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Mechanical Properties of Stratified Hydrate-bearing Sediments
Available online at www.sciencedirect.com
ScienceDirect Energy Procedia 105 (2017) 200 – 205
The 8th International Conference on Applied Energy – ICAE2016
Mechanical properties of Stratified hydrate-bearing sediments Tingting Luoa, Weiguo Liua*, Yanghui Lia, Yongchen Songa, Qi Wua, Zhaoran Wua a
Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, P. R. China
Abstract Methane hydrate–bearing layers will be disturbed during the production of methane hydrates, which may induce the deformation or settlement of the layers, and the destruction of engineering structures, so it’s important to study the mechanical properties of the hydrate-bearing sediments. In this paper, specimens were prepared in which the methane hydrates were in different location of the specimens by a special deposition method in which the methane hydrate was put in the mold separating with the kaolin, the volume of methane hydrate was 40% of the whole volume of the specimen. A series of triaxial shear tests were carried out under different confining pressures of 1.25 MPa, 2.5 MPa, 3.75 MPa and 5 MPa, conditions with temperature of -6 oC and strain rate of 1 %/min. The results indicated that the maximum deviator stress of the sediments increased with the declining of the clay of hydrate and the failure strength achieved maximum when the hydrate clay was in the center of the sediments; the failure strength increased with the increasing of the confining pressure in the low confining pressure stage.
© 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2016 The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). responsibility of of ICAE Selection and/or peer-reviewofunder Peer-review under responsibility the scientific committee the 8th International Conference on Applied Energy.
Keywords:hydrate-bearing sediments; mechanical properties; stratified; failure strength; location.
1. Introduction With the big amount of resource and high energy density, gas hydrate is a great development prospect of clean energy [1]. Natural gas hydrate distribute in a very wide range, mainly in the permafrost, and deep water sediments of the sea or the continental margin [4-6]. In the world many regions of gas hydrate deposits were found [2]. However, unlike conventional petroleum, natural gas and other resources, gas
* Corresponding author. Tel.: +86-13009489152; fax: +86-411-8470-8015. E-mail address: [email protected].
1876-6102 © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 8th International Conference on Applied Energy. doi:10.1016/j.egypro.2017.03.302
201
Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
hydrate form in the reservoir supported by the cemented or skeletal form [3.4]. As a metastable substance, the rise of the temperature or the reduction of pore pressure possibly cause dissociation of hydrate [5.6]. Therefore, before the commercialization exploitation of gas hydrate resource, a comprehensive analysis about the stability of the gas hydrate deposits should be studied to fully grasp inherent mechanism of the reservoir, to avoid the damage of the climate caused by the dissociation of the gas hydrate. In recent years, the study on the mechanical properties of methane hydrate has been popular. Hyodo did a series of triaxial compression test on methane hydrate-bearing sediments and proved that the strength of gas hydrate deposits increased with the increasing of confining pressure [7]. Miyazaki did a series of triaxial compression tests for methane hydrate-bearing sediments and discovered that the effective confining pressure would limit the lateral deformation of sediments [8]. But the study on the stratified hydratebearing sediments was little. In this work, a series of triaxial shear tests were carried out under the different confining pressures to study the mechanics characteristics of stratified hydrate-bearing sediments. The triaxial test system was used to measure the mechanical properties of stratified hydrate specimens, and the test specimens were made of a certain mole fraction of methane hydrate containing ice and kaolin clay. 2. Experimental Methods 2.1. Specimen preparation The brief process diagram of specimen preparation has been introduced in our previous work [9]. In this paper, ice powder particles with a particle size of about 250 μm was put into stainless steel reactors, and then methane gas of 10 MPa were rejected into the chamber with temperature kept at -10 oC for more than 48 hours to generate the hydrate. Next, the prepared mold and pressure crystallization device were placed into a freezer (-10 oC) to be cooled to prevent hydrate dissociation on mold-pressure process due to the higher temperature, then the hydrate containing ice and kaolin clay were put into the cold condition(10 oC). Most importantly the author used a special deposition way, the hydrates and kaolin were put separately in the mold under the load conditions (10 MPa) and be axially pressed into the desired size (50mm × 100mm). In the forming the sample in the refrigerator, the layer of hydrates and kaolin were separated. 2.2. Testing apparatus
Fig.1. The schematic diagram of triaxial testing system
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Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
Fig 1 shows the schematic diagram of the triaxial apparatus used in this study. The triaxial apparatus primarily consists of four systems which are temperature system, axial compression system, computer control system and confining pressure servo system. 2.3. Testing procedures Before taking the specimen place in confining chamber, it needed to do that matched two end caps at the top and bottom of the specimen respectively, and then wrapped it with a rubber membrane which could prevent the hydraulic oil flowing into the specimen. In the test process of all the experiment, the time that the specimen shifted from mold into the pressure chamber was as possible as shorter as 5 min in order to reduce hydrates dissociation. In addition, the whole testing procedures were accomplished in a cold storage room (-10 oC). Tests conditions were the temperature of -6 oC, confining pressures of 1.25 MPa, 2.5 MPa, 3.75 MPa and 5 MPa and strain rate of 1 %/min. As showed in Fig 2, in this paper, the 1-1 location was that the clay of hydrate was in the top of the sediment, the 1-2 location was that the clay of hydrate was below 1/3 volume of the kaolin clay, and the 1-3 location was that the clay of hydrate was in the center of the sediment.
