Deep Underground Science and Engineering最新文献

{"title":"Multiple injection techniques to stimulate complex fracture networks in coal reservoirs: A case study on gas disaster reduction of subsurface coal mine in southwest China","authors":"Delei Shang,&nbsp;Farui Shi,&nbsp;Jun Lu,&nbsp;Minghui Li,&nbsp;Cunbao Li,&nbsp;Heping Xie","doi":"10.1002/dug2.70059","DOIUrl":"https://doi.org/10.1002/dug2.70059","url":null,"abstract":"<p>The development and utilization of coalbed methane or coal mine gas has been a key way to ensure safe production and solve gas disaster reduction issues in coal mines. As an effective method, the hydraulic fracturing technique can increase both the number of fractures and their degree of connectivity, thereby improving the gas permeability in coal reservoirs. This study concentrates on the stimulation effectiveness of multiple fracturing techniques in coal reservoirs. First, with a novel self-constructed true tri-axial experimental setup, the indoor hydraulic fracturing experiments were conducted on sandstone, similar material to coal, and conglomerate cement under various injection schemes. The results show that long-interval multiple fracturing cannot promote the production of complex fractures but helps to communicate natural cracks, whether it is high (1206.4 mL/min) or low (120.6 mL/min) displacement. In contrast, short-interval multiple fracturing has a benefit in increasing the number of fractures and communicating natural fractures. Subsequently, the stress criterion of composite fracturing cracks caused by multiple fracturing was derived based on fracture mechanics. The theory analysis implies that the elasto-plastic zone at the hydraulic fracture tip possibly exists, and the stress shadow significantly affects fracture initiation and propagation. Besides the geostress and reservoir physical properties, sensitivity analysis shows that pore pressure caused by water and gas can also affect the stimulation effectiveness in the coal reservoirs. Finally, the in situ case studies demonstrate that multiple fracturing can change a large portion of the structure of the roof and floor strata, leading to better stimulation effectiveness by hydraulic fracturing. The extraction rate of a single borehole can be increased by more than 2.64–20.60 times compared to the original. These findings from case studies and experimental studies can provide enhanced insight into the fracturing behaviors in coal reservoirs and promote subsequent on-site application of multiple injection techniques.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"787-808"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70059","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Generalized Matsuoka–Nakai criterion considering hydrostatic pressure dependence in the brittle–ductile region","authors":"Jiacun Liu,&nbsp;Junjie Xiao,&nbsp;Dongping Liu,&nbsp;Ying Xu","doi":"10.1002/dug2.70036","DOIUrl":"https://doi.org/10.1002/dug2.70036","url":null,"abstract":"<p>A generalized Matsuoka–Nakai criterion is proposed in this study, taking the form of a polynomial function, incorporating two parameters to characterize the evolution of the failure envelope within the deviatoric plane. These two parameters exhibit an inverse correlation with both the aspect ratio and curvature. Besides, the first parameter <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>α</mi>\u0000 </mrow>\u0000 </mrow>\u0000 </semantics></math> primarily affects the curvature around the triaxial compression state, while the second parameter <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 \u0000 <mrow>\u0000 <mi>β</mi>\u0000 </mrow>\u0000 </mrow>\u0000 </semantics></math> predominantly influences the curvature around the triaxial extension state. Three sets of strength data under true triaxial stress states were selected to evaluate the generalized strength criterion. These sets include three types: hydrostatic pressure independent within the brittle region (HPI-B), hydrostatic pressure dependent within the brittle region (HPD-B), and hydrostatic pressure dependent within the brittle–ductile region (HPD-BD). In the case of HPI, the failure envelope within the deviatoric plane remains constant and is accurately described by two fixed deviatoric parameters. In contrast, for the HPD type, the shape of the failure envelope varies with hydrostatic pressure, and this variation is precisely captured using two deviatoric parameters. The experimental data are distributed around the edges of the three-dimensional failure envelope. Additionally, a comparison with existing criteria further validates the accuracy of the proposed criterion.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"699-711"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70036","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation study on the evolution of the temperature field and frozen wall in fractured rock mass","authors":"Chenyi Zhang,&nbsp;Tingting Luo,&nbsp;Tao Zhang,&nbsp;Tao Han,&nbsp;Xiaodong Zhao,&nbsp;Haipeng Li,&nbsp;Yanfei Ma,&nbsp;Faxing Zhang,&nbsp;Madhusudhan Bangalore Narasimha Murthy,&nbsp;Weihao Yang","doi":"10.1002/dug2.70073","DOIUrl":"https://doi.org/10.1002/dug2.70073","url":null,"abstract":"<p>Artificial ground freezing (AGF) method is a ground reinforcement and waterproofing technique employed in underground engineering to address complex geological conditions. Such strata typically encompass fractured rock mass with intricate fracture networks, where groundwater