scholarly journals Methane Hydrate Distribution from Prolonged and Repeated Formation in Natural and Compacted Sand Samples: X-Ray CT Observations

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Emily V. L. Rees ◽  
Timothy J. Kneafsey ◽  
Yongkoo Seol

To study physical properties of methane gas hydrate-bearing sediments, it is necessary to synthesize laboratory samples due to the limited availability of cores from natural deposits. X-ray computed tomography (CT) and other observations have shown gas hydrate to occur in a number of morphologies over a variety of sediment types. To aid in understanding formation and growth patterns of hydrate in sediments, methane hydrate was repeatedly formed in laboratory-packed sand samples and in a natural sediment core from the Mount Elbert Stratigraphic Test Well. CT scanning was performed during hydrate formation and decomposition steps, and periodically while the hydrate samples remained under stable conditions for up to 60 days. The investigation revealed the impact of water saturation on location and morphology of hydrate in both laboratory and natural sediments during repeated hydrate formations. Significant redistribution of hydrate and water in the samples was observed over both the short and long term.

2021 ◽  
pp. 131531
Author(s):  
Vincent W.S. Lim ◽  
Peter J. Metaxas ◽  
Michael L. Johns ◽  
Zachary M. Aman ◽  
Eric F. May

2009 ◽  
Vol 118 (5) ◽  
pp. 872-882 ◽  
Author(s):  
Tatsuji KAWASAKI ◽  
Hailong LU ◽  
Tetsuya FUJII ◽  
John A. RIPMEESTER

Energies ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 3231
Author(s):  
Stian Almenningen ◽  
Per Fotland ◽  
Geir Ersland

This paper reports formation and dissociation patterns of methane hydrate in sandstone. Magnetic resonance imaging spatially resolved hydrate growth patterns and liberation of water during dissociation. A stacked core set-up using Bentheim sandstone with dual water saturation was designed to investigate the effect of initial water saturation on hydrate phase transitions. The growth of methane hydrate (P = 8.3 MPa, T = 1–3 °C) was more prominent in high water saturation regions and resulted in a heterogeneous hydrate saturation controlled by the initial water distribution. The change in transverse relaxation time constant, T2, was spatially mapped during growth and showed different response depending on the initial water saturation. T2 decreased significantly during growth in high water saturation regions and remained unchanged during growth in low water saturation regions. Pressure depletion from one end of the core induced a hydrate dissociation front starting at the depletion side and moving through the core as production continued. The final saturation of water after hydrate dissociation was more uniform than the initial water saturation, demonstrating the significant redistribution of water that will take place during methane gas production from a hydrate reservoir.


2020 ◽  
Author(s):  
Aliakbar Hassanpouryouzband ◽  
Katriona Edlmann ◽  
Jinhai Yang ◽  
Bahman Tohidi ◽  
Evgeny Chuvilin

<p>Power plants emit large amounts of carbon dioxide into the atmosphere primarily through the combustion of fossil fuels, leading to accumulation of increased greenhouse gases in the earth’s atmosphere. Global climate changing has led to increasing global mean temperatures, particularly over the poles, which threatens to melt gas hydrate reservoirs, releasing previously trapped methane and exacerbating the situation.  Here we used gas hydrate-based technologies to develop techniques for capturing and storing CO<sub>2</sub> present in power plant flue gas as stable hydrates, where CO<sub>2</sub> replaces methane within the hydrate structure. First, we experimentally measured the thermodynamic properties of various flue gases, followed by modelling and tuning the equations of state. Second, we undertook proof of concept investigations of the injection of CO2 flue gas into methane gas hydrate reservoirs as an option for economically sustainable production of natural gas as well as carbon capture and storage. The optimum injection conditions were found and reaction kinetics was investigated experimentally under realistic conditions. Third, the kinetics of flue gas hydrate formation for both the geological storage of CO<sub>2</sub> and the secondary sealing of CH<sub>4</sub>/CO<sub>2</sub> release in one simple process was investigated, followed by a comprehensive investigation of hydrate formation kinetics using a highly accurate in house developed experimental apparatus, which included an assessment of the gas leakage risks associated with above processes.  Finally, the impact of the proposed methods on permeability and mechanical strength of the geological formations was investigated.</p>


2021 ◽  
Author(s):  
Hassan Al Majou ◽  
Ary Bruand ◽  
Olivier Rozembaum ◽  
Emmanuel Le Trong

