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Alwyn North Field Ocean Bottom Node (OBN) - A Step Change in Seismic Imagery, Inversion & Interpretation.
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
This paper presents the results of interpretation of first sparse ocean bottom node (OBN) survey over Alwyn North field, UKCS. Objectives of this new acquisition were twofold: firstly to enhance seismic imagery over Triassic reservoir and secondly to acquire quality data for detailed reservoir characterization. The Triassic sequence is a low net to gross system with thin sand bodies and lateral extension from a few to hundreds of meters. Owing to deep burial and diagenesis, Triassic sands have low porosity and permeability and hence limited recovery factor. Previous efforts to delineate them by inversion achieved limited success due to insufficient seismic data quality. This OBN acquired with full azimuth and long offset provides both PP and PS-wave datasets for interpretation and pre-stack inversion. On depth-migrated outputs a step change in imaging is observed compared to vintage streamer data. The structural interpretation of P-wave data has led to better understanding of the reservoir geometry, structural architecture and ultimately to a robust structural framework with less uncertainty.
An elastic PP inversion has been performed in 2016. This inversion together with seismic interpretation resulted in improved 3D mapping of Triassic sands, confirmation of regional sedimentary trends and better coherence with dynamic information.