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.