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