# US 7,610,960 B2 · Depth correlation device for fiber optic line > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,610,960 B2 - Document ID: US7610960B2 - Status: Granted - Kind: B2 - Application number: 11/739,949 - Filed: 2007-04-25 - Published: 2008-10-30 - Granted: 2009-11-03 - Earliest claimed: 2007-04-25 - Assignees: Baker Hughes Incorporated - Inventors: Luis E. Mendez; Stephen H. Poland - Web page: https://patentgrep.com/patent/US7610960B2 ## CPC - E21B 47/04: Measuring depth or liquid level - E21B 47/07: Temperature - E21B 47/09: Locating or determining the position of objects in boreholes or wells {, e.g. the position of an extending arm}; Identifying the free or blocked portions of pipes - E21B 47/135: using light waves, e.g. infrared or ultraviolet waves - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A correlation system is provided to allow association of readings from a cable that is supported by a string but that is coiled around or has slack in one or many locations to a specific location along the string itself. Heat sources can be placed along the string to periodically or continuously give off heat that can be detected by a cable such as a fiber optic. The location of the sources along the string is known and the location along the cable is determined from the location on the cable where the heat generated by the source is sensed. One or more sources can be used and correlation can be by periodic sampling or in real time. The sources may by powered locally or from the surface. ## Claims ### Claim 1 A wellbore depth correlation apparatus, comprising: a tubular string interval extending in a wellbore; a line adjacent said string that in said interval is a different length than said string; at least one device mounted to said string at a predetermined location and capable of correlating actual running length of said line to a position in said interval where said device is mounted. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein: said device transmits a signal sensed by said line. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein: said line collects data from the wellbore. ### Claim 4 (depends on 3) The apparatus of claim 3, wherein: said line comprises a fiber optic. ### Claim 5 (depends on 4) The apparatus of claim 4, wherein: said line collects wellbore temperature data. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein: said device transmits heat or vibration to said fiber optic. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein: said transmitted heat is discretely detected among the well temperature data collected by said fiber optic. ### Claim 8 (depends on 7) The apparatus of claim 7, wherein: said fiber optic is coiled around said string at least once in said interval. ### Claim 9 A wellbore depth correlation apparatus, comprising: a tubular string interval extending in a wellbore; a line adjacent said string that in said interval is a different length than said string; at least one device mounted to said string at a predetermined location and capable of correlating actual running length of said line to a position in said interval where said device is mounted; said device transmits a signal sensed by said line; said line collects data from the wellbore; said line comprises a fiber optic; said line collects wellbore temperature data; said device transmits heat or vibration to said fiber optic; said transmitted heat is discretely detected among the well temperature data collected by said fiber optic; said line has slack in said interval. ### Claim 10 (depends on 7) The apparatus of claim 7, wherein: said transmitted heat from said device is communicated out of said interval with the collected well temperature data. ### Claim 11 (depends on 6) The apparatus of claim 6, wherein: said device comprises a local power supply. ### Claim 12 (depends on 11) The apparatus of claim 11, wherein: said device generates heat or vibration either constantly or intermittently. ### Claim 13 (depends on 1) The apparatus of claim 1, wherein: said at least one device comprises a plurality of devices at predetermined locations in said interval. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein: said devices are identical. ### Claim 15 (depends on 13) The apparatus of claim 13, wherein: said line comprises a fiber optic and said devices transmit heat sensed by said fiber optic or vibration discretely from other well temperature data. ### Claim 16 (depends on 13) The apparatus of claim 13, wherein: said line either senses a well parameter, delivers material to said interval or collects material from said interval. ### Claim 17 A wellbore depth correlation apparatus, comprising: a tubular string interval extending in a wellbore; a line adjacent said string that in said interval is a different length than said string; at least one device mounted to said string at a predetermined location and capable of correlating actual running length of said line to a position in said interval where said device is mounted; said at least one device comprises a plurality of devices at predetermined locations in said interval; said line is at least in part coiled around said string. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein: said devices transmit heat or vibration in real time or intermittently. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein: said devices are locally powered or powered from outside the interval. ### Claim 20 (depends on 13) The apparatus of claim 13, wherein: said predetermined locations are identical. ### Claim 21 (depends on 4) The apparatus of claim 4, wherein: the refractive index of the fiber optic is either variable along its length or varies from the expected value for the material used. ### Claim 22 (depends on 15) The apparatus of claim 15, wherein: the refractive index of the fiber optic is either variable along its length or varies from the expected value for the material used.