Geothermics最新文献_第3页

Influence of ground source heat exchanger operation modes on multi-borehole mid-deep ground source heat pump system performance 地源热泵换热器运行模式对多钻孔中深层地源热泵系统性能的影响

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-30 DOI: 10.1016/j.geothermics.2024.103186

Zuohai Wang , Jian Ding , Mingzhi Yu , Yudong Mao , Ke Zhu , Wenke Zhang , Ping Cui , Zhaoyi Zhuang , Shiyu Zhou

The operation economy of mid-deep ground source heat pump (MGSHP) system is significantly influenced by the operation mode of multi-borehole mid-deep borehole heat exchangers (MMBHE). However, as to now, the understanding about it is very limited and far from enough. This study explores the effects of the MMBHE different operating modes on the performance of MGSHP system, and the factors such as full boreholes operation arrangement, circulating water flow rate variation of individual boreholes, and building heating load variations during the heating season. The study analyzed the circulating water temperature variation, underground temperature field distribution and evolution, heat pump unit COP, coefficient of system performance (CSP), heat extraction of MMBHE, reverse heat transfer depth of MBHE, and power consumption. The results indicate that the operation mode of letting all boreholes operate throughout the whole heating season and reducing circulating water flow rate when the heating load is small and increasing it while the load is large is much better than other operation modes. With this kind of operation mode, the MGSHP system has the lowest power consumption. Even though the overall borehole extracts heat from the ground, the upper section of the borehole sometimes injects heat. The length of the heat release section can be effectively shortened by reducing the circulating water flow rate and decreases as the operation time extends. The reduction is most significant when all boreholes are put into operation. Reducing the circulating water flow rate when the load is small and increasing it when the load turns large can result in a reduction of >50 % in the fifth year compared to that in the first year.

中深层地源热泵（MGSHP）系统的运行经济性在很大程度上受到多孔中深层井热交换器（MMBHE）运行模式的影响。然而，到目前为止，人们对它的了解还非常有限，远远不够。本研究探讨了多孔中深孔热交换器（MMBHE）不同运行模式对 MGSHP 系统性能的影响，以及全孔运行布置、单孔循环水流量变化和采暖季建筑供热负荷变化等因素。研究分析了循环水温度变化、地下温度场分布和演变、热泵机组 COP、系统性能系数（CSP）、MMBHE 热量提取、MBHE 反向传热深度和耗电量。结果表明，让所有井眼在整个采暖季运行，并在采暖负荷较小时降低循环水流量，在负荷较大时提高循环水流量的运行模式比其他运行模式要好得多。在这种运行模式下，MGSHP 系统的耗电量最低。尽管整个钻孔从地下抽取热量，但钻孔上部有时也会注入热量。通过降低循环水流量可以有效缩短放热段的长度，并随着运行时间的延长而缩短。当所有钻孔都投入运行时，这种缩短效果最为明显。在负荷较小时降低循环水流量，在负荷变大时增加循环水流量，可使第五年的耗水量比第一年减少 50%。

{"title":"Influence of ground source heat exchanger operation modes on multi-borehole mid-deep ground source heat pump system performance","authors":"Zuohai Wang , Jian Ding , Mingzhi Yu , Yudong Mao , Ke Zhu , Wenke Zhang , Ping Cui , Zhaoyi Zhuang , Shiyu Zhou","doi":"10.1016/j.geothermics.2024.103186","DOIUrl":"10.1016/j.geothermics.2024.103186","url":null,"abstract":"<div><div>The operation economy of mid-deep ground source heat pump (MGSHP) system is significantly influenced by the operation mode of multi-borehole mid-deep borehole heat exchangers (MMBHE). However, as to now, the understanding about it is very limited and far from enough. This study explores the effects of the MMBHE different operating modes on the performance of MGSHP system, and the factors such as full boreholes operation arrangement, circulating water flow rate variation of individual boreholes, and building heating load variations during the heating season. The study analyzed the circulating water temperature variation, underground temperature field distribution and evolution, heat pump unit COP, coefficient of system performance (CSP), heat extraction of MMBHE, reverse heat transfer depth of MBHE, and power consumption. The results indicate that the operation mode of letting all boreholes operate throughout the whole heating season and reducing circulating water flow rate when the heating load is small and increasing it while the load is large is much better than other operation modes. With this kind of operation mode, the MGSHP system has the lowest power consumption. Even though the overall borehole extracts heat from the ground, the upper section of the borehole sometimes injects heat. The length of the heat release section can be effectively shortened by reducing the circulating water flow rate and decreases as the operation time extends. The reduction is most significant when all boreholes are put into operation. Reducing the circulating water flow rate when the load is small and increasing it when the load turns large can result in a reduction of >50 % in the fifth year compared to that in the first year.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103186"},"PeriodicalIF":3.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Deep thermal state on the southern margin of the Zhangzhou Basin based on the electrical conductivity model 基于电导率模型的漳州盆地南缘深部热力状态

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-30 DOI: 10.1016/j.geothermics.2024.103188

Chaofeng Wu , Dong Xu , Shuojian Yang , Yixin Ye

Exploring the internal spatial and thermal structure of the Zhangzhou Basin is of great scientific significance in understanding the properties of the deep heat sources and the heating mechanism of hot springs in this region. This study estimates the temperature distribution within the upper mantle of the Basin's southern margin using the Arrhenius equation and Hashin-Shtrikman bounds based on a two-dimensional crust-mantle electrical resistivity model. We also employ a layered simulation technique to calculate the crustal temperature distribution using a one-dimensional steady-state heat conduction equation, constrained by the upper mantle's top and ground surface temperatures. This approach displays the characteristics of the longitudinal variations and horizontal inhomogeneities in crust-mantle temperature. Additionally, we estimate the heat flow values within the study area. Our findings reveal that: (i) the upper mantle (at depths of 30 - 50 km) exhibits a temperature range of 700 - 1100 °C, with the presence of local Moho and upper mantle uplifts; (ii) the crustal temperature spans from 21 - 900 °C, with a diminishing influence of the upper mantle uplift area on crustal temperature at shallower depths; (iii) the surface heat flow values derived from our simulations range between 87 and 100 mW/m², averaging at 93.23 mW/m²; (iv) the exploration of dry heat rock in this region is likely to reach a depth of at least 6 km. These results suggest that the genesis of hot springs in the study area is not solely influenced by the heat energy extracted from large-area granitic surrounding rocks during a long transport process, but is also considerably affected by local deep thermal anomalous bodies and deep-large faults.

