Unraveling a Carbonate System through Chrono-Stratigraphic Horizon Tracking and Wheeler Transformation

McBeath, Kirstin A.¹, Geert De Bruin², Paul De Groot² (1) University of Leeds, Leeds LS2 9JT, United Kingdom (2) dGB Earth Sciences BV, 7511 JM Enschede, Netherlands

This paper describes the application of a new seismic interpretation technique to a green-field carbonate exploration play. The aim of the study was to assess and understand the spatial and temporal significance of potential reservoir facies within a complex carbonate system in both the time-depth and Wheeler transformed ‘flattened seismic' domain. Systems tracts interpretation allowed for the prediction of potential reservoir facies distribution prior to drilling a deepwater well offshore West Africa. A three dimensional pre-stack time-migrated seismic volume of good-quality was used within the analysis and due to the largely unexplored nature of the area, no well control was available.

The analysis was based on classic sequence stratigraphic interpretation principles using new seismic interpretation software tools. The primary technique involved chrono-stratigraphic horizon tracking and Wheeler transformation. Auto-tracked chrono-stratigraphic surfaces (i.e. surfaces as a function of relative geological time) are generated for every seismic reflection event at sub-seismic accuracy and tracked throughout the seismic volume within the limits of conventionally mapped sequence-bounding surfaces. Through establishing such a chrono-stratigraphic framework, the subsequent visualization of such chrono-stratigraphic surfaces and corresponding ‘flattened seismic' in the Wheeler transformed domain is achieved. The depositional configuration and the presence of erosional truncations and non-depositional hiatuses are revealed in the Wheeler transformed domain, enabling detailed systems tracts interpretation to be performed through specifying chrono-stratigraphic ranges. Synchronized visualization of the seismic volume, corresponding chrono-stratigraphy and systems tracts interpretation in both the time-depth and Wheeler transformed domain led to new insights in carbonate facies progradation, aggradation, retrogradation, erosion and non-deposition.