Hydro-mechanical modeling of the first and second hydraulic stimulations in a fractured geothermal reservoir in Pohang, South Korea

Author(s): Yoo, H; Park, S; Xie, L; Kim, KI; Min, KB; Rutqvist, J; Rinaldi, AP | Abstract: This study presents comprehensive coupled hydro-mechanical numerical modeling of the first and second hydraulic stimulations at Pohang enhanced geothermal system (EGS) site in order to improve understanding on key stimulation mechanisms fractured reservoir. Two models for PX-2 PX-1 wells were developed including fracture zones different orientations permeability. Shear dilation frictional plastic strain-softening implemented a non-linear stress dependent model. A history matching wellhead pressure curves was carried out early days each stimulation. The model with jacking mechanism achieved reproduction highly reversible aperture changes observed situ. successfully simulated peak drop associated shear slip by applying strain softening. Simulated critical near well greater than prediction simple potential analysis due local poroelastic effect. confirmed that combination adequate capture evolution during increasing step-rate test PX-1. Besides, spatio-temporal pressure, total stress, permeability evaluated greatly behavior caused stimulations. possibility lower away from suggested an alternative current demonstrates processes reservoir can be reproduced.