Seismic noise cancellation in a geothermal field

Geophysics ◽  
1991 ◽  
Vol 56 (10) ◽  
pp. 1677-1680 ◽  
Author(s):  
D. B. Harris ◽  
S. P. Jarpe ◽  
P. E. Harben
Keyword(s):  
Seismic Noise ◽  
Noise Suppression ◽  
Noise Cancellation ◽  
Geothermal Field ◽  
Monitoring Site ◽  
High Background ◽  
Reflection And Refraction ◽  
Geothermal Fields ◽  
Passive Seismic ◽  
Adaptive Noise

High background seismic noise due to process machinery in production oil or geothermal fields can present a major problem for active seismic studies such as reflection and refraction surveys and passive seismic studies such as microearthquake monitoring. The general noise suppression problem is a difficult one since process noise may be due to a large number of sources distributed over a large region. In some situations, one or a few sources may dominate the noise field locally, presenting an opportunity for noise suppression by cancellation. In this note we describe an application of adaptive noise cancellation (Widrow, et al., 1975) in which we attempt to suppress noise recorded at a primary monitoring site using reference noise recorded at a major nearby noise source.

scholarly journals Fluid activity detection in geothermal areas using a single seismic station by monitoring horizontal-to-vertical spectral ratios

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kyosuke Okamoto ◽  
Hiroshi Asanuma ◽  
Hiro Nimiya
Keyword(s):  
Carbon Capture ◽  
Seismic Station ◽  
Carbon Capture And Storage ◽  
Fluid Flows ◽  
Temporal Variations ◽  
Geothermal Field ◽  
Spectral Ratios ◽  
Subsurface Structures ◽  
Geothermal Fields ◽  
Single Station

AbstractSubsurface structure survey based on horizontal-to-vertical (H/V) spectral ratios is widely conducted. The major merit of this survey is its convenience to obtain a stable result using a single station. Spatial variations of H/V spectral ratios are well-known phenomena, and it has been used to estimate the spatial fluctuation in subsurface structures. It is reasonable to anticipate temporal variations in H/V spectral ratios, especially in areas like geothermal fields, carbon capture and storage fields, etc., where rich fluid flows are expected, although there are few reports about the temporal changes. In Okuaizu Geothermal Field (OGF), Japan, dense seismic monitoring was deployed in 2015, and continuous monitoring has been consistent. We observed the H/V spectral ratios in OGF and found their repeated temporary drops. These drops seemed to be derived from local fluid activities according to a numerical calculation. Based on this finding, we examined a coherency between the H/V spectral ratios and fluid activities in OGF and found a significance. In conclusion, monitoring H/V spectral ratios can enable us to grasp fluid activities that sometimes could lead to a relatively large seismic event.

scholarly journals Adaptive Noise Cancellation of an Analog Fiber Optic Link

2021 ◽  
Author(s):  
Mohammad Nazrul Islam
Keyword(s):  
Optical Fiber ◽  
Fiber Optic ◽  
Signal To Noise Ratio ◽  
Optical Power ◽  
Noise Cancellation ◽  
Adaptive Noise Cancellation ◽  
Fiber Link ◽  
The Mean ◽  
Simulation Results ◽  
Adaptive Noise

There are three dominant noise mechanisms in an analog optical fiber link. These are shot noise that is proportional to the mean optical power, relative intensity noise (RIN) that is proportional to the square of the instanteaneous optical power. This report describes an adaptive noise cancellation of these dominant noise processes that persist an analog optical fiber link. The performance of an analog optical fiber link is analyzed by taking the effects of these noise processes. Analytical and simulation results show that some improvement in signal to noise ratio (SNR) and this filter is effective to remove noise adaptively from the optical fiber link.

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