Processing and Preliminary Interpretation of the Ultra High-Density Full-Azimuth 3D Seismic Survey, Dukhan Field, Qatar

Abstract

The Dukhan Field 3D seismic survey is an ultra high-density wide azimuth survey (i.e., point source and receiver, short source and receiver line interval, and full azimuth recording) intended to provide a significant uplift in quality and resolution to enable the imaging of reservoir sub-layers and fine-scale structural features. This paper presents the challenges and lessons learned from full-field processing and inversion. Seismic interpretation demonstrates added value to the field, which leads to improved reservoir models and support to well operations through improved well placement. Subtle structural, stratigraphic, and diagenetic features are now imaged.Knowledge gained from processing this survey includes: 1) cost, time, and effort invested on the Dukhan 3D survey is worthwhile as high quality results are obtained at 15m bin processing; 2) 3.75m bin processing is now possible, and could be performed to improve image quality over the full seismic bandwidth for all reservoir intervals; 3) Pre-Stack Depth Migration (PSDM) workflow is recommended for optimal offset and azimuth reconciliation and noise attenuation; 4) the adverse effect of near-surface geologic variability on seismic data quality can be improved by utilizing microgravity and resistivity (Vertical Electrical Sounding) techniques; and 5) proper preconditioning of the input data is critical for reliable prediction of reservoir properties away from well control.While industry's knowledge and experience in acquisition and field operation of ultra high-density full-azimuth seismic has increased over the last 3 years, processing of such data to ensure optimal imaging and reliable reservoir property predictions (e.g., porosity) has lagged. QP believes that lessons learned through this round of processing can provide insight for prediction of rock properties in the major Dukhan reservoirs.