A guideline for assessing seismic risk induced by gas extraction in the Netherlands

Abstract

In the Netherlands, seismicity is induced by the reactivation of faults because of the extraction of gas. The Dutch mining law requires a seismic-risk assessment as part of the license application process. For this purpose, a risk-assessment guideline has been developed over the past decade. The guideline contains three assessment levels. At the first level, a screening occurs to assess the potential of inducing seismicity. On the basis of three key parameters and an analysis of the maximum potential magnitude, each field can be classified for induced-seismicity risk prior to the onset of production. For fields with a low seismicity potential, the existing national monitoring network suffices. At the second level, for fields with medium and high seismicity potential, a qualitative assessment of hazard and risk is required based on a risk-matrix approach. The large Groningen gas field is considered a field with high seismic risk requiring a level 3 assessment. For such fields, a probabilistic seismic-risk assessment and risk-management plan are required. The risk assessment requires special attention because most of the seismic risk is associated with low-probability events that can induce large ground accelerations.

Categorizing seismic risk for the onshore gas fields in the Netherlands

“…This is in accordance with the guideline's first step analysis (Muntendam-Bos et al, 2015). The justification is the fact that if the central event (strong ground motion) does not occur, the risk will not occur either.…”

“…The guideline presented by Muntendam-Bos et al (2015) identified the need to include the public sensitivity and tolerance to seismicity, and the construction standards of the buildings in the exposed area. As an escalation factor an estimate of the possible extent of damage to infrastructure and buildings and an estimate of the social, financial, and reputational impact of a seismic event was suggested.…”

“…In the seismic risk guideline (Muntendam-Bos et al, 2015) central to the assessment of seismic risk is the bow-tie assessment methodology. In a bow-tie analysis, the causes and consequences of a central event are examined.…”

“…A quantitative seismic risk analysis has been done for the induced seismicity of the Groningen gas field (NAM, 2016). Because of the large difference in risk between the Groningen field and the other smaller gas fields, the guideline (Muntendam-Bos et al, 2015) deems it sufficient to carry out a qualitative risk analysis for the other gas fields in the Netherlands, as performed here. Fig.…”

“…In 2016, using input from the geological survey of the Netherlands (TNO) and the onshore operators, SSM formulated a guideline (Muntendam-Bos et al, 2015) for a qualitative seismic risk analysis for the small fields in the Netherlands consisting of three steps. The guideline addresses the risk matrix approach of the second step, which follows international practice, however it provides no details.…”