探索漳州盆地内部空间和热力结构，对了解该地区深部热源性质和温泉加热机制具有重要的科学意义。本研究基于二维地壳-地幔电阻率模型，利用阿伦尼乌斯方程和Hashin-Shtrikman约束估算了盆地南缘上地幔内部的温度分布。我们还采用分层模拟技术，在上地幔顶部和地表温度的约束下，利用一维稳态热传导方程计算地壳温度分布。这种方法显示了地壳-地幔温度纵向变化和横向不均匀的特点。此外，我们还估算了研究区域内的热流值。我们的研究结果表明(i) 上地幔（深度为 30 - 50 千米）的温度范围为 700 - 1100 °C，存在局部莫霍面和上地幔隆起；(ii) 地壳温度范围为 21 - 900 °C，上地幔隆起区对较浅深度地壳温度的影响逐渐减小；(iii) 模拟得出的地表热流值介于 87 - 100 mW/m2 之间，平均值为 93.23 mW/m2；(iv) 该区域干热岩的勘探深度可能至少达到 6 千米。这些结果表明，研究区域的温泉成因并不仅仅受大面积花岗岩围岩在长运移过程中提取的热能的影响，还在很大程度上受到当地深部热异常体和深大断层的影响。

{"title":"Deep thermal state on the southern margin of the Zhangzhou Basin based on the electrical conductivity model","authors":"Chaofeng Wu , Dong Xu , Shuojian Yang , Yixin Ye","doi":"10.1016/j.geothermics.2024.103188","DOIUrl":"10.1016/j.geothermics.2024.103188","url":null,"abstract":"<div><div>Exploring the internal spatial and thermal structure of the Zhangzhou Basin is of great scientific significance in understanding the properties of the deep heat sources and the heating mechanism of hot springs in this region. This study estimates the temperature distribution within the upper mantle of the Basin's southern margin using the Arrhenius equation and Hashin-Shtrikman bounds based on a two-dimensional crust-mantle electrical resistivity model. We also employ a layered simulation technique to calculate the crustal temperature distribution using a one-dimensional steady-state heat conduction equation, constrained by the upper mantle's top and ground surface temperatures. This approach displays the characteristics of the longitudinal variations and horizontal inhomogeneities in crust-mantle temperature. Additionally, we estimate the heat flow values within the study area. Our findings reveal that: (i) the upper mantle (at depths of 30 - 50 km) exhibits a temperature range of 700 - 1100 °C, with the presence of local Moho and upper mantle uplifts; (ii) the crustal temperature spans from 21 - 900 °C, with a diminishing influence of the upper mantle uplift area on crustal temperature at shallower depths; (iii) the surface heat flow values derived from our simulations range between 87 and 100 mW/m<sup>2</sup>, averaging at 93.23 mW/m<sup>2</sup>; (iv) the exploration of dry heat rock in this region is likely to reach a depth of at least 6 km. These results suggest that the genesis of hot springs in the study area is not solely influenced by the heat energy extracted from large-area granitic surrounding rocks during a long transport process, but is also considerably affected by local deep thermal anomalous bodies and deep-large faults.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103188"},"PeriodicalIF":3.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Natural recovery from Fe-oxyhydroxide clogging of a geothermal well in Osaka, Japan 日本大阪地热井氧化铁堵塞的自然恢复

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-28 DOI: 10.1016/j.geothermics.2024.103187

Harue Masuda , Yasuhisa Nakaso , Masaki Nakao , Linri Cui

Causes of clogging and the following unique recovering process of an ATES (Aquifer Thermal Energy Storage) system in Maishima (Osaka, Japan) are documented based on the geochemical analyses of groundwater and stagnant water in the system. Fe-oxyhydroxides precipitation clogged screens in an ATES geothermal well during cooling operation. Chemical analyses of waters in the aquifers and plumbing pipes found out that oxidation of dissolved Fe occurred in association with intrusion of ambient air, which was leaked through inadvertently opened air bent valve, into the well. Dual heat-extraction system was installed in the two aquifers of the same wells separated by packers, and the closing occurred in the plumbing pipe installed in the shallow aquifer of one of the thermal wells. This aquifer could not be used as the ATES until when the Fe-oxyhydroxides were naturally dissolved in about a half year after the clogging. Then, the ATES system recovered to be useful. Increasing dissolved Fe with increasing NH₄⁺ and decreasing oxidation–reduction potential indicated that the Fe-oxyhydroxides were dissolved by microbially induced reduction reactions. This case suggests that some clogs can be mitigated without chemical and/or physical treatment, and that monitoring of groundwater chemistry is essential for diagnosing and treating clogs.

