*Do Digital Sensors Preserve Amplitude Better? Case Studies
Denis Mougenot1 and Lv Shuying1
Point receiver acquisition has become a common practice with the availability of high-channel count recorders and digital sensors like MEMS-based accelerometers. As a result of the combination of higher trace density and single-sensor recording, successful case studies have been published showing improvement in the vertical resolution thanks to wider frequency content and a better signal-to-noise ratio. However, another less-emphasized benefit is related to the enhanced amplitude preservation of both pre- and post-stack data. Even though this benefit is more difficult to demonstrate on seismic sections, it is of paramount importance since amplitude is the main input used for AVO and inversion.
In this paper, we use as examples recent surveys in China aimed at comparing MEMS-based accelerometers (DSU) with groups of geophones in different terrain types (loess plateau, deltaic plain). Prestack time-migration of each single sensor is a critical step in enhancing the signal as shown by CRPs after residual move-out corrections. These gathers display more consistent reflections from near- to far-offsets, while geophone data gets attenuated and lower frequency at far offset as already apparent on CMPs. This better consistency of the prestack amplitude is confirmed by computing AVO attributes. Digital sensors laid-out with adequate spacing display increased continuity of intercept and gradient over the whole section compared to the geophone groups that seem to be affected by near surface variations and directional array filtering. Together with better vertical resolution, such improved amplitude preservation has open the way to more accurate reservoir characterization.
AAPG Search and Discovery Article #90188 ©GEO-2014, 11th Middle East Geosciences Conference and Exhibition, 10-12 March 2014, Manama, Bahrain