Optimizing the Weighted-sum Signal to Represent the Actual Force Output from the Vibrator

Vibrators are the most widely used land seismic sources. To obtain a high quality image of the subsurface, it is important and necessary to know the outgoing signal from the vibrator. This outgoing signal is called the vibrator ground force and is often estimated by using a weighted sum of accelerations of the reaction mass and the baseplate. This weighted-sum method has a limited frequency bandwidth because of the low rigidity of the vibrator baseplate. Using force sensors such as load cells can provide a true measurement of the vibrator ground force, but are not yet robust enough for routine use. With an optimized baseplate accelerometer position on a stiffer baseplate the weighted-sum method yields a significantly better representation for the vibrator ground force. This finding is also supported by the proportional relationship between harmonic components of the weighted-sum signal and the far-field signal.