根据对该系统中地下水和积水的地球化学分析，记录了位于日本大阪舞岛的 ATES（含水层热能储存）系统的堵塞原因和随后的独特恢复过程。在 ATES 地热井的冷却运行过程中，铁氧氢氧化物沉淀堵塞了滤网。对含水层和管道中的水进行化学分析后发现，溶解铁的氧化与环境空气的侵入有关，而环境空气是通过不慎打开的空气弯管阀泄漏到井中的。同一口井的两个含水层被封隔器隔开，安装了双汲取热量系统，其中一口热力井的浅层含水层的管道发生关闭。该含水层无法用作 ATES，直到堵塞发生约半年后，铁氧氢氧化物自然溶解。之后，ATES 系统才恢复正常。随着 NH4+ 的增加和氧化还原电位的降低，铁的溶解度也在增加，这表明铁氧氢氧化物是通过微生物诱导的还原反应溶解的。这一案例表明，有些堵塞可以在不进行化学和/或物理处理的情况下得到缓解，而监测地下水化学性质对于诊断和处理堵塞至关重要。

{"title":"Natural recovery from Fe-oxyhydroxide clogging of a geothermal well in Osaka, Japan","authors":"Harue Masuda , Yasuhisa Nakaso , Masaki Nakao , Linri Cui","doi":"10.1016/j.geothermics.2024.103187","DOIUrl":"10.1016/j.geothermics.2024.103187","url":null,"abstract":"<div><div>Causes of clogging and the following unique recovering process of an ATES (Aquifer Thermal Energy Storage) system in Maishima (Osaka, Japan) are documented based on the geochemical analyses of groundwater and stagnant water in the system. Fe-oxyhydroxides precipitation clogged screens in an ATES geothermal well during cooling operation. Chemical analyses of waters in the aquifers and plumbing pipes found out that oxidation of dissolved Fe occurred in association with intrusion of ambient air, which was leaked through inadvertently opened air bent valve, into the well. Dual heat-extraction system was installed in the two aquifers of the same wells separated by packers, and the closing occurred in the plumbing pipe installed in the shallow aquifer of one of the thermal wells. This aquifer could not be used as the ATES until when the Fe-oxyhydroxides were naturally dissolved in about a half year after the clogging. Then, the ATES system recovered to be useful. Increasing dissolved Fe with increasing NH<sub>4</sub><sup>+</sup> and decreasing oxidation–reduction potential indicated that the Fe-oxyhydroxides were dissolved by microbially induced reduction reactions. This case suggests that some clogs can be mitigated without chemical and/or physical treatment, and that monitoring of groundwater chemistry is essential for diagnosing and treating clogs.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103187"},"PeriodicalIF":3.5,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Numerical modeling of the Nevados de Chillán fractured geothermal reservoir 奇廉内瓦多斯断裂地热储层的数值建模

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-22 DOI: 10.1016/j.geothermics.2024.103181

Isa Oyarzo-Céspedes , Gloria Arancibia , John Browning , Jorge G.F. Crempien , Diego Morata , Valentina Mura , Camila López-Contreras , Santiago Maza

Numerical models can be utilized to understand and anticipate the future behavior of a geothermal reservoir, and hence aid in the development of efficient reservoir engineering strategies. However, as each system has a unique geological context, individual characterization is required. In this research, the Nevados de Chillán Geothermal System (NChGS) in the Southern Volcanic Zone of the Andes is considered. The NChGS is controlled by the geology of the active Nevados de Chillán Volcanic Complex (NChVC) including their basement units (Miocene lavas and volcaniclastic layers from Cura-Mallín Formation and the Miocene, Santa Gertrudis granitoids) as well as the key structural control from crustal scale faults, all of which combine to influence the reservoir characteristics. The presence of faults acts to generate a high secondary permeability which favors the circulation of hydrothermal fluids. Based on previous studies in the NChGS, we designed a thermo-hydraulic model in COMSOL Multiphysics® combining equations of heat transfer and Darcy's law in order to determine the distribution of isotherms and surface heat flux. The boundary conditions of the model were informed by a conceptual model of depth 3 km and width of 6.6 km which considers a highly fractured granitic reservoir, a clay cap behavior of Miocene lavas and volcaniclastic units, and transitional zones between a regional zone and the reservoir. A low-angle reverse fault affecting the clay cap unit was also incorporated into the models. Results indicate convective behavior in the reservoir zone and a surface heat flux of 0.102 W/m² with a local peak up to 0.740 W/m² in the area affected by the low-angle reverse fault zone. The models suggest hydrothermal fluid residence times of around 9–15 thousand years are required to reach a steady-state thermal configuration, which is consistent with the deglaciation age proposed for the NChVC latitude of the complex (c. 10–15 ka). Permeability in the fractured reservoir is one of the most complex parameters to estimate and the most sensitive and hence requires further constraint. Finally, using the volumetric method and the results obtained in this research, we estimate a geothermal potential of 39 ± 1 MWe for the NChGS.

数字模型可用于了解和预测地热储层的未来行为，从而帮助制定高效的储层工程战略。然而，由于每个系统都有其独特的地质背景，因此需要进行单独的特征描述。本研究考虑的是安第斯山脉南部火山区的内瓦多斯德希廉地热系统（NChGS）。内瓦多斯-德-奇廉活跃火山群（Nevados de Chillán Volcanic Complex，NChVC）的地质情况控制着内瓦多斯-德-奇廉地热系统，包括其基底单元（中新世的库拉-马林地层的熔岩和火山碎屑层以及中新世的圣格特鲁迪斯花岗岩），以及来自地壳规模断层的关键结构控制，所有这些因素共同影响着储层的特征。断层的存在产生了高二次渗透率，有利于热液的循环。根据之前对 NChGS 的研究，我们在 COMSOL Multiphysics® 中结合传热方程和达西定律设计了一个热液模型，以确定等温线和表面热通量的分布。该模型的边界条件参考了一个深度为 3 千米、宽度为 6.6 千米的概念模型，该模型考虑了高度断裂的花岗岩储层、由中新世熔岩和火山碎屑岩单元组成的粘土盖层以及区域带与储层之间的过渡带。影响粘土帽单元的低角度逆断层也被纳入模型。结果表明，储层区存在对流行为，地表热通量为 0.102 W/m2，受低角逆断层区影响的局部峰值高达 0.740 W/m2。模型表明，热液停留时间约为 9-15 千年，才能达到稳态热配置，这与为该复合体北西向断裂带纬度提出的脱冰期（约 10-15 ka）相一致。裂缝储层的渗透性是最复杂的估算参数之一，也是最敏感的参数，因此需要进一步的约束。最后，利用容积法和本次研究获得的结果，我们估算出 NChGS 的地热潜力为 39 ± 1 MWe。

