# US 2014/0191761 A1 · Fiberoptic Systems and Methods for Subsurface EM Field Monitoring > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191761 A1 - Document ID: US20140191761A1 - Status: Published application - Kind: A1 - Application number: 13/736,487 - Filed: 2013-01-08 - Published: 2014-07-10 - Earliest claimed: 2013-01-08 - Assignees: Halliburton Energy Services, Inc. ("HESI") - Applicants: Halliburton Energy Services, Inc. ("Hesi") - Inventors: Luis E. SAN MARTIN; Etienne M. SAMSON; Burkay DONDERICI - Web page: https://patentgrep.com/patent/US20140191761A1 ## CPC - G01V 3/20: operating with propagation of electric current - E21B 47/0228: using electromagnetic energy or detectors therefor - E21B 47/135: using light waves, e.g. infrared or ultraviolet waves - G01V 3/28: using induction coils - E21B 47/017: Protecting measuring instruments - G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A disclosed subsurface electromagnetic field monitoring system employs at least one fiberoptic cable to optically communicate measurements from an array of electromagnetic field sensors in a borehole. A data processing system that receives the measurements and responsively models the subsurface electromagnetic field, which in at least some cases is generated by a controlled source such as a downhole electric or magnetic dipole source or a casing that serves as an electrode for injecting a distributed current into the formation. At least some disclosed method embodiments include: receiving measurements from an array of electromagnetic field sensors via a fiberoptic cable in a borehole; modeling a subsurface electromagnetic field based on estimated formation parameters to predict said measurements; adjusting the estimated formation parameters to improve a match between predicted measurements and received measurements; and displaying the estimated formation parameters after matching the predicted measurements to the received measurements. ## Claims ### Claim 1 A subsurface electromagnetic field monitoring system that comprises: at least one fiberoptic cable that optically communicates measurements from an array of electromagnetic field sensors in a borehole; and a data processing system that receives said measurements and responsively models the subsurface electromagnetic field. ### Claim 2 (depends on 1) The system of claim 1, further comprising a controlled source that generates said subsurface electromagnetic field. ### Claim 3 (depends on 2) The system of claim 2, wherein the controlled source injects a distributed current via a casing in said borehole. ### Claim 4 (depends on 3) The system of claim 3, wherein the controlled source injects a current via a casing in a second borehole. ### Claim 5 (depends on 2) The system of claim 2, wherein the controlled source is an electric dipole source positioned in an annular space between a casing and a wall of said borehole. ### Claim 6 (depends on 2) The system of claim 2, wherein the controlled source is a magnetic dipole source positioned in an annular space between a casing and a wall of said borehole. ### Claim 7 (depends on 2) The system of claim 2, wherein the data processing system derives a multi-dimensional model of formation resistivity or conductivity based at least in part on said subsurface electromagnetic field. ### Claim 8 (depends on 7) The system of claim 7, wherein the data processing system determines a fluid interface location based at least in part on the multi-dimensional model of formation resistivity or conductivity. ### Claim 9 (depends on 1) The system of claim 1, wherein said sensors each provide a measure of magnetic field strength or gradient. ### Claim 10 (depends on 9) The system of claim 9, wherein said sensors are atomic magnetometers. ### Claim 11 (depends on 9) The system of claim 9, wherein said sensors include a magnetic element that displaces a reflective surface in response to the magnetic field. ### Claim 12 (depends on 1) The system of claim 1, wherein said sensors each provide a measure of a magnetic field derivative. ### Claim 13 (depends on 12) The system of claim 12, wherein said sensors include a coil antenna. ### Claim 14 (depends on 1) The system of claim 1, wherein said sensors each provide a measure of electric field strength. ### Claim 15 (depends on 14) The system of claim 14, wherein said sensors include a charged element that displaces a reflective surface in response to the electric field. ### Claim 16 A subsurface electromagnetic field monitoring method that comprises: receiving measurements from an array of electromagnetic field sensors via a fiberoptic cable in a borehole; modeling a subsurface electromagnetic field based on estimated formation parameters to predict said measurements; adjusting the estimated formation parameters to improve a match between predicted measurements and received measurements; and displaying the estimated formation parameters after matching the predicted measurements to the received measurements. ### Claim 17 (depends on 16) The method of claim 16, wherein the estimated formation parameters include resistivity or conductivity. ### Claim 18 (depends on 17) The method of claim 17, further comprising deriving a location of a fluid front from the estimated formation parameters. ### Claim 19 (depends on 16) The method of claim 16, wherein said sensors each include an atomic magnetometer. ### Claim 20 (depends on 16) The method of claim 16, wherein said sensors each include a coil antenna.