permeates fractures to form high-velocity dominant flow. Variations in fracture conditions significantly impact both the development of frozen walls and subsequent construction safety; however, current AGF-based numerical simulations rarely consider the influence of fracture seepage on the freezing process. To address this gap, a thermal-hydraulic coupled model for freezing pipes acting on fractured rock mass incorporating fracture phase transition is developed in this study. The effects of fracture aperture, flow velocity, and inclination on the thermal-hydraulic field and frozen wall evolution are simulated, and the results are validated against existing physical model test data. The duration for the two scenarios ranged from 7.0 to 55.9 days and 5.1 to 55.9 days, respectively. Fracture inclination modifies the affected zone around freezing pipes; thus, the frozen wall development rate of a 40° inclined fracture decreases by 92.5% compared to a horizontal fracture. However, the phase transition extent is a dominant factor for heat transfer in fractured rock mass compared to the aforementioned fracture conditions. Temperature distributions within fractures from numerical simulation closely match physical model test results, while the discrepancy in frozen wall development rate diminishes as fracture flow velocity increases.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"919-932"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70073","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The damage and failure mechanism of prestatically loaded rock during medium-strain rate cyclic impact loading","authors":"Wei Wang,&nbsp;Hanpeng Wang,&nbsp;Zicheng Wang,&nbsp;Xinyuan Xie,&nbsp;Yunhao Wu,&nbsp;Jinhou Zhang,&nbsp;Dekang Sun","doi":"10.1002/dug2.70048","DOIUrl":"https://doi.org/10.1002/dug2.70048","url":null,"abstract":"<p>To study the rock damage mechanism under high static loading and superimposed medium strain rate cyclic impact loading, a series of tests were carried out. First, the rock was preloaded with a static load (27.5, 32.5, 37.5, 42.5 MPa), and then cyclic impact loads with different peak values (6, 8, 10, 12 MPa) and different frequencies (0.5, 1.0, 1.5, 2.0 Hz) were continuously applied until the rock failure. The test results show that the axial strain of the preloaded rock with a static load during cyclic impact follows an inverted S-shaped pattern. This pattern begins with cracks compacted and closed, then crack gentle development, and finally high-speed crack expansion. The severe degree of the rock failure process is mainly related to the number of cumulative cyclic impacts. Analysis suggests that the greater the cumulative cyclic impact number, the greater the energy transmitted and dissipated at the tips of rock pores and fractures, making the propagation path of the main penetrating crack more complex. Furthermore, the shorter the rock failure duration, the greater the fractal dimension of the crack/fragments. The cumulative cyclic impacts number is negatively correlated with static load and impact peak, and positively correlated with impact frequency. Based on test results, a rock damage accumulation model under cyclic impact loading was developed. This model uses the inverted S-type logistic inverse function and considers factors like preapplied static load, impact peak, impact frequency, and the number of impacts. The theoretical calculation results are compared with the damage factors derived from axial strain test data, verifying the reliability of the damage accumulation model.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"829-842"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70048","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical and experimental study on P-wave propagation across a rock joint with different orientations","authors":"Yaghoob Zarei,&nbsp;Mojtaba D. Fallahi,&nbsp;Ali Uromeihy,&nbsp;Mohammad R. Nikoodel,&nbsp;Mohammad Fathollahy","doi":"10.1002/dug2.70061","DOIUrl":"https://doi.org/10.1002/dug2.70061","url":null,"abstract":"<p>Determination of the required parameters in different science contexts using the ultrasonic wave velocity (UWV) has been one of the favorite topics of researchers in recent years. This paper presents numerical and experimental studies to investigate the effect of joint orientation on longitudinal wave (P-wave) velocity. The study started with a numerical simulation, in which a cylindrical sample containing joints with different orientations (0°, 15°, 30°, 45°, 60°, 75°, and 90°) to the wave propagation is modeled using the discrete element method. The results show that the P-wave velocity is dependent on joint orientation due to factors such as wave refraction and reflection, interference in the transmitted wave, and normal and shear stresses derived from the axial load. More precisely, the maximum velocity was recorded at zero-degree angles of joint and then reduced to 30°. The P-wave velocity increases slightly in the range of 30° to 45° and decreases sharply from 45° to 90° angles again. Finally, the numerical study is validated by laboratory tests, which show a close correlation.