Laboratory Experimental Study on the Pressure Relief Effect of Boreholes in Sandstone under High-Stress Conditions

Xiaowei Lu, Jingyu Jiang (), Wen Wang, Xuewen Cao and Lei Hong
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Xiaowei Lu: School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
Jingyu Jiang: School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China
Wen Wang: School of Energy Scinence and Engineering, Henan Polytechnic University, Jiaozuo 454003, China
Xuewen Cao: School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China
Lei Hong: School of Energy Scinence and Engineering, Henan Polytechnic University, Jiaozuo 454003, China

Sustainability, 2023, vol. 15, issue 21, 1-14

Abstract: To study the effects of deep rock drilling pressure relief under high stress conditions in enhanced geothermal systems, two kinds of drilling pressure relief experiments were conducted on sandstone—the staged drilling of pressure relief holes before peak stress and one-time drilling. Pressure relief experiments were carried out on sandstone with two borehole methods of the stage-by-stage drilling and one-time drilling of pressure relief boreholes ahead of the experiments. FLAC3D was used to analyze the plastic zone evolution during drilling and the relationship between stress and plastic zone volume. The results reveal the pre-peak stress change characteristics and pressure relief features of non-prefabricated boreholes under high stress. The experiments show that the staged drilling of pressurized samples involves stages of rapid and gradual decreases in stress, with total relief amplitudes increasing but single-borehole relief decreasing with more holes. Under the same conditions, staged drilling has better relief effects and results in greater energy dissipation, indicating that incremental pre-peak pressure relief is beneficial for reducing the surrounding rock’s impact tendency and improving stability. The research results can provide good guidance and reference for the long-term stability analysis of borehole-containing rock and rock burst hazard control.

Keywords: rock mechanics; drilling under pressure; uniaxial compression; numerical simulation; energy dissipation (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
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