# US 9,519,072 B2 · Method and apparatus for locating gas hydrate > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,519,072 B2 - Document ID: US9519072B2 - Status: Granted - Kind: B2 - Application number: 11/432,269 - Filed: 2006-05-11 - Published: 2007-11-15 - Granted: 2016-12-13 - Earliest claimed: 2006-05-11 - Assignees: Schlumberger Technology Corporation - Applicants: Robert Kleinberg; Jakob B.U. Haldorsen - Inventors: Robert Kleinberg; Jakob B.U. Haldorsen - Web page: https://patentgrep.com/patent/US9519072B2 ## CPC - G01V 1/288: {Event detection in seismic signals, e.g. microseismics (G01V1/36 takes precedence)} - G01V 3/083: {Controlled source electromagnetic [CSEM] surveying} - G01V 3/12: operating with electromagnetic waves {(operating with millimetre waves G01V8/005)} - E21B 41/0099: {specially adapted for drilling for or production of natural hydrate or clathrate gas reservoirs; Drilling through or monitoring of formations containing gas hydrates or clathrates} - G01V 2210/647: Gas hydrates - G01V 2210/65: Source localisation, e.g. faults, hypocenters or reservoirs - 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 An exploration paradigm for detecting and/or characterizing gas hydrate deposits using either electromagnetic or seismic surveys, that accounts for the possibility that gas hydrate may accumulate in vertical or subvertical dikes. Geologic factors, such as the presence of the gas hydrate stability zone, indications that a prolific source of gas exists (or existed) below the gas hydrate stability zone and indications that a high flux of gas could be transported into the gas hydrate stability zone, may be considered as part of an exploration strategy. Data may be collected using seismic techniques, such as a walk-away vertical seismic profile techniques, or electromagnetic surveys that are adapted to detecting the presence of vertical or subvertical dikes. In one example, data processing and acquisition techniques may be adapted to detect hydrate dikes, and do not assume a horizontally isotropic earth model. ## Claims ### Claim 1 A method of detecting gas hydrate, the method comprising: collecting electromagnetic surveying data about a region using an electromagnetic surveying technique; and characterizing at least one hydrate dike formation based at least in part on the electromagnetic surveying data, wherein characterizing the at least one hydrate dike formation includes estimating at least one of a dip and strike of a hydrate dike using the electromagnetic surveying data. ### Claim 2 (depends on 1) The method as claimed in claim 1, wherein collecting the electromagnetic surveying data includes performing an electromagnetic survey of the region using a transmitter and receiver system adapted to detect macroscopic subseafloor electrical anisotropy. ### Claim 3 (depends on 2) The method as claimed in claim 2, wherein performing the electromagnetic survey includes site includes performing the electromagnetic survey of the region using a transmitter and receiver system including a cross dipole-dipole array of antennas. ### Claim 4 (depends on 1) The method as claimed in claim 1, wherein collecting the electromagnetic surveying data includes estimating a direction of maximum horizontal stress in the region; towing a transmitter-receiver system over the site in a first direction parallel to the direction of maximum horizontal stress to collect first electromagnetic surveying data; towing the transmitter-receiver system over the site in a second direction perpendicular to the first direction to collect second electromagnetic surveying data; and comparing the first and second electromagnetic surveying data to detect evidence of macroscopic electrical anisotropy in the subsurface. ### Claim 5 (depends on 1) The method as claimed in claim 1, further comprising: collecting geologic information about the region; and determining a likelihood of significant hydrate presence in the region based at least in part on the geologic information. ### Claim 6 (depends on 5) The method as claimed in claim 5, wherein collecting the geologic information comprises identifying a location of a gas hydrate stability zone. ### Claim 7 (depends on 6) The method as claimed in claim 6, wherein collecting the geologic information further comprises determining a presence of a substantial source of gas below the gas hydrate stability zone. ### Claim 8 (depends on 6) The method as claimed in claim 6, wherein collecting the geologic information further comprises determining a presence of at least one of a fault or fracture extending into the gas hydrate stability zone from below the gas hydrate stability zone. ### Claim 9 An exploration method for detecting marine gas hydrate comprising: selecting an exploration site based on a geologic indication of a probable presence of hydrate dikes; surveying the exploration site using an electromagnetic survey technique to collect electromagnetic surveying data about the exploration site; and processing the electromagnetic surveying data based on an earth model that accounts (i) for the probable presence of hydrate dikes and (ii) for possible horizontal anisotropy. ### Claim 10 (depends on 9) The exploration method as claimed in claim 9, wherein surveying the exploration site includes performing an electromagnetic survey of the exploration site using a transmitter and receiver system adapted to detect macroscopic subseafloor electrical anisotropy. ### Claim 11 (depends on 10) The exploration method as claimed in claim 10, wherein surveying the exploration site includes performing the electromagnetic survey of the exploration site using a transmitter and receiver system including a cross dipole-dipole array of antennas. ### Claim 12 (depends on 10) The exploration method as claimed in claim 10, wherein surveying the exploration site includes performing the electromagnetic survey of the exploration site using a transmitter and receiver system comprising an array of horizontal electric dipole antennas, including at least two transmitter antennas and at least two receiver antennas; and wherein the antennas are arranged so as to provide at least four transmitter-receiver pairs, including a transverse electric pair and a transverse magnetic pair.