碳中和愿景下中国煤层气开发现状与展望

煤层气作为一种非常规天然气,加强其抽采与利用对实现碳中和的目标、温室气体减排具有重要的意义.该文分析了中国煤层气资源特征、产气状况及影响因素,总结并分析了煤矿井下煤层气与地面煤层气开发技术的现状与特点;通过对煤层气产业发展的政策与煤层气高质量开发技术的展望,指出提高中央财政补贴标准、进行煤层气开发企业税费改革、明确矿权等政策的必要性,提出加强井下与地面联动抽采、废弃矿井煤层气高效抽采、井下长钻孔分段高效压裂抽采、自动化与智能化煤层气高效抽采及低浓度煤层气利用等技术建议.     

煤田地质特征与煤层气地质因素关系的研究

本文探讨，论述了影响煤层气富集高产的煤层生气量，储气能力，煤层孔隙，割理，裂隙发育，煤层渗透率，煤层气解吸压力等地质因素，分析研究了煤田形成演化历史和构造地质特征对上述煤层气地质因素的影响控制关系，为煤层气资源地质评价和开发选区提供了理论依据。     

沁南煤层气田开发区块内煤层气生产接替研究

通过对煤层富气高渗地质规律及煤层气井排采主控因素的研究,结合对开发区块煤层气井工程数据与测试资料的分析,提出了沁南煤层气田开发区块内煤层气生产接替方法,依据煤层富气高渗等级和地解压差等级将开发区划分为5类煤层气开发单元.研究表明:I类至V类开发单元面积分别占研究区面积的1.10%,20.86%,47.44%,28.96%,1.64%;开发单元的分布受地质构造的影响最为显著,开发单元展布与煤层含气性、渗透性的区域性变化及煤层压差吻合程度较高;区块内煤储层压力四周高、中心低且变化梯度大的部位,地解压差小,有利于压降扩展,开发单元类型级别高;开发区内地形较为平缓,开发单元多位于煤层埋深1000 m以浅地区,对煤层气开发施工较为有利.开发区内产能接替工艺开发技术表明:后期井网部署应以现有井网为中心,以埋深1000 m为界,在Ⅲ类以上开发单元区域向四周布井,布井时考虑地形落差可采用分层次(多层次)布井;现有井网内煤层气井产能低下区域采用二次压裂或补充小井距井以提高煤层气井产能;在地层稳定、构造简单的地形和缓区可考虑水平井生产工艺.     

焦作煤田煤层气资源特征及开发利用研究

煤层气是国家高度重视和亟待勘查开发的重要能源矿种,也是我国紧缺与需要的战略能源.通过对焦作煤田煤层气地质条件、资源特征及开发利用方法现状的研究,认为焦作煤田具备煤层气开采条件及煤层气赋存地质条件;焦作煤田有大面积的石炭二叠系含煤地层分布,并且含煤层数多,煤层较为稳定,储量大;因此,焦作煤田拥有丰富的煤层气资源,含气饱和度和煤层渗透率较高,资源密度高,有利于煤层气开发利用.焦作煤田煤层气的开发对改善焦作市能源供给结构,提高资源利用率、保护生态环境具有重要意义.     

焦作煤田煤层气资源特征及开发利用研究

煤层气是国家高度重视和亟待勘查开发的重要能源矿种,也是我国紧缺与需要的战略能源．通过对焦作煤田煤层气地质条件、资源特征及开发利用方法现状的研究,认为焦作煤田具备煤层气开采条件及煤层气赋存地质条件;焦作煤田有大面积的石炭二叠系含煤地层分布,并且含煤层数多,煤层较为稳定,储量大;因此,焦作煤田拥有丰富的煤层气资源,含气饱和度和煤层渗透率较高,资源密度高,有利于煤层气开发利用．焦作煤田煤层气的开发对改善焦作市能源供给结构,提高资源利用率、保护生态环境具有重要意义．     

