天然气水合物形成与生长影响因素综述

天然气水合物(NGH)是水分子和天然气分子形成的一种复杂的笼型晶体,其在油气管道输送、天然气储存和制冷等行业中都具有重要的研究意义和利用价值,但天然气水合物的形成是一个多组分、多阶段的复杂过程,不同因素对于天然气水合物形成和生长的影响尚有待明确。本文介绍了天然气水合物形成的物理过程以及水合物成核的3种机理假说;详细梳理了基质两亲性、添加剂、多孔介质环境和杂质、液体组成、温度压力以及流动条件等因素对于天然气水合物形成和生长的影响,并对其作了简要分析。同时指出,原油组成对于水合物抑制效果的定量化、蜡晶结构对于水合物形成过程中传质和传热的影响以及微观化的动力学抑制剂抑制机理等都是水合物相关研究中需要进一步深入探究和明确的问题。     

天然气水合物形成与解堵

天然气水合物是有两种物体形成,分别是碳氢化合物以及通过水一起组成的结晶化合物。天然气长输管道所处环境温度较低且输送压力高,易形成水合物而堵塞管道。本文简述了水合物形成条件、机理和解堵方法。     

天然气水合物的研究现状与发展趋势

介绍了天然气水合物的形成机制,阐述了天然气水合物作为新型清洁能源的巨大潜在价值;国内外对天然气水合物的研究进展。介绍了天然气水合物在开采中可能存在的环境问题,对比了热激发开采法、减压开采法以及化学试剂注入开采法等开采方式的优劣。介绍了天然气水合物在储运天然气以及作为汽车燃料方面的发展趋势,并对天然气水合物的未来市场前景进行了展望。     

水合物储气促进技术研究进展

气体水合物是一种笼形晶体化合物，单位体积的水合物可包含标准状况下160～180（v/v）的天然气，是一种潜在的固态天然气储运方法，受到广泛关注。由于天然气在水中溶解度小，天然气水合物在纯水中通常难以形成，形成的水合物中天然气含量也不高。为提高水合物储存天然气的密度，提高水合物生长速度，研究者探索了多种促进水合物形成的方法，如物理强化以及热力学与动力学促进剂等化学强化方法。本文总结了搅拌、喷雾、鼓泡等机械方法和向水合体系中添加热力学促进剂、动力学促进剂等方法对水合物形成和储气能力的影响，讨论了这些技术措施影响水合物形成与储气能力的机理。指出表面活性剂与其他促进技术的协同是改善水合物生长和储气密度的有效方法，其复合作用机理有待进一步研究。     

普光气田集输管道堵塞原因分析及防治

天然气水合物是在一定压力和温度的条件下,与由天然气中的液态水形成的化合物,水合物的形成将严重影响高含硫气田的开采和集输。本文结合普光气田实际情况,介绍了高含硫天然气水合物的性质、形成温度、危害及防止水合物形成措施。最后通过实例,充分说明防止天然气水合物形成对高含硫气田安全生产的必要性。     

促进天然气水合物形成的影响因素分析

天然气水合物(NGH)工业化生产中面临的主要问题是天然气水合物的合成速率较低。天然气水合物的生成反应为相间界面反应,任何影响气液相之间传质或传热的操作均可以增加天然气水合物的生成速率。结合影响天然气水合物形成的特点,从改善相平衡条件、增加气水接触面积和增加天然气的溶解度三方面介绍了促进天然气水合物形成的办法,并分析了各自的优缺点。     

一种新型天然气水合物抑制剂现场试验研究

在天然气开采及储运过程中,天然气可以在管道、井筒以及地层多孔介质中形成水合物,天然气水合物会导致井筒堵塞、气井停产、管道停输等严重事故。因此天然气水合物的防治是一个困扰生产多年的问题。天然气工业中最有效和常用的方法是注入水合物抑制剂,甲醇作为传统热力学水合物抑制剂药剂已经逐渐不能适应气田安全、环保、低成本开发的需要。为替代甲醇,开展了一种新型天然气水合物抑制剂的现场试验。现场试验结果表明,通过合理的加注工艺抑制剂可以起到良好的水合物抑制效果,新型天然气水合物抑制剂既适用于高压集气工艺,也适用于采用井下节流的中低压集气工艺。     

天然气水合物成藏分析与研究

目前,天然气水合物的勘探开发已经引起了世界各国的高度关注。在高压、低温条件下,水和天然气混合形成一种外观像冰的固态物质,这种物质遇火可燃,称为天然气水合物,即"可燃冰"。本文主要介绍了天然气水合物的形成过程,成藏条件和成藏模式,其中重点介绍天然气水合物的5种成藏条件:水合稳定条件、水源条件、气源条件、气体运移条件以及储集空间条件,以期对天然气水合物勘探开发的专业人员提供一定的参考和借鉴。     

