# US 2021/0340862 A1 · Electronic sensing of discontinuities in a well casing > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0340862 A1 - Document ID: US20210340862A1 - Status: Published application - Kind: A1 - Application number: 16/473,183 - Filed: 2018-06-28 - Published: 2021-11-04 - Earliest claimed: 2018-06-28 - Assignees: Halliburton Energy Services, Inc. - Applicants: Halliburton Energy Services, Inc. - Inventors: Trond HAGEN - Web page: https://patentgrep.com/patent/US20210340862A1 ## CPC - E21B 47/007: Measuring stresses in a pipe string or casing (for locating blocked portions of pipes E21B47/09) - E21B 47/092: by detecting magnetic anomalies - G01V 3/26: operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device (with electromagnetic waves G01V3/30) - G01V 3/30: operating with electromagnetic waves - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) ## Abstract Detecting discontinuities in a well casing according to some aspects includes actively monitoring the electric current response in an antenna or in antennas during the insertion of a tubing string. The method does not require permanent magnets, or any hardware elements beyond those that are already present in a typical behind-casing measurement system. A system according to some aspects includes an antenna that is mounted in or on a tubing string and a voltage source that can be connected to the antenna. A processing device is connected to the antenna and the voltage source. The processing device applies an AC voltage to the antenna and monitors a current generated in the antenna while the AC voltage is being applied. ## Claims ### Claim 1 A system comprising: an antenna mountable in or on a tubing string; a voltage source connectable to the antenna; and a processing device connectable to the antenna and the voltage source, the processing device being operable to: apply an AC voltage to the antenna using the voltage source; monitor a current generated in the antenna while the AC voltage is being applied to the antenna and while the tubing string is deployed within a well casing; sense a discontinuity in the well casing by detecting a difference between the current generated in the antenna when the antenna is proximate to the discontinuity and the current generated in the antenna when the antenna is not proximate to the discontinuity; and provide at least a relative position indication based on sensing the discontinuity. ### Claim 2 (depends on 1) The system of claim 1 further comprising a current sensing component connectable to the antenna, and wherein the current generated in the antenna is monitored by measuring a voltage drop across the current sensing component. ### Claim 3 (depends on 1) The system of claim 1 wherein the processing device is further operable to control the voltage source to set a frequency of the AC voltage in accordance with a physical characteristic of the tubing string, the well casing, or both. ### Claim 4 (depends on 1) The system of claim 1 wherein the processing device is further operable to store a count of discontinuities encountered by the antenna. ### Claim 5 (depends on 1) The system of claim 1 wherein the antenna comprises a plurality of antennas, and wherein the processing device is operable to monitor a current generated in each of the plurality of antennas while the AC voltage is being applied and while the tubing string is deployed within the well casing. ### Claim 6 (depends on 5) The system of claim 5 wherein the processing device is operable to determine a direction of movement for the tubing string by detecting a difference in the current generated in at least two of the plurality of antennas. ### Claim 7 (depends on 1) The system of claim 1 wherein the discontinuity comprises at least one of a shorting ring or a collar joint. ### Claim 8 A method of sensing a discontinuity in a well casing, the method comprising: applying an AC voltage to an antenna mounted in or on a tubing string; monitoring a current generated in the antenna while the AC voltage is being applied to the antenna and while the tubing string is deployed within the well casing; sensing the discontinuity in the well casing by detecting a difference between the current generated in the antenna when the antenna is proximate to the discontinuity and the current generated in the antenna when the antenna is not proximate to the discontinuity; and providing at least a relative position indication based on sensing the discontinuity. ### Claim 9 (depends on 8) The method of claim 8 wherein the current generated in the antenna is monitored by measuring a voltage drop across a current sensing component. ### Claim 10 (depends on 8) The method of claim 8 further comprising setting a frequency of the AC voltage in accordance with a physical characteristic of the tubing string, the well casing, or both. ### Claim 11 (depends on 8) The method of claim 8 further comprising storing a count of discontinuities encountered by the antenna. ### Claim 12 (depends on 8) The method of claim 8 wherein the antenna comprises a plurality of antennas, and the current generated in each of the plurality of antennas is monitored. ### Claim 13 (depends on 12) The method of claim 12 further comprising determining a direction of movement for the tubing string by detecting a difference in the current generated in at least two of the plurality of antennas. ### Claim 14 (depends on 12) The method of claim 12 wherein the discontinuity comprises at least one of a shorting ring or a collar joint. ### Claim 15 A system for sensing collar joints in a well casing, the system comprising: an antenna mountable in or on a tubing string; a driver module connectable to the antenna; a transmission line connectable to the driver module; and a controller connectable to the transmission line, the controller operable to: apply an AC voltage to the antenna; monitor a voltage drop across a sensing resistor connected to the antenna while the tubing string is deployed within the well casing; sense a collar joint in the well casing by detecting a difference between the voltage across the sensing resistor when the antenna is proximate to the collar joint and the voltage across the sensing resistor when the antenna is not proximate to the collar joint; and provide at least a relative position indication based on sensing the collar joint. ### Claim 16 (depends on 15) The system of claim 15 wherein the controller is further operable to set a frequency of the AC voltage in accordance with the physical characteristics of the tubing string, the well casing, or both. ### Claim 17 (depends on 15) The system of claim 15 wherein the controller is further operable to store a count of collar joints encountered by the antenna. ### Claim 18 (depends on 15) The system of claim 15 wherein the antenna comprises a plurality of antennas, and wherein the controller is operable to monitor the voltage across the sensing resistor for each of the plurality of antennas while the AC voltage is being applied and while the tubing string is deployed within the well casing. ### Claim 19 (depends on 18) The system of claim 18 wherein the controller is operable to determine a direction of movement for the tubing string by detecting a difference in the voltage across the sensing resistor for at least two of the plurality of antennas. ### Claim 20 (depends on 15) The system of claim 15 wherein the driver module comprises a signal improvement filter.