Coalbed methane: the focus of world energy
At present, the contradiction between international energy supply and demand is prominent, energy security has increasingly become the focus of attention of various countries, and the exploration and development of coalbed methane has attracted the attention of the world. Considering their economic and political interests, major powers have increased their investment in coalbed methane, and the exploration and development technologies of coalbed methane in developed countries have become increasingly mature.
当前国际能源供需矛盾突出,能源安全日益成为各国关注的焦点，煤层 气勘探开发聚焦了世界的目光。主要大国 处于经济和政治利益的考虑，加大对煤层 气的投入，发达国家煤层气勘探开发技术 也日趋成熟。
The world's coalbed methane reserves The world's coalbed methane resources are 256.3 trillion cubic meters. They are mainly distributed in North America, the former Soviet Union and China, as shown in Table 1. About 50% of conventional natural gas resources; The five countries together accounted for 90%.
China is rich in CBM resources. CBM resources are the country with the third largest reserves after Russia and Canada, accounting for 13% of the total resources of the top 12 countries in the world. China's coalbed methane reserves are shown in Figure 1.
世界煤层气储量 世界煤层气资源 量为256.3万亿立方米.主要分布在北 美、前苏联和中国，见表1.约为常规天 然气资源坦的50%；其中俄、加、中、 美、澳五国合计占90%。
中国煤层气资源丰富，煤层气资源 是继俄罗斯、加拿大之后的第三大储量 国，占世界排名前12位国家资源总量的 13%。中国煤层气储量，见图1。
World CBM Production The United States, Canada, and Australia have formed industrial scale production. In 2006, the output reached 540, 60 and 100 million cubic meters respectively, as shown in Figure 3 and Figure 4. CBM production accounts for an important proportion of the total U.S. natural gas production and is an important part of U.S. natural gas energy. In the 1990s, the increase in U.S. coalbed methane production accounted for 60% of the total increase in U.S. natural gas production. In 2007, the total coalbed methane production in the United States accounted for 7.5% of the total natural gas production.
CBM resources in Canada are mainly distributed in the Alberta Basin. Currently, southeastern and central Alberta, northeastern and southeastern British Columbia, and Vancouver Island are all CBM exploration and development work areas. Figure 4 shows Canada's coalbed methane production in recent years. Australian coalbed methane is mainly distributed in four eastern Permian hard coal basins: Sydney-Gonnedah, Born, Galilee and Cooper basins. Queensland and New South Wales are major CBM commercial development areas.
世界煤层气产量 美国、加拿大、 澳大利亚三国已形成工业化规模生产， 2006年产量分别达到了540、60和怕亿 立方米，见图3、图4。煤层气产量在美 国天然气总产量中占重要比例，是美国天 然气能源的重要组成部分。上世纪90年 代，美国煤层气产量的増长占美国天然气 产量总增长的60%。2007年美国的煤层 气总产量占天然气总产量的7.5%O
加拿大煤层气资源主要分布在阿尔伯 塔盆地，目前阿尔伯塔东南部和中部、大不列颠哥伦比亚的东北部和东南部以及温哥华岛均为煤层气勘探开发工作区。图4为 加拿大近年煤层气产量。澳大利亚煤层气 主要分布在东部4个二叠系硬煤盆地：悉 尼-冈尼达、博恩、加利利和库泊盆地。 昆士兰和新南威尔士是主要煤层气商业开 发区。
In 2007, China's surface coalbed methane production capacity exceeded 1 billion cubic meters, and the companies producing surface coalbed methane with an output of nearly 500 million cubic meters mainly included China United, PetroChina, and Shanxi Coal Group, which were concentrated in the southern Qinshui Basin. In 2007, the gas drainage volume of key coal mines was 3.06 billion cubic meters, with a drainage rate of 48%; the gas utilization volume was 900 million cubic meters, with a utilization rate of 30%.
2007年中国煤层气地面产能超过10 亿立方米，产量近5亿立方米口地面煤层 气开发的企业主要有中联公司、中国石 油、晋煤集团等，集中在沁水盆地南部。 2007年重点煤矿瓦斯抽放量30.6亿立方 米，抽放率48%；瓦斯利用量9亿立方 米，利用率30%。
advanced coalbed methane
Resource Exploration Technology and Method
In the 1940s, German scholars put forward the theory of coalbed methane to guide the exploration and evaluation of natural gas. In the 1950s, the natural gas exploration in the Basso-Europe, Central Asia and West Siberia had obvious effects. The natural gas theory is developed from the one-element gas-forming theory, that is, only saprophytic organic matter in the petroliferous basin can form natural gas, to the dual-element gas-forming theory, that is, the humic organic matter in the coal-bearing basin and its strata can also form natural gas. There are three sources of CBM origin: early biogas, mid-stage pyrolysis gas, and late secondary biogas: in different parts of the same basin, sometimes one origin dominates, sometimes two coexist, sometimes even three Mixed causes.
