Comprehensive in-situ stress estimation in a fractured geothermal reservoir in Pohang, South Korea using drilling data, hydraulic stimulations, and induced seismicity
Sehyeok Park, Kwang-Il Kim, Hwajung Yoo, Juhyi Yim, Ki-Bok Min
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引用次数: 0
Abstract
A comprehensive in situ stress estimation is carried out in the fractured reservoir at the enhanced geothermal system development site in Pohang, South Korea. Various types of stress indicators were collected from the hydraulic stimulation data, drilling records, lost circulation records, well logs, seismic events, and the stress constraints from previously proposed stress models. The comprehensive comparison of the collected stress constraints was performed, and resulted in the possible stress magnitude range and corresponding limits on the range of possible friction coefficients. The resulting stress ratio is SV: Shmin: SHmax = 1 : 0.92–0.94 : 1.42–1.66 with the azimuth of SHmax in N101°E –N110°E range, based on the compilation of both direct and indirect stress information. The results also suggest a friction coefficient range of 0.35–0.38 that can best explain the involved stress constraints. The stress model suggested in this study can explain the characteristics of the Mw 5.5 Pohang earthquake in November 2017 in terms of reproducing the slip rake of mainshock and the slip tendency of the corresponding fault. Therefore, the result can be used for clarifying the causal mechanism of the Pohang earthquake, providing an insight for fault stability analysis or possible geo-energy application in the southeastern part of the Korean Peninsula. Comprehensive in-situ stress estimation method suggested in this study integrating extensive direct and indirect stress indicators can improve the credibility of the in-situ stress model at a fractured reservoir.
期刊介绍:
The International Journal of Rock Mechanics and Mining Sciences focuses on original research, new developments, site measurements, and case studies within the fields of rock mechanics and rock engineering. Serving as an international platform, it showcases high-quality papers addressing rock mechanics and the application of its principles and techniques in mining and civil engineering projects situated on or within rock masses. These projects encompass a wide range, including slopes, open-pit mines, quarries, shafts, tunnels, caverns, underground mines, metro systems, dams, hydro-electric stations, geothermal energy, petroleum engineering, and radioactive waste disposal. The journal welcomes submissions on various topics, with particular interest in theoretical advancements, analytical and numerical methods, rock testing, site investigation, and case studies.