10.11440060695_si_001.pdf (9.22 MB)
Modelling Fine-scale Sedimentological Heterogeneity for Optimal Production from the Neptune Field, Aeolian Gas Reservoir UKCS
journal contribution
posted on 2020-04-30, 14:20 authored by R. GARDEN, M. MENTIPLY, R. COOK, I. SYLVESTERThe Neptune Field lies on the NW margin of the Southern North Sea gas basin in block
47/4b and extends into blocks 47/5a and 42/29. Following development drilling of the
field, a rebuild of the deterministic reservoir simulation model failed to provide a
reasonable history match except for Flowing Bottom Hole Pressures (FBHP). The poor
dynamic history match was due to the modelling not incorporating the permeability
heterogeneity seen in the aeolian sandstones of the Neptune Field. A stochastic
reservoir model was produce that captured the broad range of scales of critical facies and
petrophysical heterogeneities present within this aeolian reservoir. The challenge for the stochastic reservoir model was to capture the key heterogeneities
in this high net to gross system. Facies modelling was undertaken using the General
Mark Point Processing in Roxar's RMS. Dunes were modelled as prolate ellipsoids with
long axes alignment constrained by dip-meter interpretation. Dune dimensions were
estimated from outcrop analogues and were conditioned to well data. Aeolian sandsheet
and damp interdune facies were modelled as sheet-like oblate ellipsoids inclined at
similar dips to the aeolian dunes. Permeability variations due to lamina grain size segregation in aeolian dune foresets
were modelled using sector models to capture cross lamina permeability (kx, kz) and
lamina parallel flow (ky). The results of sector modelling were incorporated into the
stochastic petrophysical realisations where spatial variation in permeability within dunes
was modelled using object specific linear piecewise trend porosity and permeability
transformations. Dunes were simulated with low permeability dune bases, high
permeability lower dune slipfaces and moderate to low permeability upper dune slipfaces.
Other minor aeolian and fluvial facies were assumed to be petrophysically isotropic.
The stochastic permeability map gave a better BHP response and history match at the
development wells than any deterministic permeability distribution modelled.
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Modelling Fine-scale Sedimentological Heterogeneitylamina grain size segregationaeolian dune foresetsFBHPpermeability distribution modelledreservoir modelNeptune Fielddune slipfacessheet-like oblate ellipsoidsRMSNWpermeability dune basesSouthern North Sea gas basinGeneral Mark Point ProcessingFlowing Bottom Hole PressuresAeolian Gas Reservoir UKCSBHPreservoir simulation modelGeology