{"title":"Numerical modeling of the Nevados de Chillán fractured geothermal reservoir","authors":"Isa Oyarzo-Céspedes , Gloria Arancibia , John Browning , Jorge G.F. Crempien , Diego Morata , Valentina Mura , Camila López-Contreras , Santiago Maza","doi":"10.1016/j.geothermics.2024.103181","DOIUrl":"10.1016/j.geothermics.2024.103181","url":null,"abstract":"<div><div>Numerical models can be utilized to understand and anticipate the future behavior of a geothermal reservoir, and hence aid in the development of efficient reservoir engineering strategies. However, as each system has a unique geological context, individual characterization is required. In this research, the Nevados de Chillán Geothermal System (NChGS) in the Southern Volcanic Zone of the Andes is considered. The NChGS is controlled by the geology of the active Nevados de Chillán Volcanic Complex (NChVC) including their basement units (Miocene lavas and volcaniclastic layers from Cura-Mallín Formation and the Miocene, Santa Gertrudis granitoids) as well as the key structural control from crustal scale faults, all of which combine to influence the reservoir characteristics. The presence of faults acts to generate a high secondary permeability which favors the circulation of hydrothermal fluids. Based on previous studies in the NChGS, we designed a thermo-hydraulic model in COMSOL Multiphysics® combining equations of heat transfer and Darcy's law in order to determine the distribution of isotherms and surface heat flux. The boundary conditions of the model were informed by a conceptual model of depth 3 km and width of 6.6 km which considers a highly fractured granitic reservoir, a clay cap behavior of Miocene lavas and volcaniclastic units, and transitional zones between a regional zone and the reservoir. A low-angle reverse fault affecting the clay cap unit was also incorporated into the models. Results indicate convective behavior in the reservoir zone and a surface heat flux of 0.102 W/m<sup>2</sup> with a local peak up to 0.740 W/m<sup>2</sup> in the area affected by the low-angle reverse fault zone. The models suggest hydrothermal fluid residence times of around 9–15 thousand years are required to reach a steady-state thermal configuration, which is consistent with the deglaciation age proposed for the NChVC latitude of the complex (<em>c.</em> 10–15 ka). Permeability in the fractured reservoir is one of the most complex parameters to estimate and the most sensitive and hence requires further constraint. Finally, using the volumetric method and the results obtained in this research, we estimate a geothermal potential of 39 ± 1 MWe for the NChGS.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103181"},"PeriodicalIF":3.5,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Modeling proppant transport and settlement in 3D fracture networks in geothermal reservoirs 地热储层三维裂缝网络中支撑剂迁移和沉降建模

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-19 DOI: 10.1016/j.geothermics.2024.103176

Baohua Liu, Dharmendra Kumar, Ahmad Ghassemi

In this paper, we develop an efficient proppant transport model using the Eulerian-Eulerian approach for simulating proppant transport in fractures and 3D fracture networks in geothermal reservoirs. The proposed model accounts for proppant settling, pack/bed formation, bridging/screenout, proppant concentration effect, fracture wall effect, and the transition from Poiseuille flow (fracture channel) to Darcy flow (proppant pack). Notably, the heat transfer process and its impact on proppant transport are also considered—a facet often overlooked in previous proppant transport models. A three-dimensional displacement discontinuity method (3D DDM) that incorporates the stress shadow effect is employed to generate the fracture geometry. The governing equations for slurry flow, proppant transport, and heat transfer are discretized and solved using the finite volume method (FVM). The model is verified against analytical solutions and published experimental data, demonstrating good agreement with these references. To demonstrate the proposed model, we applied it to both low-temperature (depleted hydrocarbon wells) and high-temperature (dry hot rocks) enhanced geothermal systems (EGS). The simulation results highlight the significant influence of reservoir temperature on proppant transport and settlement in a reservoir environment. Heating of the slurry by higher temperature reservoir rocks reduces fluid viscosity and accelerates proppant settling, thereby shortening the transport distance and reducing the coverage area of the proppant. Both ultra-light and micro-proppant are effective in mitigating proppant settlement in enhanced geothermal systems. However, proppant is susceptible to bridging at fracture intersections, where the fracture widths are narrower due to more pronounced stress shadow effects in these areas. Consequently, the use of micro-proppant could offer substantial benefits over ultra-light proppant in enhancing proppant coverage area in enhanced geothermal systems.

