Relative permeability from borehole resistivity measurements

Abstract

Methods for deriving relative permeability from resistivity measurements in the laboratory and from downhole resistivity measurements are described. Further, systems and methods for determining relative permeability from borehole resistivity measurements made during a water flooding event such as drilling with water-based mud, water injection and/or water invasion are described.

What is claimed is: 
     
         1 . A method for determining relative permeability for a subterranean rock formation comprising:
 receiving downhole resistivity data representative of resistivity measurements made in a wellbore penetrating the subterranean rock formation during a water flooding event of the subterranean rock formation; and   determining one or more relative permeability values for the subterranean rock formation based at least in part on the downhole resistivity data.   
     
     
         2 . A method according to  claim 1 , wherein the one or more permeability values include relative permeability for wetting and non-wetting phases during an imbibition mode corresponding to the water flooding event. 
     
     
         3 . A method according to  claim 2 , wherein the wetting phase is an aqueous fluid and the non-wetting phase is an oil fluid. 
     
     
         4 . A method according to  claim 3 , wherein said resistivity measurements are made by a logging-while-drilling tool, the aqueous wetting phase is a water-based drilling mud and said water flooding event is introduction of said water-based drilling mud into the rock formation during a drilling process. 
     
     
         5 . A method according to  claim 1 , wherein the water flooding event is caused by water being injected from an injection well. 
     
     
         6 . A method according to  claim 5 , wherein said resistivity measurements are made from said injection well. 
     
     
         7 . A method according to  claim 1 , wherein the water flooding event is caused by a brine invasion from a second rock formation. 
     
     
         8 . A method according to  claim 1 , wherein said resistivity measurements are made from a production well configured to produce fluid from the rock formation. 
     
     
         9 . A method according to  claim 1 , wherein said resistivity measurements are made from an observer well. 
     
     
         10 . A method according to  claim 1 , wherein said determining one or more relative permeability values are further based on one or more values for porosity of the rock formation. 
     
     
         11 . A method according to  claim 10 , wherein said one or more values for porosity are based at least in part on borehole measurements. 
     
     
         12 . A method according to  claim 11 , wherein the borehole measurements upon which the one or more values for porosity are based are selected from a group consisting of: neutron density measurements, NMR measurements, dielectric measurements, and acoustic measurements. 
     
     
         13 . A method according to  claim 1 , wherein said determining one or more relative permeability values are further based on one or more derived Archie's law parameters. 
     
     
         14 . A method according to  claim 13 , wherein said one or more derived Archie's law parameters are selected from a group consisting of: saturation exponent and cementation factor. 
     
     
         15 . A method according to  claim 13 , wherein said one or more derived Archie's law parameters are based at least in part on a laboratory core analysis procedure. 
     
     
         16 . A method according to  claim 13 , wherein said one or more derived Archie's law parameters are based at least in part on borehole measurements. 
     
     
         17 . A method according to  claim 16 , wherein said borehole measurements on which said one or more Archie's law parameters is based at least in part are made using a borehole dielectric measurement tool. 
     
     
         18 . A system for determining relative permeability for a subterranean rock formation comprising:
 a downhole resistivity measurement tool configured to be deployed in a borehole penetrating the rock formation and take resistivity measurements during a water flooding event of the rock formation; and   a processing system configured to determine one or more relative permeability values for the subterranean rock formation based at least in part on downhole measurements made during the water flooding event made by said resistivity tool.   
     
     
         19 . A system according to  claim 18 , wherein the one or more permeability values include relative permeability for a wetting aqueous fluid phase and a non-wetting oil fluid phase during an imbibition mode corresponding to the water flooding event. 
     
     
         20 . A system according to  claim 19 , wherein said downhole resistivity tool is a logging-while-drilling tool, the aqueous wetting phase is a water-based drilling mud and said water flooding event is an introduction of said water-based drilling mud into the rock formation during a drilling process. 
     
     
         21 . A system according to  claim 19 , wherein the water flooding event is due to a cause selected from a group consisting of: water being injected from an injection well, and a brine invasion from a second rock formation. 
     
     
         22 . A system according to  claim 21 , wherein said downhole resistivity tool is permanently or semi permanently resistivity sensor mounted in a well type selected from a group consisting of: injection well, observer well and production well. 
     
     
         23 . A system according to  claim 18 , wherein said one or more relative permeability values determined by said processing system are further based on one or more values for porosity of the rock formation. 
     
     
         24 . A system according to  claim 23 , wherein said one or more values for porosity are based at least in part on borehole measurements selected from a group consisting of: neutron density measurements, NMR measurements, dielectric measurements, and acoustic measurements. 
     
     
         25 . A system according to  claim 18 , wherein said one or more relative permeability values determined by said processing system are further based on one or more derived Archie's law parameters. 
     
     
         26 . A system according to  claim 25 , wherein said one or more derived Archie's law parameters are based at least in part on a laboratory core analysis procedure. 
     
     
         27 . A system according to  claim 25 , wherein said one or more derived Archie's law parameters are based at least in part on borehole measurements.