geomechanical model exhibits a prediction of at least one of pore pressure and in-situ stresses within the portion of the reservoir;   defining a wellbore path in the geomechanical model through the portion of the reservoir;   identifying an estimated hydraulic fracturing geometry of the portion of the reservoir at first and second fracturing locations along the wellbore path, wherein the estimated hydraulic fracturing geometry is based on at least one of a geostress and a formation material mechanical property existing at the first and second fracturing locations;   creating, in computer readable storage, an electronically stored fracturing geometry model of the estimated hydraulic fracturing geometry at the first and second fracturing locations;   estimating a first stimulated reservoir volume of the portion of the reservoir;   adding to the electronically stored fracturing geometry model an estimated hydraulic fracturing geometry at a third fracturing location along the wellbore path between the first and second fracturing locations;   calculating a manipulated stress anisotropy of the portion of the reservoir based on the addition of the estimated hydraulic fracturing geometry at the third fracturing location;   estimating a second stimulated reservoir volume of the portion of the reservoir; and   calculating a difference between the first stimulated reservoir volume and the second stimulated reservoir volume.   
     
     
         2 . The method of  claim 1 , further comprising iteratively changing at least one variable within the fracturing geometry model, recalculating the manipulated stress anisotropy, and estimating a third stimulated reservoir volume of the portion of the reservoir. 
     
     
         3 . The method of  claim 2 , wherein the at least one variable is selected from the group consisting of well interval, perforation interval, perforation order and a combination thereof. 
     
     
         4 . The method of  claim 1 , further comprising performing a numerical stress analysis of a reservoir interval between the first and second fracturing locations. 
     
     
         5 . The method of  claim 1 , wherein the third fracturing location is disposed within a reservoir interval and located a first perforation interval from the first fracturing location and a second perforation interval from the second fracturing location, and wherein the method further comprises determining a change in stress in one or more directions within the reservoir interval. 
     
     
         6 . The method of  claim 5 , further comprising determining a change in treating pressure based on the change in stress. 
     
     
         7 . The method of  claim 5 , further comprising determining a likelihood that hydraulic fracturing at the third fracturing location will cause fractures of increased complexity in the reservoir interval between the first and second fracturing locations. 
     
     
         8 . The method of  claim 5 , further comprising determining a manipulated horizontal stress anisotropy (HSAI*) of the reservoir interval based on the first and second perforation intervals, wherein HSAI* is determined according to the equation: 
       
         
           
             
               
                 HSAI 
                 * 
               
               = 
               
                 
                   
                     SH 
                     - 
                     
                       Sh 
                       * 
                     
                   
                   
                     Sh 
                     * 
                   
                 
                 . 
               
             
           
         
       
     
     
         9 . The method of  claim 8 , further comprising determining a plurality of HSAI* values based on a plurality of different values for at least one of the first and second perforation intervals. 
     
     
         10 . The method of  claim 9 , further comprising identifying a position of the third fracturing location along the reservoir interval at which a target HSAI* value exists. 
     
     
         11 . The method of  claim 5 , further comprising determining a manipulated vertical stress anisotropy (VSAI*) of the reservoir interval, wherein VSAI* is determined according to the equation: 
       
         
           
             
               
                 VSAI 
                 * 
               
               = 
               
                 
                   
                     Sv 
                     - 
                     
                       Sh 
                       * 
                     
                   
                   
                     Sh 
                     * 
                   
                 
                 . 
               
             
           
         
       
     
     
         12 . The method of  claim 11 , further comprising identifying a position of the third fracturing location along the reservoir interval at which a target VSAI* value exists. 
     
     
         13 . A computer-based system for designing a hydraulic fracturing operation for a hydrocarbon reservoir, comprising:
 a central processing unit mounted within the computer-based system;   a data input unit connected to the central processing unit, the data input unit receiving fracability data pertaining to the hydrocarbon reservoir;   a database connected to the central processing unit, the database storing the fracability data for the hydrocarbon reservoir; and   a storage device connected to the central processing unit, the storage device storing computer-readable instructions therein, the computer-readable instructions executable by the central processing unit to:   define an anisotropy of a formation material in the reservoir;   define a heterogeneity of a formation material in the reservoir;   create a geomechanical model of at least a portion of the reservoir based on at least the anisotropy and the heterogeneity, wherein the geomechanical model exhibits a prediction of at least one of pore pressure and in-situ stresses within the portion of the reservoir; and   define a wellbore path in the geomechanical model through the portion of the reservoir.   
     
     
         14 . The computer-based system of  claim 13 , wherein the computer-readable instructions further cause the central processing unit to identify an estimated hydraulic fracturing geometry of the portion of the reservoir at first and second fracturing locations along the wellbore path, the estimated hydraulic fracturing geometry based on at least one of a geostress and a formation material mechanical property existing at the first and second fracturing locations. 
     
     
         15 . The computer-based system of  claim 14 , wherein the computer-readable instructions further cause the central processing unit to:
 create an electronically stored fracturing geometry model of the estimated hydraulic fracturing geometry at the first and second fracturing locations;   estimate and a first stimulated reservoir volume of the portion of the reservoir; and   add to the electronically stored fracturing geometry model an estimated hydraulic fracturing geometry at a third fracturing location along the wellbore path between the first and second fracturing locations.   
     
     
         16 . The computer-based system of  claim 15 , wherein the computer-readable instructions further cause the central processing unit to:
 calculate a manipulated stress anisotropy of the portion of the reservoir based on the addition of the estimated hydraulic fracturing geometry at the third fracturing location;   estimate a second stimulated reservoir volume of the portion of the reservoir; and   calculate a difference between the first stimulated reservoir volume and the second stimulated reservoir volume.   
     
     
         17 . A computer-readable medium storing computer-readable instructions for causing a computer to design a hydraulic fracturing operation for a hydrocarbon reservoir, the computer-readable instructions comprising instructions that, when executed by a processor, cause the computer to:
 define an anisotropy of a formation material in the reservoir;   define a heterogeneity of a formation material in the reservoir;   create a geomechanical model of at least a portion of the reservoir based on at least the anisotropy and the heterogeneity, wherein the geomechanical model exhibits a prediction of at least one of pore pressure and in-situ stresses within the portion of the reservoir; and   define a wellbore path in the geomechanical model through the portion of the reservoir.   
     
     
         18 . The computer-readable medium of  claim 17 , wherein the computer-readable instructions further cause the computer to identify an estimated hydraulic fracturing geometry of the portion of the reservoir at first and second fracturing locations along the wellbore path, the estimated hydraulic fracturing geometry based on at least one of a geostress and a formation material mechanical property existing at the first and second fracturing locations. 
     
     
         19 . The computer-readable medium of  claim 18 , wherein the computer-readable instructions further cause the computer to:
 create an electronically stored fracturing geometry model of the estimated hydraulic fracturing geometry at the first and second fracturing locations;   estimate and a first stimulated reservoir volume of the portion of the reservoir; and   add to the electronically stored fracturing geometry model an estimated hydraulic fracturing geometry at a third fracturing location along the wellbore path between the first and second fracturing locations.   
     
     
         20 . The computer-readable medium of  claim 19 , wherein the computer-readable instructions further cause the computer to:
 calculate a manipulated stress anisotropy of the portion of the reservoir based on the addition of the estimated hydraulic fracturing geometry at the third fracturing location;   estimate a second stimulated reservoir volume of the portion of the reservoir; and   calculate a difference between the first stimulated reservoir volume and the second stimulated reservoir volume.