Acquisition Geometry

The survey was designed with the aim of providing a wide range of azimuthal coverage that would allow study of the azimuthal variations in the velocities, the reflectivity maps and the AVO gradient. A Button-Patch geometry was chosen and a total of ten patches were deployed. Figure 4 shows the survey layout and the pattern of the buttons. The survey used a total of 840 shots and 3840 receivers. Each geophone array is composed of 12 geophones over a 30 ft circle. Figure 5 shows the actual receiver's geometry where some geophone groups are missing and some buttons were not covered because of field conditions. A full fold of 20 was achieved across the interest zone of 4.5 miles. The nominal and maximum offsets are 12,000 and 18,000 ft. The maximum reflection angle at the target, as determined from the far absolute offset, is about 60 degrees.

 

layout
Figure 4 Button-Patch acquisition geometry (provided by Darnal, J. M; Arco Exploration and Production Technology.

 

geometry
Figure 5 Layout of the receiver groups in the 3-D survey.