Surface deformation can be detected with satellite-based geodetic sensors, providing important insights on subsurface geomechanical properties. In this study, we use Interferometric Synthetic Aperture Radar (InSAR) observations to measure ground deformation due to fluid extraction and due to an induced seismic event at the Los Humeros Geothermal Field (Puebla, Mexico). The result of the PS-InSAR (Persistent Scatterer by Synthetic Aperture Radar Interferometry) analysis shows that the subsidence at the LHGF was up to 8 mm/year between April 2003 - March 2007, which is small relative to the produced volume of 5x106 m3/year. The subsidence pattern indicates that the geothermal field is controlled by sealing faults separating the reservoir into several blocks. Our models imply small volume changes in the reservoir and the different nuclei of strain solutions differ only slightly. These findings suggest that the pressure within the reservoir is well supported and that reservoir recharge is taking place. The occurrence of induced seismicity is independent evidence for the development of effective stresses. The inversion of the coseismic deformation due to the 8 February 2016, Mw 4.2 earthquake showed activation of a shallow normal fault in a reverse manner. Even with the limited compaction observed from the subsidence, the stress development was enough to induce seismicity. Pore pressure contrasts over a fault will increase the stress development. However, the fault structure will be more complex than assumed in the present study, because an acceptable joint match of ascending and descending surface movement data was not possible. An integrated study into the complex reservoir behaviour and the associated stress development over complex faults is therefore warranted.@en

Surface deformation due to fluid extraction can be detected by satellite-based geodetic sensors, providing important insights on subsurface geomechanical properties. In this study, we use Differential Interferometric Synthetic Aperture Radar (DInSAR) observations to measure ground deformation due to fluid extraction at the Los Humeros Geothermal Field (Puebla, Mexico). Our main goal is to reveal the pressure distribution in the reservoir and to identify reservoir compartmentalization, which can be important aspects for optimizing the production of the field. The result of the PS-InSAR (Persistent Scatterer by Synthetic Aperture Radar Interferometry) analysis shows that the subsidence at the LHGF was up to 8 mm/year between April 2003 and March 2007, which is small relative to the produced volume of 5×106 m3/year. The subsidence pattern indicates that the geothermal field is controlled by sealing faults separating the reservoir into several blocks. To assess if this is the case, we relate surface movements with volume changes in the reservoir through analytical solutions for different types of nuclei of strain. We constrain our models with the movements of the PS points as target observations. Our models imply small volume changes in the reservoir, and the different nuclei of strain solutions differ only slightly. These findings suggest that the pressure within the reservoir is well supported and that reservoir recharge is taking place.

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In this paper we present results of a global resource assessment for geothermal energy within deep aquifers for direct heat utilization. Greenhouse heating, spatial heating, and spatial cooling are considered in this assessment. We derive subsurface temperatures from geophysical data and apply a volumetric heat-in-place method to improve current global geothermal resource base estimates for direct heat applications. The amount of thermal energy stored within aquifers depends on the Earth's heat flow, aquifer volume, and thermal properties. We assess the thermal energy available by estimating subsurface temperatures up to a depth of three kilometer depending on aquifer thickness. The distribution of geothermal resources is displayed in a series of maps and the depth of the minimum production temperature is used as an indicator of performance and technical feasibility. Suitable aquifers underlay 16% of the Earth's land surface and store an estimated 4·10⁵ to 5·10⁶ EJ that could theoretically be used for direct heat applications. Even with a conservative recovery factor of 1% and an assumed lifetime of 30 years, the annual recoverable geothermal energy is in the same order as the world final energy consumption of 363.5 EJ yr⁻¹. Although the amount of geothermal energy stored in aquifers is vast, geothermal direct heat applications are currently underdeveloped with less than one thousandth of their technical potential used.

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We present first results of PS-InSAR (Persistent Scatterer by Synthetic Aperture Radar Interferometry) time-series over the eastern sector of the Trans-Mexican Volcanic Belt including several volcanic systems. The study area covers the Los Humeros and Acoculco geothermal fields. Los Humeros is one of the largest geothermal fields in Mexico connected to a caldera system that has been active from 0.46 Ma until recent. We performed PS time series analysis using the StaMPS method on Sentinel-1 images acquired between October 2016 and December 2017 to resolve ongoing ground deformation. The Sentinel-1 satellite provides regular observations with fine temporal resolution over large areas, which facilitates detection of satellite line-of-sight surface movements important for monitoring geothermal exploration activities. Generally, the interferograms are of good quality with high coherence even on long time scales. Most of the study area is located at high altitudes (above 2000 m) with strong relief. Asa result, the interferograms seem to be influenced by topography-related atmospheric phase delays, identified by the high correlation between phase and elevation. We correct the topography-related atmospheric phase delays and compare the InSAR estimated displacements with the available GPS data. Our goal is to obtain the deformation associated with ongoing geothermal activities over the Los Humeros geothermal field and other tectonic processes that might be present in the area. Here we present our first results, which will be further extended to estimate volume changes related with the geothermal exploration by inversion methods.@en