Microphone suppression of air-noise on geophones

Air-noise in seismic records creates a loss in signal quality, reducing seismic image clarity. A microphone may be used to estimate and remove air-noise in seismic records. This thesis covers the characterization of air-noise on a prototype 4-Component geophone (3-C geophone plus microphone), as well as the development of two air-noise removal filters. Vibration-isolated, noise characterization experiments were performed to determine the 4-C geophone’s directional and frequency dependent response to air-noise. Sensor placement within the geophone appeared to affect each geophone component’s directional response; showing increased sensitivity to sounds from the same side the sensor was mounted. In addition, a walk-away seismic survey was performed to determine the effect of distance on geophone air-noise. Peak amplitude decay rates differed from the theoretical 1/R, R representing total distance. The microphone and inline geophone decayed at 1/R^1.4, the crossline component at 1/R^1.15, and the vertical component at 1/R^1.81. These results indicate a loss of energy to heat through air-ground interactions. Results from the noise characterization tests were used to develop two air-noise filters; a real-time filter, which could remove air-noise from geophone signals before they are recorded; and a post-acquisition filter, which could be used to more precisely remove air-noise. Both filters were effective at reducing air-noise, up to 21 dB reduction for near offsets. However, the real-time filter affected seismic data due to microphone recorded seismic events.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Geophysics

Grantor

University of Houston

Year dc:date.issued

2012

Author dc:creator

• Babcock, Nathan

Advisor dc:contributor.advisor

• Stewart, Robert R.

Committee members dc:contributor.committeemember

• Liner, Christopher L.
• Danbom, Stephen H.

• Seismic data
• Air-noise
• Real-time filter
• 4-Component geophone

Statement dc:rights

• The author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/10657/ETD-UH-2012-08-503

OAI identifier oai:identifier

oai:uh-ir.tdl.org:10657/ETD-UH-2012-08-503