K\GUDWH OD\HU
Fig.2. The schematic diagram of different location hydrate-bearing sediments
3. Results and Discussions 3.1. The relationships between the mechanical properties with location of the hydrate clay of stratified hydrate-bearing sediments
3.4
4.5
1-1 1-2 1-3
4.0
3.2
Failure strength (MPa)
Deviator stress (MPa)
3.5 3.0 2.5 2.0 1.5
o
Temperature: -6 C Strain rate: 1 %/min Confining pressure:3.75MPa
1.0
3.0
2.8
2.6
o
Temperature: -6 C Strain rate: 1 %/min Confining pressure:3.75MPa
2.4
0.5
2.2
0.0 0
5
10
Axial stain (%)
15
20
1-1
1-2
Location (%)
1-3
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Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
Fig.3. Relationship of deviator stress with hydrate clay location of the stratified hydrate-bearing sediments
Fig.4. The failure strength of the stratified hydrate-bearing sediments in different locations of hydrate clay
Fig 3 indicates the relationship between the failure strength and the distribution of clay of hydrate in sediments under the same conditions of temperature -6 oC, confining pressure 3.75 MPa. From Fig 3, it can be found that in the initial stage of the shear (axial strain of less than 0.5% -1.0%), the deviator stress of the specimens increased linearly with the increasing of the axial strain, and showed some elastic properties. With axial strain increasing, the sample axial deviator stress continued to increase, but the rate of increasing gradually decreased, then the sample elastic-plastic deformation occurred. When the axial deviator stress reached a certain level, the sample started to yield. Related studies show that stress-strain curve of materials can be divided into three stages, quasi-elastic phase, hardening phase and the yield phase. It can be found in Fig 3, the three stages of the stress-strain curve appeared in the methane hydratebearing hydrate sediments. Fig 4 indicates that failure strength increases with the declining of the clay of hydrate, when the location of clay of hydrate was in the center of the sediments, the failure strength reached maximum. 3.2. The relationships between the mechanical properties with confining pressures of the stratified hydrate-bearing sediments Fig 5 shows the relationship between deviator stress and confining pressure of the 1-3 location hydrate-bearing sediments.