20世纪40年代德国学者提出了煤层 气理论，指导天然气勘探与评价，50年 代布西欧、中亚和西西伯利亚盆地天然气 勘探中效果明显。使天然气理论从一元成 气论即只有含油气盆地腐泥型有机质才能 形成天然气的论点，发展为二元成气论即 含煤盆地及其地层中腐植型有机质也可形 成天然气。煤层气的成因有3种来源：早 期生物气、中期热裂解气和晚期次生生物 气:同一盆地不同部位，有时是一种成因 占主导地位，有时是两种成因共存，有时 甚至是三种成因混合。
In addition to the caprock conditions, the gas-generating layers, gas-storage layers and traps of the coalbed methane reservoirs are all coalbeds themselves. Therefore, the coalbeds are required to have high gas-generating potential and strong storage and adsorption capacity. It also requires a certain permeability to facilitate the migration and emission of coalbed methane. Only when the coalbed itself has both the above properties and functions, can a coalbed methane reservoir be formed. Coal reservoir properties include fracture-pore properties, adsorption, gas-bearing properties, permeability, coal reservoir pressure, etc., and are an important direction of coalbed methane geological research. Coal reservoir is composed of pores and fissures. Double pore structure system. Coal reservoir is a ternary fissure-pore medium composed of macro fissures, micro fissures and pores. Coal reservoirs are affected by magmatic rocks. Typical microporous structure and fissures, large gas generation, high gas content, and methane concentration as high as 95%.
在成禮要素中除盖层条件外，煤层 气藏的生气层、储气层和圈闭都是煤层本 身，因此要求煤层有很高的生气潜力，又要 求煤层具有很强的储集吸附能力，还要求一 定的渗透率以利于煤层甲烷的运移和排放 等，只有当煤层本身兼有以上各种性能和作 用时，才能形成煤层气藏。煤储层特性包括 裂隙一孔隙特性、吸附性、含气性、渗透 性、煤储层压力等，是煤层气地质研究的一 个重要方向。煤储层是由孔隙、裂隙组成的 ••双重孔隙"结构系统，煤储层是由宏观 裂隙、显微裂隙、孔隙共同组成的三元裂 隙一孔隙介质°受岩浆岩影响的煤储层具典 型的微孔结构和裂隙，生气量大、含气量 高，甲烷浓度高达95%。
CBM exploration methods include geological method, geophysical method, geochemical exploration method, drilling method, and multidisciplinary comprehensive exploration is the development direction of CBM exploration. Developed countries such as the United States, Canada and Australia have mature CBM development technologies. At present, the CBM exploration and development depth of lignite and low coalification bituminous coal has exceeded 1,500 meters.
煤层气勘探方法有地质法、地球物 理法、地球化学勘探法、钻井法、采用多 学科综合勘探是煤层气勘探发展方向。美 国、加争大、澳大利亚等发达国家具句成 熟煤层气开发技术。目前褐煤和低煤化烟 煤的煤层气勘探开发深度突破1500米。
Multilateral Well Technology Multilateral wells are developed on the basis of horizontal and directional wells, which refer to the drilling of several lateral wells into the oil and gas reservoir in a main wellbore (vertical well, directional well, horizontal well). Lateral wells can obtain the maximum total horizontal displacement from a single wellbore, drilling through multiple oil and gas formations at different depths in the same or different directions, as shown in Figure 5. Multilateral wells form an interconnected network in the coal seam. Maximize the communication between coal seam fractures and cleat systems, reduce the flow resistance of fluid in coal seam fractures, improve the speed of coal seam drainage and pressure reduction and the speed of coalbed methane desorption and migration, increase coalbed methane production, improve recovery, shorten gas acquisition time, and improve Economic benefits of coalbed methane development.
