Digital Accelerometers: Expectations and Practical Achievements

With the dawn of this century came a new generation of seismic sensors. These are 1C or 3C MEMS based accelerometers integrated with electronics to deliver a well calibrated digital signal. Contrary to arrays of geophones, they must be recorded individually as point receivers. Since noise is only filtered during processing, the interval between receivers must be reduced to avoid spatial aliasing of the noise and to increase fold coverage. The benefits provided by digital sensors are both operational (weight, power consumption, integration with the line…) and geophysical (amplitude & phase response, vector fidelity, tilt detection…). Early 2D-3C tests as well as 3D production surveys, including those performed by the highest channel count crews (35,000+), confirm the benefits of these new sensors: immunity to pick-up noise due to full digital transmission; increase of the frequency bandwidth of the signal and of the associated vertical resolution; well calibrated amplitude suitable for AVO and inversion.