© 2007 EAGE
77
focus on azimuth first break volume 25, March 2007
The problem of collecting seismic data is rather like attending
a football match, as described in the textbook ‘Introduction
to petroleum seismology’ (Ikelle and Amundsen, 2005). Your
view of the game depends not only on the lighting system of
the stadium but also on where you are sitting. For example,
a journalist may prefer to be in the stands where he or she
will have a good view of the entire game, which is necessary
for analyzing and reporting all of the moves and tactics. A
photographer, however, may prefer to be near the touch-
line where he or she can immortalize the goals, even at the
expense of not seeing the rest of the game. The ticket prices
for these special positions may be more than that of a stand-
ard seat; but the extra cost will pay off handsomely .
As in football matches, the view of the subsurface given
by seismic data is determined by the location of the sound
sources for ‘illuminating’ the area of interest, and the loca-
tion and types of sensors that capture the ground motion
caused by the passage of seismic waves.
Standard towed-streamer seismic surveys may be unsuit-
able for obtaining the very best reservoir images, especial-
ly in geologically complex areas. However, the recording of
ocean bottom seismic (OBS) data – although more expen-
sive – offers the distinct advantage of flexible acquisition
geometries. Virtually any pattern of sound sources (shots)
and receivers is possible with the aim of capturing the most
revealing images. True 3D data acquisition is realized by
using a stationary seabed sensing system combined with a
survey vessel shooting over a predetermined grid on the sea
surface. Every subsurface point on the target can thus be
illuminated from all directions and a large number of angles
during an OBS survey .
Introduction
During the summer of 2005 the EAGE and SEG organized
a Summer Research Workshop, dedicated to multi-compo-
nent seismic, held in Pau, France. During this workshop
it was observed that the largest increase, from the previ-
ous Boise (2000) workshop, in ‘proven’ multi-component
capability was in reservoir monitoring. Surprisingly , the
driver behind the multi-component business was not shear
Experiences with full-azimuth acquisition
in ocean bottom seismic
Mark Thompson,
1*
Børge Arntsen,
1
and Lasse Amundsen
1
1
Statoil ASA, Arkitekt Ebbels veg 10, 7005, Trondheim, Norway; E-mail: math@statoil.com.
*
Corresponding author; E-mail:MATH@statoil.com.
Figure 1 Schematic cross-section of the Statfjord field.