多分支井技术 多分支井是在水平 并、定向井基础上发展起来的，指在一口 主井眼（直井、定向井、水平井）中钻出 若干进入油气藏的分支井眼。分支井可以 从一个井眼中获得最大的总水平位移，在 相同或不同方向上钻穿不同深度的多套油 气层，见图5。多分支井在煤层形成相互 连通的网络。最大限度地沟通煤层裂隙和 割理系统，降低了煤层裂隙内流体的流动 阻力，提高煤层排水降圧速度和煤层气解 吸运移速度，增加煤层气产量，提高采出 程度，缩短釆气时间，提高煤层气开发经济效益。
Halliburton has a complete set of drilling, completion, production and branch well re-entry supporting technologies and tools and equipment for branch wells. The technology is suitable for low-permeability coal-bearing areas of medium and high coal rank. By increasing the exposed area of coal seams, communicating natural cleats and fissures, improving single-well production and recovery rate, and solving the problems of low single-well production and poor economic benefits in low-permeability areas . This technology can also be used in thin coal seams with high gas content. Appalachian Basin, West Virginia, USA, the coal-bearing seam is Carboniferous, middle-high coal rank, coking coal, vitrinite reflectance 15%, coal thickness 1.22 ~ 2m, gas content 8.5 - 15.6m3/t, Panto The rate of 3~4mD, using multilateral horizontal wells, the daily gas production of a single well is (3.4~5.6) x 104m3, the production location is more than 20 times higher than that of hydraulic fracturing, while the daily gas production of vertical well fracturing is only 1700m3, and recoverable reserves are recovered in 6 years. 85%.
哈里伯顿公司拥有分支井的全套钻 井、完井、开采和分支井重新进入等配 套技术和工具装备，拥有20余项专利技 术，技术处于世界领先地位。技术适用于 中、高煤阶低渗透含煤区，通过增加煤层 裸露面积，沟通天然割理、裂隙，提高单 井产量和采收率，解决低滲区单井产量 低、经济效益差的问题。高含气薄煤层 也可釆用这一技术。美国西弗吉尼亚阿 巴拉契亚盆地，含煤层为石炭系，中一 高煤阶，焦煤，镜质组反射率为15%, 煤厚 1.22 ~ 2m,含气量8.5 - 15.6m3/t, 潘透率3~4mD,应用多分支水平井，单 井日产气（3.4~5.6 ） x104m3,产置比 水力压裂提高20倍以上，而直井压裂开 采日产气只有1700m3, 6年采出可采储量 85%O
Fracturing technology Fracturing technology is the key technology in the process of CBM development. Fracturing transforms the production layers to improve the production of the production layers. At present, the fracturing technologies used abroad for different storage screens mainly include cross-linked gel fracturing, sand-added hydraulic fracturing, non-sand-added hydraulic fracturing and nitrogen foam fracturing, all of which have passed the test. In addition, multiple fracturing is used in production practice.
压裂技术 压裂技术是煤层气开发过 程中的关键技术，压裂对产层进行改造， 以提高生产层的产量。目前国外针对不同 储屏采用的压裂技术主要有交联凝胶用 裂、加砂水力压裂、不加砂水力压裂和氮 气泡沫压裂，各项技术均已过关。此外， 在生产实践中采用了多次压裂。
In the early stage of coalbed methane development in the United States, the vertical well fracturing technology of the large well group was widely used in the development of coalbed methane in the middle-rank coal-bearing basins of San Juan and Black Warriors. This technology is mainly suitable for the middle-rank coal-bearing area, and its key technology lies in Long-term and continuous pumping and drainage after drilling large well groups and fracturing, large-scale depressurization of the methane gas adsorbed by the coal seam is desorbed and produced.
在美国煤层气开发早期，大井组直井 压裂技术曾广泛应用于圣胡安、黑勇士中 煤阶含煤盆地的煤层气开发之中°该技术 主要适合于中煤阶区，其技术关键在于钻 大井组压裂后长期、连续抽排，大面积降 压后煤层吸附的甲烷气大量解吸而产出。
Gas injection to enhance coalbed methane recovery technology Gas injection to exploit coalbed methane is to inject N2, CO2, flue gas and other gases into the reservoir. Its essence is to inject energy into the coalbed to change the pressure transfer characteristics and increase or keep the diffusion rate unchanged. , so as to achieve the purpose of improving unit yield and recovery rate, as shown in Figure 6. The adsorption capacity of gas molecules on the surface of the coal matrix is certain. When nitrogen and carbon dioxide gas are injected into the coal seam, the gas molecules will replace the methane molecules to a certain extent, so that the methane molecules are separated from the coal matrix and enter a free state, mixed with the flowing gas. In the gas flow, so as to achieve the purpose of increasing the production of coalbed methane. According to this principle, the United States, Canada and other countries recycle and treat the flue gas discharged from the power plant and inject it into the coal seam. Tests have proved that it can improve coalbed methane production and recovery, while reducing greenhouse gas emissions. Currently, '16 companies in the United States and Canada have adopted this technology.
