Tuesday, March 20, 1:00pm

Mr. Robert Root

PhD Candidate, NCPGG, The University of Adelaide

The Application of High-resolution Sequence Stratigraphy to Reservoir Development and Characterisation - A Case Study from the Eromanga Basin


Central to reservoir development is an understanding of the distribution, geometry and internal architecture of reservoir bodies at detailed scales of analysis. The sequence stratigraphic approach to stratigraphic analysis hinges on the recognition of "psuedo-chronostratigraphic" surfaces representing significant changes in depositional style. The implicit emphasis of the approach on depositional processes and the rates at which they occur is inexorably linked with the geometry of sandbodies and their position relative to the larger, siliciclastic depositional system. While the integration of the sequence stratigraphy and reservoir development seems obvious, surprisingly little information exists regarding the industrial value of sequence stratigraphy to reservoir development or regarding the approach in applying sequence stratigraphy to reservoir development.

The theoretical evolution of sequence stratigraphy in the last two decades has broadened the applicability of the approach beyond passive margin settings where eustacy is the dominant control on depositional style. This broadened applicablity has lead to optimism in the literature regarding its use in high-resolution, reservoir development studies (Van Wagoner et al. 1990, Kennard et al. 1999, Posamentier and Allen 1999). However, where sequence stratigraphy is applied to reservoir development, the emphasis shifts from the prediction of large-scale, subsurface lithologic change to the prediction of reservoir quality and distribution (i.e. the spatial variation in reservoir flow properties).

The predictive value ascribed to sequence stratigraphy in the late seventies and eighties is often inferred for high-resolution reservoir development studies based on work establishing the existence of sequence stratigraphic surfaces at virtually all scales and in virtually all depositional settings. Generally however, the value of the sequence stratigraphic approach will change in high-resolution reservoir development scenarios. In addition to large scale stacking patterns and gross lithologic prediction, diagenetic reservoir enhancement and degradation, changes in sandstone provenance, and small-scale changes in stratal architecture must be considered. Additionally the constraints of the development database will influence the approach in applying sequence stratigraphic principles.

The Wyandra Sandstone Member of the Cadna-Owie Formation provides a good opportunity to document the application the sequence stratigraphic approach to a reservoir development scenario. The influence of diagenesis and small-scale controls on depositional style play a significant role in controlling the spatial variation of reservoir flow properties. Additionally, the constraints of the development database must be considered. The value of the sequence stratigraphy and the approach in applying sequence stratigraphy is viewed in the context of these 'real life' parameters with a view to getting the maximum value from the sequence stratigraphic approach.

Biography of the Speaker

Robert Root graduated from Queensland University of Technology in 1998 with a B. App. Sc. in Geology followed by a M. Sc. in reservoir characterisation and sequence stratigraphy of alluvial and marginal marine strata in the Eromanga Basin. Robert is currently working on a PhD as part of the APCRC program on the Geological Disposal of CO2 (GEODISC).