因應氣候變遷與環境污染等議題，地熱能的穩定熱源、長時間運行與應用領域廣泛等優點，被視為具有潛力的再生能源。地熱井系統在生產和回注過程中，流體受到溫度、壓力、pH值、流速、飽和度等因素改變化學組成而發生結垢現象，導致管道或岩層阻塞，使地熱井系統熱提取效率下降甚至無法運作，因此解決結垢的問題為地熱井開發必經的過程。
本研究使用ABAQUS有限元素分析軟體，以清水地熱區為模擬環境，分析在震波衝擊除垢系統瞬間釋放壓力100 bar與200 bar條件下對於圓形孔篩管及條形孔篩管的應力分布情形，並了解在篩管與井壁緊密貼合情形、篩管不與井壁貼合不排水情形及篩管不與井壁貼合排水情形下岩體周圍的應力狀態與橫向影響範圍。
研究結果顯示，在相同釋放壓力情況下，條形孔篩管之最大von Mises應力遠大於圓形孔篩管，且應力集中於孔洞周圍的情形更為明顯，有較高之破壞風險。震波衝擊除垢系統於地熱井中實際情形較貼近於篩管不與井壁貼合不排水情形，此環境中使用圓形孔篩管之最大剪應力影響範圍較遠，當釋放壓力由100 bar提升至200 bar時亦有最遠的影響範圍增加量達0.53 m，且在井壁周圍短距離內有更強的破壞潛力，提升除垢效果。

In response to climate change and environmental pollution, geothermal energy is considered a promising renewable energy source. However, during geothermal well operations, fluid composition changes due to temperature, pressure, pH, flow rate, and saturation variations lead to scaling. This scaling obstructs pipes or rock formations, reducing thermal extraction efficiency or even rendering the system inoperative. Therefore, addressing scaling is crucial in geothermal well development.
This study uses the finite element analysis software, ABAQUS, to investigate the stress distribution of circular and rectangular slot screens under shockwave descaling system conditions with pressure releases of 100 bar and 200 bar. The Chingshui geothermal area serves as the simulated environment. The study also examines the stress state and lateral influence range around the rock under three scenarios: tight contact between the screen and the wellbore, non-contact between the screen and the wellbore under undrained conditions, and non-contact between the screen and the wellbore with drainage.
Results indicate that under the same release pressure, the maximum von Mises stress of the rectangular slot screen pipe is significantly greater than that of the circular one, with more pronounced stress concentration, indicating a higher failure risk. The actual conditions of the shock wave descaling system in geothermal wells resemble the scenario where the screen is not in contact with the wellbore under undrained conditions. In this scenario, the circular hole screen pipe shows a wider range of maximum shear stress influence. When the release pressure increases from 100 bar to 200 bar, the increase in the influence range reaches up to 0.53 meters, and there is a higher potential for damage near the wellbore, enhancing descaling effectiveness.

[1] 姜智文, "利用電性構造模型評估清水地熱區之發電潛能," 鑛冶：中國鑛冶工程學會會刊, vol. 61, no. 1, pp. 20-30, 2017, doi: 10.30069/mm.201703_61(1).0002.
[2] 李伯亨 et al., "宜蘭清水地熱儲集層數值模型與生產模擬研究," 臺灣鑛業, vol. 65, no. 4, pp. 1-12, 2013. [Online]. Available: https://tpl.ncl.edu.tw/NclService/JournalContentDetail?SysId=A14001100.
[3] 王建力 et al., 震波衝擊橫向傳遞模擬分析 (財團法人工業技術研究院綠能與環境研究所分包研究計畫). 2023.
[4] 苗志銘 and 吳振源, 井下震波衝擊系統模擬分析 (財團法人工業技術研究院綠能與環境研究所分包研究計畫). 2023.
[5] D. Moya et al., "Geothermal energy: Power plant technology and direct heat applications," Renewable & Sustainable Energy Reviews, vol. 94, pp. 889-901, Oct 2018, doi: 10.1016/j.rser.2018.06.047.
[6] K. Abid et al., "A Review on Geothermal Energy and HPHT Packers for Geothermal Applications," Energies, vol. 15, no. 19, Oct 2022, Art no. 7357, doi: 10.3390/en15197357.
[7] W. Q. Zhang et al., "Experimental study on the variation of physical and mechanical properties of rock after high temperature treatment," Applied Thermal Engineering, vol. 98, pp. 1297-1304, Apr 2016, doi: 10.1016/j.applthermaleng.2016.01.010.
[8] H. J. Zhao et al., "Research progress on scaling mechanism and anti-scaling technology of geothermal well system," Journal of Dispersion Science and Technology, vol. 44, no. 9, pp. 1657-1670, Jul 2023, doi: 10.1080/01932691.2022.2033625.