注气提高煤层气采收率技术 注气 开采煤层气就是向储层注入N2、CO2、 烟道气等气体，其实质是向煤层注入能 量，改变压力传导特性和增大或保持扩 散速率不变，从而达 到提高单产量和回收 率的目的，见图6。 煤基质表面对气体分 子的吸附能力是一定 的，向煤层中注入氮 气、二氧化碳气，其 气体分子会在一定程 度上宣换甲烷分子， 使甲烷分子脱离煤基 质束缚而进入游离状 态，混入流动的气流 中，从而达到提高煤 层气产量的目的。美 国、加拿大等国根据 这一原理，将电厂等 排出的烟道气回收处 理后注入煤层。试验 证明可以提高煤层气 产量和采收率，同时 还可以减少温室气体 排放，目前美、加两 国己有'16家公司采用 这一技术。
The open-hole/cave completion technology adopts the open-hole screen completion or cave completion in the coal seam section to increase the exposed area of the coal seam and improve the Single well production c This technology is mainly used in the San Juan and Powder River basins.
裸眼/洞穴完井技术针对低煤阶、 高潘、厚煤层钻井易 拥塌和煤层污染间 题，釆用了煤层段裸 眼下筛管完井或洞穴完井方式，以増加煤 层裸露面积，提高单井产量c该项技术主 要应用在圣胡安、粉河盆地。
Drilling along the coal seam and integrated extraction technology is suitable for the coal seam with a steep stratum inclination. After reaching the coal seam through ground drilling, drilling along the coal seam for more than 500 meters, as long as the coal seam stability permits, it can also drill longer footage. The section adopts open hole completion. This technology can also be applied in the vicinity of coal mines, combined with roadway extraction to realize the integration of coal and gas, which not only utilizes resources, but also solves the safety of coal mine production. This technology is a technology used in the development of coalbed methane in Australia.
沿煤层钻井和一体化抽采技术 技术适用于地层倾角较陡的煤层c通过地 面钻井到达煤层后，沿煤层钻进500米以 上，只要煤层稳定性许可，也可钻进更长 的进尺，煤层段采用裸眼完井°该技术还 可以在煤矿区附近应用，结合巷道抽采实现釆煤釆气一体化，既利用资源，又解 决了煤矿生产安全。该项技术是澳大利亚 开发煤层气时采用的一种技术
Coalbed methane development and coal mining integration technology Gas drainage must be carried out before shallow coal mining, so it is easy to realize the integration of coalbed methane development and coal mining. It is difficult and costly to mine deep coal resources, but it is still economical to use the integrated technology of coalbed methane and coal mining for high gassy deep coal. This technology mainly uses the water jet of the drill bit nozzle to flush the oblique perforation in the coal seam section, circulate the water coal slurry and the coalbed methane, and carry out the three-phase separation of solid, liquid and gas on the ground, and then the coal and the coalbed methane can be recovered. Water can also continue to be injected into the well for reuse. This technology is especially suitable for pulverized coal with high CBM content, large thickness, low strength, and no interlayers; if the coal seam contains a large amount of water star, combined with the CWS technology, its economic benefits are historically high.
煤层气开发与采煤一体化技术 浅层煤炭开釆之前要先进行瓦斯抽放，实现 煤层气开发与采煤一体化很容易。开采深 层煤炭资源难度大、成本高，但对高瓦斯 深层煤炭釆用煤层气与采煤一体化技术， 还是有经济效益的。这项技术主要是利用 钻头喷嘴的水射流在煤层段斜穿孔冲洗，循环出水煤浆和煤层气，在地面进行固、 液、气三相分离，即可采出煤和煤层气， 分离出来的水还可继续注入井内重复利 用。这种技术特别适用于煤层气含量高、 厚度大、强度低、不含夹层的粉煤；如果 煤层含水星较大，与制水煤浆技术结合， 其经济效益史高。
Drainage and extraction technology Coalbed methane production is realized through drainage and gas extraction. The commonly used technologies are mainly gas lift method and tubular kowtow machine. The power source of the kowtow machine is the electric motor in the developed area, and the coalbed methane produced by the gas well in the area where the power grid cannot reach the small gas power plant. Record.
