A New Structural Geology Workflow to Expedite and Validate Seismic Interpretation in a Structurally Complex Area: A Case Study from Exmouth Plateau, Australia

Roy, S. (Schlumberger) | Massara, P. (Woodside Energy) | Ellwood, M. (Schlumberger)



The Exmouth Plateau is a subsided, stretched and rifted continental platform that forms the northern part of the Northern Carnarvon Basin off Western Australia's northwest coast. The plateau is bound on three sides by oceanic crust and consists of more than eight kilometres of Palaeozoic to Mesozoic sediments (Exon & Willcox, 1978). Due to its geological history, the area presents significant structural challenges for interpretation and prospect evaluation. A new structural interpretation workflow has been developed, leveraging the efficiency of working in one single geoscience platform. The workflow reduces interpretation time and improves accuracy compared to traditional interpretation approaches. A significant advantage of this approach is that a structurally validated framework model is one of the primary outputs.

Structural interpretation from seismic data is one of the most important steps in understanding the subsurface. Geoscientists spend a considerable amount of interpretation time picking faults and horizons from seismic data to understand the subsurface structure. A traditional interpretation workflow, commonplace in the oil and gas industry, is to consecutively investigate separate 2D sections and subsequently combine the interpretations to build a 3D picture. This limits the understanding of the subsurface geology in highly faulted, structurally complex areas.

This study involved the application of a new workflow for producing a structurally validated interpretation on 3D seismic data from the eastern part of the Exmouth Plateau. This workflow incorporates seismic preconditioning, fault framework modelling, structural reconstruction and structural analysis techniques to validate the interpretation (Figure A––1). By constructing framework models of the data it is possible to visualize the interpretation in the richness of 3D. This ensures a valid interpretation of the subsurface geology and is critical for subsequent decision-making processes, such as prospect maturation or well-planning. The final result is clean, faulted seismic horizons and a highly accurate structural framework model. This model can then be used for fault throw analysis to understand growth faults and reactivation zones and investigate zonal fault juxtaposition for prospect analysis. The predictive capability of the framework model is key in ensuring exploration success in plays reliant on fault juxtaposition seal.

A new workflow to produce structurally validated interpretations in structurally complex regions.

The framework model also becomes the foundation for geo-cellular modelling and further detailed analysis of dynamic behavior. This ensures the verified structural interpretation is carried throughout the entire exploration and production lifecycle.