本文采用欧拉-欧拉方法开发了一种高效的支撑剂输送模型，用于模拟地热储层裂缝和三维裂缝网络中的支撑剂输送。所提出的模型考虑了支撑剂沉降、包/床形成、架桥/筛出、支撑剂浓度效应、裂缝壁效应以及从波赛流（裂缝通道）到达西流（支撑剂包）的过渡。值得注意的是，该模型还考虑了热传导过程及其对支撑剂输送的影响--这是以前的支撑剂输送模型经常忽略的一个方面。三维位移不连续法（3D DDM）结合了应力阴影效应，用于生成断裂几何形状。泥浆流动、支撑剂输送和传热的控制方程采用有限体积法（FVM）进行离散化和求解。我们根据分析解法和已公布的实验数据对模型进行了验证，结果表明模型与这些参考文献非常吻合。为了证明所提出的模型，我们将其应用于低温（枯竭碳氢化合物井）和高温（干热岩）强化地热系统（EGS）。模拟结果凸显了储层温度对支撑剂在储层环境中的运移和沉降的重要影响。温度较高的储层岩石对泥浆的加热降低了流体粘度，加速了支撑剂的沉降，从而缩短了输送距离，减少了支撑剂的覆盖面积。超轻支撑剂和微支撑剂都能有效缓解强化地热系统中的支撑剂沉降。然而，支撑剂容易在裂缝交汇处架桥，因为这些区域的应力阴影效应更明显，裂缝宽度更窄。因此，与超轻型支撑剂相比，使用微型支撑剂在增强地热系统中提高支撑剂覆盖面积方面具有很大优势。

{"title":"Modeling proppant transport and settlement in 3D fracture networks in geothermal reservoirs","authors":"Baohua Liu, Dharmendra Kumar, Ahmad Ghassemi","doi":"10.1016/j.geothermics.2024.103176","DOIUrl":"10.1016/j.geothermics.2024.103176","url":null,"abstract":"<div><div>In this paper, we develop an efficient proppant transport model using the Eulerian-Eulerian approach for simulating proppant transport in fractures and 3D fracture networks in geothermal reservoirs. The proposed model accounts for proppant settling, pack/bed formation, bridging/screenout, proppant concentration effect, fracture wall effect, and the transition from Poiseuille flow (fracture channel) to Darcy flow (proppant pack). Notably, the heat transfer process and its impact on proppant transport are also considered—a facet often overlooked in previous proppant transport models. A three-dimensional displacement discontinuity method (3D DDM) that incorporates the stress shadow effect is employed to generate the fracture geometry. The governing equations for slurry flow, proppant transport, and heat transfer are discretized and solved using the finite volume method (FVM). The model is verified against analytical solutions and published experimental data, demonstrating good agreement with these references. To demonstrate the proposed model, we applied it to both low-temperature (depleted hydrocarbon wells) and high-temperature (dry hot rocks) enhanced geothermal systems (EGS). The simulation results highlight the significant influence of reservoir temperature on proppant transport and settlement in a reservoir environment. Heating of the slurry by higher temperature reservoir rocks reduces fluid viscosity and accelerates proppant settling, thereby shortening the transport distance and reducing the coverage area of the proppant. Both ultra-light and micro-proppant are effective in mitigating proppant settlement in enhanced geothermal systems. However, proppant is susceptible to bridging at fracture intersections, where the fracture widths are narrower due to more pronounced stress shadow effects in these areas. Consequently, the use of micro-proppant could offer substantial benefits over ultra-light proppant in enhancing proppant coverage area in enhanced geothermal systems.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103176"},"PeriodicalIF":3.5,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531181","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Three-dimensional electrical imaging of the Aravali-Tural-Rajwadi geothermal system, West Coast of India 印度西海岸阿拉瓦利-图拉尔-拉杰瓦迪地热系统的三维电气成像

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-18 DOI: 10.1016/j.geothermics.2024.103185

Khasi Raju , Vasu Deshmukh , P.V. Vijaya Kumar , P.B.V. Subba Rao , A.K. Singh

The West Coast geothermal system is a prominent geothermal region in the Indian subcontinent, and understanding its geothermal reservoirs is crucial for societal benefits. In the present study, we employed 3D modeling of Audio and broad-band Magnetotelluric (AMT & MT) data for the first time in the West Coast geothermal region, covering the Aravali, Tural, and Rajwadi geothermal zones, to gain insights into the evolution of geothermal zone and geothermal reservoir characteristics. The 3D inversion results revealed the presence of a thin layer of granitic crustal layer, which decreases in thickness towards the west. The rifting process along the western continental margin of India has introduced magmatism (underplated) to the crustal level, which manifests as a moderate conductivity (100–500 Ωm) layer in shallow depths (∼10 km). The cooling and solidification of underplating materials contribute to the heat flux along the West Coast geothermal zone (WCGZ). The circulation of meteoric water within the deep layers gets heated up by these mantle materials and is ejected along the fracture and fault zones that appear as hot springs. Considering a thin crustal layer, a shallow Moho, and an upwelling asthenosphere along the west coast, the WCGZ is considered a convective geothermal play type. This study enhances an understanding of the WCGZ geothermal potential and geological processes, which can have significant implications for harnessing this valuable energy resource.

西海岸地热系统是印度次大陆的一个重要地热区，了解其地热储层对社会效益至关重要。在本研究中，我们首次在西海岸地热区（涵盖阿拉瓦里、图拉勒和拉杰瓦迪地热区）采用了音频和宽带磁触伦（AMT & MT）数据的三维建模，以深入了解地热区的演变和地热储层的特征。三维反演结果显示存在一层薄的花岗岩地壳层，厚度向西递减。印度西部大陆边缘的断裂过程在地壳层中引入了岩浆活动（下伏），在浅层（10 千米以下）表现为中等导电率（100-500 Ωm）层。底板材料的冷却和凝固促进了西海岸地热区（WCGZ）的热通量。深层中的流星水循环被这些地幔物质加热，沿断裂带和断层带喷出，形成温泉。考虑到地壳层较薄、莫霍河较浅以及西海岸沿岸的上涌岩浆层，WCGZ 被认为是一种对流地热作用类型。这项研究加深了人们对 WCGZ 地热潜力和地质过程的了解，对利用这一宝贵的能源资源具有重大意义。