[9] C. Penot et al., "Corrosion and Scaling in Geothermal Heat Exchangers," Applied Sciences-Basel, vol. 13, no. 20, Oct 2023, Art no. 11549, doi: 10.3390/app132011549.
[10] U. Rajvanshi, "Effect of Mineral Scaling on Geothermal Wells: Carbonate Scaling," Bachelor, Delft University of Technology, 2018. [Online]. Available: http://resolver.tudelft.nl/uuid:3890a9fa-d16c-43a9-bcf2-d5f5dbf1f68d
[11] I. Gunnarsson and S. Arnórsson, "Impact of silica scaling on the efficiency of heat extraction from high-temperature geothermal fluids," Geothermics, vol. 34, no. 3, pp. 320-329, Jun 2005, doi: 10.1016/j.geothermics.2005.02.002.
[12] F. T. Haklidir and M. Haklidir, "Fuzzy control of calcium carbonate and silica scales in geothermal systems," Geothermics, vol. 70, pp. 230-238, Nov 2017, doi: 10.1016/j.geothermics.2017.07.003.
[13] R. Corsi, "Scaling and Corrosion in Geothermal Equipment: Problems and Preventive Measures," Geothermics, vol. 15, no. 5-6, pp. 839-856, 1986, doi: 10.1016/0375-6505(86)90097-0.
[14] M. Bagheri et al., "A review of oil well cement alteration in CO2-rich environments," Construction and Building Materials, vol. 186, pp. 946-968, Oct 2018, doi: 10.1016/j.conbuildmat.2018.07.250.
[15] L. Zhang et al., "Scaling and blockage risk in geothermal reinjection wellbore: Experiment assessment and model prediction based on scaling deposition kinetics," Journal of Petroleum Science and Engineering, vol. 209, Feb 2022, Art no. 109867, doi: 10.1016/j.petrol.2021.109867.
[16] R. Boch et al., "Scale-fragment formation impairing geothermal energy production: interacting H2S corrosion and CaCO3 crystal growth," Geothermal Energy, vol. 5, no. 1, Dec 2017, Art no. 4, doi: 10.1186/s40517-017-0062-3.
[17] J. R. Haizlip et al., "Origin and Impacts of High Concentrations of Carbon Dioxide in Geothermal Fluids of Western Turkey," in 41st Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, February 22-24 2016.
[18] H. Kristmannsdóttir, "Types of scaling occurring by geothermal utilization in Iceland," Geothermics, vol. 18, no. 1, pp. 183-190, 1989/01/01/ 1989, doi: 10.1016/0375-6505(89)90026-6.
[19] 李小凡, "油气井解堵增产技术研究现状及展望," 石化技术, vol. 23(11), pp. 75-77, 2016. [Online]. Available: http://www.oilsns.com/article/169752.
[20] C. Yu et al., "Study on Unblocking and Permeability Enhancement Technology with Rotary Water Jet for Low Recharge Efficiency Wells in Sandstone Geothermal Reservoirs," Energies, vol. 15, no. 24, Dec 2022, Art no. 9407, doi: 10.3390/en15249407.
[21] B. A. Xian et al., "Coalbed methane recovery enhanced by screen pipe completion and jet flow washing of horizontal well double tubular strings," Journal of Natural Gas Science and Engineering, vol. 99, Mar 2022, Art no. 104430, doi: 10.1016/j.jngse.2022.104430.
[22] D. Morton-Thompson and A. M. Woods, Development Geology Reference Manual. American Association of Petroleum Geologists, 1992.
[23] T. S. Ma et al., "Drilling and completion technologies of coalbed methane exploitation: an overview," International Journal of Coal Science & Technology, vol. 9, no. 1, Dec 2022, Art no. 68, doi: 10.1007/s40789-022-00540-x.
[24] X. D. Sun and B. J. Bai, "Comprehensive review of water shutoff methods for horizontal wells," Petroleum Exploration and Development, vol. 44, no. 6, pp. 1022-1029, Dec 2017, doi: 10.1016/s1876-3804(17)30115-5.
[25] A. I. Mohammed et al., "Casing structural integrity and failure modes in a range of well types - A review," Journal of Natural Gas Science and Engineering, vol. 68, Aug 2019, Art no. 102898, doi: 10.1016/j.jngse.2019.05.011.
[26] G. S. Kaldal et al., "Structural modeling of the casings in high temperature geothermal wells," Geothermics, vol. 55, pp. 126-137, May 2015, doi: 10.1016/j.geothermics.2015.02.003.
[27] H. Klapper and J. Stevens, Challenges for metallic materials facing HTHP geothermal drilling. 2013.
