Geophone noise attenuation and wavefield separation using a multidimensional decomposition technique
Kenneth L. Craft, Josef Paffenholz · 2007
Combination of dual sensor (hydrophone and vertical geophone) data has long been used as a technique for attenuating ghost reflections from the air water interface. The fundamental concept is that up-going and down-going waves are measured differently by a velocity sensor while direction of progression of the wave has no polarity significance to the hydrophone. At its simplest, dual sensor processing for ghost elimination consists of simply summing recordings made with co-located hydrophones and geophones placed on the sea floor. It has been shown that, for a vertical wave path, a scalar can be applied to one of the two sensors to account for bottom reflectivity and suppress water layer reverberations (Barr and Sanders, 1989). Additional corrections are required when the geophone is not firmly coupled with the ocean bottom or there is significant reflectivity in the earth directly and immediately below the position of the sensor. Also, the geophone provides attenuated amplitude sensitivity to waves arriving at the sensor package in a direction other than its presumably vertical orientation while the hydrophone shows indifference to angle of arrival.