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Journal ArticleDOI

Modeling on Gas Hydrate Formation Conditions in the Qinghai-Tibet Plateau Permafrost

01 Jan 2009-Chinese Journal of Geophysics (John Wiley & Sons, Ltd)-Vol. 52, Iss: 1, pp 202-213

AbstractBased on the field-investigated gas geochemistry, the modeling of gas hydrate formation conditions is conducted in the Qinghai-Tibet plateau permafrost (QTPP) in combination with predecessors' data such as the permafrost ground temperature (T0), the thermal gradient within the frozen layer (G1) and the thermal gradient below the frozen layer (G2). The modeled results show that the permafrost characteristics generally meet the requirements for gas hydrate formation conditions in the study area. Gas composition, temperaturerelated permafrost parameters (e.g. T0,G1,G2) are the most important factors affecting gas hydrate formation conditions in the study area, whose spatial variations may cause the heterogeneity of gas hydrate occurrences. The most probable gas composition to form gas hydrate is the hybrid of methane and weight hydrocarbon gases (ethane and propane). In the predicted gas hydrate locations, the minimal upper depth of gas hydrate occurrence is less than one hundred meters and the maximum lower depth can reach one thousand meters with the thickness up to several hundred meters. Compared with Canadian Mallik gas hydrate field, the QTPP is favorable for gas hydrate formation in aspects of G1, G2 and gas composition, except for relatively thin permafrost, still suggesting great gas hydrate potentials.

Topics: Clathrate hydrate (59%), Gas composition (59%), Permafrost (55%), Methane (55%)

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Citations
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Journal ArticleDOI
01 Apr 2013-Energy
Abstract: In November 2008, gas hydrate samples were recovered during the scientific gas hydrate drilling project conducted in the Qilian Mountain permafrost located in the Qinghai-Tibet Plateau, China. This region is expected to become a strategic gas hydrate exploitation area in China. Based on the gas hydrate characteristics at the DK-3 drilling site located in this region, we used using Tough + Hydrate to numerically simulate the gas production potential of the gas hydrate deposits using a single vertical well by depressurization. The simulation results indicated that for a 1.5 MPa wellbore pressure, the average CH 4 production rate of hydrate dissociation was approximately 188 ST m 3 /d, the reservoir average total CH 4 production rate was approximately 539 ST m 3 /d, and the cumulative CH 4 volume produced from the reservoir was approximately 35% and 39% larger than those for wellbore pressures of 1 MPa and 2.5 MPa. Moreover, we numerically simulated the spatial distribution evolution of temperature, hydrate saturation and gas saturation in the reservoir for a 1.5 MPa wellbore pressure; the simulation indicated that a large volume of free CH 4 remained in the reservoir. During the dissociation time, the gas hydrate dissociation effective radius in the reservoir was less than 20 m, and the actual dissociated gas hydrates only accounted for 2.3% of the total gas hydrates in the simulated system. The results may suggest that the single vertical well by depressurization method is not optimal for the development of gas hydrate deposits in the Qilian Mountain permafrost. Other production strategies, such as a horizontal well design or the combination of depressurization and thermal stimulation, may be more economically feasible.

102 citations


Journal ArticleDOI
Abstract: Four scientific experimental wells were drilled in the Qilian Mountain permafrost of Qinghai Province, China, in 2008 and 2009. Gas hydrate was obtained from three of four wells and its related anomalous phenomena were observed in all the four wells. Raman spectroscopy was used in the laboratory to evaluate the type of clathrates recovered from these sites, including structures containing large and small cages of hydrocarbon gases. Gas hydrate and associated anomalies occur mainly in fractured mudstone, oily shale, siltstone, and fine-grained sandstone. Secondary occurrences were also present in the pore space of fine to medium grained sandstone in a zone between 133 and 396 mbs. This interval was vertically discontinuous and horizontally did not appear to correlate between wells. Gas hydrate occurrences in these wells are not solely related to lithology and are strongly controlled by fissures in the Qilian Mountain permafrost. Gas geochemical characteristics reveal that gas hydrate is primarily composed of CH4, with secondary components of C2H6, C3H8, and CO2. Raman spectra analysis indicates a sII gas hydrate structure. Gas composition and carbon and hydrogen isotope geochemistry show that gases from gas hydrate are mainly thermogenic with a biogenic fraction. In the study area, gas hydrate and its related anomalous phenomena are confined to the gas hydrate stability zone which is constrained by permafrost pressure and temperature conditions. Core observations indicate that individual gas hydrate occurrences are controlled by fissures. It is speculated that, when hydrocarbon gases reach the gas hydrate stability zone, they form into gas hydrate that occurred preferably in fissures beneath the permafrost.

78 citations


Cites result from "Modeling on Gas Hydrate Formation C..."

  • ...Since the preliminary results were possibly indicative of gas hydrate potentials in the Qinghai-Tibet railway permafrost (Lu et al., 2009), China Geological Survey formally initiated a project for “investigation on gas hydrate prospects within permafrost areas around China from 2004 to 2006”....

