Surface deformation study for a geothermal operation field

Abstract

Abstract. GeoMechanics Technologies has investigated the surface deformation that occurred at a geothermal field operation located in New Zealand. The thermal area associated with this field has extensive surface infrastructures that are in close proximity to a lake. Geothermal operations initially began in 1997 while surface subsidence has been observed since early 2004. We were contracted by the client to review and analyze the impact of future development plans on ground level changes in hopes to mitigate further compaction and subsidence in the area. There is significant concern that continued surface subsidence may cause the lake to flood the surrounding area. An integrated 3-D geological model, geomechanical model, and fluid and heat flow model were developed for this study. To ensure accuracy, a history match and calibration was performed on the geomechanical model using historical subsidence survey data and on the fluid and heat flow simulation using historical injection and production data. The calibrated geomechanical model was then applied to simulate future scenarios to predict surface subsidence and provide a guideline to optimize field development plans.