Journal of Earth Sciences and Geotechnical Engineering

Weathered Layer Delineation in an ‘X’ Field in the Niger Delta Basin of Nigeria: The Uphole Data Acquisition Technique

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• Abstract

  A total of sixty-one (61) uphole refraction surveys carried out in the “X” field in the Niger Delta Basin of Nigeria were analysed using the time-intercept technique to evaluate the weathered layer. Results from the generated isopach and isovelocity maps suggest a three layer case comprising of weathered, sub-weathered and consolidated layers. With velocities varying from 318 – 1050 m/s, the first layer was interpreted to be a weathered layer whose thickness ranges from 1.6 – 8.6 m. The thickness of the sub-weathered layer ranges from 16.3 to 28.7 m while its velocity varies from 692 to 2549 m/s. The consolidated layer velocity ranges from 1100 to 3223 m/s with an average of 2427 m/s. The average thickness of the weathered layer to the first refractor consolidated layer is 25.5 m. This is therefore the suggested depth at which shots are to be taken to obtain high quality seismic reflection data. The results will be utilized in seismic data processing for a reliable delineation of structural and stratigraphic traps in oil and gas exploration in the Southern part of the Niger Delta.