A waterless fracturing treatment: liquid nitrogen fracturing and its application prospect

Cai, C.; Li, G.; Huang, Z.; Chi, H.

doi:10.5510/ogp20150300250

Cited by 2 publications

(2 citation statements)

References 8 publications

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“…Scholars both domestically and internationally have conducted extensive research on the feasibility and mechanism of this technology. Cai et al (2015) summarized the mechanism and key technologies of rock fracturing using liquid nitrogen. They pointed out that liquid nitrogen fracturing has advantages such as high efficiency and effective extraction of reservoir heat energy.…”

Section: Introductionmentioning

confidence: 99%

Effect of weakening characteristics of mechanical properties of granite under the action of liquid nitrogen

Wang,

Zhang,

Cao

et al. 2023

Front. Ecol. Evol.

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Liquid nitrogen fracturing and hot dry rock geothermal development are both emerging technologies in the field of energy. However, during the extraction of geothermal energy, it can cause the evolution of geological fractures, leading to the diffusion of groundwater and pollutants, thereby causing environmental pollution issues. Currently, geothermal energy has become a focal point in the global development of renewable energy. However, traditional hydraulic fracturing methods used in harnessing geothermal resources suffer from limitations such as limited fracture creation, uncertain initiation points, and environmental pollution. In contrast, liquid nitrogen has emerged as a promising reservoir stimulation technique, exhibiting significant effects on rock fracturing. In this study, we conducted three-point bending tests on granite samples subjected to liquid nitrogen treatment at temperatures of 300°C, with varying numbers of cooling cycles. Changes in fundamental mechanical parameters were analyzed. Additionally, through acoustic emission monitoring, we studied the variations in characteristic parameters of acoustic emissions under different cooling cycle conditions. Furthermore, based on the theory of energy evolution, we analyzed the energy evolution process during sample failure under different cooling cycle conditions. Using a compact scanning electron microscope, we observed changes in the microstructure of granite and analyzed the influence of cooling treatment on its surface characteristics and failure modes, thereby revealing the thermal damage process of granite. Moreover, by employing a non-metallic ultrasonic testing analyzer, we scanned the fracture surface morphology of granite and investigated the variations in fracture surface morphology features and surface roughness parameters caused by cooling treatment. The results indicate that liquid nitrogen cooling treatment can more effectively reduce the mechanical properties of rocks, and this effect is further enhanced at high temperatures. Under the condition of 300°C, after undergoing different cycles of liquid nitrogen cooling, granite will exhibit a more diverse macroscopic and microscopic structural failure characteristics, consistent with the expected formation of fluid flow channels in high-temperature rock formations.

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Section: Introductionmentioning

confidence: 99%

Effect of weakening characteristics of mechanical properties of granite under the action of liquid nitrogen

Wang,

Zhang,

Cao

et al. 2023

Front. Ecol. Evol.

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“…This law will be more obvious and reflected in the natural cracks in the rock. Cai et al [17] explored the speed of sound wave propagation in the rock and the law of permeability change of the rock under low temperature. They found through research that liquid nitrogen can cause the rock to cool down and crack, and at the same time, liquid nitrogen will gasify in the rock, which will produce gasification expansion and lead to rock fracture [18].…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of High-Temperature Granite under Liquid Nitrogen Cooling

et al. 2023

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The cooling characteristics of liquid nitrogen can effectively weaken the mechanical properties of dry hot rock reservoirs, improve the porosity and permeability of dry hot rock, and thus improve the development and utilization of geothermal resources. In order to explore the weakening effect of liquid nitrogen cooling characteristics on high-temperature reservoir rocks, uniaxial compression tests, Brazil splitting tests, and three-point bending tests were conducted on high-temperature granite, and synchronous acoustic emission tests were conducted to monitor the damage evolution of rocks. It is found that under the action of liquid nitrogen, the elastic modulus, peak strength, fracture toughness, and other mechanical properties of granite decrease to varying degrees. At different initial temperatures, the damage degree of liquid nitrogen to granite is different. The higher the initial temperature of granite, the greater the damage effect of liquid nitrogen on granite. The low-temperature characteristics of liquid nitrogen not only have the effect of cracking damage on granite but also have the effect of thermal stress on granite. If the temperature difference between the two is large, the heat released in the combination process will be higher. The greater the temperature difference, the greater the damage to granite. Under the action of liquid nitrogen, the acoustic emission characteristics of granite also show different evolution laws, and the ringing count of rock increases significantly, which indicates that liquid nitrogen aggravates the internal damage of granite, making the rock more fractured during fracturing. The research results can provide some scientific guidance for the development and utilization of geothermal energy.

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A waterless fracturing treatment: liquid nitrogen fracturing and its application prospect

Cited by 2 publications

References 8 publications

Effect of weakening characteristics of mechanical properties of granite under the action of liquid nitrogen

Effect of weakening characteristics of mechanical properties of granite under the action of liquid nitrogen

Mechanical Properties of High-Temperature Granite under Liquid Nitrogen Cooling

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