6
4.5
1.25MPa 2.5MPa 3.75MPa 5MPa
4.0
Failure strength (MPa)
Deviator stress (MPa)
5
4
3
2 o
Temperature: -6 C Strain rate: 1 %/min Location͵ 1-3
1
0
0
4
8
12
16
3.5
3.0
2.5
o
Temperature: -6 C Strain rate: 1 %/min Location͵ 1-3
2.0
20
Axial strain (%)
Fig.5. The deviator stress of the 1-3 location stratified hydratebearing sediments in different confining pressures
1.5 1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Confining pressure (MPa)
Fig.6. The failure strength of 1-3 location stratified hydratebearing sediments in different confining pressures
From Fig 5, it can be found that the stress of the hydrate-bearing sediments also experienced three compression stages in different confining pressures, and the failure strength of the sediments increased with the increase of confining pressure in the low confining pressure stage and reached maximum when the confining pressure is 5 MPa. From Fig 6, it can be observed that when the confining pressure was less than 5 MPa, the failure strength of the hydrate-bearing sediments increased with the increase of confining pressure, this phenomenon was similar with CH4 hydrate-bearing sediments which were mixed equally,
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Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
which indicated that the effects of confining pressure on the stratified hydrate-bearing sediments may be similar to that on the mixed hydrate-bearing sediments. 6
3.6
Failure strength (MPa)
Deviator stress (MPa)
3.8
1.25MPa 2.5MPa 3.75MPa 5 MPa
5
4
3
2
o
Temperature: -6 C Strain rate: 1 %/min location: 1-2
1
0
0
4
8
12
16
3.4
3.2 o
Temperature: -6 C Strain rate: 1 %/min location: 1-2
3.0
2.8
20
Axial strain (%)
Fig.7. The deviator stress of the 1-2 location stratified hydratebearing sediments in different confining pressures
2.6 1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Confining pressure (MPa)
Fig.8. The failure strength of 1-2 location stratified hydratebearing sediments in different confining pressures
Fig 7 shows the relationships between deviator stress with confining pressures of the 1-2 location hydrate-bearing sediments. From Fig 7, it can be found that the stress experience of the 1-2 location hydrate-bearing sediments were same as the 1-3 location hydrate-bearing sediments in different confining pressures. Fig 8 showed that the failure strength of the sediments also increased with the confining pressure and reached maximum when the confining pressure is 5 MPa. Furthermore, in this paper, the increase of confining pressure could lead to the compaction and consolidation of specimen at a lowconfining pressure stage, the increasing confining pressure would enhance the cementation between hydrates particles and between soil grains particles, which would made the hydrates particles and between soil grains particles harder to slide or eversion, causing the higher failure strength of the hydrate-bearing sediments. 4. Conclusion Based on the experimental results and analysis above, the following were concluded: (a) The failure strength of the sediments increased with the declining of the clay of hydrate and the strength achieved maximum when the clay of hydrate was in the center of the sediments; (b) The failure strength increased with the increasing of the confining pressure in the low confining pressure stage and achieved maximum in the 5 MPa confining pressure, effects of confining pressure on the stratified hydrate-bearing sediments may be similar to that on the equal mixed hydrate-bearing sediments.
Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
Acknowledgements This study has been supported by the Natural Science Foundation of China (No.51276028), the National High Technology Research and Development Program of China (Grant No. 2013AA09250302), the National Natural Science Foundation of China (Grant No. 51227005), the China Postdoctoral Science Foundation (Grant No. 2014M560206), the Liaoning Provincial Department of Education Research Project (Grant No. L2014019), and the Fundamental Research Funds for the Central Universities (Grant No. DUT14RC (3) 059). References [1] Lee SY, Holder GD. Methane hydrates potential as a future energy source. J Sci Fuel Processing Technology 2001;71(13):181-186. [2] Kvenvolden KA, Lorenson TD. The global occurrence of natural gas hydrate. J Sci Geophysical monograph 2001;124(322):3-18. [3] Waite WF, Winters WJ, Mason DH. Methane hydrate formation in partially water-saturated Ottawa sand. J Sci American Mineralogist 2004;89(8-9):1202-1207. [4] Priest JA, Rees EV, Clayton CR. Influence of gas hydrate morphology on the seismic velocities of sands. J Sci Journal of Geophysical Research: Solid Earth 2009;114(B11205). [5] Sloan ED. Gas hydrates: Review of physical/chemical properties. J Sci Energy & Fuels 1998;12(2):191-196. [6] Sloan ED. Fundamental principles and applications of natural gas hydrate. J Sci Nature 2003;426(6964):353-359. [7] Hyodo M, Nakata Y, Yoshimoto N. Basic research on the mechanical behavior of methane hydrate-sediments mixture. J Sci Soils and foundations 2005;45(1): 75-85. [8] Miyazaki K, Masui A, Aoki K. Strain-rate dependence of triaxial compressive strength of artificial methane-hydrate-bearing sediment. J Sci International Journal of Offshore and Polar Engineering 2010;20(4): 256-264. [9] Li YH, Song YC, Yu F, Liu WG, Zhao JF. Experimental study on mechanical properties of gas hydrate-bearing sediments using kaolin clay. J Sci China Ocean Engineering 2011;25(1):113-122.
Biography Weiguo Liu was born in Shandong, China and completed his PhD at Dalian University of Technology. He is currently Professor at Dalian University of Technology and his interesting fields are focus on the methane hydrate formation kinetics and the mechanical properties of hydrate-bearing sediments.