{"title":"Three-dimensional electrical imaging of the Aravali-Tural-Rajwadi geothermal system, West Coast of India","authors":"Khasi Raju , Vasu Deshmukh , P.V. Vijaya Kumar , P.B.V. Subba Rao , A.K. Singh","doi":"10.1016/j.geothermics.2024.103185","DOIUrl":"10.1016/j.geothermics.2024.103185","url":null,"abstract":"<div><div>The West Coast geothermal system is a prominent geothermal region in the Indian subcontinent, and understanding its geothermal reservoirs is crucial for societal benefits. In the present study, we employed 3D modeling of Audio and broad-band Magnetotelluric (AMT & MT) data for the first time in the West Coast geothermal region, covering the Aravali, Tural, and Rajwadi geothermal zones, to gain insights into the evolution of geothermal zone and geothermal reservoir characteristics. The 3D inversion results revealed the presence of a thin layer of granitic crustal layer, which decreases in thickness towards the west. The rifting process along the western continental margin of India has introduced magmatism (underplated) to the crustal level, which manifests as a moderate conductivity (100–500 Ωm) layer in shallow depths (∼10 km). The cooling and solidification of underplating materials contribute to the heat flux along the West Coast geothermal zone (WCGZ). The circulation of meteoric water within the deep layers gets heated up by these mantle materials and is ejected along the fracture and fault zones that appear as hot springs. Considering a thin crustal layer, a shallow Moho, and an upwelling asthenosphere along the west coast, the WCGZ is considered a convective geothermal play type. This study enhances an understanding of the WCGZ geothermal potential and geological processes, which can have significant implications for harnessing this valuable energy resource.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103185"},"PeriodicalIF":3.5,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142531179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Experimental and numerical research on the thermal performance of a vertical earth-to-air heat exchanger system 垂直土-空气热交换器系统热性能的实验和数值研究

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-16 DOI: 10.1016/j.geothermics.2024.103182

Kailiang Huang , Qihai Sun , Guohui Feng , Lei Zhang , Ainong Li , Jiaxing Wei , Xiao Zhang , Xianghua Meng

The Earth-to-Air Heat Exchanger (EAHE) system is an efficient and clean geothermal application technology that can be used for pre-cooling in summer and heating in winter. This paper proposes a novel Vertical Earth-to-Air Heat Exchanger (VEAHE) system that uses baffles to divide the vertical duct into two ventilation tunnels with a hollow area at the bottom for air circulation. This system occupies a small land area and has a relatively high geothermal energy utilization efficiency. This study evaluates the thermal performance of the system through experimental tests under various operating conditions. Additionally, a numerical model of the system was established to explore the influence of baffles length, thickness, and duct depth on its thermal performance. The experimental results show that the 2.5-meter deep VEAHE system achieves an average air pre-cooling temperature reduction of 5.42 °C, with a maximum temperature reduction of up to 7.58 °C. Below the 1.2-meter mark of the system, the cooling capacity of the descending pipe is 1.52 times that of the ascending pipe. The simulation showed a Maximum Absolute Relative Error (MARE) of 3.15 % compared to the experimental results. As the length and thickness of the baffles, duct length, and soil thermal conductivity increase, the average outlet air temperature gradually decreases, while the system's heat exchange capacity significantly improves, in contrast to the duct diameter. Among the influencing factors, the duct length has the greatest impact on the system. Under the recommended configuration, the system's maximum pre-cooling potential is 915.90 W, with the outlet air temperature ranging from 12.05 °C to 14.79 °C.

地-空气热交换器（EAHE）系统是一种高效、清洁的地热应用技术，可用于夏季预冷和冬季供暖。本文提出了一种新颖的垂直地-空气热交换器（VEAHE）系统，该系统利用挡板将垂直管道分为两个通风隧道，底部为中空区域，用于空气流通。该系统占地面积小，地热能利用效率相对较高。本研究通过各种运行条件下的实验测试，对该系统的热性能进行了评估。此外，还建立了该系统的数值模型，以探讨挡板长度、厚度和管道深度对其热性能的影响。实验结果表明，2.5 米深的 VEAHE 系统可使空气预冷温度平均降低 5.42 °C，最高可降低 7.58 °C。在系统的 1.2 米以下，下降管道的冷却能力是上升管道的 1.52 倍。模拟结果与实验结果相比，最大绝对相对误差（MARE）为 3.15%。随着挡板长度和厚度、管道长度以及土壤导热系数的增加，平均出口空气温度逐渐降低，而系统的热交换能力则显著提高，与管道直径形成鲜明对比。在影响因素中，风道长度对系统的影响最大。在推荐配置下，系统的最大预冷潜能为 915.90 W，出口空气温度范围为 12.05 °C 至 14.79 °C。

{"title":"Experimental and numerical research on the thermal performance of a vertical earth-to-air heat exchanger system","authors":"Kailiang Huang , Qihai Sun , Guohui Feng , Lei Zhang , Ainong Li , Jiaxing Wei , Xiao Zhang , Xianghua Meng","doi":"10.1016/j.geothermics.2024.103182","DOIUrl":"10.1016/j.geothermics.2024.103182","url":null,"abstract":"<div><div>The Earth-to-Air Heat Exchanger (EAHE) system is an efficient and clean geothermal application technology that can be used for pre-cooling in summer and heating in winter. This paper proposes a novel Vertical Earth-to-Air Heat Exchanger (VEAHE) system that uses baffles to divide the vertical duct into two ventilation tunnels with a hollow area at the bottom for air circulation. This system occupies a small land area and has a relatively high geothermal energy utilization efficiency. This study evaluates the thermal performance of the system through experimental tests under various operating conditions. Additionally, a numerical model of the system was established to explore the influence of baffles length, thickness, and duct depth on its thermal performance. The experimental results show that the 2.5-meter deep VEAHE system achieves an average air pre-cooling temperature reduction of 5.42 °C, with a maximum temperature reduction of up to 7.58 °C. Below the 1.2-meter mark of the system, the cooling capacity of the descending pipe is 1.52 times that of the ascending pipe. The simulation showed a Maximum Absolute Relative Error (MARE) of 3.15 % compared to the experimental results. As the length and thickness of the baffles, duct length, and soil thermal conductivity increase, the average outlet air temperature gradually decreases, while the system's heat exchange capacity significantly improves, in contrast to the duct diameter. Among the influencing factors, the duct length has the greatest impact on the system. Under the recommended configuration, the system's maximum pre-cooling potential is 915.90 W, with the outlet air temperature ranging from 12.05 °C to 14.79 °C.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103182"},"PeriodicalIF":3.5,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142442824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Macroscopic permeability progression of Nanan granite under confining pressures and its microscopic evolution after cooling at atmospheric pressure: A comparative study 南安花岗岩在约束压力下的宏观渗透率变化及其在常压下冷却后的微观演变：对比研究

