From Field Tapes to 3D Depth Volume in 2 Months: A Challenging and Successful Project in The North Bardawill Area
By
Kamal Barsoum1, Dario Cegani2, Flavio Doniselli2, Luigi Pizzaferri2
(1) ENI/AGIP - IEOC (Egyptian Branch), Cairo, Egypt (2) ENI Agip Division, San Donato Milanese, Italy
In the North Bardawil Concession area, operated by IEOC, the exploration
target is represented by the turbiditic sands beneath the Messinian Evaporitic
complex. Their seismic image is heavily affected by the overburden velocity
variations and only a correct depth imaging approach can remove these
distortions clearly visible in the time volume.
A depth imaging project was then started with the main target of resolving
the depth positioning of the seismic reflectors. This objective would have
required a careful velocity
analysis
and a proper depth migration. Another
strict constrain was its time schedule: due to exploration obligations the whole
depth imaging project was due to be completed in two months. Then a work flow
was designed to try to accommodate either the quality requirements and the short
time frame. Since the construction of a detailed
velocity
volume could only be
achieved via a
velocity
analysis
in the depth domain, 31 seismic lines were
extracted from the relevant 3D survey, processed from field tapes to deconvolved
CMP
gathers
, further improved in the pre-stack depth domain and used to derive a
consistent 3D
velocity
volume. A 3D Post Stack Depth Migration (PoSDM) algorithm
was applied to the stack volume producing a depth volume down to 7800 m, over
the 800 sqKm of the 3D survey.
The strict cooperation between time processors, depth imagers, geophysicists and geologists coupled with the availability of adequate computer facilities proved to be the winning factor for the successful completion of this challenging project.