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"907-918"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70061","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084030","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Slip versus dilation tendency parameter space as a tool for prospecting structurally controlled geothermal systems in greenfield: insights from the greater Ruhr region","authors":"Michal Kruszewski,&nbsp;Alessandro Verdecchia,&nbsp;Oliver Heidbach,&nbsp;Rebecca M. Harrington,&nbsp;David Healy","doi":"10.1002/dug2.70038","DOIUrl":"https://doi.org/10.1002/dug2.70038","url":null,"abstract":"<p>Faults play a vital role in the Earth's hydraulic system by facilitating fluid flow when dilating but are simultaneously known to enhance the hazard of the system once slipping in shear mode. As dilation of a fault enhances its permeability, shear failure can lead to loss of boreholes or seismic events of societal concern. This study investigates the interrelationships and temporal evolution of slip and dilation tendencies of mapped faults in the greater Ruhr region (NW Germany) for prospecting structurally controlled geothermal energy resources. In light of limited geological data from deep geothermal reservoirs, we use an analytical–probabilistic model to estimate fault reactivation potential, accounting for uncertainties in in situ stress conditions, fault geometries, and frictional properties. The cumulative distribution functions of dilation tendency, slip tendency, and fracture susceptibility indicate that more than half of the combined length of NW-SE faults have a high reactivation probability, whereas the NE-SW faults remain not optimally oriented for shear failure in the current stress field. Utilizing the slip versus dilation tendency parameter space, we prove that the NW-SE faults experience mostly hybrid failure modes and positive dilation, whereas NE-SW faults experience exclusively compactive failure modes and negative dilation. Introducing the reduced-risk dilation tendency, we identify fault segments that are most suitable for geothermal development, which show high hydraulic conductivity and low shear failure potential. With a temporal evolution of the slip and dilation tendencies computed using a fully coupled thermo–hydro–mechanical model, we show the fault reactivation potential and its failure mode evolution in time and space during geothermal fluid production. We conclude that the combined static and time-dependent slip versus dilation tendency parameter space offers a promising framework for prospecting structurally controlled deep geothermal energy systems in greenfield areas.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"669-684"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An assessment of stress and production rate of sucker rod heat pipes in oil well pumping system","authors":"R. S. Anand,&nbsp;Ang Li,&nbsp;Wenbo Huang,&nbsp;Juanwen Chen,&nbsp;Qingshan Ma,&nbsp;Fangming Jiang","doi":"10.1002/dug2.70046","DOIUrl":"https://doi.org/10.1002/dug2.70046","url":null,"abstract":"<p>The implementation of the heat pipe concept in sucker rods for oil pumping systems negates the requirement for an external heat source, thereby eliminating the necessity for expensive approaches such as separate heating systems. This method enhances the production rate by minimizing heat loss to the wellbore formation, facilitating direct heat transfer, and maintaining a lower viscosity of the oil. This study aims to assess stress evaluation and oil production through the utilization of a sucker rod heat pipe across lengths of 1.5, 2.0, 2.5, and 3.0 km within an oil pumping system. The assessment is conducted for the sucker rod heat pipe, for various inner to outer diameters of 15–27, 20–32, 25–37, and 30–42 mm, with a ratio of 0.550, 0.625, 0.670, and 0.710, respectively. This analysis considers polishing rod stroke lengths ranging from 2 to 4 m, pumping speeds between 3 and 9 strokes per minute, and different plunger diameters from 32 to 50 mm. A conceptual framework is established that incorporates the weight of the sucker rod heat pipe working fluid and its frictional impacts throughout an entire operational cycle. The observed relationship between the outcomes and the established oil well data highlights the efficacy of the method employed. The findings indicate a significant increase of 46.2% in extreme upstroke load as the inner and outer diameter changes from 15–27 to 30–42 mm, with a length extending from 1.5 to 3.0 km. Additionally, the diameter ratio and length of the sucker rod heat pipe are found to be directly correlated with the pumping speed and polishing rod stroke length during the stress evaluation. The production rate increases by 3.4%, 6.7%, 12.2%, and 21.7% for 1.5, 2.0, 2.5, and 3.0 km sucker rod heat pipe respectively, when the inner-outer diameter is changed from 15–27 to 30–42 mm and by considering higher values of polishing rod stroke length, plunger diameter, and pumping speed. In addition, it is inferred that the production rate is influenced by the material's elasticity, which decreases as the length of the rod increases. The mathematical method that enables the selection of an appropriate sucker rod heat pipe for oil pumping within the permissible limits of available equipment is delineated.