De-risking the energy transition by quantifying the uncertainties in fault stability

The operations needed to decarbonize our energy systems increasingly involve faulted rocks in the subsurface. To manage the technical challenges presented by these rocks and the justifiable public concern over induced seismicity, we need to assess the risks. Widely used measures for fault stability, including slip and dilation tendency and fracture susceptibility, can be combined with response surface methodology from engineering and Monte Carlo simulations to produce statistically viable ensembles for the analysis of probability. In this paper, we describe the implementation of this approach using custom-built open-source Python code (pfs – probability of fault slip). The technique is then illustrated using two synthetic examples and two case studies drawn from active or potential sites for geothermal energy in the UK and discussed in the light of induced seismicity focal mechanisms. The analysis of probability highlights key gaps in our knowledge of the stress field, fluid pressures, and rock properties. Scope exists to develop, integrate, and exploit citizen science projects to generate more and better data and simultaneously include the public in the necessary discussions about hazard and risk.

An overview of induced seismicity in the Netherlands

We present an overview of induced seismicity due to subsurface engineering in the Netherlands. Our overview includes events induced by gas extraction, underground gas storage, geothermal heat extraction, salt solution mining and post-mining water ingress. Compared to natural seismicity, induced events are usually small (magnitudes ≤ 4.0). However, due to the soft topsoils in combination with shallow hypocentres, in the Netherlands events exceeding magnitude 1.5–2.0 may be felt by the public. These events can potentially damage houses and infrastructure, and undermine public acceptance. Felt events were induced by gas production in the north of the Netherlands and by post-mining water ingress in the south-east. Notorious examples are the earthquakes induced by gas production from the large Groningen gas field with magnitudes up to 3.6. Here, extensive non-structural damage incurred and public support was revoked. As a consequence, production will be terminated in 2022 leaving approximately 800 billion cubic metres of gas unexploited. The magnitudes of the events observed at underground gas storage, geothermal heat production and salt solution mining projects have so far been very limited (magnitudes ≤ 1.7). However, in the future larger events cannot be excluded. Project- or industry-specific risk governance protocols, extensive gathering of subsurface data and adequate seismic monitoring are therefore essential to allow sustainable use of the Dutch subsurface now and over the decades to come.

Movers and Shakers: Stock Market Response to Induced Seismicity in Oil and Gas Business

Investors increasingly need to account for concerns about non-financial performance and to consider the environmental impact of fossil fuel investment. We analyze how financial investors appreciate induced seismicity in oil and gas fields in the US and the Netherlands. We employ an event study to investigate the stock market reaction of investors in two fossil fuel majors, ExxonMobil and Royal Dutch Shell. We establish that stock market participants’ response is positively but weakly related to induced seismicity with ExxonMobil. This suggests that markets might interpret this seismicity as a signal of future productivity. With Royal Dutch Shell, there is no significant association, suggesting that their investors do not specifically appreciate its externalities. We conclude that the externality of induced seismicity goes unpriced.