# US 10,767,466 B2 · Active ranging-while-drilling with magnetic gradiometry > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,767,466 B2 - Document ID: US10767466B2 - Status: Granted - Kind: B2 - Application number: 15/546,235 - Filed: 2017-01-10 - Published: 2018-11-22 - Granted: 2020-09-08 - Earliest claimed: 2016-02-12 - Assignees: Halliburton Energy Services, Inc. - Applicants: Halliburton Energy Services, Inc. - Inventors: Glenn Andrew Wilson; Paul F. Rodney; Akram Ahmadi Kalateh Ahmad; Hsu-Hsiang Wu - Web page: https://patentgrep.com/patent/US10767466B2 ## CPC - E21B 47/0228: using electromagnetic energy or detectors therefor - E21B 47/022: of the borehole, e.g. using geomagnetism - G01C 21/20: Instruments for performing navigational calculations (G01C21/24, G01C21/26 take precedence) - E21B 43/2406: {Steam assisted gravity drainage [SAGD]} - E21B 47/18: through the well fluid {, e.g. mud pressure pulse telemetry} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S) ## Abstract Systems and methods for active ranging-while-drilling (ARWD) for collision avoidance and/or well interception. A method for ranging while drilling may comprise employing a rotating magnet assembly to induce a changing magnetization and/or electric current in a conductive member disposed in a target wellbore, wherein the rotating magnet assembly may be employed in a second wellbore; measuring at least one component of a magnetic gradient tensor using receivers; and calculating a relative location of the conductive member based at least in part on the measurements of the at least one component of the magnetic gradient tensor. ## Claims ### Claim 1 A method for ranging-while-drilling comprising: employing a rotating magnet assembly to induce a changing magnetization and/or electric current in a conductive member disposed in a target wellbore, wherein the rotating magnet assembly is employed on a bottom-hole-assembly (BHA) disposed in a second wellbore, the rotating magnet assembly comprising a plurality of magnet arrays configured to provide a magnetization direction, and wherein the magnetization direction is oriented at an angle between thirty degrees and sixty degrees with respect to a central axis of the BHA; measuring at least one component of a magnetic gradient tensor using receivers employed at one or more locations of the BHA; and calculating a relative location of the conductive members with respect to the BHA based at least in part on the measurements of the at least one component of the magnetic gradient tensor. ### Claim 2 (depends on 1) The method of claim 1, wherein the rotating magnet assembly comprises a permanent magnet and/or an electromagnet. ### Claim 3 (depends on 1) The method of claim 1, wherein at least one of the two or more conductive members is a casing string. ### Claim 4 (depends on 1) The method of claim 1, further comprising measuring at least one vector component of a magnetic field with the receivers. ### Claim 5 (depends on 1) The method of claim 1, further comprising rotating the rotating magnet assembly up to about 300 revolutions per minute. ### Claim 6 (depends on 1) The method of claim 1, wherein the rotating magnet assembly is positioned on a bottom hole assembly. ### Claim 7 (depends on 1) The method of claim 1, wherein the rotating magnet assembly is positioned about 2 feet to about 40 feet from a drill bit. ### Claim 8 A method for ranging while drilling comprising: employing a rotating magnet assembly, wherein the rotating magnet assembly induces a changing magnetic moment and/or electric current in a conductive members disposed in a target wellbore, wherein the rotating magnet assembly is employed on a bottom-hole-assembly (BHA) disposed in a second wellbore, the rotating magnet assembly comprising a plurality of magnet arrays configured to provide a magnetization direction, and wherein the magnetization direction is oriented at an angle between thirty degrees and sixty degrees with respect to a central axis of the BHA; measuring one or more components of a magnetic gradient tensor using rotating magnetic sensors at two different positions along the second wellbore; calculating a gradient field from the one or more components of the magnetic gradient tensor; and calculating a relative location of the conductive members with respect to the BHA based at least in part on the at least two measurements of the magnetic sensors. ### Claim 9 (depends on 8) The method of claim 8, wherein the rotating magnet assembly comprises a permanent magnet and/or an electromagnet. ### Claim 10 (depends on 9) The method of claim 9, wherein the rotating magnet assembly comprises permanent magnets positioned around a flow bore of an electromagnetic ranging tool. ### Claim 11 An electromagnetic ranging system comprising: an electromagnetic ranging tool disposed on a drill string, wherein the electromagnetic ranging tool comprises a magnetic source that induces a changing magnetization and/or an electric current in a conductive members and a receiver operable to measure at least one component of a magnetic gradient tensor, wherein the magnetic source comprises a rotating magnet assembly, the rotating magnet assembly comprising a plurality of magnet arrays configured to provide a magnetization direction, and wherein the magnetization direction is oriented at an angle between thirty degrees and sixty degrees with respect to a central axis of the BHA; and an information handling system operable to determine a relative location of the conductive members with respect to the drill string from one or more components of a magnetic gradient tensor measured by the receiver. ### Claim 12 (depends on 11) The electromagnetic ranging system of claim 11, wherein the rotating magnet assembly comprises a permanent magnet and/or an electromagnet. ### Claim 13 (depends on 11) The electromagnetic ranging system of claim 11, wherein the magnetic source comprises Sm2Co17. ### Claim 14 (depends on 11) The electromagnetic ranging system of claim 11, wherein the plurality of magnet arrays are positioned around a flow bore of the electromagnetic ranging tool.