205
ScienceDirect Energy Procedia 105 (2017) 200 – 205
The 8th International Conference on Applied Energy – ICAE2016
Mechanical properties of Stratified hydrate-bearing sediments Tingting Luoa, Weiguo Liua*, Yanghui Lia, Yongchen Songa, Qi Wua, Zhaoran Wua a
Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, School of Energy and Power Engineering, Dalian University of Technology, Dalian 116024, P. R. China
Abstract Methane hydrate–bearing layers will be disturbed during the production of methane hydrates, which may induce the deformation or settlement of the layers, and the destruction of engineering structures, so it’s important to study the mechanical properties of the hydrate-bearing sediments. In this paper, specimens were prepared in which the methane hydrates were in different location of the specimens by a special deposition method in which the methane hydrate was put in the mold separating with the kaolin, the volume of methane hydrate was 40% of the whole volume of the specimen. A series of triaxial shear tests were carried out under different confining pressures of 1.25 MPa, 2.5 MPa, 3.75 MPa and 5 MPa, conditions with temperature of -6 oC and strain rate of 1 %/min. The results indicated that the maximum deviator stress of the sediments increased with the declining of the clay of hydrate and the failure strength achieved maximum when the hydrate clay was in the center of the sediments; the failure strength increased with the increasing of the confining pressure in the low confining pressure stage.
© 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license © 2016 The Authors. Published by Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/4.0/). responsibility of of ICAE Selection and/or peer-reviewofunder Peer-review under responsibility the scientific committee the 8th International Conference on Applied Energy.
Keywords:hydrate-bearing sediments; mechanical properties; stratified; failure strength; location.
1. Introduction With the big amount of resource and high energy density, gas hydrate is a great development prospect of clean energy [1]. Natural gas hydrate distribute in a very wide range, mainly in the permafrost, and deep water sediments of the sea or the continental margin [4-6]. In the world many regions of gas hydrate deposits were found [2]. However, unlike conventional petroleum, natural gas and other resources, gas
* Corresponding author. Tel.: +86-13009489152; fax: +86-411-8470-8015. E-mail address: [email protected].
1876-6102 © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 8th International Conference on Applied Energy. doi:10.1016/j.egypro.2017.03.302
201
Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
hydrate form in the reservoir supported by the cemented or skeletal form [3.4]. As a metastable substance, the rise of the temperature or the reduction of pore pressure possibly cause dissociation of hydrate [5.6]. Therefore, before the commercialization exploitation of gas hydrate resource, a comprehensive analysis about the stability of the gas hydrate deposits should be studied to fully grasp inherent mechanism of the reservoir, to avoid the damage of the climate caused by the dissociation of the gas hydrate. In recent years, the study on the mechanical properties of methane hydrate has been popular. Hyodo did a series of triaxial compression test on methane hydrate-bearing sediments and proved that the strength of gas hydrate deposits increased with the increasing of confining pressure [7]. Miyazaki did a series of triaxial compression tests for methane hydrate-bearing sediments and discovered that the effective confining pressure would limit the lateral deformation of sediments [8]. But the study on the stratified hydratebearing sediments was little. In this work, a series of triaxial shear tests were carried out under the different confining pressures to study the mechanics characteristics of stratified hydrate-bearing sediments. The triaxial test system was used to measure the mechanical properties of stratified hydrate specimens, and the test specimens were made of a certain mole fraction of methane hydrate containing ice and kaolin clay. 2. Experimental Methods 2.1. Specimen preparation The brief process diagram of specimen preparation has been introduced in our previous work [9]. In this paper, ice powder particles with a particle size of about 250 μm was put into stainless steel reactors, and then methane gas of 10 MPa were rejected into the chamber with temperature kept at -10 oC for more than 48 hours to generate the hydrate. Next, the prepared mold and pressure crystallization device were placed into a freezer (-10 oC) to be cooled to prevent hydrate dissociation on mold-pressure process due to the higher temperature, then the hydrate containing ice and kaolin clay were put into the cold condition(10 oC). Most importantly the author used a special deposition way, the hydrates and kaolin were put separately in the mold under the load conditions (10 MPa) and be axially pressed into the desired size (50mm × 100mm). In the forming the sample in the refrigerator, the layer of hydrates and kaolin were separated. 2.2. Testing apparatus
Fig.1. The schematic diagram of triaxial testing system
202
Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
Fig 1 shows the schematic diagram of the triaxial apparatus used in this study. The triaxial apparatus primarily consists of four systems which are temperature system, axial compression system, computer control system and confining pressure servo system. 2.3. Testing procedures Before taking the specimen place in confining chamber, it needed to do that matched two end caps at the top and bottom of the specimen respectively, and then wrapped it with a rubber membrane which could prevent the hydraulic oil flowing into the specimen. In the test process of all the experiment, the time that the specimen shifted from mold into the pressure chamber was as possible as shorter as 5 min in order to reduce hydrates dissociation. In addition, the whole testing procedures were accomplished in a cold storage room (-10 oC). Tests conditions were the temperature of -6 oC, confining pressures of 1.25 MPa, 2.5 MPa, 3.75 MPa and 5 MPa and strain rate of 1 %/min. As showed in Fig 2, in this paper, the 1-1 location was that the clay of hydrate was in the top of the sediment, the 1-2 location was that the clay of hydrate was below 1/3 volume of the kaolin clay, and the 1-3 location was that the clay of hydrate was in the center of the sediment.
