# US 2009/0260879 A1 · Magnetic ranging while drilling using an electric dipole source and a magnetic field sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2009/0260879 A1 - Document ID: US20090260879A1 - Status: Published application - Kind: A1 - Application number: 12/105,698 - Filed: 2008-04-18 - Published: 2009-10-22 - Earliest claimed: 2008-04-18 - Assignees: Schlumberger Technology Corporation - Inventors: Brian Clark; Jaideva C. Goswami - Web page: https://patentgrep.com/patent/US20090260879A1 ## CPC - E21B 47/0228: using electromagnetic energy or detectors therefor - E21B 43/2406: {Steam assisted gravity drainage [SAGD]} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A system and methods for drilling a well in a field having an existing well are provided. In accordance with one embodiment, a method of drilling a new well in a field having an existing well includes drilling the new well using a bottom hole assembly (BHA) having a drill collar divided by an insulated gap, generating a current on the drill collar of the BHA while drilling the new well, and measuring from the existing well a magnetic field caused by the current on the drill collar of the BHA. Using measurements of the magnetic field, the relative position of the new well to the existing well may be determined. ## Claims ### Claim 1 A method comprising: drilling a new well in a field having an existing well using a bottom hole assembly (BHA) having a drill collar divided by an insulated gap; generating a current on the BHA while drilling the new well; and measuring from the existing well a magnetic field caused by the current on the drill collar of the BHA. ### Claim 2 (depends on 1) The method of claim 1, comprising determining the relative position of the new well to the existing well using measurements of the magnetic field. ### Claim 3 (depends on 2) The method of claim 2, wherein the relative position of the new well to the existing well is determined based on a comparison of the measurements of the magnetic field to a theoretical model or to data from a table based on a relationship describing a magnetic field generated by an electric dipole. ### Claim 4 (depends on 1) The method of claim 1, comprising using measurements of the magnetic field to determine a point of closest approach between the new well and the existing well. ### Claim 5 (depends on 4) The method of claim 4, comprising using measurements of the magnetic field to determine a distance between the new well and the existing well at the point of closest approach ### Claim 6 (depends on 5) The method of claim 5, comprising performing the method in the recited order. ### Claim 7 (depends on 1) The method of claim 1, wherein drilling the new well comprises drilling the new well such that a segment of the new well is located within 50 meters of a segment of the existing well. ### Claim 8 (depends on 7) The method of claim 7, wherein drilling the new well comprises drilling the new well such that the segment of the new well located within 50 meters of the segment of the existing well is not parallel to segment of the existing well. ### Claim 9 A method of drilling a well comprising: drilling a horizontal well in a field having a vertical well using a bottom hole assembly (BHA) having a drill collar divided by an insulated gap; generating a current on the drill collar of the BHA while drilling the horizontal well; and measuring from the vertical well a magnetic field caused by the current on the BHA. ### Claim 10 (depends on 9) The method of claim 9, comprising adjusting a drilling trajectory of the BHA while drilling the horizontal well based on measurements of the magnetic field when a drill bit of the BHA approaches within 30 m of the vertical well. ### Claim 11 (depends on 9) The method of claim 9, comprising locating in the vertical well a point of closest approach between the vertical well and the horizontal well based on measurements of the magnetic field. ### Claim 12 (depends on 11) The method of claim 11, comprising estimating a distance between the vertical well and the horizontal well at the point of closest approach. ### Claim 13 (depends on 11) The method of claim 11, wherein the point of closest approach is located by observing when a vector component of the magnetic field changes sign. ### Claim 14 (depends on 11) The method of claim 11, wherein the point of closest approach is located by observing when a vector component of the magnetic field reaches a peak. ### Claim 15 (depends on 9) The method of claim 9, comprising estimating a distance between the vertical well and the horizontal well based on a change in magnetic flux as the BHA moves toward or away from the vertical well. ### Claim 16 (depends on 9) The method of claim 9, wherein the horizontal well and the vertical well are Toe to Heel Air Injection (THAI) wells. ### Claim 17 A method of drilling a well comprising: drilling a second horizontal well above a first horizontal well using a bottom hole assembly (BHA) having a drill collar divided by an insulated gap; generating a current on the drill collar of the BHA while drilling the second horizontal well; and measuring from the first horizontal well a magnetic field caused by the current on the BHA. ### Claim 18 (depends on 17) The method of claim 17, comprising adjusting a trajectory of the BHA such that the second horizontal well will be drilled substantially perpendicular to the first horizontal well based on measurements of the magnetic field. ### Claim 19 (depends on 17) The method of claim 17, comprising locating in the first horizontal well a point of closest approach between the first horizontal well and the second horizontal well based on measurements of the magnetic field. ### Claim 20 (depends on 18) The method of claim 18, comprising estimating a distance between the first horizontal well and the second horizontal well at the point of closest approach. ### Claim 21 (depends on 17) The method of claim 17, comprising estimating a distance between the first horizontal well and the second horizontal well based on a change in magnetic flux as the BHA moves toward or away from the first horizontal well. ### Claim 22 (depends on 17) The method of claim 17, wherein the first horizontal well and the second horizontal well are Cross Well Steam Assisted Gravity Drainage (X-SAGD) wells. ### Claim 23 A drilling system comprising: a bottom hole assembly (BHA) having a drill collar divided by an insulated gap and an electric current driving tool, the electric current driving tool being configured to generate an electric current on the drill collar of the BHA while drilling; and a magnetometer configured to measure from an existing well a magnetic field generated by the electric current. ### Claim 24 A method of drilling a well comprising: drilling a new well in a field having an existing well; generating a magnetic field from an electric dipole in the new well; and measuring the magnetic field using a magnetometer disposed in the existing well. ### Claim 25 (depends on 24) The method of claim 24, comprising adjusting a drilling trajectory of the new well based on measurements of the magnetic field. ### Claim 26 (depends on 24) The method of claim 24, comprising determining the relative position of the new well to the existing well based on measurements of the magnetic field. ### Claim 27 (depends on 26) The method of claim 26, wherein the relative position of the new well to the existing well is determined based on a comparison of the measurements of the magnetic field to calculations based on a relationship describing a magnetic field generated by an electric dipole.