Abstract. The modelling of peatland functioning, in particular the impact of anthropogenic warming and direct human disturbance on CO2, CH4 and N2O, requires detailed knowledge of the peat structure and of both water and gas flow with respect to the groundwater table level. To this end, freezing is nowadays increasingly used to obtain small size peat samples for X-ray micro computed tomography (X-ray μ-CT) as required by the need to increase the resolution of the 3D X-ray CT images of the peat structure recorded. The aim of this study was to analyze the structure of a peat material before and after freezing using X-ray μ-CT and to look for possible alterations in the structure by investigating looking at the air-filled porosity. A highly decomposed peat material close to water saturation was selected for study and collected between 25 and 40 cm depth. Two samples 4 × 4 × 7 cm3 in volume were analyzed before and after freezing using an X-ray μ-CT Nanotom 180NF (GE Phoenix X-ray, Wunstorf, Germany) with a 180 kV nanofocus X-ray tube and a digital detector array (2304 × 1152 pixels Hamamatsu detector). Results showed that the continuity and cross section of the air-filled tubular pores several hundreds to about one thousand micrometers in diameter were altered after freezing. Many much smaller air-filled pores not detected before freezing were also recorded after freezing with 470 and 474 pores higher than one voxel in volume (60 × 60 × 60 μm3 in volume each) before freezing, and 4792 and 4371 air-filled pores higher than one voxel in volume after freezing for the two samples studied. Detailed analysis showed that this increase resulted from a difference in the whole range of pore size studied and particularly from a dramatic increase in the number of air-filled pores ranging between 1 voxel (216 103 μm3) and 50 voxels (10.8 106 μm3) in volume. Theoretical calculation of the consequences of the increase in the specific volume of water by 8.7 % when it turns from liquid to solid because of freezing led to the creation of a pore volume in the organic matrix which remains saturated by water when returning to room temperature and consequently to the desaturation of the largest pores of the organic matrix as well as the finest tubular pores which were water-filled before freezing. These new air-filled pores are those measured after freezing using X-ray μ-CT and their volume is consistent with the one calculated theoretically. They correspond to small air-filled ovoid pores several voxels in volume to several dozen voxels in volume and to discontinuous air-filled fine tubular pores which were both detected after freezing. Finally, the increase in the specific volume of water because of freezing appears also be also responsible for the alteration of the already air-filled tubular pores before freezing as shown by the 3D binary images and the pore volume distribution.


2019 ◽  
Vol 7 (38) ◽  
pp. 21634-21661 ◽  
Author(s):  
Yan He ◽  
Meng-Ting Sun ◽  
Chen Chen ◽  
Guo-Dong Zhang ◽  
Kun Chao ◽  
...  

Surfactant-promoted methane hydrate formation during the past 2–3 decades has been reviewed, aiming toward achieving a comprehensive evaluation on the current research status and effective guidance on the research prospects.


2021 ◽  
Author(s):  
Khalik Mohamad Sabil ◽  
Omar Nashed ◽  
Bhajan Lal ◽  
Khor Siak Foo

Abstract Nanofluids are known of having the capability to increase heat and mass transfer and their suitability to be used as kinetic gas hydrate promoters have been recently investigated. They have favorable properties such as high thermal conductivity, large surface area, recyclable, ecofriendly, and relatively cheap that are favorable for kinetic gas hydrate promoters. However, the nanomaterials face challenges related to their stability in the base fluid. Therefore, it is crucial to investigate the impact of surfactant free nanofluid on hydrate formation and dissociation kinetics. In this work, COOH-MWCNT suspended in water is used to study the effect of surfactant free nanofluid on CO2 hydrates formation kinetic and stability. Kinetic study on CO2 hydrates formation as well as self-preservation are conducted in a stirred tank reactor. The kinetic experiments are carried out at 2.7 MPa and 274.15 K. The induction time, initial gas consumption rate, half-completion time t50, semi completion time t95 are measured to evaluate the effect of COOH-MWCNT. Furthermore, the dissociation rate was calculated to assess the impact of COOH-MWCNT on self-preservation at 271.15 K and atmospheric pressure. The results are compared with that of sodium dodecyl sulphate (SDS). The study of CO2 hydrates formation kinetic shows that the induction time is not affected by COOH-MWCNT. The impact of nanofluid is more pronounced during the hydrate growth. The initial formation rate is the highest at 0.01 wt% of COOH-MWCNT whereas 0.01 and 0.03 wt% shows the same and shortest t50. However, t95 found to be decreased with increasing the concentration. The effect of COOH-MWCNT is attributed to the strong functional group. Self-preservation results shows CO2 hydrates are less stable in the presence of COOH-MWCNT. The result of this work may provide significant finding that can be used to developed kinetic gas hydrate promoter based on nanofluid that work better than SDS to eliminate gas hydrate formation in oil and gas pipeline.


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