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Journal ArticleDOI
01 Apr 2012-Energy
Abstract: Based on the geological data of the Qinghai-Tibet plateau permafrost, such as the permafrost ground temperature, the thermal gradient within and below the frozen layer, we numerically investigate the gas production potential from hydrates at the DK-3 drilling site of the Qilian Mountain permafrost, which is located in the north of the Qinghai-Tibet plateau. We employ the huff and puff method using a single horizontal well in the middle of the Hydrate-Bearing Layer (HBL). The simulation results indicate that desirable gas-to-water ratio and energy efficiency can be obtained under suitable injection and production conditions in the huff and puff process. However, the absolute gas production rate remains low during the whole production process. The sensitivity analysis indicates that the gas production performance is strongly dependent on the intrinsic permeability of the hydrate deposits, the sediment porosity, the injection and production rates, the temperature of the injected water, the irreducible water saturation and P 01 . The relative permeability exponents appear to have limited effect on the gas production behavior using the huff and puff method. The sensitivity analysis also indicates that the production potential of the natural gas hydrate deposit will be better than that of pure methane hydrate in this simulation.

73 citations


Journal ArticleDOI
Abstract: In 2008–2009, gas hydrate deposits were confirmed to exist in the Qinghai–Tibet Plateau permafrost (QTPP) during the Scientific Drilling Project of Gas Hydrate in Qilian Mountain permafrost. Gas hydrate samples were successfully collected from three drilling sites: DK-1, DK-2, and DK-3. Based on the limited geological data from site measurements, gas was produced from the hydrate deposits of DK-2 zone in a two-spot well system through numerical simulation, and its commercial viability was evaluated. The two wells were placed on the same horizontal plane in the middle of the hydrate-bearing layer (HBL), and the depressurization and thermal stimulation methods were employed simultaneously in this system. Simulation results showed that desirable gas production performance could be obtained under suitable operation conditions when using this kind of well design. During the production process, large amount of free gas accumulated in the vicinity of the injection well until the flow channels between the two wells were gradually opened. It was found that the gas production performance was more favored with larger depressurization driving force, while the heat injection rate should be determined cautiously. Dependences of gas production performance on the various properties of hydrate deposits were also assessed.

33 citations


Journal ArticleDOI
Abstract: China has carried out several drilling campaigns for natural gas hydrate both in marine and terrestrial areas and successfully obtained the samples. The marine gas hydrate samples were firstly recovered from Shenhu area in 2007 and then from the Pearl River Mouth basin in 2013 in South China Sea (SCS). The terrestrial gas hydrate samples were recovered from Qilian Mountain permafrost (QMP) in 2009 and 2013, respectively. In this paper, systematic analyses have been carried out on these gas hydrate samples to compare the characteristics of gas hydrates from SCS with those from QMP. The results indicate that the characteristics of occurrence, structure and gas composition are obviously different. Marine gas hydrate from SCS shows different kinds of occurrence and demonstrates a typical structure I (sI), with cage occupancy of more than 99% methane in large cage and 90% in small cage, respectively, corresponding to hydration numbers of approximately 6.0 by thermodynamic calculation. The guest molecules are predominantly methane (> 99%) from biogenic origin produced by CO 2 reduction. However, the terrestrial gas hydrates from QMP occur as a thin layer within the cracks of fine-grained sandstones, siltstones and mudstones, showing a possible structure II (sII) hydrate based on its Raman spectra and gas composition. The molecular composition of hydrate-bound gas indicates that CH 4 only accounts for ~ 60% of the guests while the others are heavier hydrocarbons (e.g. C 2 H 6 , C 3 H 8 and C 4 H 10 ).The cage occupancy ratio of methane in small and large cage (θ S /θ L ) is around 7.5, suggesting that larger molecules preferentially occupy the large cage of the hydrate. The isotopic analysis shows that hydrate-bound gases in QMP are from thermogenic origin.

32 citations


References
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Journal ArticleDOI
Abstract: Major progress, problems, and challenges of recent investigation of the Tibetan Plateau uplift processes and resulting environmental changes are reviewed and summarized briefly, which especially covers the National Tibetan Research Projects of the Chinese Eighth (1992—1996) and Ninth (1997—2001) "Five-Year Projects" The Tibetan Plateau uplift is a complicated multiple cyclic process The Gangdise and Himalayas began to uplift in the Middle Eocene and Early Miocene respectively, while the main part of the Plateau merely underwent corresponding passive deformation and secular denudation, resulting in two planation surfaces The third and also the strongest uplift involved the whole Plateau and its marginal mountains commenced at 36 Ma Successive Kunlun-Huanghe movement at 11—06 Ma and Gonghe movement at 015 Ma raised the Plateau to its present height The Asian monsoonal system and Asian natural environment formed in response to these tectonic uplifts

397 citations


"Modeling on Gas Hydrate Formation C..." refers background in this paper

  • ...When entering into Holocene, although the large-scaled glaciation was finished, the whole QTP was still under gradual uplifting and its altitude rose to more than 4000 meters, of which the peculiar highness guaranteed that the whole plateau was still on the glacial margin ([26])....

