A Successful Application of 3D Seismic Attributes in Exploration for Eolian Stratigraphic Traps in Central Saudi Arabia

摘要

The purpose of this presentation is to demonstrate the successful application of 3D seismic attributes in exploration for Permo-Carboniferous eolian stratigraphic traps in central Saudi Arabia. To explore for these traps, we have integrated regional geological studies and rock property analysis, and tied these to the seismic attribute response. Permo-Carboniferous eolian reservoirs are the primary objective for oil and gas exploration in central Saudi Arabia. Due to the nature of the mixed fluvio-eolian setting, this is a very challenging target, especially for stratigraphic traps. The eolian setting comprises a complex mix of depositional systems including eolian ergs, ephemeral streams, and ephemeral (playa) lakes. Eolian sand dunes and sand sheet deposits are the two main reservoir facies, while lateral facies changes result in the primary up-dip seals. We carried out detailed well-to-seismic correlations at the reservoir level and found that the following seismic attributes were useful in exploring for these stratigraphically trapped eolian reservoirs: 1. Reservoir thickness and quality: (1) sum of positive amplitude over the target interval, (2) isochron from Early Triassic to Early Permian, (3) isochron from top to base of the target, (4) frequency decomposition, (5) acoustic impedance inversion, and (6) deformation of seismic wavelet. 2. Up-dip seal: Sum of the negative amplitude over the target interval. 3. Hydrocarbon potential: AVO/AVA inversion. Exploration results in the study area indicate that the above mentioned seismic attributes correlate very well to changes in geologic environment, and to log and reservoir properties. The integration of 3D seismic attributes with regional geologic studies and existing well control has been very successful in exploring for eolian stratigraphic traps in central Saudi Arabia.