# US 2017/0285198 A1 · Method and system for marine seismic acquisition > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0285198 A1 - Document ID: US20170285198A1 - Status: Published application - Kind: A1 - Application number: 15/475,309 - Filed: 2017-03-31 - Published: 2017-10-05 - Earliest claimed: 2016-04-05 - Assignees: Cgg Services SAS - Applicants: Cgg Services SAS - Inventors: Benoit JUPINET; Risto SILIQI - Web page: https://patentgrep.com/patent/US20170285198A1 ## CPC - G01V 1/3817: {Positioning of seismic devices} - G01V 1/3808: {Seismic data acquisition, e.g. survey design} - 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 seismic acquisition system for acquiring seismic data includes a streamer spread including first and second streamers, each of the first and second streamers having at least one seismic receiver and at least one position control device, and a seismic source located within an area underlined by the streamer spread and configured to generate seismic waves. The streamer spread and the source are towed independent of each other, a streamer separation DS between the first and second streamers varies along a length of the spread to comply with a given survey characteristic, and the streamer separation varies from a front-end value DS(F) at a front-end of the spread, to a middle of the spread value DS(O), to a back-end value DS(B) at a back-end of the spread, and the middle of the spread value is smaller than the front-end value and smaller than the back-end value. ## Claims ### Claim 1 A seismic acquisition system for acquiring seismic data, the system comprising: a streamer spread including first and second streamers, each of the first and second streamers having at least one seismic receiver and at least one position control device; and a seismic source located within an area underlined by the streamer spread and configured to generate seismic waves, wherein the streamer spread and the source are towed independent of each other, a streamer separation DS between the first and second streamers varies along a length of the spread to comply with a given survey characteristic, and the streamer separation varies from a front-end value DS(F) at a front-end of the spread, to a middle of the spread value DS(O), to a back-end value DS(B) at a back-end of the spread, and the middle of the spread value is smaller than the front-end value and smaller than the back-end value. ### Claim 2 (depends on 1) The system of claim 1, wherein the given survey characteristic is associated with a size of a Fresnel zone. ### Claim 3 (depends on 2) The system of claim 2, wherein the streamer separation is varied to achieve a constant size of the Fresnel zone for both small and large offsets. ### Claim 4 (depends on 1) The system of claim 1, wherein the front-end value is equal to the back-end value. ### Claim 5 (depends on 1) The system of claim 1, wherein the streamer separation DS changes continuously along the length of the spread. ### Claim 6 (depends on 1) The system of claim 1, wherein the first and second streamers are curved in a horizontal plane. ### Claim 7 (depends on 1) The system of claim 1, wherein the source is located at a middle of the length of the spread. ### Claim 8 (depends on 7) The system of claim 7, wherein a smallest value of the streamer separation is at the middle of the length of the spread. ### Claim 9 (depends on 1) The system of claim 1, wherein the source is located away from a middle of the length of the spread. ### Claim 10 (depends on 9) The system of claim 9, wherein a smallest value of the streamer separation is at a location of the source. ### Claim 11 (depends on 1) The system of claim 1, wherein a smallest value of the streamer separation is dynamically moved along the length of the spread with the position location devices. ### Claim 12 A method for acquiring seismic data, the method comprising: towing a streamer spread including first and second streamers, each of the first and second streamers having at least one seismic receiver and at least one position control device; towing a seismic source located within an area underlined by the streamer spread and configured to generate seismic waves; and controlling with the position location devices a streamer separation DS between the first and second streamers so that the streamer separation DS varies along a length of the spread to comply with a given survey characteristic, wherein the streamer spread is towed by a first vessel and the source is towed by a second vessel, and wherein the streamer separation varies from a front-end value DS(F) at a front-end of the spread, to a middle of the spread value DS(O), to a back-end value DS(B) at a back-end of the spread, and the middle of the spread value is smaller than the front-end value and smaller than the back-end value. ### Claim 13 (depends on 12) The method of claim 12, wherein the given survey characteristic is associated with a size of a Fresnel zone. ### Claim 14 (depends on 13) The method of claim 13, further comprising: varying the streamer separation along the length of the spread to achieve a constant size of the Fresnel zone for both small and large offsets. ### Claim 15 (depends on 12) The method of claim 12, wherein the front-end value is equal to the back-end value. ### Claim 16 (depends on 12) The method of claim 12, wherein the streamer separation DS changes continuously along the length of the spread. ### Claim 17 (depends on 12) The method of claim 12, wherein the source is located at a middle of the length of the spread. ### Claim 18 (depends on 12) The method of claim 12, further comprising: dynamically moving, with the position location devices, a smallest value of the streamer separation along the length of the spread. ### Claim 19 A method for acquiring seismic data, the method comprising: calculating plural streamer separations DS between first and second streamers of a spread so that the streamer separation DS varies along a length of the spread to comply with a given survey characteristic; calculating forces to be applied by birds, which are located on the first and second streamers, to maintain the streamer separations DS along the length of the spread; and programming the birds to hold the forces during a seismic survey to maintain the streamer separations DS while the first and second streamers move through the water, wherein there is a streamer separation DS(F) at a front-end of the spread, a streamer separation DS(O) at a middle of the spread, and a streamer separation DS(B) at a back-end of the spread, and the streamer separation at the middle of the spread is smaller than the streamer separations at the front-end and the back-end. ### Claim 20 (depends on 19) The method of claim 19, wherein the given survey characteristic is associated with a size of a Fresnel zone.