Abstract
Seismic time-depth conversion for reservoir depth determination and digital well log interpretation of associated fluids was carried out in an X-field of the Niger delta with a view to establishing time-depth functions, in the vicinity of control wells, that could be used to estimate the reservoir depths and thickness of a pay zone (Horizon M10) elsewhere in the field prior to drilling. A combination of check-shot data and time picks on seismic section was used to generate time-depth functions from which depths to the top and bottom of the reservoir in the vicinity of two wells were established. An integrated multi parameter well log analysis was used to interpret the reservoir fluids within the selected horizon. Results showed that the top of Horizon M10 in the vicinity of well-7 was 5230 ft while its bottom was estimated to be 5327 ft with thickness; 97 ft. Around Well-4, the horizon was calculated to be 5108 ft at the top and 5194 ft at the bottom, its thickness was found to be 86 ft. Comparison with wire-line log depth recordings in the reference Wells showed that depth estimates from the seismic time-depth conversion fell well within the reservoir limits even though the reservoir thickness seem to be slightly underestimated. It was concluded that the seismic time-depth conversion for this X-field has an acceptable limit of accuracy and hence reliable for application elsewhere in the X-field. The fluid interpretation of the reservoir was found to be gas sands around well-7 and oil sands in the vicinity of well-4.
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