Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
8
1
Introduction
Winningsplan 2016
In April 2016, NAM submitted the Groningen Winningsplan 2016 (Ref. 1) to the Minister of Economic Affairs and
Climate Policy. This Winningsplan was accompanied by a Technical Addendum (Ref. 2) providing further background
to the hazard and risk assessments used in the Winningsplan. The Mining Law requires that winningsplannen are
approved by the Minister of Economic Affairs and Climate Policy. The approval was granted in the
Instemmingsbesluit Winningsplan Groningenveld, issued on the 30
th
of September 2016 (Ref. 3).
Hazard and Risk Assessment November 2017
In response to the specific obligation in the Instemmingsbesluit, NAM prepared the report “Induced Seismicity in
Groningen, Assessment of Hazard, Building Damage and Risk – November 2017” (Ref. 5), which was submitted to
the Minister of Minister of Economic Affairs and Climate Policy and to SodM on 1
st
November 2017. This describes
the full hazard and risk assessment for induced seismicity in Groningen, starting from the production of gas (the
cause) to the effects on people and buildings.
The Wijzigingsbesluit of 24
th
May 2017 (Ref. 4), limited the production in an average temperature year to 21.6
Bcm/year. However, in the Wijzigingsbesluit special circumstances were identified that could require an increase in
the production from the field: (1) a year with lower than average ambient temperatures or (2) upsets in the gas
production and distribution system. The Hazard and Risk Assessment of November 2017 (Ref. 5) was therefore
prudently based on an average annual production level of 24 Bcm/year gas production, which covered these
eventualities.
Complementary production scenarios
To assess the effect of different production scenarios on seismic risk, a complementary set of production scenarios
covering a wide range of production levels was presented in the addendum to the November 2017 Hazard and Risk
Assessment, in Reference 6, issued March 2018. The set of production scenarios analysed included the production
aspirations as outlined in the Regeerakkoord (10/10/2017) and several production scenarios as included in reports
by GTS, which were based on different utilisation of the existing nitrogen blending plant and the construction of an
additional nitrogen blending plant. The same workflow and model suite was utilized as used in “Induced Seismicity
in Groningen, Assessment of Hazard, Building Damage and Risk – November 2017” issued March 2018 (Ref. 5).
Basispad Kabinet (29/3/2018)
The letter sent by the Minister of Economic Affairs and Climate Policy to Parliament (Kamerbrief) on 29
th
March 2018
(Ref. 7) announced the ambition of the cabinet to reduce the production from the Groningen field as soon as possible,
leading to cessation of production around 2030. It contained annual production volumes for the period 2018-2031,
which was labelled “Basispad Kabinet” (Fig. 1.1 and 1.2).
Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
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Figure 1.1
Production scenario prepared by GTS (including construction of a nitrogen blending plant) in orange and
production scenario “Basispad Kabinet” in blue from reference 7. Both these production scenarios are for a
sequence of cold ambient temperature years.
Figure 1.2
Production scenario “Basispad Kabinet” for a sequence of cold temperature years (in blue), average
temperature years (in green) and of warm temperature years (in orange) from refence 7.
Seismic Risk Assessment for Production Scenario “Basispad Kabinet” for the Groningen field - June 2018
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Expectation Letter (2/5/2018)
An Expectation Letter (Verwachtingenbrief) was sent to NAM on 2
nd
May 2018 (Ref. 8 and Appendix B) by the
Minister of Economic Affairs and Climate Policy. It details the expectations for further NAM technical studies in
preparation of a new Winningsplan decision (due by 15
th
November 2018 latest). NAM was requested to perform a
hazard and risk assessment for the “Basispad Kabinet” scenario, to indicate the impact of the strong reduction of
production on safety risk and the scope of the structural upgrading needed to comply with the Meijdam-Norm (Ref.
9 to 11). With the Expectation Letter the Minister of Economic Affairs and Climate Policy has provided the Groningen
quality demand dataset to NAM which served as basis for the HRA.
In an addendum to the Expectation Letter, the request was further described. NAM was requested to provide
(translated from Expectation Letter) (Ref. 8):
1.
A Hazard & Risk Assessment based on the “basispad” of the cabinet for a cold, average and warm year, such
that for the assessment of the warm and cold year the principle is used that the years preceding and following
the warm or cold temperature year are average temperature years. This is based on a 85% utilisation of the
combined use of Ommen and Wieringermeer. The detailed production (per month) is documented in an excel
sheet shared digitally with NAM.
2.
For the distribution of the production over the different production clusters and regions NAM will use the results
of the Optimisation Study of December 2017, taking into account the volume restrictions imposed by SodM
based on the Zeerijp-advice (1 February 2018).
3.
NAM will as a reference perform a risk assessment for the 24 Bcm/year scenario of the Hazard and Risk
Assessment of 1
st
November 2017.
4.
For each production scenario the number of people and buildings at risk will be assessed in line with the advice
of the Committee Meijdam. Both a mean value and the uncertainty band will be provided.
5.
The results for both scenarios will be provided as:
a)
Annual assessment of risk (hazard maps and LPR-Curves) for each to the first 10 years.
b)
5-yearly assessment of risk for the next 15 years.
c)
NAM will provide for each scenario de following graphs:
i.
Buildings mean and uncertainty band LPR>10
-4
/year against time;
ii.
Buildings mean and uncertainty band LPR>10
-5
/year against time;
d)
Map of the locations of the buildings with a chance that these are member of a building typology with a
chance of a fatality > 10
-4
/year;
e)
Map of the locations of the buildings with a chance that these are member of a building typology with a
chance of a fatality > 10
-5
/year;
f)
NAM will also provide these data in a table.
g)
Table with all building typologies with a risk >10
-4
/year and >10
-5
/year.
The current report provides the requested Hazard and Risk Assessment based on the requested optimisation
strategy and present the associated maps and graphs.
It should be noted, the provided demand profiles sent 2
nd
May 2018 includes some small deviations from the
“Basispad Kabinet” scenario as presented by the minister in his March 28
th
Letter to Parliament, because of different
underlaying assumptions (Figure 1.3). Further on in this report, when “Basispad Kabinet” is mentioned, it will refer
to these 2
nd
of May production profiles.