Papers by Keyword: Gas Hydrate

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Authors: Yu Feng Chen, De Qing Liang, Neng You Wu
Abstract: An understanding of the physical properties of hydrate-bearing sediment is necessary for interpretation of geophysical data collected in field settings. We have conducted a laboratory experiment to measure the electrical property of initially water saturated sediment containing natural gas hydrate. When gas hydrate was formed from pore fluid in ocean sediment, bulk sediment resistivity was significantly increased. The resistivity of the sediment was largely changed below 20% hydrate saturation. With the increasing hydrate saturation, the resistivity of sediment was increased and the resistivity of pore fluid was decrease. In the final process of hydrate formation, the resistivity depression was found mainly due to the transition of gas hydrate morphology. The electrical resistivity of hydrate specimens varied from 1.930 Ohm.m to 3.950 Ohm.m for saturation ranging from 0% to 52.68%. Besides, the dependence of the resistivity index versus hydrate saturation is inconsistent with Archies law. The results of our studies have important implications for quantitative laboratory and field calibration of geophysical measurements within gas hydratebearing intervals.
Authors: C.A. Koh, J.L. Savidge, C.C. Tang, R.E. Motie, X.P. Wu, R.I. Nooney, R. Westacott
Authors: Shou Jun Li, Feng You Chu, Yin Xia Fang, Zi Yin Wu
Abstract: Abstract:The study area of this paper is the slope of Shenhu Area in the northern South China Sea. We interpreted both sub-bottom and single-channel seismic profiles to describe the acoustic characteristic of gas hydrate sediment and to discuss the cause of its formation. We distinguished some abnormal physiognomy and geologic objects that are relative to gas hydrate in profiles. Protuberance, shallow fault, acoustic blank patch, partial enhanced reflection and acoustic blank zone were discovered in the legible sub-bottom profile. The shallow gassy belt locates under the seabed from 34 to 82 m. Contrasting the sub-bottom profile with the data of Chinese first gas hydrate expedition, we believed that the gas in the shallow gassy belt came from the decompounding of gas hydrate in deep stratum. Pockmark, seepage, fold and Bottom Simulating Reflector (BSR) were recognized in the single-channel seismic profile. The depth of BSR is slightly deeper than that of the samples of Chinese first gas hydrate expedition in the study area. We think the BSR in the seismic profile may be the bottom of gas hydrate. Based on the time-depth conversion, we plotted out Oligocene, early Miocene, middle Miocene and Pliocene in the seismic profile according to the sedimentary thickness, sedimentary rate and age of ODP site 1148 and set up the chronology of the gas hydrate sediment.
Authors: Jian Zhang, Yu Guang Ye, Gao Wei Hu, Shao Bo Diao
Abstract: It is necessary to know gas hydrate saturation in evaluating gas hydrate volume. So far, there are only few models to estimate gas hydrate saturation. These models are often empirical or derived from observed data. Therefore, we need to confirm their legitimacy and get an approach to use the correct model. For the first time, we combine Ultrasonic Wave and Time Domain Reflectometry to study the relationship between gas hydrate saturation and acoustic parameters, which gets fine results. Subsequently, it attempts to compare the calculated data by time-average equation, Wood’s equation, Lee’s weighted equation and BGTL with the observed data in experiments. The results show the experimental method is very effective. It suggests that the Lee’s weighted equation and BGTL are more applicable in our experiments and various sediments.
Authors: Jing Tao Shang, Meng Meng Wu
Abstract: As a new efficient energy, the exploration work for gas hydrate increasingly attracts world attention. This paper introduces the advances in gas hydrate exploration, and then discusses the importance of applying geophysical logging in the work. Based on the characteristics of gas hydrate well log data, this paper discusses its process, and we designed and developed the gas hydrate logging processing system combined with computer technology. The applications in work showed that the system could process well log data quickly and effectively, and provide a strong support for the exploration work.
Authors: Ded Xun Liu Liu, Hong Yan Wang, Qun Zhao, Hong Lin Liu
Abstract: Many countries in the world begin to attach great importance to the utilization of the unconventional gas. In some areas, tight gas, Coalbed methane (CBM) and shale gas have came into commercial development. The unconventional gas resources are very abundant in China. They developed rapidly in recent years, and some progress has been made. CBM in Qinshui Basin has been commercially developed successfully. Shale gas resource is also very abundant and has a good development prospect. Besides, the gas hydrate has a great potential in resources.
Authors: Qiang Chen, Chang Ling Liu, Yu Guang Ye
Abstract: In this paper, we focused on the determination of phase equilibrium conditions of hydrates formed in the pore water and porous media from South China Sea. High pressure differential scanning calorimetry (HP DSC), a relatively new thermo-analytical technique was applied to this research. During the study, nitrogen hydrates and methane hydrates phase equilibrium conditions were determined in thewater-hydrates- gas (W-H-G) system. Then a series of experiments were carried on using core sample drilled from South China Sea to determine the phase equilibrium properties in pore water and porous media systems. It show that the hydrates phase equilibrium point is about 2K lower than in pure water from pressure range 10 to 30 MPa, due to the thermodynamic inhibition effect of brine solution.
Authors: Rong Zhao, Hua Jin Chang, Ke Long Chen
Abstract: Gas hydrate samples were collected in Muli area (Qinghai Province, China) of Tibetan Plateau permafrost, which is the first discovery of gas hydrate in Chinese permafrost and in the low to middle latitude permafrost of the world. Although the exploitation of gas hydrate in Tibetan Plateau permafrost has lots of important significance, environmental risks including permafrost and alpine meadow ecosystem degeneration, global climate influence, and environmental pollution would take place in the exploitation process. In order to avoid or decrease the risk, safe and dependable exploitation technique, carbon capture and storage technology, engineering process control, legislation and emergency preparatory scheme should be put into practice.
Authors: Yu Ming Gao, Ji Lin Cao, Panpan Chen, Hong Fei Guo, Zhao Yang Tan
Abstract: The phase equilibrium of the quaternary system H2O-H2O2-CO(NH2)2-C3H8 with gas hydrate formation had been studied at high pressure and low temperature. The temperature and pressure of gas hydrate formed from different hydrogen peroxide concentration aqueous were determined at adding surfactants and no surfactants separately. It was concluded that the equilibrium pressure of gas hydrate formation was increasing with the increase of the hydrogen peroxide concentration, the urea concentration and the temperature, the mother liquor amount entrained in the gas hydrate after liquid separation by sinking was very high when surfactants was not added, but the equilibrium pressure of gas hydrate formation was decreased and the mother liquor amount entrained in gas hydrate was also decreased when surfactants was added to the system. In addition, the equilibrium pressure of gas hydrate formation in the quaternary system H2O-H2O2-CO(NH2)2-C3H8 was calculated according to Chen-Guo thermodynamic model, improved UNIFAC mathematical equation and Aasberg-Peterson fugacity coefficient model. The calculated data was in agreement with the experiment data.
Authors: Volodymyr Bondarenko, Iryna Kovalevska, Denys Astafiev, Olha Malova
Abstract: The analysis of sudden outbursts of coal and gas in coal mines is presented in the article. Phase transitions of gas to gashydrate state are investigated in the laboratory. Thermobaric parameters of phase transitions of mine methane are established. The new hypothesis is described of sudden outbursts of gas that is based on a gashydrate condition of methane in mines at depths (near 1000 m and more) and their explosion-like failure – Percy Bridgman’s effect.
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