Relatively stable pressure effects and time-increasing thermal contraction control Heber geothermal field deformation

• Published in: Nature communications Vol. 15; no. 1; pp. 5159 - 14
• Main Authors: Jiang, Guoyan, Barbour, Andrew J., Skoumal, Robert J., Materna, Kathryn, Taron, Joshua, Crandall-Bear, Aren
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.06.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 704/2151/241; 704/2151/2809; 704/4111; Deformation; Deformation effects; Earthquakes; Fault lines; Heat; Humanities and Social Sciences; Injection; multidisciplinary; Poroelasticity; Power plants; Pressure; Pressure effects; Science; Science (multidisciplinary); Seismic activity; Seismicity; Siphoning; Subsidence; Temperature; Thermal contraction; Trends; Uplift
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-49363-1

Due to geological complexities and observational gaps, it is challenging to identify the governing physical processes of geothermal field deformation including ground subsidence and earthquakes. In the west and east regions of the Heber Geothermal Field (HGF), decade-long subsidence was occurring despite injection of heat-depleted brines, along with transient reversals between uplift and subsidence. These observed phenomena contradict current knowledge that injection leads to surface uplift. Here we show that high-yield production wells at the HGF center siphon fluid from surrounding regions, which can cause subsidence at low-rate injection locations. Moreover, the thermal contraction effect by cooling increases with time and eventually overwhelms the pressure effects of pressure fluctuation and poroelastic responses, which keep relatively stable during geothermal operations. The observed subsidence anomalies result from the siphoning effect and thermal contraction. We further demonstrate that thermal contraction dominates long-term trends of surface displacement and seismicity growth, while pressure effects drive near-instantaneous changes. Thermal contraction effect increases with time dominates the long-term deformation trend of the Heber geothermal field, while pressure effects of pressure fluctuation and poroelastic responses keep relatively stable and drive short-term changes.