Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
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Figure 3-1:
Production by region and start-up group (“Basispad Kabinet” – Average Temperature)
Reservoir pressure
The associated change in reservoir pressure in the direct vicinity of the production clusters is given in Figure 3.2
4
. It
can be observed that in the first few years the South-East clusters are most heavily utilized (steepest pressure decline
and lowest overall reservoir pressure are observed in this area). Beyond 2021, the South-East production rates have
decreased such that the effect of pressure equilibration across the entire reservoir becomes larger than the local
depletion due to production. In other words, the gas flow from the higher pressure North-West of the field
(Loppersum area) towards the more depleted South-East, becomes larger than the production from the South-East
and the net effect is a stabilization and eventual increase of reservoir pressure in the entire South. The associated
depletion in the Loppersum area is some 10 bar, following a relatively steady-state decline with no notable pressure
fluctuations. The pressure fluctuations visible in the pressure response around the producing areas, due to
production ramp-ups and cluster maintenance downtime, are fully dampened in the Loppersum area due to the
distance from the producing clusters and the high compressibility of the gas.
Figure 3-3 shows a reservoir pressure map at 1/1/2018. The forecasted pressure decline over the next 5 years
(1/1/2018 to 1/1/2023) is given in Figure 3.4. A consequence of the production distribution is that pressure decline
is predominantly located in the South-East corner of the field. In the South-West corner of the field (clusters
4 Reservoir pressure is calculated by averaging the values in grid cells around the respective wells. The radius of this region is a function of permeability, but is typically in the order of a few hundred meters.
Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
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Kooipolder, Slochteren, Froombosch) a net increase in reservoir pressure of some 2-3 bar is observed. This is because
the combined net influx from the North of the field and from the Eemskanaal block (both at higher pressures) is
larger than the combined production (start-up group SW3 in Table 2-2) and outflux towards the South-East. Within
the Eemskanaal block itself there is also a net pressure increase. This is the area of the Eemskanaal-13 well, which
seized production in 2014. This area is now recharged by adjacent higher pressured blocks to the North and by the
aquifer to the West of the field.
Figure 3-2:
Reservoir pressure for “Basispad Kabinet” Average Temperature. Lines by production cluster, colours by
production region.
Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
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Figure 3-3:
Reservoir pressure at 1/1/2018. Both figures show the same data. On the left is the output from the reservoir
simulator constrained to the Groningen field, while on the right is pressure used as input to the hazard and risk
assessment.
Figure 3-4
Reservoir pressure decline from 1/1/2018 to 1/1/2023 for “Basispad Kabinet” – Average Temperature.
Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
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Production capacity
Figure 3-5 compares the production to the available capacity in each region (under the unlikely assumption that all
clusters remain available). The downward spikes in the region capacities are related to planned shutdowns of
production clusters for maintenance and inspections, while the seasonal fluctuation in capacity is a reflection of the
fact that the ambient temperature influences the efficiencies of the coolers and hence the total compressor efficiency.
Another observation that can be made is that the production capacity is relatively constant through time for most
regions. The South-East region shows a notable decline in capacity until 2022, after which the decline is halted and
eventually capacity starts to increase again. This behaviour is a function of the reservoir pressure in the direct vicinity
of the production clusters within each region. A declining reservoir pressure yields a declining production capacity,
whereas an increasing reservoir pressure yields an increase in production capacity.
The associated load factors (fraction of total available capacity that is being produced) are given in Figure 3-6,
reflecting the model implementation as outlined in section 2.4, with different start-up groups being ramped-up until
overall field demand is met.
Figure 3-5:
Forecasted production (green lines) and capacity (blue lines) per region for average temperature