This project focuses on assessing the maximum earthquake magnitude (Mmax), that could be induced by gas production from the small gas fields in the Netherlands.
Numerical (physics-based) models shall be developed for the currently 12 producing onshore gas fields, which are associated or can be associated with induced seismicity if earthquake location uncertainty is considered (i.e., active class A and B fields using the definition of KEM-07). Each model shall be calibrated using its production history and the observed seismicity (data available via nlog.nl). Scenario simulations, associating earthquakes with different faults within their location errors, shall be performed to account for the (large) uncertainties of earthquake location.
Earthquake evolution during future production shall be simulated for each scenario, yielding Mmax estimates for the most likely and end-member scenarios. These estimates shall be compared to the current approach of estimating Mmax based on the available fault area.
This project will target the following research questions:
1. What is the maximum magnitude for the producing small gas fields, considering production history, reservoir geometry, fault geometry, material parameters, local geological and stress conditions, and uncertainties associated with earthquake observations?
a. Which faults within the small fields are identified as seismogenic and why?
b. What is the maximum magnitude for the respective faults within the fields?
2. How does Mmax compare to the value derived from the maximum available fault area?
3. Can the findings be generalized? Can a stress-based criterion be formulated that is applicable for all fields (those considered here and possibly other fields in NL)?
a. What are the main parameters influencing the vertical extension of slip?
b. What is the maximum vertical extension of fault slip with a variation of these parameters and accounting for model uncertainties (sensitivity study)?
Finally, recommendations on a general approach to assessing Mmax for arbitrary gas fields in the Netherlands shall be provided, based on numerical considerations of background stresses, slip extension and variability of the latter within the simulations.
The research has been awarded to TNO and started in 2025.