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"712-727"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70046","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface hydration-induced damage in tight oil-bearing sandy conglomerate reservoirs","authors":"Anbang Zhao,&nbsp;Shuheng Du,&nbsp;Yuan Zhang,&nbsp;Jinghong Hu,&nbsp;Bo Zhou,&nbsp;Yun Wei","doi":"10.1002/dug2.70060","DOIUrl":"https://doi.org/10.1002/dug2.70060","url":null,"abstract":"<p>This study focuses on the surface hydration-induced damage in the tight oil-bearing sandy conglomerate reservoirs of the Mahu oilfield. Through experiments on core samples, a distinct two-stage surface hydration process is identified. In the first 0–100 min, the hydration rate is high, with diverse sample reactions, while from 100 to 540 min, the rate is lower and sample reactions are more uniform. Mineralogically, smectite promotes hydration, particularly in the later stage, while chlorite may inhibit it. Plagioclase shows a promoting effect, but the impact of potassium feldspar on hydration remains ambiguous. Elementally, carbon facilitates hydration, while silicon hinders it. Magnesium does not enhance hydration and may be linked to reduced oil content and increased porosity, and calcium oxide may promote hydration and porosity increase. Infrared thermal imaging indicates that hydration causes fragmentation of sandy conglomerates, attributed to smectite's water-absorption expansion, mineral dissolution/precipitation, and hydrolysis. These findings not only contribute to a deeper understanding of the hydration mechanism in the tight oil-bearing sandy conglomerate reservoirs of the Mahu oilfield but also provide crucial references for the development of sandstone and conglomerate reservoirs with similar geological conditions worldwide. By grasping the influence laws of minerals and elements on hydration, petroleum engineers can more accurately formulate extraction strategies, effectively improve reservoir recovery rates, and promote the efficient development and utilization of unconventional oil and gas resources.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"809-828"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70060","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Instability mechanism and failure characteristics of underground cavern in block system under the action of seismic waves","authors":"Xiao Wang,&nbsp;Jinxiao Liu,&nbsp;Gaoshuo Zhang,&nbsp;Wenxin Li,&nbsp;Changdi He","doi":"10.1002/dug2.70068","DOIUrl":"https://doi.org/10.1002/dug2.70068","url":null,"abstract":"<p>Geological discontinuities and excavation surfaces divide the surrounding rock of underground caverns into blocks, whose instability under seismic loading poses risks to both construction and long-term stability. While stress wave propagation in jointed rock masses has been widely studied, the opening and sliding behaviors of rock joints under seismic loading remain insufficiently addressed. This study investigates the sliding instability of cavern rock blocks under the action of seismic waves based on wave propagation theory and Universal Distinct Element Code numerical simulations. The analysis includes the response of a single block under varying seismic wave parameters, e.g., amplitude, frequency, and duration, and the overall failure characteristics of a block system under seismic excitation. Results show that seismic waves can reduce joint friction and alter sliding forces, leading to block instability when sufficient sliding space exists. The sliding behavior is governed by both seismic wave characteristics and geological structure conditions. These findings enhance understanding of failure mechanisms in jointed rock caverns and offer valuable guidance for improving the safety and stability of underground construction.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"869-882"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70068","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Caving-enhanced geothermal system overwhelms fracturing- and pipe-enhanced geothermal system in heat extraction","authors":"Fangchao Kang,&nbsp;Tianjiao Li,&nbsp;Yingchun Li,&nbsp;Jinlong Men,&nbsp;Chun'an Tang","doi":"10.1002/dug2.70057","DOIUrl":"https://doi.org/10.1002/dug2.70057","url":null,"abstract":"<p>Fracturing a geothermal reservoir of hot dry rock (HDR) by the engineered stimulation is a prerequisite to efficient heat extraction of an enhanced geothermal system (EGS). However, the heat extraction performances of different EGSs employing distinct stimulation strategies remain unclear, resulting in the conundrum that which stimulation mode is optimal for heat extraction. Here, we numerically simulated the reservoir response to different stimulation modes through varying fractures/pipes assemblages, and examined the hydraulic and thermal processes and associated heat extraction performances. We found that the caving-EGS (C-EGS) with an adequately fractured reservoir yields the best heat extraction performance. Fractures/pipes in geothermal reservoirs of the fracturing-EGS and pipe-EGS inevitably produce preferential flow paths, which accelerate thermal drawdown and shorten the operation lifespan. Increasing connected/unconnected fractures can weaken the effect of preferential flow paths, postpone thermal drawdown, and therefore lead to a more remarkable heat extraction rate. Caving the geothermal reservoir into suitable-sized blocks is the most effective stimulation in maximizing heat extraction efficiency, and thus, the C-EGS owns great potential in geothermal energy commercialization. Our key findings facilitate the optimization of geothermal reservoir stimulation for large-scale HDR exploitation.</p>","PeriodicalId":100363,"journal":{"name":"Deep Underground Science and Engineering","volume":"5 3","pages":"854-868"},"PeriodicalIF":5.0,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dug2.70057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149084077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}