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-14 DOI: 10.1016/j.geothermics.2024.103180

Zhennan Zhu , Wangxing Hong , Shengqi Yang , Ting Bao , Jingyu Xie , Hao Fan , Yilong Yuan , Yu Zhang , Hong Tian , Jun Zheng , Jin Chen , Guosheng Jiang

Permeability is one of the key factors for influencing the mass transfer behavior in rocks and plays a key role in heat extraction of enhanced geothermal systems (EGSs), so the practice of EGSs needs cooling water to be injected to enhance the permeability within geothermal reservoirs. Macroscopic and microscopic experimental investigation on how cool water affects permeability evolution is still limited. To solve this, we experimentally explored the permeability evolution of Nanan granite after air and water cooling under different confining pressures combined with optical microscopy and X-ray micro computed tomography (CT) observation. Lots of microdefects were observed in Nanan granite after two cooling paths, which dominantly drives the evolution of permeability from a microscopic scale. The permeabilities of granite under water-cooling conditions are always larger than those under air-cooling conditions, because the comparison shows that water-cooling treatment enhances the permeability of specimens. The permeabilities of granite specimens after two cooling paths decrease with the confining stress. More microcracks and better connectivity among microcracks produce a larger permeability within the specimen after water cooling. The observed microcracks are regarded as the seepage channels and direct microscale evidence of the permeability evolution of granite after two cooling paths. Our results provide support that cooled water injection is an efficient way for permeability enhancement due to thermal microcracks propagation in thermal simulation.

渗透性是影响岩石传质行为的关键因素之一，在强化地热系统（EGSs）的热量提取中起着关键作用，因此，EGSs 的实践需要注入冷却水以提高地热储层内的渗透性。关于冷却水如何影响渗透率演化的宏观和微观实验研究仍然有限。为了解决这个问题，我们结合光学显微镜和 X 射线显微计算机断层扫描（CT）观测，实验探索了南安花岗岩在不同约束压力下空冷和水冷后的渗透率演化。结果表明，南安花岗岩在两种冷却方式下均存在大量微缺陷，从微观尺度上主导了渗透率的演化。水冷条件下花岗岩的渗透率总是大于空冷条件下的渗透率，因为比较表明水冷处理提高了试样的渗透率。经过两种冷却路径后，花岗岩试样的渗透率随着约束应力的增加而降低。水冷却后，更多的微裂缝和微裂缝之间更好的连通性在试样内部产生了更大的渗透性。观察到的微裂缝被视为渗流通道，是花岗岩经过两种冷却路径后渗透性演变的直接微观证据。我们的研究结果证明，在热模拟中，冷却水注入是通过热微裂纹传播提高渗透率的有效方法。

{"title":"Macroscopic permeability progression of Nanan granite under confining pressures and its microscopic evolution after cooling at atmospheric pressure: A comparative study","authors":"Zhennan Zhu , Wangxing Hong , Shengqi Yang , Ting Bao , Jingyu Xie , Hao Fan , Yilong Yuan , Yu Zhang , Hong Tian , Jun Zheng , Jin Chen , Guosheng Jiang","doi":"10.1016/j.geothermics.2024.103180","DOIUrl":"10.1016/j.geothermics.2024.103180","url":null,"abstract":"<div><div>Permeability is one of the key factors for influencing the mass transfer behavior in rocks and plays a key role in heat extraction of enhanced geothermal systems (EGSs), so the practice of EGSs needs cooling water to be injected to enhance the permeability within geothermal reservoirs. Macroscopic and microscopic experimental investigation on how cool water affects permeability evolution is still limited. To solve this, we experimentally explored the permeability evolution of Nanan granite after air and water cooling under different confining pressures combined with optical microscopy and X-ray micro computed tomography (CT) observation. Lots of microdefects were observed in Nanan granite after two cooling paths, which dominantly drives the evolution of permeability from a microscopic scale. The permeabilities of granite under water-cooling conditions are always larger than those under air-cooling conditions, because the comparison shows that water-cooling treatment enhances the permeability of specimens. The permeabilities of granite specimens after two cooling paths decrease with the confining stress. More microcracks and better connectivity among microcracks produce a larger permeability within the specimen after water cooling. The observed microcracks are regarded as the seepage channels and direct microscale evidence of the permeability evolution of granite after two cooling paths. Our results provide support that cooled water injection is an efficient way for permeability enhancement due to thermal microcracks propagation in thermal simulation.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103180"},"PeriodicalIF":3.5,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Damage characteristics of high-temperature coal under different cooling rates 不同冷却速率下高温煤的损伤特征

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-07 DOI: 10.1016/j.geothermics.2024.103179

Su Wang , Hanpeng Wang , Wei Wang , Bing Zhang , Youshi Wang , Dekang Sun

The damage characteristics of high-temperature coal under water cooling was analyzed.As the heating temperature increases, the internal pore development and crack propagation in coal intensify, with the failure mode gradually shifting from brittle to plastic. There exists a threshold temperature that accelerates damage. The rapid temperature drop caused by water cooling accelerates damage and cracking in the coal. The thermal shock factor resulting from the rapid temperature drop can quantitatively represent the damage induced by water cooling. The results are expected to provide guidance for the utilization of thermal energy in coal field fire areas.

