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 179

D3D02 D3D03 D3D04 D3D05

D3D01

2 m

Fig. 9. Synthetic wells (D3D01 - D3D05) of all four scenarios (Initial, Base case, Q low and Q high ) showing net-to-gross ratio
(N/G; see Fig. 8 for colour scale). The synthetic wells show typical deltaic features such as coarsening and fining upward
as well as lag deposits. See text for further explanation. For locations see Figs 7 and 8.

Table 3. Overview reservoir modelling. Individual sand bodies are represented by representative
colours in Fig. 10.

Overview reservoir modelling

Connected volumes of NRV (%) for individual sand
bodies (SB)

Net Rock Volume
(*10 6 m 3 )

Scenario

SB1 SB2 SB3 SB4 SB5 sum

Initial case 10.46 55.6 24.8 15.7 1.2 1.0 98.3

Base case 9.41 74.9 17.5 3.6 1.3 1.0 98.3

Case Q low 12.75 96.8 1.0 0.7 0.5 0.4 99.4

Case Q high 28.30 100 - - - - 100

succession is also unaffected by ongoing low discharge
( Q low scenario) but some minor fluvial reworking
occurs at the top of the succession during the Q high
scenario. Well D3D05 is located in front of the main
distributary channel and therefore is characterised
by a sand-rich coarsening-upward succession repre-
senting delta progradation, capped by a fining-upward
delta plain deposit. Wave reworking in this deltaic
headland is effective, leading to significant erosion of
the delta succession for all three wave scenarios. In
case of the Q high scenario, a sand bed associated with
alongshore transport has been deposited on top of
the original prodelta fines.
Overall it is evident that wave reworking changes
the original delta succession quite dramatically.

The changes differ in character and intensity
depending on location, which is valuable informa-
tion when trying to infer process-control from
subsurface wells or outcrop logs.

Net Rock Volume and connected reservoirs

Not all deltaic deposits have good reservoir proper-
ties. We have applied a net-to-gross ratio criterion
of > 0.8 to identify sands with good reservoir prop-
erties, which results in Net Rock Volumes (NRV)
with different values for the four scenarios. A
higher NRV was obtained for the Q low and Q high
scenarios (Table 3). This may be attributed to the
effective removal of fines during the Q low and Q high