Numerical modeling of induced seismicity associated with fluid injection and withdrawal using 2D discrete element fracture network model

摘要

This study investigates induced seismicity in deep geothermal reservoir associated with fluidrninjection and production in doublet and triplet reservoir systems with a hydro-mechanical coupled numericalrnmodel. The model is using 2D discrete element model with embedded discrete fracture network. Fluid injectionrnis performed for 6 hours with sequentially increased flow rate in three steps and the resulting induced seismicityrnis monitored. It is followed by constant rate fluid production at a point (doublet) and at two points (triplet)rndistances away from the injection point maintained for 20 hours. Spatio-temporal distribution of fluid pressure,rninjection/production induced seismic events, their magnitudes and source characters are investigated. The simulationrnshows that production induced seismic events mostly occur along the line at steep fluid pressure gradientrnwith mostly implosion source characteristics. It was simulated that larger magnitude events can be induced inrnthe vicinity of the production well and near pre-existing fractures when combined with abrupt slipping.