天然气水合物开采方法的数值模拟研究进展

天然气水合物具有含气量高、污染低、储量大等优点,但存在埋藏深、导热性差等问题。介绍了国内外天然气水合物开采技术的研究和应用进展,概述了传统天然气水合物开采方法的优缺点,指出天然气水合物开采难度大的普遍问题,分析其原因为天然气水合物开采效率低、能耗高、风险大,以及天然气水合物开采背景与该产业链发展水平不相匹配等。在此基础上提出了利用数值模拟技术对海底和冻土层下的天然气水合物开采进行研究,并叙述了数值模拟技术在天然气水合物开采领域的发展现状,利用该方法便捷、经济、高效的特点,最终形成天然气水合物开采方法与数值模拟技术相结合的新型开采理念。     

天然气水合物勘探和开采方法研究进展

天然气水合物是水和天然气在低温和高压条件作用下形成的一种固态可燃物质,其优点为清洁无污染、燃烧热值高、使用便捷。分析了我国天然气水合物的研究现状,叙述了天然气水合物勘探和开采方法研究进展,并在此基础上,提出了天然气水合物开采对环境的影响。天然气水合物的勘探和开采发是一项复杂而艰巨的工作,建立清洁安全的天然气水合物勘探、开采工艺是最具前景的开发方式。     

地面集输管线中水合物堵塞预测研究

天然气水合物一旦在地面集输管线中形成就会造成阀门堵塞、管道停输等严重事故,造成重大的经济损失。气流组成、温度、压力和含水量是影响地面集输管线中水合物形成的主要因素,此外,气井产量、管线长度、油管直径等对水合物的形成也有一定的影响。本文综合国内外有关水合物研究成果,并结合长庆气田某气藏生产过程中天然气水合物的生成条件及防治措施,对地面集输管线中天然气水合物堵塞的生成条件及预测模型进行了研究。     

Compositional and structural identification of natural gas hydrates collected at site 1249 on ocean drilling program leg 204

In contrast to the structural studies of laboratory-grown gas hydrate, this study has been performed on naturally grown clathrate hydrates from the sea floor. The PXRD pattern of natural gas hydrate shows that the sample had a structure I hydrate. The¹³C NMR spectrum was obtained for the natural gas hydrate sample in order to identify the cage occupancy of guest molecules and determine the hydration number. The NMR spectrum reveal that the natural gas hydrates used in this study contain only methane with no noticeable amount of other hydrocarbons. The existence of two peaks at different chemical shifts indicates that methane molecules are encapsulated in both large and small cages. In addition, Raman spectroscopic analysis is also carried out to identify natural hydrates and compared with the NMR results. Investigating the composition and structure of natural gas hydrates is essential for applying natural gas hydrates as a novel energy source.     

多孔介质中天然气水合物相平衡条件研究进展

天然气水合物主要赋存于各种沉积物孔隙之中,只有6%左右以块状纯水合物的形式存在。现在对于天然气水合物相平衡条件的研究主要集中在对多孔介质各因素的考察。就目前研究成果来看,理论预测自然条件中水合物稳定条件的准确性仍然较差,其主要原因：水合物稳定存在的天然条件影响因素远比实验室中（大多预测模型基于实验室建立）的影响因素复杂得多;实际中的介质微孔孔径并不恒定,呈分布状态,且分布比较复杂;自然条件下的多孔介质的成分、结构都非常复杂。     

Phase behavior of gas hydrates in nanoporous materials: Review

A precise understanding of phase behavior for a variety of both artificial and natural processes is essential to achieving scientific and technological goals. There has been growing research interest in gas hydrates confined in nanoporous media aiming to simulate and analyze the unique behavior of natural gas hydrates in sediments. Moreover, the appearance of peculiar properties due to the confinement effect stimulates research on gas hydrate technology for gas separation, such as CO₂ capture from versatile pre/post combustion emissions. In spite of their importance, reliable phase equilibrium data on gas hydrates confined at a nanoscale are scattered throughout the literature, while those in bulk state are abundant. Accordingly, we surveyed the previous studies on the phase behavior of gas hydrates in various nanoporous materials to include and provide valuable information and knowledge for start-up researchers in various gas hydrate fields.     

天然气水合物研究进展

天然气水合物作为清洁、高效、储量巨大的新型能源,其巨大的能源潜力引起世界上很多国家的注意,纷纷投入巨额资金和人力对其进行研究.直到20世纪80年代末期我国才有学者关注和研究天然气水合物,起步相对较晚,因此研究人员做了大量文献资料调研和资料处理等初步研究工作.从20世纪90年代初首次人工合成天然气水合物开始,随着我国政府支持力度的不断增大,在本世纪初我国在东海、南海等地发现天然气水合物矿藏,同时对天然气水合物的成因、动力学机理、形成的条件等方面进行了研究.但如何开采天然气水合物,以及如何防止天然气水合物所带来的温室效应仍是亟待解决的问题.     