关于某区块煤层气开发项目的分析及对策

煤层气作为一种优质高效清洁能源,具有采收率较高、发热量高等优点,其开发和利用不仅可以缓解优质能源供需矛盾,也可以从根本上保障煤矿安全生产、减少温室气体排放、改善全球大气环境。中国能源60%以上来自煤炭,而采煤产生的煤层气在世界温室气体排放物中占据首位,煤层气对全球气温变暖的影响是二氧化碳的23倍,因此,煤层气产业不应仅仅作为一个资源利用的产业,更是一个关系到国家能源安全和科学发展的基础产业。目前国家逐步认识到开发煤层气资源的重要性和迫切性,已相继出台了税收优惠、财政补贴等多项扶持鼓励政策,煤层气大规模开发利用的市场前景十分广阔。     

准噶尔盆地低阶煤煤层气资源及勘探潜力分析

本文分析和探讨了目前国内外煤层气勘探开发和资源分布状况，研究了煤层气的成因、赋存特点和富集因素，在此基础上，结合准噶尔盆地中下侏罗统煤层的地质分布和演化特点，指出八道湾和西山窑组在盆地南缘最为发育，虽然演化主要处于低煤阶阶段，但含气率较高煤岩的模拟实验亦证实，生气能力较强。借鉴美国开发低煤阶煤层气的成功经验，对煤层气成藏有利区进行了预测，即侏罗系西山窑组是勘探煤层气最有利层系；南缘东部是勘探煤层气最有利地区。     

我国煤层气资源及开发现状

抽放煤层气是减少矿井瓦斯涌出量、防止瓦斯爆炸和突出事故的根本措施．煤层气是一种洁净能源,热效率高,尤其在当今我国能源结构不合理的情况下,加快煤层气的勘探、开发和利用具有巨大的社会效益和经济效益．从含煤盆地、成煤时代、煤层气的储层类型和埋藏深度等方面论述了我国的煤层气资源,并讨论了我国煤层气的开发现状．     

我国煤层气资源及开发现状

抽放煤层气是减少矿井瓦斯涌出量、防止瓦斯爆炸和突出事故的根本措施.煤层气是一种洁净能源,热效率高,尤其在当今我国能源结构不合理的情况下,加快煤层气的勘探、开发和利用具有巨大的社会效益和经济效益.从含煤盆地、成煤时代、煤层气的储层类型和埋藏深度等方面论述了我国的煤层气资源,并讨论了我国煤层气的开发现状.     

柳林矿区煤层气演化史数值模拟研究

运用数值模拟方法对河东煤田柳林矿区主煤层煤层气地质演化史进行了定量模拟研究。结果表明：研究区内煤层气演化史可分为三个阶段。初期阶段内煤层气的生成、赋存和散失等作用较弱;聚集高峰阶段内各种演化作用剧烈,是本区煤层气聚集的重要阶段;散失阶段主要发生各种散失作用。此外,研究区西南部是煤层气聚集的有利地区。     

煤层气储层压裂水平井产能计算

煤层气作为一种重要资源，近多年来其研究和开发活动迅速增加。由于煤层气储层低孔、低渗特征，采用常规开采方法开发效果不佳。压裂技术和水平井技术是提高煤层气藏产量的有效方法。基于位势理论和叠加原理，建立了煤层气储层压裂水平井产能计算模型，考虑了煤层气储层非均质性、裂缝部分穿透储层、裂缝条数因素的影响。通过实例计算，分析了影响因素的敏感性。结果表明，煤层气产量与裂缝条数和穿透率成正比，每千米水平井段内合理的裂缝条数应不超过10条；裂缝穿透率宜控制在0．15之内，高于0．15煤层气井产量对穿速率则不敏感。     

Reservoir reconstruction technologies for coalbed methane recovery in deep and multiple seams