K\GUDWH OD\HU
Fig.2. The schematic diagram of different location hydrate-bearing sediments
3. Results and Discussions 3.1. The relationships between the mechanical properties with location of the hydrate clay of stratified hydrate-bearing sediments
3.4
4.5
1-1 1-2 1-3
4.0
3.2
Failure strength (MPa)
Deviator stress (MPa)
3.5 3.0 2.5 2.0 1.5
o
Temperature: -6 C Strain rate: 1 %/min Confining pressure:3.75MPa
1.0
3.0
2.8
2.6
o
Temperature: -6 C Strain rate: 1 %/min Confining pressure:3.75MPa
2.4
0.5
2.2
0.0 0
5
10
Axial stain (%)
15
20
1-1
1-2
Location (%)
1-3
203
Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
Fig.3. Relationship of deviator stress with hydrate clay location of the stratified hydrate-bearing sediments
Fig.4. The failure strength of the stratified hydrate-bearing sediments in different locations of hydrate clay
Fig 3 indicates the relationship between the failure strength and the distribution of clay of hydrate in sediments under the same conditions of temperature -6 oC, confining pressure 3.75 MPa. From Fig 3, it can be found that in the initial stage of the shear (axial strain of less than 0.5% -1.0%), the deviator stress of the specimens increased linearly with the increasing of the axial strain, and showed some elastic properties. With axial strain increasing, the sample axial deviator stress continued to increase, but the rate of increasing gradually decreased, then the sample elastic-plastic deformation occurred. When the axial deviator stress reached a certain level, the sample started to yield. Related studies show that stress-strain curve of materials can be divided into three stages, quasi-elastic phase, hardening phase and the yield phase. It can be found in Fig 3, the three stages of the stress-strain curve appeared in the methane hydratebearing hydrate sediments. Fig 4 indicates that failure strength increases with the declining of the clay of hydrate, when the location of clay of hydrate was in the center of the sediments, the failure strength reached maximum. 3.2. The relationships between the mechanical properties with confining pressures of the stratified hydrate-bearing sediments Fig 5 shows the relationship between deviator stress and confining pressure of the 1-3 location hydrate-bearing sediments.
