Declination compensation for seismic survey

US9354343B2 · kind B2 · utility

Assignee

• ION Geophysical Corporation · US

Inventors

• Phillip Roberts · San Diego, US
• Robert Fischer · Erlangen, DE
• Noel Zinn · Houston, US
• Curt Schneider · Houston, US
• Joseph R. Gagliardi · Katy, US
• Shawn Rice · Spring, US
• Timothy A. Dudley · Houston, US
• John Grant · Livingston, GB
• Kevin Simpson · Dunfermline, GB

Key dates

• Filing date: May 23, 2011
• Grant date: May 31, 2016
• Expiry date: May 23, 2031

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/31772
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

In seismic survey for icy waters, streamers are towed behind a vessel under the water's surface to avoid ice. GPS readings may not be consistently obtained because the ice prevents a tail buoy with a GPS receiver from trailing from streamer at the surface. Instead, a device tows on the streamer under the water's surface. The streamer's absolute position is tracked by intermittently bringing the towed device toward the surface so GPS readings can be obtained. The streamer's absolute position can then be used in conjunction with compass readings and can correlate various seismic sensor signals obtained along the streamer during the survey. The compass readings can be corrected for declination using declinometer readings, which can be compensated for iron effects from the vessel or other device carrying the declinometer.