随着加热温度的升高，煤的内部孔隙发育和裂纹扩展加剧，破坏模式逐渐从脆性转向塑性。存在一个加速破坏的临界温度。水冷造成的快速降温会加速煤炭的损坏和裂纹。快速降温导致的热冲击因子可以定量地表示水冷所引起的破坏。研究结果有望为煤田火区的热能利用提供指导。

引用次数: 0

Breakage mechanism analysis of bedded sandstone impacted by abrasive water jet using an integrated SPH-DEM-FEM and cohesive element method 利用综合 SPH-DEM-FEM 和内聚元素法分析受到磨料水射流冲击的层状砂岩的破碎机理

IF 3.5 2区工程技术 Q3 ENERGY & FUELS

Geothermics

Pub Date : 2024-10-07 DOI: 10.1016/j.geothermics.2024.103177

Zhe Zhou , Chao Tian , Zhaolong Ge , Zhongtan Li , Qinglin Deng

Abrasive water jet (AWJ) is an emerging technique for improving the drilling efficiency for geothermal energy development. Rock bedding significantly influences the effectiveness of rock breaking during drilling. In this study, to investigate the damage modes and the mechanism of the bedded sandstone under abrasive water jet erosion, smooth particle hydrodynamics (SPH) and discrete element method (DEM) are used to establish the jet, and cohesive elements are inserted into finite elements to model the bedded sandstone, simulating the process of water and abrasive into the nozzle to form an abrasive water jet impacting bedded sandstone. The numerical results showed that the depth and diameter of fractures in bedded sandstone decrease and then stabilize as the bedding angle increases under AWJ, and the error in the ratio of erosion hole diameter and depth between the simulated and experimental results was <10.8 %. In addition, two damage modes of the bedded sandstone were determined, which include Case I damage mode: the sandstone is well consolidated, and the damage is in the form of erosion holes (0°≤α≤60°), dominated by the tensile damage, and Case II damage mode: the rock is fractured along the bedding and splits into two halves (60°<α≤90°), and the process can be divided into two stages during this mode. The first stage is the impact kinetic energy carried by the jet to form a crater, and the second stage is the water wedge effect to fracture the rock. The results of this study complement the damage mechanism of fractured bedded rocks by AWJ, which provides a theoretical reference for the application of AWJ to break bedded rocks in subsurface energy extraction.

加砂水射流（AWJ）是一种提高地热能源开发钻探效率的新兴技术。岩石垫层对钻探过程中的破岩效果有很大影响。本研究采用光滑粒子流体力学（SPH）和离散元法（DEM）建立射流，并在有限元中插入内聚元，模拟水和磨料进入喷嘴形成磨料水射流冲击层状砂岩的过程，研究磨料水射流侵蚀下层状砂岩的破坏模式和机理。数值结果表明，在 AWJ 作用下，层状砂岩的裂缝深度和直径随着层理角的增大而减小，然后趋于稳定，模拟结果与实验结果之间侵蚀孔直径与深度之比误差为 10.8%。此外，还确定了床层砂岩的两种破坏模式，包括情况 I 破坏模式：砂岩固结良好，破坏形式为侵蚀孔（0°≤α≤60°），以拉伸破坏为主；情况 II 破坏模式：岩石沿床层断裂并分裂为两半（60°<α≤90°），该模式下的破坏过程可分为两个阶段。第一阶段是射流携带的冲击动能形成陨石坑，第二阶段是水楔效应使岩石断裂。该研究结果补充了 AWJ 对破裂基岩的破坏机理，为在地下能源开采中应用 AWJ 破坏基岩提供了理论参考。

{"title":"Breakage mechanism analysis of bedded sandstone impacted by abrasive water jet using an integrated SPH-DEM-FEM and cohesive element method","authors":"Zhe Zhou , Chao Tian , Zhaolong Ge , Zhongtan Li , Qinglin Deng","doi":"10.1016/j.geothermics.2024.103177","DOIUrl":"10.1016/j.geothermics.2024.103177","url":null,"abstract":"<div><div>Abrasive water jet (AWJ) is an emerging technique for improving the drilling efficiency for geothermal energy development. Rock bedding significantly influences the effectiveness of rock breaking during drilling. In this study, to investigate the damage modes and the mechanism of the bedded sandstone under abrasive water jet erosion, smooth particle hydrodynamics (SPH) and discrete element method (DEM) are used to establish the jet, and cohesive elements are inserted into finite elements to model the bedded sandstone, simulating the process of water and abrasive into the nozzle to form an abrasive water jet impacting bedded sandstone. The numerical results showed that the depth and diameter of fractures in bedded sandstone decrease and then stabilize as the bedding angle increases under AWJ, and the error in the ratio of erosion hole diameter and depth between the simulated and experimental results was <10.8 %. In addition, two damage modes of the bedded sandstone were determined, which include Case I damage mode: the sandstone is well consolidated, and the damage is in the form of erosion holes (0°≤α≤60°), dominated by the tensile damage, and Case II damage mode: the rock is fractured along the bedding and splits into two halves (60°<α≤90°), and the process can be divided into two stages during this mode. The first stage is the impact kinetic energy carried by the jet to form a crater, and the second stage is the water wedge effect to fracture the rock. The results of this study complement the damage mechanism of fractured bedded rocks by AWJ, which provides a theoretical reference for the application of AWJ to break bedded rocks in subsurface energy extraction.</div></div>","PeriodicalId":55095,"journal":{"name":"Geothermics","volume":"125 ","pages":"Article 103177"},"PeriodicalIF":3.5,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0