# US 2014/0152298 A1 · Positioning method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152298 A1 - Document ID: US20140152298A1 - Status: Published application - Kind: A1 - Application number: 14/131,750 - Filed: 2012-07-11 - Published: 2014-06-05 - Earliest claimed: 2011-07-11 - Assignees: Welltec A/S - Inventors: Jørgen Hallunbæk; Mathias Francke - Web page: https://patentgrep.com/patent/US20140152298A1 ## CPC - E21B 47/092: by detecting magnetic anomalies - G01B 7/003: {for measuring position, not involving coordinate determination (coordinate measuring G01B7/004)} - 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) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS - 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 The invention relates to a positioning method for determining a position of a downhole tool moving at a velocity in a casing in a well, comprising the steps of measuring a magnitude and/or direction of a magnetic field by means of a first sensor several times over a time period while moving along a first part of the casing manufactured from metal, determining a manufacturing pattern of the casing along the first part from the measurement measuring a magnitude and/or direction of a magnetic field by means of the first sensor several times over a time period while moving along a second part of the casing manufactured from metal, determining the velocity of the tool along the second part, adjusting the determined velocity of the tool along the second part based upon the manufacturing pattern. ## Claims ### Claim 1 A positioning method for determining a position of a downhole tool moving in a casing in a well, comprising the steps of: measuring a magnitude and/or direction of a magnetic field several times over a time period by means of a first sensor comprised in the downhole tool, while moving along a first part of the casing, determining a manufacturing pattern of the first part of the casing based on the measurement, and determining a position of the downhole tool by comparing a reference manufacturing pattern of the first part of the casing with the determined manufacturing pattern of the first part of the casing. ### Claim 2 (depends on 1) A positioning method according to claim 1, further comprising the steps of: determining a reference manufacturing pattern by measuring a magnitude and/or direction of a magnetic field several times over a time period by means of a first sensor comprised in the downhole tool, while moving along a first part of the casing of a known length, estimating a wave length of the reference manufacturing pattern based on the number of waves of the reference manufacturing pattern and the known length of the first part of the casing having been measured, and counting the number of waves passing as the downhole tool moves along the first part of the casing, starting from the point of reference, wherein the position of the downhole tool is determined continuously with respect to the point of reference as the downhole tool moves along the first part of the casing, based on the number of waves counted and the estimated wave length. ### Claim 3 (depends on 1) A positioning method according to claim 1, further comprising the steps of: measuring a magnitude and/or direction of a magnetic field several times over a time period by means of a second sensor comprised in the downhole tool, while moving along the first part of the casing, the second sensor being arranged in the downhole tool with an axial distance to the first sensor, and determining the velocity of the downhole tool along the first part of the casing from a measured time period between the first sensor measuring a first point of the casing and the second sensor measuring the same first point of the casing. ### Claim 4 (depends on 3) A positioning method according to claim 3, further comprising the steps of: measuring a magnitude and/or direction of a magnetic field several times over a time period by means of the first sensor, while moving along a second part of the casing, determining a manufacturing pattern of the second part of the casing based on the measurement, determining the velocity of the downhole tool along the second part of the casing from a measured time period between the first sensor measuring a first point of the casing and the second sensor measuring the same first point of the casing, and comparing the manufacturing pattern of the first part of the casing and the manufacturing pattern of the second part of the casing to determine the position of the downhole tool to be able to adjust the determined velocity of the tool along the second part based on the manufacturing pattern. ### Claim 5 (depends on 1) A positioning method according to claim 1, wherein the determined manufacturing pattern results from thickness variations in the casing. ### Claim 6 (depends on 1) A positioning method according to claim 1, wherein the determined manufacturing pattern results from a rolling process, mill rolling, cold drawing or hot drawing. ### Claim 7 (depends on 1) A positioning method according to claim 1, wherein the determined manufacturing pattern results from a distance between a local minimum or maximum thickness of the casing and a next local minimum or maximum thickness of the casing. ### Claim 8 (depends on 1) A positioning method according to claim 1, wherein the sensors are arranged in a detecting unit arranged in a tool (1) and comprising two magnets (4) and two sensors (5, 6) arranged with an axial distance (d2) from each other and in a same plane (7), such as on a plate (8). ### Claim 9 (depends on 1) A positioning method according to claim 1, wherein the manufacturing pattern is several manufacturing pattern fractions identified along part of the casing. ### Claim 10 (depends on 1) A positioning method according to claim 1, wherein the casing is connected by means of casing collars and the first and second parts of the casing are arranged between two collars. ### Claim 11 (depends on 1) A positioning method according to claim 1, wherein the first part of the casing comprises several casing sections connected by collars. ### Claim 12 (depends on 1) A positioning tool for carrying out the method according to claim 1, comprising: a detecting unit comprising two magnets (4) and two sets of sensors (5, 6) arranged with an axial distance (d2) from each other and in a same plane (7), such as on a plate (8). ### Claim 13 (depends on 1) A positioning tool for carrying out the method according to claim 1. ### Claim 14 (depends on 1) Use of the method according to claim 1 for displaying a condition downhole in real time. ### Claim 15 (depends on 1) Use of the method according to claim 1, for displaying a position downhole in real time.