CO2 injection-induced complex cloud-fracture networks in granite at conventional and superhot geothermal conditions
CO2 injection-induced complex cloud-fracture networks in granite at conventional and superhot geothermal conditions
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常规和超热地热条件下花岗岩中二氧化碳注入引起的复杂云裂缝网络
DOI：
10.1016/j.geothermics.2021.102265
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
Komai Takeshi
中科院分区：
文献类型：
--
作者：
Pramudyo Eko;Goto Ryota;Watanabe Noriaki;Sakaguchi Kiyotoshi;Nakamura Kengo;Komai Takeshi
复杂的云裂缝网络有利于加强地热系统储层的开发，在超热地热条件下（温度约为 400-500°C），通过在这些温度下注入低粘度水，可以在花岗岩中实现复杂的云裂缝网络。然而，水的利用有几个缺点，例如它与造岩矿物的反应性。二氧化碳（CO2）在超热和低温常规地热条件下都具有与低粘度水相似的低粘度，是克服这些挑战的替代品。二氧化碳的低粘度促使其在各种地热条件下创建云裂缝网络。本研究首次通过在常规和真实三轴应力状态下在 200 至 450°C 温度下进行的一系列 CO2 压裂实验，证明了在两种地热条件下花岗岩中云裂缝网络的形成。格里菲斯破坏准则被证明适用于两种地热条件下云裂缝网络的形成，因为它表明裂缝网络是由预先存在的微裂缝的刺激形成的。云裂缝网络的形成具有潜在的优势，例如在存在较大天然裂缝的情况下进行额外的压裂，并且诱发地震活动的风险较低；然而，CO2压裂在常规地热条件下存在裂缝孔径较窄的挑战，应在未来的研究中解决。
Complex cloud-fracture networks, favorable for enhanced geothermal system reservoir development, were shown to be able to be achieved in granite under superhot geothermal conditions, with temperatures of approximately 400–500 °C, by injecting low-viscosity water at these temperatures. Nonetheless, water utilization has several drawbacks, such as its reactivity with rock-forming minerals. Carbon dioxide (CO2), which has a low viscosity similar to that of the low-viscosity water under both superhot and lower-temperature conventional geothermal conditions, is a proposed replacement to overcome these challenges. This low viscosity of CO2motivates its application to create cloud-fracture networks under various geothermal conditions. The present study, for the first time, demonstrated the formation of cloud-fracture networks in granite under both geothermal conditions through a set of CO2fracturing experiments conducted from 200 to 450 °C under conventional and true triaxial stress states. The Griffith failure criterion was shown to be applicable for the formation of a cloud-fracture network in both geothermal conditions because it indicated that the fracture network was formed by the stimulation of pre-existing microfractures. The formation of cloud-fracture networks has potential advantages, such as additional fracturing in the presence of sizable natural fractures and a lower risk of induced seismicity; however, CO2fracturing has the challenge of narrower fracture apertures under conventional geothermal conditions, which should be addressed in future research.
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影响因子：
4.6
作者：
N. Watanabe;K. Sakaguchi;Ryota Goto;T. Miura;K. Yamane;T. Ishibashi;Youqing Chen;T. Komai;N. Tsuchiya
通讯作者：
N. Watanabe;K. Sakaguchi;Ryota Goto;T. Miura;K. Yamane;T. Ishibashi;Youqing Chen;T. Komai;N. Tsuchiya
稻田花岗岩热性能、超声波波速、强度性能和变形能力的各向异性
DOI：
10.5110/jjseg.44.175
发表时间：
2003
期刊：
Journal of the Japan Society of Engineering Geology
影响因子：
--
作者：
Weiren Lin;Toshiaki Nakamura;Manabu Takahashi
通讯作者：
Manabu Takahashi
影响因子：
1.7
作者：
Cox, S. F.
通讯作者：
Cox, S. F.
利用超临界和超热系统生产电力、氢气和矿物的灵活综合组合，提高地热经济性
DOI：
--
发表时间：
2018
期刊：
--
影响因子：
--
作者：
W. Elders;Jim Shnell;G. Ó. Friðleifsson;A. Albertsson;R. Zierenberg
通讯作者：
R. Zierenberg