DGMK 825

Numerical modeling of geological control factors for production-induced seismicity in North German gas fields

What controls the occurrence or absence of production-induced seismicity in natural gas fields in the North German Basin? DGMK project 825 addresses this question by comparing observational data and numerical modeling.

Änderung der Scherspannung im Verlauf der Produktion in Pa.

Facts about the project

Project manager: Dr. Tobias Hergert +++ Duration: 01.01.2020 – 31.08.2021 +++ Project funding: DGMK e.V., Hamburg

Click here for the official website of the DGMK 825 project

Epicenters of historical (purple circles) and instrumentally recorded earthquakes up to 2014 in northern Germany. Red circles mark epicenters of earthquakes of tectonic origin, yellow circles epicenters of suspected production-induced earthquakes near natural gas fields (blue areas). (Source: Bischoff et al. 2014).
Epicenters of historical (purple circles) and instrumentally recorded earthquakes up to 2014 in northern Germany. Red circles mark epicenters of earthquakes of tectonic origin, yellow circles epicenters of suspected production-induced earthquakes near natural gas fields (blue areas). (Source: Bischoff et al. 2014).

In some North German gas fields, small earthquakes have occurred within or in the immediate vicinity of the reservoir during the production phase, while other gas fields show no seismicity. Previous studies (e.g. APIS 1) have used numerical simulations to identify some factors that generally favor the occurrence of critical stress states on faults within the reservoir or at its rim, which can ultimately result in earthquake activity. DGMK project 825 is dedicated to the question whether for individual natural gas fields there is indeed a correlation between the occurrence of seismicity and the geological factors favoring fault reactivation. Different types of reservoirs in the North German Basin, which differ in particular in their subsurface geometry and stratigraphic age, are considered.

Section from a model discretized into finite elements, representative of a Rotliegend reservoir in a high position on a graben shoulder.
Section from a model discretized into finite elements, representative of a Rotliegend reservoir in a high position on a graben shoulder.

Generic finite element models are used to examine how the development of stress on faults differs in the course of production for the individual reservoir types and whether a correlation with the seismicity observed can be determined. The model geometries are based on the typical characteristics of Rotliegend and Zechstein reservoirs in the North German Basin. The modeling results are used to quantify an evaluation matrix in which possible control factors for production-induced seismicity in the North German Basin are compiled for 25 natural gas fields.

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