[28] F. S. Zhang et al., "Hydraulic fracturing induced fault slip and casing shear in Sichuan Basin: A multi-scale numerical investigation," Journal of Petroleum Science and Engineering, vol. 195, Dec 2020, Art no. 107797, doi: 10.1016/j.petrol.2020.107797.
[29] K. Dong et al., "Geomechanical analysis on casing deformation in Longmaxi shale formation," Journal of Petroleum Science and Engineering, vol. 177, pp. 724-733, Jun 2019, doi: 10.1016/j.petrol.2019.02.068.
[30] Z. W. Huang et al., "Comparison experiment on steel and non-steel slotted screen pipes used in coalbed methane wells," Petroleum Exploration and Development, vol. 39, no. 4, pp. 522-527, Aug 2012, doi: 10.1016/s1876-3804(12)60071-8.
[31] H. L. Liao et al., "Study on the Erosion of Screen Pipe Caused by Sand-Laden Slurry," Journal of Engineering Research, vol. 8, no. 4, pp. 258-271, Dec 2020, doi: 10.36909/jer.v8i4.9069.
[32] A. S. Talberg et al., "Laboratory Experiments on Ultrasonic Logging Through Casing for Barrier Integrity Validation," in ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering, 2017, vol. Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology, V008T11A035, doi: 10.1115/omae2017-62645.
[33] Y. H. Lin et al., "Experimental studies on corrosion of cement in CO2 injection wells under supercritical conditions," Corrosion Science, vol. 74, pp. 13-21, Sep 2013, doi: 10.1016/j.corsci.2013.03.018.
[34] T. Gu et al., "Coupled effect of CO2 attack and tensile stress on well cement under CO2 storage conditions," Construction and Building Materials, vol. 130, pp. 92-102, Jan 2017, doi: 10.1016/j.conbuildmat.2016.10.117.
[35] 徐景祥, "淺談岩石基礎之承載能力," 臺灣公路工程, vol. 31, pp. 2-12, 2005. [Online]. Available: https://tpl.ncl.edu.tw/NclService/JournalContentDetail?SysId=A05003649.
[36] S. B. Chai et al., "Analysis of stress wave propagation through a rock structural plane considering rock mass stresses," Rock and Soil Mechanics, vol. 43, pp. 184-192, Jun 2022, doi: 10.16285/j.rsm.2021.0058.
[37] S. Ronen, "Psi, pascal, bars, and decibels," The Leading Edge, vol. 21, no. 1, pp. 60-62, 2002, doi: 10.1190/1.1487322.
[38] E. Cox et al., "Comparison of methods for modelling the behaviour of bubbles produced by marine seismic airguns," Geophysical Prospecting, vol. 52, no. 5, pp. 451-477, Sep 2004, doi: 10.1111/j.1365-2478.2004.00425.x.
[39] Y. Chen et al., "Using an airgun array in a land reservoir as the seismic source for seismotectonic studies in northern China: experiments and preliminary results," Geophysical Prospecting, vol. 56, no. 4, pp. 601-612, Jul 2008, doi: 10.1111/j.1365-2478.2007.00679.x.
[40] T. M. Brocher, "Detonation Charge Size versus Coda Magnitude Relations in California and Nevada," Bulletin of the Seismological Society of America, vol. 93, no. 5, pp. 2089-2105, 2003, doi: 10.1785/0120020185.
[41] S. Hu et al., "Transient Calculation Studies of Liquid-Solid Collision in Jet Descaling," Energies, vol. 16, no. 1, Jan 2023, Art no. 292, doi: 10.3390/en16010292.
[42] Z. Ge et al., "Experimental study on the characteristics and mechanism of high-pressure water jet fracturing in high-temperature hard rocks," Energy, vol. 270, p. 126848, May 2023, doi: 10.1016/j.energy.2023.126848.
[43] B. H. G. Brady and E. T. Brown, Rock Mechanics for Underground Mining. Allen & Unwin, 1985.
[44] J. C. Jaeger et al., Fundamentals of Rock Mechanics. Wiley, 2007.
[45] L. Zhang, "Chapter 6 - Deformability," in Engineering Properties of Rocks (Second Edition), L. Zhang Ed.: Butterworth-Heinemann, 2017, pp. 173-249.
[46] 吳偉特, "軟弱地盤基礎失敗案例-一小時內陷塌四公尺的士林康華大廈," 地工技術雜誌, no. 13, pp. 106-112, 1986.
[47] 張文城, "岩石力學基本概論," 地工技術雜誌, no. 30, pp. 104-118.
[48] M. Patel, Strength Characteristics for Limestone and Dolomite Rock Matrix using Tri-Axial System. 2015.