{"title":"超临界二氧化碳注入后干热岩力学性能演变研究","authors":"Pan Li, Hongxue Zhang, Yu Wu","doi":"10.1186/s40517-024-00306-5","DOIUrl":null,"url":null,"abstract":"<div><p>Characterizing the evolution of mechanical properties of hot dry rock (HDR) after supercritical CO<sub>2</sub> (CO<sub>2</sub>(sc)) injection is crucial for assessing the heat extraction rate and reservoir security of CO<sub>2</sub> based enhanced geothermal systems. This study designed the experiments of triaxial seepage and mechanical properties considering no CO<sub>2</sub>(sc) injection, CO<sub>2</sub>(sc) injection, and alternating injection of water-CO<sub>2</sub>(sc) (AIWC) in granite at 150–300 ℃. The experiments can reveal the mechanical properties of HDR in single-phase CO<sub>2</sub> zone, CO<sub>2</sub>-water two-phase zone and dissolved CO<sub>2</sub> liquid phase zone in HDR reservoir. The results indicate that the failure mode of the rock samples primarily exhibits sudden instability after no CO<sub>2</sub>(sc) injection and AIWC, whereas it predominantly manifests progressive instability after CO<sub>2</sub>(sc) injection. Compared with 25 ℃, the uniaxial compressive strength (UCS) after no CO<sub>2</sub>(sc) injection at 150–300 ℃ decreased by 13.86%–32.92%. After CO<sub>2</sub>(sc) injection, the UCS decreased by 40.79%–59.60%. After AIWC, the UCS decreased by 27.74–40.48%. This shows that the strength of rock mass in the single-phase CO<sub>2</sub> zone is lower than that in the other two zones, and this weakening phenomenon increases with the increase of temperature difference. At the same temperature, the elasticity modulus after AIWC was greater than that after no CO<sub>2</sub>(sc) injection and CO<sub>2</sub>(sc) injection. With no CO<sub>2</sub>(sc) injection, when the temperature was increased to 200 ℃ and 300 ℃, intergranular cracks and transgranular appeared respectively. After AIWC, mineral crystals such as calcite were precipitated on the surfaces of the connected large cracks, accompanied by kaolinite clay minerals. This increases the frictional contact of the mineral particles and enhances the stability of the HDR reservoir.</p></div>","PeriodicalId":48643,"journal":{"name":"Geothermal Energy","volume":null,"pages":null},"PeriodicalIF":2.9000,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00306-5","citationCount":"0","resultStr":"{\"title\":\"Study on the evolution of mechanical properties of hot dry rocks after supercritical CO2 injection\",\"authors\":\"Pan Li, Hongxue Zhang, Yu Wu\",\"doi\":\"10.1186/s40517-024-00306-5\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Characterizing the evolution of mechanical properties of hot dry rock (HDR) after supercritical CO<sub>2</sub> (CO<sub>2</sub>(sc)) injection is crucial for assessing the heat extraction rate and reservoir security of CO<sub>2</sub> based enhanced geothermal systems. This study designed the experiments of triaxial seepage and mechanical properties considering no CO<sub>2</sub>(sc) injection, CO<sub>2</sub>(sc) injection, and alternating injection of water-CO<sub>2</sub>(sc) (AIWC) in granite at 150–300 ℃. The experiments can reveal the mechanical properties of HDR in single-phase CO<sub>2</sub> zone, CO<sub>2</sub>-water two-phase zone and dissolved CO<sub>2</sub> liquid phase zone in HDR reservoir. The results indicate that the failure mode of the rock samples primarily exhibits sudden instability after no CO<sub>2</sub>(sc) injection and AIWC, whereas it predominantly manifests progressive instability after CO<sub>2</sub>(sc) injection. Compared with 25 ℃, the uniaxial compressive strength (UCS) after no CO<sub>2</sub>(sc) injection at 150–300 ℃ decreased by 13.86%–32.92%. After CO<sub>2</sub>(sc) injection, the UCS decreased by 40.79%–59.60%. After AIWC, the UCS decreased by 27.74–40.48%. This shows that the strength of rock mass in the single-phase CO<sub>2</sub> zone is lower than that in the other two zones, and this weakening phenomenon increases with the increase of temperature difference. At the same temperature, the elasticity modulus after AIWC was greater than that after no CO<sub>2</sub>(sc) injection and CO<sub>2</sub>(sc) injection. With no CO<sub>2</sub>(sc) injection, when the temperature was increased to 200 ℃ and 300 ℃, intergranular cracks and transgranular appeared respectively. After AIWC, mineral crystals such as calcite were precipitated on the surfaces of the connected large cracks, accompanied by kaolinite clay minerals. This increases the frictional contact of the mineral particles and enhances the stability of the HDR reservoir.