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  • ...After entering into Holocene, the whole QTP arrived at the altitude of greater than 4000 meters, which in return determines the whole plateau was still on the glacial margin ([26])....

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ReportDOI
01 Jul 2005
Abstract: This publication chronicles the results of the Mallik 2002 Gas Hydrate Production Research Well Program which is a joint effort of 300 scientists from Japan, Canada, Germany, the United States and India. As a leader in gas hydrate research, Japan has collaborated with the Geological Survey of Canada on a gas hydrate project at the Mallik site. The JAPEX/JNOC/GSC et al. Mallik 3L-38, 4L-38 and 5L-38 exploratory wells were drilled in the Mackenzie Delta on the coast of the Beaufort Sea in Canada's Northwest Territories to examine the feasibility of methane gas production from permafrost-related gas hydrate. The Mallik site is one of the world's most intensely studied gas hydrate sites. Several research projects were initiated, including coring of the gas hydrate zones, extensive geophysical and mud-gas logging, reservoir-evaluation testing, cross-well tomographic seismic studies, and vertical seismic profiling. The 63 technical research papers and accompanying databases included in this publication provide details on new research and insight on gas hydrate production testing. In addition, new studies are reported on in situ physical and geophysical properties of gas hydrate. New appraisals on the relevance of gas hydrate to energy, climate and geohazard research were also presented. This publication also includes an interactive database available as an appendix on a DVD. refs., tabs., figs.

302 citations


Journal ArticleDOI

262 citations


"Modeling on Gas Hydrate Formation C..." refers background in this paper

  • ..., which spans about 550 km along the Qinghai-Tibet railway (QTR) ([6]), where a series of Mesozoic-Cenozoic remnant basins such as the Kekexili basin, the Tuotuo River basin, the Qiangtang basin, the Tanggula basin....

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  • ...5×106 km2, accounting for 70% and 7% of the total permafrost in China and in the world respectively[6], is generally regarded as an important potential area for gas hydrate....

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  • ...The QTPP mainly extends from the northern slope of the Kunlun Mt. to the northward Anduo County, the southern slope of the Tanggula Mt., which spans about 550 km along the Qinghai-Tibet railway (QTR)[6], where a series of Mesozoic-Cenozoic remnant basins such as the Kekexili basin, the Tuotuo River basin, the Qiangtang basin, the Tanggula basin....

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  • ...In contrast we investigated the hydrocarbon gases from the mediums of low atmosphere, cold vent, subsurface ice, subsurface sediment in the QTPP along the QTR....

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  • ...The past investigated gas geochemical results show that there exist certain amounts of propane and normal butane in the mediums of subsurface sediment and subsurface ice besides methane and ethane in the QTPP along the QTR....

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Journal ArticleDOI
Abstract: Near-surface indications of migrating hydrocarbons provide the petroleum systems analyst critical information about source (organic matter type), maturation (organic maturity), migration (migration pathway delineation), and in selected geologic settings, specific prospect hydrocarbon charge. All petroliferous basins exhibit some type of near-surface signal, but the hydrocarbon leakage to surface is not always detectable with conventional seep detection methods. Understanding the Petroleum Seepage System, hence petroleum dynamics of a basin, is key to understanding and using near-surface geochemical methods for basin assessment and prospect evaluation. The relationships between near-surface hydrocarbon seepage and subsurface petroleum generation and entrapment are often complex. The petroleum seepage system contain four key elements: seepage activity (qualitative expressions of relative leakage rates, active vs passive, and episodic vs continuous), seepage type (concentration of migrated thermogenic hydrocarbon relative to in situ material, macro vs micro), migration focus (major direction of bulk flow leakage relative to the subsurface hydrocarbon generation and/or entrapment), and near-surface seep disturbances (near-surface processes which can greatly alter or block seepage signals). The rate and volume of hydrocarbon seepage to the surface greatly control near-surface geological and biological responses, and thus are the best method of sampling and analysis to detect hydrocarbon leakage effectively. To properly predict subsurface petroleum properties, interpretation of near-surface geochemical data must recognize many potential problems including recent organic matter input, transported hydrocarbons, bacterial alteration, mixing, contamination, and fractionation effects. Surface geochemical data should always be integrated with other geological data. Calibration datasets to determine the utility of near-surface geochemical techniques within particular basinal settings are essential when evaluating prospects for hydrocarbon charge.

193 citations


"Modeling on Gas Hydrate Formation C..." refers background in this paper

  • ...According to the variation of gas diffusion rate, the presence of ethane, propane, butane associated with methane basically indicates that gases are not simply originated from in situ organic matter but probably from the deep migration ([28]), especially the occurrence of butane, indicating the deep seepage and diffusion ([29])....

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