Orthogonal sweeps of vibroseis

Vibroseis is a method that imparts coded seismic energy into the ground. The energy is recorded with geophones and then processed using the known (coded) input signal. The resulting time-domain representation of vibroseis data is an impulsive wavetrain with wavelet properties consistent with the coded input signal convolved with the earth’s reflectivity series. Historically vibratory seismic surveys collect data from one source location at a time summing one or more sources at each location. In this abstract, we present a method of designing orthogonal sweeps using the concept of combisweeps. The orthogonal sweeps allow simultaneous recording and later separation of two (or more) unique source locations. Orthogonality of sweeps permits separation of the data into unique source location field records by a simple correlation procedure. Coincident generation and recording of two vibroseis sweeps at different locations would allow almost double the data recorded for a given occupation time. Simulations suggest separation performance of 33 dB.