Sarah Riordan

PhD student - Geo

Biography

• 1991 Bachelor of Applied Science (Applied Geology) from RMIT
• 1992 BSc (Hons) at National Centre for Petroleum Geology and Geophysics, Adelaide University
• 1993-2000 Employed by Santos Ltd in Adelaide, working primarily as a development geologist in the Cooper Basin.

PhD/MEng Research Project

Managing the inter-disciplinary needs of 3D geological models

Supervisor/s: Assoc Prof Bruce Ainsworth

Co-supervisor: Dr Tobi Payenberg, Dr Simon Lang, Dr Jochen Kassan

Technical support: Exxon-Mobil

Project Description

Historically reservoir simulations have been carried out with a coarse cell size due to non-geological constraints. As computers become more powerful, cell numbers may become less of a constraint, leading to the temptation to build ever more detailed geological models. Is this the best way to go?

When building geological models much thought is given to the vertical scale of the model, while the lateral scale is often dictated by the constraints related to borehole distribution and computer power. At present many geological models are built to satisfy the needs of the geologist and then scaled up so that engineers can carry out reservoir simulation - not always with consideration for depositional environments and the impact they have on reservoir distribution. As simulation run-times are of critical importance in the economics of reservoir modelling, upscaling will continue in many commercial environments. Given this constraint, is possible to identify, based on depositional environments, where finer scale geological models are not necessarily better, and to identify cell dimensions beyond which upscaling will result in the loss of critical geological detail.

The Flounder Field in the Gippsland Basin is being used as a case study for studying how depositional environments should be used as the foundations for the design of 3D geological models that are to be taken through to reservoir simulation. Three distinct depositional environments (barrier island, attached shoreline, fluvial-filled incised valley) are present within one reservoir interval in the Flounder Field, making it ideal for studying the impact that different cell sizes and orientations can have on the capture and preservation of geological detail in 3D geological models.

Modern and ancient analogues are being studied to determine the dimensions of depositionally controlled features that will affect the way fluid flows through the reservoir. The results of this work are being incorporated into the Atlas of Reservoir Analogues that is being produced by the ASP as one of the out comes of the Reservoir Characterization Project of the APCRC.

Publications

• RIORDAN, S.J., LANG, S.C. and PAYENBERG, T.H.D., 2004. Sequence stratigraphy of the intra-Latrobe Group, Flounder field, Gippsland Basin. Implications for the building and upscaling of 3D geological models. In: P.J. Boult, D.R. Johns and S.C. Lang (Editors), Eastern Australasian Basins Symposium II. Petroleum Exploration Society of Australia, Adelaide, Australia.  pp523-536
• RIORDAN, S.J., LANG, S.C. & PAYENBERG, T.H.D. 2007. Atlas of Reservoir Analogues. Australian School of Petroleum, University of Adelaide.
• RIORDAN S.J., LANG, S.C. & PAYENBERG, T.H.H in prep. Building a 3D geological model of a shoreline system - an example from the Flounder Field, Gippsland Basin, Australia. In Hampson, Steel, Burgess & Dalrymple (editors), Recent advances in shallow-marine stratigraphy. SEPM Special Publication 90.