# US 8,770,283 B2 · Systems and methods for distributed interferometric acoustic monitoring > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,770,283 B2 - Document ID: US8770283B2 - Status: Granted - Kind: B2 - Application number: 13/706,227 - Filed: 2012-12-05 - Published: 2013-04-18 - Granted: 2014-07-08 - Earliest claimed: 2007-11-02 - Assignees: Schlumberger Technology Corporation - Applicants: Schlumberger Technology Corporation - Inventors: Arthur H. Hartog; J. Ernest Brown; John Cook; Jonathan James Elphick; Paul Simon Hammond; Ashley Johnson - Web page: https://patentgrep.com/patent/US8770283B2 ## CPC - E21B 47/06: Measuring temperature or pressure - E21B 47/135: using light waves, e.g. infrared or ultraviolet waves - G01V 1/226: {Optoseismic systems} - 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 A method and system for acoustic monitoring using a fiber optic cable. The optical fiber is used as a distributed interferometer that may be used to monitor activity, such as activity with respect to a conduit, wellbore or reservoir. The distributed interferometric monitoring provides for accurate detection of acoustic occurrences along the fiber optic cable and these acoustic occurrences may include fluid flow in a pipeline or wellbore, processes taking place in a wellbore or pipeline, fracturing, gravel packing, production logging and/or the like. ## Claims ### Claim 1 A method for distributed acoustic detection or monitoring of activity, comprising: transmitting a monitoring signal through a fiber optic cable, wherein the monitoring signal comprises a pulse of a coherent beam of electromagnetic radiation where a coherence time of the coherent beam of electromagnetic radiation is equal to or longer than a time duration of the pulse, and wherein the fiber optic cable is disposed in a subterranean section of the Earth; detecting coherent Rayleigh noise generated by the transmission of the coherent beam of radiation through the fiber optic; processing the detected coherent Rayleigh noise to identify one or more acoustic occurrences in the subterranean section of the Earth; and monitoring or detecting the activity using the identified one or more acoustic occurrences. ### Claim 2 (depends on 1) The method of claim 1, wherein the fiber optic cable is disposed along or is disposed appurtenant to at least one of a wellbore, a cable and a pipeline. ### Claim 3 (depends on 2) The method of claim 2, wherein the cable comprises one of a power cable and a communications cable. ### Claim 4 (depends on 2) The method of claim 2, wherein the cable comprises copper. ### Claim 5 (depends on 1) The method of claim 1, wherein the activity comprises at least one of digging in the subterranean section of the Earth, walking on a surface of the subterranean section of the Earth, driving on the surface of subterranean section of the Earth and removing an item from the subterranean section of the Earth. ### Claim 6 (depends on 1) The method of claim 1, further comprising: using a time-of-flight of the pulse to identify a location of the one or more acoustic occurrences along the fiber optic cable. ### Claim 7 (depends on 1) The method of claim 1, wherein the fiber optic cable comprises at least one end that is non-reflective. ### Claim 8 (depends on 1) The method of claim 1, further comprising: measuring at least one of pressure and temperature in the subterranean section of the Earth; and using the measured at least one of temperature and pressure to process the detected coherent Rayleigh noise. ### Claim 9 (depends on 1) The method of claim 1, wherein one or more microphones are coupled along the fiber optic cable and configured to detect the one or more acoustic occurrences. ### Claim 10 (depends on 1) The method of claim 1, wherein the step of monitoring or detecting the activity comprises comparing the identified acoustic occurrences with an acoustic signature associated with the activity. ### Claim 11 (depends on 1) The method of claim 1, wherein the acoustic signature associated with the activity is determined from at least one of experimentation, modeling, previous use of the fiber optic cable and theoretical calculations. ### Claim 12 (depends on 1) The method of claim 1, further comprising: transmitting a second monitoring signal through the fiber optic cable, wherein the second monitoring signal comprises a second pulse of coherent electromagnetic radiation where a coherence time of the coherent electromagnetic radiation is equal to or longer than a time duration of the second pulse, and wherein the step of processing the detected coherent Rayleigh noise to identify one or more acoustic occurrences in the subterranean section of the Earth comprises comparing the coherent Rayleigh noise generated from the monitoring signal and a second coherent Rayleigh noise generated from the second pulse. ### Claim 13 (depends on 1) The method of claim 1, wherein the one or more acoustic occurrences comprise acoustic signals generated in the subterranean section of the Earth by the activity. ### Claim 14 A system for distributed acoustic detection or monitoring of activity, comprising: a fiber optic cable disposed in a subterranean section of the Earth; a source of coherent electromagnetic radiation coupled with the fiber optic cable and configured in use to inject a pulse of coherent electromagnetic radiation into the fiber optic cable, wherein a coherence time of the coherent beam of electromagnetic radiation is equal to or longer than a time duration of the pulse; a detector coupled with the fiber optic cable and configured to detect coherent Rayleigh noise generated in the fiber optic cable by the pulse of coherent electromagnetic radiation; and a processor in communication with the detector and configured to detect or monitor activity by processing the detected coherent Rayleigh noise. ### Claim 15 (depends on 14) The system of claim 14, further comprising: a database of acoustic signatures associated with different activities. ### Claim 16 (depends on 15) The system of claim 15, wherein the different activities comprise walking on a surface of the subterranean section of the Earth, driving on the surface of the subterranean section of the Earth, digging in the subterranean section of the Earth and removing an object from the subterranean section of the Earth. ### Claim 17 (depends on 14) The system of claim 14, wherein the fiber optic cable comprises one or more gratings. ### Claim 18 (depends on 14) The system of claim 14, wherein the fiber optic cable comprises one or more microphones. ### Claim 19 (depends on 14) The system of claim 14, wherein the fiber optic cable comprises one or more amplifiers. ### Claim 20 (depends on 14) The system of claim 14, wherein the fiber optic cable is arranged in a grid or a spiral in the subterranean section of the Earth. ### Claim 21 (depends on 14) The system of claim 14, wherein fiber optic cable comprises a plurality of fiber optic cables.