An integrated shear-wave velocity model for the Groningen gas field, The Netherlands

Abstract

A regional shear-wave velocity (V S) model has been developed for the Groningen gas field in the Netherlands as the basis for seismic microzonation of an area of more than 1000 km 2. The V S model, extending to a depth of almost 1 km, is an essential input to the modelling of hazard and risk due to induced earthquakes in the region. The detailed V S profiles are constructed from a novel combination of three data sets covering different, partially overlapping depth ranges. The uppermost 50 m of the V S profiles are obtained from a high-resolution geological model with representative V S values assigned to the sediments. Field measurements of V S were used to derive representative V S values for the different types of sediments. The profiles from 50 to 120 m are obtained from inversion of surface waves recorded (as noise) during deep seismic reflection profiling of the gas reservoir. The deepest part of the profiles is obtained from sonic logging and V P-V S relationships based on measurements in deep boreholes. Criteria were established for the splicing of the three portions to generate continuous models over the entire depth range for use in site response calculations, for which an elastic half-space is assumed to exist below a Electronic supplementary material The online version of this article (

A Shallow Seismic Velocity Model for the Groningen Area in the Netherlands

“…This range matches well with the S wave velocities for the second depth interval (50 to 100 m) found in this study (Figure ). The large amount of source‐receiver paths used to construct the V S 65 map in Kruiver et al () allowed a much higher spatial resolution, but the overall pattern agrees quite well.…”

“…When comparing the maps of Figure , it should be noted that the values from this study are interpolated in between the stations. It therefore has lower spatial resolution and will not be able to map the geological structures that can be identified in the map by Kruiver et al (). However, the large‐scale lateral differences in S wave velocity are in agreement.…”

“…Kruiver et al () presented a V S 65 model based on the (re)interpretation of surface wave data. The values in their model are average S wave velocities for a depth interval from 50 m to 120 m and range from 298 m/s to 453 m/s.…”

“…In Figure , we can see that from the second to the lowest interval (50 m to 200 m depth) the average S wave velocity increases with a linear trend from 384 m/s to 498 m/s. In Kruiver et al () the deeper V S structure is also assumed to increase linearly from 65 m to 350 m depth, where it reaches a stationary value of 639 m/s.…”

“…The associations are based on seismic cone penetration tests for each of the lithologies and assumed to represent the average seismic S wave velocity for the top 30 m. This approach is completely different from the method used in this study, allowing an independent comparison of the results. In Figure 17, the V S30 from Kruiver et al (2017) is plotted next to the V S50 results from this study.…”