--> ABSTRACT: The Combined Use of Sequence Stratigraphy and Stochastic Modelling to Reservoir Management of the Ness Formation, Statfjord Field, Norwegian North Sea--Part 2: Stochastic Modelling, by Tarald Svanes, Olav Sundt, Per Ivar Skarnes, Inge Kaas; #91020 (1995).
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The Combined Use of Sequence Stratigraphy and Stochastic Modelling to Reservoir Management of the Ness Formation, Statfjord Field, Norwegian North Sea--Part 2: Stochastic Modelling

Tarald Svanes, Olav Sundt, Per Ivar Skarnes, Previous HitIngeTop Kaas

In recent years probabilistic modelling of reservoir heterogeneities has become an integrated part of reservoir description, and various methods and software programs have been introduced. In general, the process of generating a stochastic 3D model consists of four stages: 1) simulate isochore maps of each time-zone, 2) distribute facies heterogeneities within the isochores, 3) simulate petrophysical properties and 4) translate the fine-scale model to a coarser flow simulation grid.

Based on interpreted sequence stratigraphic zonation and facies distribution the Ness Formation was subdivided into 13 modelling zones. In most cases a modelling zone consists of lowstand deposits or combined transgressive and highstand deposits. Each zone was modelled independently because they represent individual sedimentary characteristics. The time-zone thicknesses were simulated using moving average method conditioning to wells, including anisotropy, trend and variogram. An integrated stochastic reservoir modelling package called STORM was applied performing steps 2, 3, and 4. Different facies algorithms are available and a marked point process designed for fluvial systems was used to model the lowstand time-zones. For the combined transgressive and highstand zones a semi-Markov method, suitable for shallow marine systems, was applied.

The aim of the stochastic modelling work was threefold: 1) to make realistic fine-scale geological models that are consistent with observed data and geological understanding, 2) to calculate uncertainties in oil in place volume and 3) to match production history to be able to predict fixture reservoir behaviour and detect unswept oil. Latest simulation data will be presented and discussed at the conference.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995