ABSTRACT: Dramatic improvements in seismic imaging using new single sensor technology

Dowdney, Roger¹, and Leon Walker²
(1) Schlumberger Oilfield Services, W. Sussex, England 
(2) Schlumberger Geco-Prakla, Jakarta, Indonesia

Conventional seismic data are acquired using arrays comprising many individual sensors hard-wired together for each output channel. This is done to improve signal strength and to attenuate specific coherent noise such as groundroll. Conventional systems often result in inadequate spatial sampling of the seismic wavefield. Arrays also act as a spatial filter, particularly for non-vertical arrivals. On land, individual geophones within the array have different elevations, variations in coupling and intra-group statics. These perturbations degrade the quality of the combined output signal. Errors and differences in positioning between time-lapse (4D) surveys add noise that can mask subtle changes in the seismic response of a reservoir; a major challenge when using marine towed streamers.

A new methodology has been developed, named Q, which records uncompromised single sensor data. Q technology can correct each sensor for sensitivity and environmental effects such as statics, elevations and coupling. Dynamic group forming ensures better signal preservation and enhanced frequency recovery, particularly at far offsets. Q delivers an optimally sampled 3D-wave field ready for imaging, analysis and interpretation into the reservoir model. With up to 30,000 channel capability, Q-Land provides a platform for wider use of multicomponent techniques onshore. Q-Marine technology reduces errors and differences in positioning between 4D datasets, enhancing the viability of time-lapse monitoring of reservoirs. Q surface seismic technology and new generation positioning systems, coupled with advanced data QC and processing, have been implemented in Q-Borehole, a multishuttle, multicomponent borehole seismic tool for single well seismic imaging.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia