Ultrasonic attenuation of pure tetrahydrofuran hydrate

Pohl, Mathias; Prasad, Manika; Batzle, Michael

doi:10.1111/1365-2478.12534

Cited by 17 publications

(11 citation statements)

References 28 publications

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“…The P and S wave attenuation results using calibrated hydrate volume fraction are shown in Figure , together with results of laboratory synthesized hydrate‐bearing sands using resonant column testing (Priest et al, ), natural hydrate‐bearing sediments from Mallik 2L‐38 research well using sonic logs (Guerin & Goldberg, ), and THF hydrate crystals using ultrasonic waves (Pohl et al, ). The results agree with the previous finding that higher hydrate saturation generally increases the specimen's stiffness and also the wave attenuation.…”

Section: Analyses and Discussionmentioning

confidence: 99%

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Tetrahydrofuran Hydrate in Clayey Sediments—Laboratory Formation, Morphology, and Wave Characterization

et al. 2019

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Fine-grained sediments host more than 90% of gas hydrates on Earth. However, the fundamental properties of hydrate-bearing silty and clayey sediments are much less understood than those of hydrate-bearing sands, mainly due to the experimental challenges in synthesizing gas hydrate in fine-grained sediments in the laboratory as the way they form in nature. This study forms tetrahydrofuran (THF) hydrate in kaolinite, visualizes the hydrate distribution and morphology using X-ray computed tomography, and uses P and S waves to characterize the formed hydrate-bearing clayey sediments. The results show that THF hydrate formed in clay is innately segregated and heterogeneous, no longer as a pore constituent as in sandy sediments. Hydrate nucleation, growth, and distribution in clays are dominated by the thermal condition and constrained by water activity and mass transport, which can result in low stoichiometric-solution-to-hydrate conversion ratios of approximately 0.4-0.7. Thus, the estimation of hydrate volume in clays based on the mass of stoichiometric solution can be erroneous. The heterogeneity in hydrate-bearing clays imposes challenges in wave velocity based characterization. The bulk elastic properties of hydrate-bearing clays can be well predicted using the self-consistent model. Specimens with higher hydrate volume fraction VF h show higher wave attenuations Q −1 , highlighting the dominant role of THF hydrate in the wave attenuation of hydrate-bearing clays. The results suggest that Q p −1 = 0.08 + 0.4VF h = 2Q s −1 , which underlines the potential of using wave attenuation based methods to quantify the hydrate volume fraction in clayey sediments. Key Points:• Tetrahydrofuran hydrate formed in kaolinite clay is visualized using X-ray computed tomography and characterized using P and S waves • Hydrate nucleation and growth in clays are dominated by thermal conditions and constrained by water activity and mass transport • Specimens with higher hydrate saturation show higher wave attenuations, highlighting the dominant role of hydrate in the wave attenuation Supporting Information:• Supporting Information S1• Data Set S1• Data Set S2• Data Set S3• Data Set S4

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Section: Analyses and Discussionmentioning

confidence: 99%

“…Pure THF crystal has a relatively high P wave attenuation Q −1 = ~0.45, possibly caused by viscous squirt flow of unconverted water within the hydrate crystals (Pohl et al, ). This value is much higher than that of water‐saturated clays with Q −1 = ~0.1 measured in this study (Figure a).…”

Section: Analyses and Discussionmentioning

confidence: 99%

Tetrahydrofuran Hydrate in Clayey Sediments—Laboratory Formation, Morphology, and Wave Characterization

et al. 2019

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“…The slope of the length over travel time is the velocity of the measured material. Similarly, the velocity for standard aluminium sample was also measured within a 0.9% deviation compared to Pohl's paper [25]. In this system, the ultrasonic transducer was not directly in contact with the pressure core sample.…”

Section: Calibration Testmentioning

confidence: 97%

“…At present, most reported apparatus used an embedded ultrasonic sensor to measure acoustic response of methane hydrate formation in bearing sediments [25][26][27][28]. However, in some special cases, such as the detection of the fidelity core on-board, an ultrasonic sensor cannot be embedded to realize the measurement of the pressure conserved cores.…”

Section: Introductionmentioning

confidence: 99%

Non-Embedded Ultrasonic Detection for Pressure Cores of Natural Methane Hydrate-Bearing Sediments

Liu

Zhang

et al. 2019

Energies

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An apparatus for the analysis of pressure cores containing gas hydrates at in situ pressures was designed, and a series of experiments to determine the compressional wave response of hydrate-bearing sands were performed systematically in the laboratory. Considering the difficulties encountered in performing valid laboratory tests and in recovering intact hydrate bearing sediment samples, the laboratory approach enabled closer study than the marine environment due to sample recovery problems. The apparatus was designed to achieve in situ hydrate formation in bearing sediments and synchronous ultrasonic detection. The P-wave velocity measurements enabled quick and successive ultrasonic analysis of pressure cores. The factors influencing P-wave velocity (Vp), including hydrate saturation and formation methodology, were investigated. By controlling the initial water saturation and gas pressure, we conducted separate experiments for different hydrate saturation values ranging from 2% to 60%. The measured P-wave velocity varied from less than 1700 m/s to more than 3100 m/s in this saturation range. The hydrate saturation can be successfully predicted by a linear fitting of the attenuation (Q−1) to the hydrate saturation. This approach provided a new method for acoustic measurement of the hydrate saturation when the arrival time of the first wave cannot be directly distinguished. Our results demonstrated that the specially designed non-embedded ultrasonic detection apparatus could determine the hydrate saturation and occurrence patterns in pressure cores, which could assist further hydrate resource exploration and detailed core analyses.

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“…The other key application area of ultrasonic waves is the characterization of gas hydrates. Experimental studies on characterization of tetrahydrofuran hydrates were carried out by Pohl et al [40]. On the other hand, pore space characteriza-tion using ultrasonic waves was performed by Schindler et al [41].…”

Section: Ultrasonic Wavesmentioning

confidence: 99%

Hydrate Dissociation Using Microwaves, Radio Frequency, Ultrasonic Radiation, and Plasma Techniques

Khan

Misra²,

Majumder

et al. 2020

ChemBioEng Reviews

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In this work, a comprehensive review of technologies employing radiation sources such as microwave, ultrasonic, and radio frequency (RF) on gas hydrates is presented. The characterizing parameters of radiation, such as frequency, wavelength, and power are highlighted for the compiled studies. In addition, characterizing parameters like hydrate dissociation rate, irradiated microwave power, complete dissociation time, reaction paths and mechanisms, differential pressure and temperature of gas hydrates during the experiments are also reported. Moreover, the work also describes the basic concept behind the working of the different wave forms such as microwaves, ultrasonic, RF wave and plasma for hydrate dissociation.

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Ultrasonic attenuation of pure tetrahydrofuran hydrate

Cited by 17 publications

References 28 publications

Tetrahydrofuran Hydrate in Clayey Sediments—Laboratory Formation, Morphology, and Wave Characterization

Tetrahydrofuran Hydrate in Clayey Sediments—Laboratory Formation, Morphology, and Wave Characterization

Non-Embedded Ultrasonic Detection for Pressure Cores of Natural Methane Hydrate-Bearing Sediments

Hydrate Dissociation Using Microwaves, Radio Frequency, Ultrasonic Radiation, and Plasma Techniques

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