Multiple coal seams widely develop in the deep Chinese coal-bearing strata. Ground in situ stress and coal seam gas pressure increase continuously with the increase of the mining depth, and coal and gas outburst disasters become increasingly severe. When the coal is very deep, the gas content and pressure will elevate and thus coal seams tends to outburst-prone seams. The safety and economics of exploited firstmined coal seams are tremendously restricted. Meanwhile, the multiple seams occurrence conditions resulted in different methane pressure systems in the coal-bearing strata, which made the reservoir reconstruction of coal difficult. Given the characteristics of low saturation, low permeability, strong anisotropy and soft coal of Chinese coal seams, a single hydraulic fracturing surface well for reservoir reconstruction to pre-drain the coalbed methane(CBM) of multiple seams concurrently under the different gas pressure systems has not yet gained any breakthroughs. Based on analyses of the main features of deep CBM reservoirs in China, current gas control methods and the existing challenges in deep and multiple seams, we proposed a new technology for deep CBM reservoir reconstruction to realize simultaneous high-efficiency coal mining and gas extraction. In particular, we determined the first-mined seam according to the principles of effectiveness and economics, and used hydraulic fracturing surface well to reconstruct the first-mined seam which enlarges the selection range of the first-mined seam. During the process of mining first-mined seam, adjacent coal seams could be reconstructed under the mining effect which promoted high-efficiency pressure relief gas extraction by using spatial and comprehensive gas drainage methods(combination of underground and ground CBM extraction methods). A typical integrated reservoir reconstruction technology, ‘‘One well for triple use", was detailed introduced and successfully applied in the Luling coal mine. The application showed that the proposed technology could effectively promote coal mining safety and simultaneously high-efficiency gas extraction.     

煤层气运移分馏机理初探

煤层气的分馏效应是指运移过程中气体组份和同位素值发生变化的现象.分馏机理的探讨对煤层气的运移聚集具有重要指导意义.本文以吸附势理论为指导,以等温吸附实验数据为依据,对甲烷碳同位素和多组分气体分馏机理进行了探讨.确定了4种分馏机理的存在:(1)解吸-扩散-运移不仅造成甲烷碳同位素分馏,而且造成多组分气体分馏.13CH4因其吸附势普遍高于12CH4而具有优先吸附、滞后解吸的特征,12CH4更容易发生运移分馏.二氧化碳与甲烷相比,具有优先吸附、滞后解吸的特征,特别是在高压下,甲烷具有强的分馏效应;(2)发生在地下水径流带的溶解作用使得13CH4被优先溶解并被运移至滞留区聚集,12CH4保留在原地;(3)浅部次生生物气的产生造成甲烷碳同位素变轻的假象;(4)高温裂解气的生成造成甲烷碳同位素变重的假象.4种分馏效应都引起浅部甲烷碳同位素变轻,深部变重,这已为众多的实例所证实.     

Preferential adsorption behaviour of CH4 and CO2 on high-rank coal from Qinshui Basin,China

In order to better understand the prevailing mechanism of CO₂ storage in coal and estimate CO₂ sequestration capacity of a coal seam and enhanced coalbed methane recovery (ECBM) with CO₂ injection into coal, we investigated the preferential adsorption of CH₄ and CO₂ on coals. Adsorption of pure CO₂, CH₄ and their binary mixtures on high-rank coals from Qinshui Basin in China were employed to study the preferential adsorption behaviour. Multiple regression equations were presented to predict CH₄ equilibrium concentration from equilibrium pressure and its initial-composition in feed gas. The results show that preferential adsorption of CO₂ on coals over the entire pressure range under competitive sorption conditions was observed, however, preferential adsorption of CH₄ over CO₂ on low-volatile bituminous coal from higher CH₄-compostion in source gas was found at up to 10 MPa pressure. Preferential adsorption of CO₂ increases with increase of CH₄ concentration in source gas, and decreases with increasing pressure. Although there was no systematic investigation of the effect of coal rank on preferential adsorption, there are obvious differences in preferential adsorption of gas between low-volatile bituminous coal and anthracite. The obtained preferential adsorption gives rise to the assumption that CO₂ sequestration in coal beds with subsequent CO₂-ECBM might be an option in Qinshui Basins, China.     

Construction of high-pressure adsorption isotherm: A tool for predicting coalbed methane recovery from Jharia coalfield,India

Adsorption isotherm relates the gas storage capacity as a function of pressure at constant temperature. In this paper, adsorption isotherm of two dry borehole samples was constructed in the laboratory using the manometric method. Isotherm was measured for two gases, i.e., CH_4 and CO_2 to pressure up to 8.4 MPa.Before the construction of sorption isotherm, coal was characterized by proximate, ultimate and petrographic analysis. Coalbed gas content of these two samples was found 2.29 m~3/t and 2.75 m~3/t. SEM images were obtained for the pore size distribution of coal using pore image analysis. Prediction of coalbed methane recovery from CH_4 adsorption isotherm showed that these coalbeds are under saturated. CO_2 isotherm was constructed to estimate enhanced coalbed methane(ECBM) recovery. Volume wise CO_2/CH_4 sorption ratio was found 2.09 times to 2.75 times respectively. This paper presents the interpretation of isotherm data to find the recovery factor of methane production from Jharia coalfield.     

