| Title | First Hydraulic Stimulation in Fractured Geothermal Reservoir in Pohang PX-2 Well |
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| Authors | Sehyeok PARK, Linmao XIE, Kwang-Il KIM, Saeha KWON, Ki-Bok MIN, Jaiwon CHOI, Woon-Sang YOON, Yoonho SONG |
| Year | 2017 |
| Conference | Stanford Geothermal Workshop |
| Keywords | enhanced geothermal system, hydraulic stimulation, Pohang, injectivity index, equivalent aperture |
| Abstract | The first hydraulic stimulation for EGS (Enhanced or Engineered Geothermal System) development in Korea had been conducted in the PX-2 well of 4,348m depth in Pohang EGS site from January 29th to February 20th, 2016. Treatment histories of injection rate, wellhead pressure and corresponding induced microseismicity data were obtained from the stimulation test upon 140 m long open hole section at the well bottom. Wellhead pressure and corresponding bottom hole pressure were up to 89 MPa and 131 MPa respectively and considerable level of flow rate was attempted up to 47 kg/sec. Microseismicity observation had been conducted from January 29th to February 24th and 344 events had been detected. A series of analyses were conducted based on the pressure-injection rate behavior to evaluate the hydro-mechanical property changes and determine the reservoir characteristics. The injectivity changes during the stimulation periods were evaluated as 2.7 times increase. Postulating the existence of a major fracture zone intersecting the open hole section, the transmissivity, hydraulic conductivity, permeability and equivalent aperture of the fracture were evaluated. Required pressures by hydrofracturing and hydroshearing mechanisms were estimated based on the various scenarios on the in-situ stress condition, major fracture zone orientation and shear failure criteria. Microseismicity observation showed a trend of bigger and more frequent seismicity occurrence in shut-in phase than in injection phase. This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20123010110010). |