排采技术 煤层气的生产是通过排 水采气实现的，常用的技术主要是气举 方法和管式蒙磕头机等。磕头机的动力 源在电冋发达区用电动机，电网不能到 达地区用气井生产的煤层气带动小型燃 气动力装買°其水温、气体埋深、排水 量、日产气量、累计产气量，全部由自 动化仪表记录。
Proposals for exploration and development
At present, CBM exploration and development has become an important part of natural gas industry in developed countries. ConocoPhillips (the largest natural gas producer in North America), ExxonMobil, Shell, BP and others are all expanding their CBM business. The current technical development directions are: developing the geological theory of coal gas layers, researching and improving technologies for improving and stabilizing single well production, strengthening fine gas reservoir description technology to improve recoverable reserves, and improving resource assessment technology to increase resources.
目前煤层气勘探开发成为发达国家 天然气工州重要组成部分。康菲（北美 最大的天然气生产商）、埃克森美孚、 壳牌、BP等公司都在扩展煤层气业务。目前技术发展方向为：发展煤气层地质理论、研发完善提高和稳定单井产 量技术、加強精细气藏描述技术攻关提 高可采储量、完善资源评估技术增加资 源量.
Developed countries have gained the following experience in the process of CBM exploration and development, but developing countries have a pity: Before the development and utilization of CBM entered into industrialization, the government gave preferential policies to support it; oil companies actively participated in the CBM industry and provided the Technical and financial guarantee; research and development and formation of coalbed methane exploration and development technology suitable for the geological conditions of domestic coalbed methane is the key to the development of coalbed methane production; construction and improvement of the pipeline network system and sales channels. The degree of perfection of infrastructure such as natural gas pipeline network and whether the sales channels are unblocked will affect the development of the coalbed methane industry.
发达国家在煤层气勘探开发过程中 取得如下经验，发展中国家可惜峑：煤层 气的开发利用在进入工业化之前，政府给 予忧惠政策支持；石油公司积极参与煤层 气产业，为煤层气勘探开发提供技术与资 金保障；研究开发并形成适合本国煤层气 地质条件的煤层气勘探开发技术，是煤层 气产亜发展的关键；建设完善管网系统和 销會渠道。天然气管网等基础设施完善程度,销吿渠道是否畅通，影响煤层气产业的发展。
At present, developing countries lack sufficient understanding of CBM resources, distribution, and industrialized exploration and development technologies. It is necessary to strengthen the evaluation of coalbed methane resources and the selection of enrichment areas, strengthen international technical cooperation, and study the supporting technologies for coalbed methane drilling, well completion and production increase suitable for the geological characteristics of developing countries. (This article is funded by the "China Petroleum Science and Technology Major Project "China Petroleum and Natural Gas Sustainable Development Battle Study", project number: 2008D-5004) P-E
目前发展中国家对煤层气资源量、 分布状况、工业化勘探开发技术缺乏足 够的认识。应加强煤层气资源评价与富 集区优选，加强国际技术合作，研究适 合发展中国家本国地质特点的煤层气钻 井、完井、増产配套技术。（本文受 “中国石油科技重大专项“中国石油天 然气可持续发展战珞硏究”资助，项目 编号：2008D-5004） P-E
Keywords关键词:World Energy Focus; World CBM Reserves; World CBM Production; Advanced CBM
Resource exploration technology and method; fracturing technology; gas injection to enhance coalbed methane recovery technology; open hole/cave completion technology; drilling and integrated drainage technology along the coal seam; coalbed methane development and coal mining integration technology; drainage technology ; Proposals for exploration and development in non-commercialized countries世界能源的焦点；世界煤层气储量；世界煤层气产量；先进的煤层气资源勘探技术与方法；压裂技术；注气提高煤层气采收率技术；裸眼/洞穴完井技术；沿煤层钻井和一体化抽采技术；煤层气开发与采煤一体化技术；排采技术；非商业化国家 勘探开发的建议
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Poster发布人: Clark Guo, CCSC Technology, Shanghai, China, 2022.06 Youtube: Clarkwellhead
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