Evolution and application of in-seam drilling for gas drainage

The presence of seam gas in the form of methane or carbon dioxide presents a hazard to underground coal mining operations. In-seam drilling has been undertaken for the past three decades for gas drainage to reduce the risk of gas outburst and lower the concentrations of seam gas in the underground ventilation. The drilling practices have reflected the standards of the times and have evolved with the development of technology and equipment and the needs to provide a safe mining environment underground. Early practice was to adapt equipment from other fields, with rotary drilling being the only form of drilling available. This form of drainage allowed various levels of gas drainage coverage but with changing emphasis, research and development within the coal industry has created specific equipment, technology and practices to accurately place in-seam boreholes to provide efficient and effective gas drainage. Research into gas content determination established a standard for the process and safe levels for mining operations to continue. Surveying technology improved from the wire-line, single-shot Eastman survey instruments which was time-dependent on borehole depth to electronic instruments located in the drill string which transmitted accurate survey data to the drilling crew without time delays. This allowed improved directional control and increased drilling rates. Directional drilling technology has now been established as the industry standard to provide effective gas drainage drilling. Exploration was identified as an additional benefit with directional drilling as it has the ability to provide exploration data from long boreholes. The ability of the technology to provide safe and reliable means to investigate the need for inrush protection and water drainage ahead of mining has been established. Directional drilling technology has now been introduced to the Chinese coal industry for gas drainage through a practice of auditing, design, supply, training and ongoing support. Experienced drilling crews can offer site specific gas drainage drilling services utilising the latest equipment and technology.     

排采连续性对煤层气开采的影响

排采连续性对煤层气开发至关重要.但是,在排采过程中关井现象不可避免,重新开井后如何排采、制定合理的排采制度是提高产量的关键.通过对煤层气生产阶段理论进行分析,结合关井前后矿场数据,同时借助数值模拟方法,对关井过程中储层参数变化进行了研究.结果表明,关井明显改变储层物性参数,造成井筒附近煤层含水饱和度增加,井底压力升高,...     

新集矿区煤层气地面开发技术探讨

作为国家煤层气示范开发区,针对新集矿区的地质条件及煤层气储存特点,选用地面垂直井开发煤层气的工艺技术,通过开发试验现场的＂1＋3＂井组工程的三口试生产井,成功地产出了煤层气,获得了单井最大日产气量3 728m3,排采三年后日产气量仍维持1 000m3。对其中的钻井、储层保护、水力压裂、排水、采气方面的关键技术的研究和实施,建立起一套适用于新集矿区地质条件及中国国情的煤层气钻井、完井、压裂和采气工艺技术。试验区地面垂直井开发煤层气的成功实施,也为矿区治理矿井瓦斯,提供了新的途径。     

我国天然气市场黄金期发展初探

我国天然气行业处于快速发展的黄金期,需求旺盛,产品清洁环保,符合国家可持续科学发展要求.对于天然行业来说,当前的主要任务是尽快提升国内天然气生产能力,科学安排天然气中长期发展规划,建立并完善相关配套政策和价格形成机制,逐步建成独立和完善的天然气管网,最终形成天然气的市场化.     

Status of research on biogenic coalbed gas generation mechanisms

Biogenic coalbed gas,how it is generated and the geochemical characteristics of the gas are gaining global attention.The ways coalbed gas is generated,the status of research on the generation mechanism and the methods of differentiating between biogenic gasses are discussed.The generation of biogenic coalbed methane is consistent with anaerobic fermentation theory.Commercial biogenic coalbed gas reservoirs are mainly generated by the process of CO2 reduction.The substrates used by the microbes living in the coal include organic compounds,CO2,H2 and acetate.The production ratio and quantity of biogenic coalbed methane depend on the exposed surface area,the solubility and permeability of the coal and the microbial concentration in the coal seam.It is generally believed that biogenic coalbed gas has a value for σ13C1＜-5.5%,C1/C1+＞0.95.The H isotope ratio is controlled by both the environment and the generation mechanism:typically σD1＜-20%.Biogenic methane formed by CO2 reduction has more σD1 than that formed by acetate fermentation.