Morphodynamic modelling of wave reworking of an alluvial delta and application of results in the standard reservoir modelling workflow - From Depositional Systems to Sedimentary Successions on the Norwegian Continental Margin - page 167

Morphodynamic modelling of wave reworking of an alluvial
delta and application of results in the standard reservoir
modelling workflow

MARTEN M. HILLEN*, NATHANAËL GELEYNSE ‡ , JOEP E.A. STORMS ‡ ,
DIRK JAN R. WALSTRA* § and REMCO M. GROENENBERG ‡
* Section of Hydraulic Engineering, Department of Hydraulic Engineering, Delft University of Technology,
PO Box 5048, 2600 GA, Delft, The Netherlands
‡ Geoscience & Engineering Department, Delft University of Technology, PO Box 5048,
2600 GA, Delft, The Netherlands (E-mail: [e-mail])
§ Hydraulic Engineering Department, Deltares, PO Box 177, 2600 MH, Delft, The Netherlands

This contribution relates to conference theme: III - Autogenic processes and products - learning
from numerical modelling.

ABSTRACT

Wave forcing has been recognised as an important mechanism of transformation in
modern and ancient delta systems. However, relatively few attempts have quantitatively
assessed its contribution to deltaic morphodynamics and time-varying stratigraphy.
Here, a high-resolution physics-based numeric model (Delft3D) is employed to study the
influence of wave forcing on a hypothetical clastic, subaerial delta. Three cases are
presented that differ from each other in the degree of fluvial input relative to a schema-
tised time-invariant quiet-weather offshore wave field. In all cases, infill of higher-order
distributaries on the delta plain is observed as well as delta front erosion in the absence
of fluvial input. Furthermore, all cases show sediment sorting: river-derived fines, stored
at the delta front, are entrained and transported in an offshore direction, to finally settle
in deeper waters. However, at some stage coarser deposits prevent underlying fines from
erosional wave stirring (armouring), thus increasing local preservation potential. In the
case of appreciable fluvial input, single-channel dominance gives rise to the formation
of bars that are laterally (coast-parallel) deformed due to wave action. Following the
physics-based modelling, the simulated stratigraphy is applied to a standard reservoir
modelling workflow to calculate properties including sandbody connectivity.

Keywords: Delta, wave, numerical model, Delft3D, morphodynamics, stratigraphy,
reworking.

modification and catchment modification, which
generally reduces sediment flux to deltas (e.g.
Syvitski & Saito, 2007). This knowledge also contrib-
utes to reconstruct palaeodeltas in oil-reservoirs and
gas reservoirs and their outcrop analogues. However,
modern-day reservoir modelling software relies on
either stochastic or geometric methods to populate
the grid cells of a deltaic reservoir model that are not
intersected by wells. Recent developments in for-
ward (process-imitating) numerical models provide
reservoir geologists with a third option to populate

INTRODUCTION

Social and scientific relevance

Deltaic deposits have been studied intensively over
the past decades for the purpose of hydrocarbon
exploration. At the same time, our understanding of
processes that govern present-day delta develop-
ment has increased significantly. Recent studies
have focussed on the effects of human activity
on deltas (e.g. Ericson et al ., 2006), such as river-