3D surface displacement estimation over the Groningen gas field, the Netherlands

Wietske S Brouwer, Ramon Hanssen 

Since 1964, the Groningen gas field in the Netherlands has experienced significant subsidence due to gas extraction. Although InSAR has been widely used to estimate the vertical displacements of the field, capturing the full three-dimensional deformation, including omnidirectional horizontal components, remained a challenge and has only been achieved from spatially sparse GNSS observations. The recent development of the InSAR strapdown method suggests a solution to this problem. Yet, for an accurate decomposition, it is essential to isolate only scatterers representative of the deep gas-production-related deformation signal. Here we present a novel, data-driven approach that first disentangles the different deformation mechanisms present in the InSAR data. We then apply the strapdown method to decompose InSAR observations into vertical and directional horizontal displacement components, using frame orientation parameters estimated
directly from the data. We incorporate uncontroversial contextual information and apply a bootstrapping method to enhance the quality of the results, and propagate the uncertainty in the input data to provide quality metrics of the final estimates. Using this approach, we obtain reliable threedimensional displacement estimates for the Groningen gas field, revealing previously unquantified horizontal displacements. Our results show that these horizontal displacements, especially close to the boundaries of the reservoir are significant and must be considered alongside vertical motion to fully understand and mitigate the impacts of gas production.