Discrete element modeling for the multistage hydraulic stimulation of a horizontal well in hot dry rock

Hydraulic fracturing aimed at building a network of fractures in hot dry rock (HDR) often induces strong seismic risks. However, few studies have focused on seismic risks, and methods for increasing the stimulated reservoir volume (SRV) while reducing seismic risks have not been adequately studied. Therefore, based on the full hydromechanical coupling, a seismic-fracturing model with a discrete fracture network (DFN) was developed, and the methods for increasing the SRV while reducing the seismic risk of horizontal wells at the FORGE site in Utah were discussed. The results showed that the fluid channeling effect between each segment is the main reason for the uneven fracture growth in the horizontal well. Additionally, the spatiotemporal evolution of fracturinginduced seismicity shows that the two ends (L1 and L3) of the horizontal well tend to form high stress concentrations and induce larger seismic events than the middle (L2). To solve these problems, a novel hydraulic fracturing method with a differentiated-stage, variable-injection volume suitable for the multi-fracturing of horizontal wells in HDR was proposed. With the application of the method, the SRV of the horizontal well was improved effectively, and the average magnitude induced by hydraulic fracturing was also decreased by 15.4%.

Automated summary

A seismic-fracturing model with a discrete fracture network (DFN) was developed to study how to increase stimulated reservoir volume (SRV) while reducing seismic risks at the FORGE site in Utah. The study found that the fluid channeling effect between each segment is the main reason for uneven fracture growth in horizontal wells. To solve these problems, a novel hydraulic fracturing method with a differentiated-stage, variable-injection volume suitable for multi-fracturing of horizontal wells in hot dry rock (HDR) was proposed.