6
4.5
1.25MPa 2.5MPa 3.75MPa 5MPa
4.0
Failure strength (MPa)
Deviator stress (MPa)
5
4
3
2 o
Temperature: -6 C Strain rate: 1 %/min Location͵ 1-3
1
0
0
4
8
12
16
3.5
3.0
2.5
o
Temperature: -6 C Strain rate: 1 %/min Location͵ 1-3
2.0
20
Axial strain (%)
Fig.5. The deviator stress of the 1-3 location stratified hydratebearing sediments in different confining pressures
1.5 1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Confining pressure (MPa)
Fig.6. The failure strength of 1-3 location stratified hydratebearing sediments in different confining pressures
From Fig 5, it can be found that the stress of the hydrate-bearing sediments also experienced three compression stages in different confining pressures, and the failure strength of the sediments increased with the increase of confining pressure in the low confining pressure stage and reached maximum when the confining pressure is 5 MPa. From Fig 6, it can be observed that when the confining pressure was less than 5 MPa, the failure strength of the hydrate-bearing sediments increased with the increase of confining pressure, this phenomenon was similar with CH4 hydrate-bearing sediments which were mixed equally,
204
Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
which indicated that the effects of confining pressure on the stratified hydrate-bearing sediments may be similar to that on the mixed hydrate-bearing sediments. 6
3.6
Failure strength (MPa)
Deviator stress (MPa)
3.8
1.25MPa 2.5MPa 3.75MPa 5 MPa
5
4
3
2
o
Temperature: -6 C Strain rate: 1 %/min location: 1-2
1
0
0
4
8
12
16
3.4
3.2 o
Temperature: -6 C Strain rate: 1 %/min location: 1-2
3.0
2.8
20
Axial strain (%)
Fig.7. The deviator stress of the 1-2 location stratified hydratebearing sediments in different confining pressures
2.6 1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Confining pressure (MPa)
Fig.8. The failure strength of 1-2 location stratified hydratebearing sediments in different confining pressures
Fig 7 shows the relationships between deviator stress with confining pressures of the 1-2 location hydrate-bearing sediments. From Fig 7, it can be found that the stress experience of the 1-2 location hydrate-bearing sediments were same as the 1-3 location hydrate-bearing sediments in different confining pressures. Fig 8 showed that the failure strength of the sediments also increased with the confining pressure and reached maximum when the confining pressure is 5 MPa. Furthermore, in this paper, the increase of confining pressure could lead to the compaction and consolidation of specimen at a lowconfining pressure stage, the increasing confining pressure would enhance the cementation between hydrates particles and between soil grains particles, which would made the hydrates particles and between soil grains particles harder to slide or eversion, causing the higher failure strength of the hydrate-bearing sediments. 4. Conclusion Based on the experimental results and analysis above, the following were concluded: (a) The failure strength of the sediments increased with the declining of the clay of hydrate and the strength achieved maximum when the clay of hydrate was in the center of the sediments; (b) The failure strength increased with the increasing of the confining pressure in the low confining pressure stage and achieved maximum in the 5 MPa confining pressure, effects of confining pressure on the stratified hydrate-bearing sediments may be similar to that on the equal mixed hydrate-bearing sediments.
Tingting Luo et al. / Energy Procedia 105 (2017) 200 – 205
Acknowledgements This study has been supported by the Natural Science Foundation of China (No.51276028), the National High Technology Research and Development Program of China (Grant No. 2013AA09250302), the National Natural Science Foundation of China (Grant No. 51227005), the China Postdoctoral Science Foundation (Grant No. 2014M560206), the Liaoning Provincial Department of Education Research Project (Grant No. L2014019), and the Fundamental Research Funds for the Central Universities (Grant No. DUT14RC (3) 059). References [1] Lee SY, Holder GD. Methane hydrates potential as a future energy source. J Sci Fuel Processing Technology 2001;71(13):181-186. [2] Kvenvolden KA, Lorenson TD. The global occurrence of natural gas hydrate. J Sci Geophysical monograph 2001;124(322):3-18. [3] Waite WF, Winters WJ, Mason DH. Methane hydrate formation in partially water-saturated Ottawa sand. J Sci American Mineralogist 2004;89(8-9):1202-1207. [4] Priest JA, Rees EV, Clayton CR. Influence of gas hydrate morphology on the seismic velocities of sands. J Sci Journal of Geophysical Research: Solid Earth 2009;114(B11205). [5] Sloan ED. Gas hydrates: Review of physical/chemical properties. J Sci Energy & Fuels 1998;12(2):191-196. [6] Sloan ED. Fundamental principles and applications of natural gas hydrate. J Sci Nature 2003;426(6964):353-359. [7] Hyodo M, Nakata Y, Yoshimoto N. Basic research on the mechanical behavior of methane hydrate-sediments mixture. J Sci Soils and foundations 2005;45(1): 75-85. [8] Miyazaki K, Masui A, Aoki K. Strain-rate dependence of triaxial compressive strength of artificial methane-hydrate-bearing sediment. J Sci International Journal of Offshore and Polar Engineering 2010;20(4): 256-264. [9] Li YH, Song YC, Yu F, Liu WG, Zhao JF. Experimental study on mechanical properties of gas hydrate-bearing sediments using kaolin clay. J Sci China Ocean Engineering 2011;25(1):113-122.
Biography Weiguo Liu was born in Shandong, China and completed his PhD at Dalian University of Technology. He is currently Professor at Dalian University of Technology and his interesting fields are focus on the methane hydrate formation kinetics and the mechanical properties of hydrate-bearing sediments.
205