Gas hydrates: A cleaner source of energy and opportunity for innovative technologies

The global energy system is characterized by a gradual de-carbonization and move to cleaner burning technologies: from wood to coal to oil and to natural gas. A final destination characterized by the term“hydrogen economy” is desired. Gas hydrate found in the earth’s crust is considered a source of natural gas that is essentially 100% methane (CH₄) gas. Natural gas hydrate estimates worldwide range from 10,000 to 40,000 trillion cubic meters (TCM). Efforts are underway to exploit this resource. These methane hydrates in the earth’s crust also have the potential to be a significant factor in global climate change. Moreover, gas hydrates offer opportunities for the development of innovative technologies (separation of CO₂ from CO₂/N₂ and CO₂/H₂ mixtures, CO₂ sequestration, natural gas transportation and storage and H₂ storage). In this work we assess the progress towards exploitation of gas hydrates as a resource for methane (cleaner energy) and summarize the state of the art with respect to the role of gas hydrates in the development of innovative technologies.     

天然气单管伴热集输管道伴热优化

天然气在开采出来之后,经常含有水,天然气水合物是天然气与水在一定的压力和温度下形成的结晶笼状固态化合物。天然气水合物可能导致管道、仪表和分离设备的堵塞,对天然气的输送是有害的。石油与天然气输送的管道中,常用采用添加除水剂的方法,压力控制方法,伴热的方法来维持生产操作及停输期间管道内介质的温度与压力。着重研究利用单管热水伴热的方法来抑制天然气集气管道中水合物的生成。主要概述了利用热水伴热方法对管道进行伴热,并且借助VB程序编制软件完成热水伴热的输送过程的相关分析计算,通过计算的数据结果进行绘图,在符合实际伴热条件的的同时,选出最优方案。     

Simulation and economic evaluation of natural gas hydrates [NGH] as an alternative to liquefied natural gas [LNG]

Despite the fact that relatively little is known about the ultimate resource potential of natural gas hydrates, it is certain that gas hydrates are a vast storehouse of natural gas and significant technical challenges need to be met before this enormous resource can be considered an economically producible reserve. In this theoretical study, a simulation scheme was suggested to produce NGH in an industrial scale using pure water as a carrier and seawater as a cooling source. Parametric study was carried out and rigorous design calculations for different operating parameters were investigated. Further more and economical evaluation was done taken data of locally produced LNG as a comparison. Production rates, storage and transportation from production region to consumer's ends were investigated. Results obtained suggested that NGH with little consideration can be a good alternative for fuel gas carrier.     

SCHEMES OF GAS PRODUCTION FROM NATURAL GAS HYDRATES

Natural gas hydrates are a kind of nonpolluting and high quality energy resources for future, the reserves of which are about twice of the carbon of the current fossil energy (petroleum, natural gas and coal) on the earth. And it will be the most important energy for the 21st century. The energy balance and numerical simulation are applied to study the schemes of the natural gas hydrates production in this paper, and it is considered that both depressurization and thermal stimulation are effective methods for exploiting natural gas hydrates, and that the gas production of the thermal stimulation is higher than that of the depressurization. But thermal stimulation is non-economic because it requires large amounts of energy. Therefore the combination of the two methods is a preferable method for the current development of the natural gas hydrates. The main factors which influence the production of natural gas hydrates are: the temperature of injected water, the injection rate, the initial saturation of the hydrates and the initial temperature of the reservoir which is the most important factor. 1 Lei Huaiyan, Wang Xianbin. Current Situation of Gas Hydrates Research and Challenges for Future. Acta Sedimentological Sinica, 1999, 17 (3)2 Shi Dou, Zheng Junwei. The Status and Prospects of Research and Exploitation of Natural Gas Hydrate in the World. Advance in Earth Sciences, 1999, 14 (4)3 Chen Huifan4g. Prediction of the Conditions for the Forming of Natural Gas Hydrate. Journal of Xi'an Petroleum Institute, 1994, 9 (1)4 Yao Yucheng, Yin Fushan. Progressin Study of Natural Gas Hydrates. Progress in Chemistry, 1997, 9 (3)5 Zhao Shengeai. Current Situation of Gas Hydrate and Our ??Country's Policy. Advancein Earth Sciences, 2002, 17 (3)6 Zhou Huaiyang, Peng Xiaotong. Development in Technology of Prospecting and Exploitation for Gas Hydrates. Geology and Prospecting, 2001, 38 (1)7 Zhu Yuenian, Shi Buqing. Control Effects of Natural Gas Hydrates on Oil and Gas Accumulation and Reservoir Preservation. Natural Gas Industry, 2000, 20 (3)8 Wim J A M Swinkels, Rik J J Drenth. Thermal Reservoir Simulation Model of Production from Naturally Occurring Gas Hydrate Accumulations. SPE 565509 Moridis G J, Collett T S, Dallimore S R, Tohru Satoh. Numerical Studies of Gas Production from Several CH_4-Hydrate Zones at the Mallik Site. LBNL 50257. Mackenzie Delta, Canada