On the use of point target characteristics in the estimation of low subsidence rates due to gas extraction in Groningen, the Netherlands.

Gini Ketelaar(1) , Freek van Leijen(1) , Petar Marinkovic(1) , and Ramon Hanssen(1)

(1) Delft University of Technology, Kluyverweg 1, 2629 HS Delft, Netherlands

Abstract

The subsurface of the north-eastern part of the Netherlands contains large gas reservoirs that have been taken into production since the late 1960s. The resulting subsidence has been precisely and reliably estimated using measurements from repeated leveling campaigns and is now for the first time unambiguously observed using PS-InSAR. The subsidence rates are small (< 1 cm/year) and the PS density is low due to the rural character of the area. Particularly it is difficult to distinguish the PS deformation components due to gas extraction from other possibly superposed deformation regimes. Besides a strict quality description of the estimated parameters, the characterization of physical PS properties is therefore of major importance.

In this paper we focus on the interpretation of PS-InSAR deformation estimates in Groningen by investigating the scattering properties of the detected PS. Through combining the shape of their complex spectrum, Signal-to-Clutter (SCR) ratio and estimated heights from PS-InSAR processing, the nature of the PS is investigated. Important issues for performing the scatterer characteristics analysis, such as coregistration and SAR amplitude calibration, are addressed. After analyzing the effect of temporal and perpendicular baseline and Doppler frequency variations, the PS-InSAR deformation estimates from different reflection types are evaluated on their performance for estimating subsidence due to gas extraction.

 

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