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Howard D. Johnson1, Matthew D. Jackson1, Shuji Yoshida2, Ann H. Muggeridge1, Allard Martinius3, Philip Ringrose3, Arve Næss3
(1) T.H. Huxley School, Imperial College, London, United Kingdom
(2) University of London, Egham, Surrey, United Kingdom
(3) Statoil R & D, 7005 Trondheim, Norway

Abstract: The impact of sedimentary heterogeneities on the recovery of hydrocarbons from tidal sandstone reservoirs

Tidal sandstone reservoirs contain a complex array of sedimentary heterogeneities at lengthscales ranging from millimetres to kilometres. To properly represent these heterogeneities in a reservoir model, the reservoir should be subdivided into a hierarchy of units which can be modelled individually, and the smaller scale heterogeneities upscaled so that their effect on flow can be represented in larger scale simulation models. This procedure is time consuming and costly; it is therefore desirable to model and upscale only those heterogeneities which have a significant impact on recovery.

We have conducted a simulation-based sensitivity analysis, designed to identify which heterogeneities have a significant impact on recovery during waterflooding. For modelling and simulation, we subdivided tidal reservoir heterogeneities into a logical, threefold hierarchy. At the highest level, we modelled the size, shape and distribution of tidal bars and channels within the Lower Jurassic Tilje Formation, part of the Heidrun field, offshore Norway. At the intermediate and lowest levels, we characterised and modelled the facies distribution within individual bars and channels, and the small-scale bedform architectures within individual facies, using quantitative data obtained from well exposed Lower Cretaceous tidal deposits in the UK, which serve as excellent outcrop analogues for the Tilje Formation. The models developed at each level of the hierarchy were combined and upscaled, and experimental design techniques used to identify the simulations required to recognise key heterogeneities. The results of this work will help to optimise the time and cost of developing appropriate tidal reservoir models.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana