Distributed fiber sensing in a packer for permanent casing and formation deformation monitoring

Abstract

An apparatus, method, and system for monitoring wellbore deformation is disclosed. The apparatus includes an expandable annular cylindrical packer and a plurality of assemblies mounted on an exterior circumferential surface of the packer. The plurality of assemblies are configured to be pressed against a wellbore surface by the packer. Each of the assemblies includes at least one fiber-optic coil embedded in a sheet of deformable substrate, a tray-shaped receptacle formed from a low thermal conductivity material and attached along the rim to an edge of the sheet with a pressure tight-seal, and an optical coupler configured to couple the fiber-optic coil to a fiber-optic cable. The assemblies further include a pressure-tight compartment containing a high-pressure inert gas that is formed by the receptacle, the sheet, and the seal.

1 .- 15 . (canceled) 
     
     
         16 . A method for monitoring wellbore deformation, comprising:
 inserting a wellbore deformation instrument, attached to a fiber-optic cable into a wellbore to a predetermined depth;   expanding the wellbore deformation instrument, wherein expanding the wellbore deformation instrument presses a plurality of deformation sensors against a wellbore surface;   launching a plurality of laser pulses, at a plurality of monitoring times separated from one another by an interval of time, from an optical analyzer located at a wellhead into the fiber-optic cable;   detecting, from each of the plurality of laser pulses, a backscattered laser pulse; and   determining a deformation of the wellbore surface based, at least in part, on a difference between the backscattered laser pulse for one or more pairs of monitoring times.   
     
     
         17 . The method of  claim 16 , wherein the plurality of deformation sensors comprise multiple distributed fiber Bragg gratings (FBGs). 
     
     
         18 . The method of  claim 16 , wherein inserting the wellbore deformation instrument comprises attaching a conveyance mechanism. 
     
     
         19 . The method of  claim 18 , wherein the conveyance mechanism comprises production tubing. 
     
     
         20 . The method of  claim 16 , wherein the optical analyzer is an optical time-domain reflectometer (OTDR) analyzer. 
     
     
         21 . The method of  claim 16 , further comprising transmitting the plurality of laser pulses to the optical analyzer, via a pulse laser. 
     
     
         22 . The method of  claim 21 , wherein the transmitting the plurality of laser pulses comprises triggering the pulse laser via a field programmable gate arrays (FPGA), and wherein the pulse laser comprises a femtosecond pulse laser. 
     
     
         23 . The method of  claim 22 , further comprising calculating the backscattered laser pulse, via a microprocessor electronically coupled to the wellbore deformation instrument, to estimate a frequency difference and an absorption profile of the FPGA. 
     
     
         24 . The method of  claim 21 , wherein transmitting the plurality of laser pulses comprises converting the plurality of laser pulses into electrical data, via an optical switch. 
     
     
         25 . The method of  claim 16 , further comprising calculating the backscattered laser pulse via a microprocessor electronically coupled to the wellbore deformation instrument. 
     
     
         26 . The method of  claim 25 , further comprising processing the calculated backscattered laser pulse via a transceiver electronically coupled to the microprocessor. 
     
     
         27 . The method of  claim 26 , further comprising storing the processing backscattered laser pulse in a data storage, the data storage comprises a supervisory control and data acquisition system. 
     
     
         28 . The method of  claim 16 , wherein inserting the wellbore deformation instrument comprises attaching an optical coupler to at least one fiber-optic coil in the wellbore deformation instrument. 
     
     
         29 . The method of  claim 16 , wherein expanding the wellbore deformation instrument comprises pressing a sheet of deformable substrate embedded with at least one fiber-optic coil against the wellbore surface. 
     
     
         30 . The method of  claim 16 , wherein detecting the backscattered laser pulse comprises detecting the backscattered laser pulse via a receiver electronically coupled to the wellbore deformation instrument. 
     
     
         31 . The method of  claim 16 , further comprising transmitting the plurality of laser pulses to at least one fiber-optic coil in the wellbore deformation instrument, via a circulator or a delay+Mach-Zehnder Interferometer (D+MZI). 
     
     
         32 . The method of  claim 16 , wherein launching the plurality of laser pulses comprises powering the optical analyzer via a power source or an electric cable, wherein the power source comprises a thermoelectric material, a microturbine, or a downhole battery.