Monitoring Geothermal Energy Extraction-Induced Ground Surface Deformation by InSAR

Global climate change underscores the critical role of renewable clean energy in achieving sustainable development. The geothermal resources associated with oilfields offer a solution for residential heating and industrial applications; however, their utilization faces environmental challenges. Improperly designed heat exchange systems have been linked to declining groundwater levels, while asynchronous patterns of water extraction and re-injection exacerbate land subsidence risks. These issues threaten the long-term viability of geothermal energy exploitation. Accurate monitoring of large-scale ground deformation in geothermal fields has therefore become imperative. This study employed the short baseline subsets-interferometric synthetic aperture radar (SBAS-InSAR) technique to monitor ground deformation in Caofeidian District, Bohai Bay Basin, North China, where the Nanpu Oilfield operates. By analyzing 55 Sentinel-1A images acquired between October 2018 and May 2022, we identified two subsidence centers: the Nanpu development zone and the Caofeidian new district. The cumulative subsidence reached − 53.54 mm and − 49.33 mm, respectively. The spatial distribution of subsidence correlates with geological stratigraphy and engineering practices. Pumping and recharging experiments near the heating project helped reveal seasonal subsidence mechanisms in the Caofeidian new district. Thermal reservoir extraction-induced drainage consolidation triggered rapid subsidence in November. In April, imbalanced water withdrawal and re-injection volumes intensified strata compaction, accelerating the subsidence trend. SBAS-InSAR proves to be a viable monitoring tool for quantifying and interpreting geothermal-induced deformation.