</p></div>\",\"PeriodicalId\":48643,\"journal\":{\"name\":\"Geothermal Energy\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.9000,\"publicationDate\":\"2024-08-06\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://geothermal-energy-journal.springeropen.com/counter/pdf/10.1186/s40517-024-00306-5\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Geothermal Energy\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://link.springer.com/article/10.1186/s40517-024-00306-5\",\"RegionNum\":2,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ENERGY & FUELS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geothermal Energy","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1186/s40517-024-00306-5","RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ENERGY & FUELS","Score":null,"Total":0}
Study on the evolution of mechanical properties of hot dry rocks after supercritical CO2 injection
Characterizing the evolution of mechanical properties of hot dry rock (HDR) after supercritical CO2 (CO2(sc)) injection is crucial for assessing the heat extraction rate and reservoir security of CO2 based enhanced geothermal systems. This study designed the experiments of triaxial seepage and mechanical properties considering no CO2(sc) injection, CO2(sc) injection, and alternating injection of water-CO2(sc) (AIWC) in granite at 150–300 ℃. The experiments can reveal the mechanical properties of HDR in single-phase CO2 zone, CO2-water two-phase zone and dissolved CO2 liquid phase zone in HDR reservoir. The results indicate that the failure mode of the rock samples primarily exhibits sudden instability after no CO2(sc) injection and AIWC, whereas it predominantly manifests progressive instability after CO2(sc) injection. Compared with 25 ℃, the uniaxial compressive strength (UCS) after no CO2(sc) injection at 150–300 ℃ decreased by 13.86%–32.92%. After CO2(sc) injection, the UCS decreased by 40.79%–59.60%. After AIWC, the UCS decreased by 27.74–40.48%. This shows that the strength of rock mass in the single-phase CO2 zone is lower than that in the other two zones, and this weakening phenomenon increases with the increase of temperature difference. At the same temperature, the elasticity modulus after AIWC was greater than that after no CO2(sc) injection and CO2(sc) injection. With no CO2(sc) injection, when the temperature was increased to 200 ℃ and 300 ℃, intergranular cracks and transgranular appeared respectively. After AIWC, mineral crystals such as calcite were precipitated on the surfaces of the connected large cracks, accompanied by kaolinite clay minerals. This increases the frictional contact of the mineral particles and enhances the stability of the HDR reservoir.
Geothermal EnergyEarth and Planetary Sciences-Geotechnical Engineering and Engineering Geology
CiteScore
5.90
自引率
7.10%
发文量
25
审稿时长
8 weeks
期刊介绍:
Geothermal Energy is a peer-reviewed fully open access journal published under the SpringerOpen brand. It focuses on fundamental and applied research needed to deploy technologies for developing and integrating geothermal energy as one key element in the future energy portfolio. Contributions include geological, geophysical, and geochemical studies; exploration of geothermal fields; reservoir characterization and modeling; development of productivity-enhancing methods; and approaches to achieve robust and economic plant operation. Geothermal Energy serves to examine the interaction of individual system components while taking the whole process into account, from the development of the reservoir to the economic provision of geothermal energy.