In-situ property determination

Abstract

In one possible implementation an in-situ property determination system includes a displacement tool configured for use in a wellbore. The displacement tool includes four or more pads symmetrically located about an axis of the displacement tool, with each pad having a contact surface configured to contact a wall of the wellbore. The four or more pads can extend from a first position proximate an outer surface of the displacement tool to a second position in contact with the wall of the wellbore such that the four or more pads deform the wellbore into an at least approximately circular cross section. The system also includes a recordation device to record force displacement information associated with extending the four or more pads from the first position to the second position.

1 . An in-situ property determination system comprising:
 a displacement tool configured for use in a wellbore in a formation, the displacement tool comprising:   four or more pads symmetrically located about an axis of the displacement tool, with each pad having a contact surface configured to contact a wall of the wellbore; wherein the four or more pads are further configured to extend from a first position proximate an outer surface of the displacement tool to a second position in contact with the wall of the wellbore such that the four or more pads deform the wellbore into an at least approximately circular cross section; and   a recordation device configured to record force displacement information associated with extending the four or more pads from the first position to the second position.   
     
     
         2 . The in-situ property determination system of  claim 1 , wherein the recordation device is located at least partially within the displacement tool. 
     
     
         3 . The in-situ property determination system of  claim 1 , further comprising:
 a property determination module configured to utilize at least a portion of the force displacement information associated with extending the four or more pads from the first position to the second position to estimate a far-field stress ratio associated with the formation.   
     
     
         4 . The in-situ property determination system of  claim 1 , wherein the recordation device is further configured to record maintenance force information associated with maintaining the four or more pads at the second position. 
     
     
         5 . The in-situ property determination system of  claim 4 , further comprising:
 a property determination module configured to utilize at least a portion of the maintenance force information associated with maintaining the four or more pads at the second position to estimate one or more of:   one or more poroelastic properties of the formation;   a hydraulic diffusivity of the formation; and   one or more rock creep properties of the formation.   
     
     
         6 . The in-situ property determination system of  claim 1 , wherein the four or more pads are further configured to retract from the second position to the first position, and further wherein the recordation device is further configured to record force displacement information associated with allowing the four or more pads to retract from the second position to the first position. 
     
     
         7 . The in-situ property determination system of  claim 6 , further comprising:
 a property determination module configured to utilize at least a portion of the force displacement information associated with allowing the four or more pads to retract from the second position to the first position to estimate Young's Modulus associated with the formation.   
     
     
         8 . A method of in-situ property determination comprising:
 activating a displacement tool at a desired depth in a wellbore in a formation to deform the wellbore from an at least approximately elliptical cross section to an at least approximately circular cross section; and   recording force displacement information associated with deforming the wellbore from the at least approximately elliptical cross section to the at least approximately circular cross section.   
     
     
         9 . The method of in-situ property determination of  claim 8 , further comprising:
 utilizing at least a portion of the force displacement information associated with deforming the wellbore from the at least approximately elliptical cross section to the at least approximately circular cross section to estimate a far-field stress ratio associated with the formation.   
     
     
         10 . The method of in-situ property determination of  claim 8 , further comprising:
 choosing the desired depth based at least in part on one or more ultrasonic images associated with the wellbore.   
     
     
         11 . The method of in-situ property determination of  claim 8 , further comprising:
 identifying a location of an axis of the at least approximately elliptical cross section at least partially through use of a wellbore image.   
     
     
         12 . The method of in-situ property determination of  claim 8 , further comprising:
 recording maintenance force information associated with maintaining the at least approximately circular cross section; and   utilizing at least a portion of the maintenance force information to estimate one or more of:   one or more poroelastic properties of the formation;   a hydraulic diffusivity of the formation; and   one or more rock creep properties of the formation.   
     
     
         13 . The method of in-situ property determination of  claim 8 , further comprising:
 recording force displacement information associated with allowing the wellbore to return from the at least approximately circular cross section to an at least approximately elliptical cross section; and   utilizing at least a portion of the force displacement information associated with allowing the wellbore to return from the circular cross section to the at least approximately elliptical cross section to estimate Young's Modulus associated with the formation at the desired depth.   
     
     
         14 . The method of in-situ property determination of  claim 8  wherein activating the displacement tool includes:
 extending four or more pads from a first position proximate an outer surface of the displacement tool to a second position in which the four or more pads have pushed a wall of the wellbore into the at least approximately circular cross section. 
 
     
     
         15 . The method of in-situ property determination of  claim 14 , further comprising:
 orienting the four or more pads in a direction of a maximum principal stress and a minimum principal stress in the formation.   
     
     
         16 . The method of in-situ property determination of  claim 8 , further comprising:
 allowing the wellbore to return from the at least approximately circular cross section to an at least approximately elliptical cross section;   turning the displacement tool by a desired angle and activating the displacement tool to deform the wellbore from an at least approximately elliptical cross section to an at least approximately circular cross section; and   recording force displacement information associated with deforming the wellbore from the at least approximately elliptical cross section to the at least approximately circular cross section.   
     
     
         17 . The method of in-situ property determination of  claim 8 , further comprising:
 moving the displacement tool to a second desired depth in the wellbore;   activating the displacement tool at the second desired depth to deform the wellbore from an at least approximately elliptical cross section to an at least approximately circular cross section; and   recording force displacement information associated with deforming the wellbore from the at least approximately elliptical cross section to the at least approximately circular cross section.   
     
     
         18 . A computer-readable tangible medium with instructions stored thereon that, when executed, direct a processor to perform acts comprising:
 accessing force displacement information associated with deforming a wellbore in a formation from an at least approximately elliptical cross section to an at least approximately circular cross section; and   utilizing at least a portion of the force displacement information associated with deforming the wellbore from the at least approximately elliptical cross section to the at least approximately circular cross section to estimate a far-field stress ratio associated with the formation.   The computer-readable tangible medium of  claim 18 , wherein the computer-readable tangible medium further includes instructions to direct a processor to perform acts comprising:   accessing maintenance force information associated with maintaining the at least approximately circular cross section of the wellbore; and   utilizing at least a portion of the maintenance force information to estimate one or more of:   one or more poroelastic properties of the formation;   a hydraulic diffusivity of the formation; and   one or more rock creep properties of the formation.   
     
     
         19 . The computer-readable tangible medium of  claim 18 , wherein the computer-readable tangible medium further includes instructions to direct a processor to perform acts comprising:
 accessing force displacement information associated with allowing the wellbore to return from an at least approximately circular cross section to an at least approximately elliptical cross section; and   utilizing at least a portion of the force displacement information associated with allowing the wellbore to return from the at least approximately circular cross section to the at least approximately elliptical cross section to estimate Young's Modulus associated with the formation.