煤炭地下气化试验综述与产业化发展建议

Summary of underground coal gasification field tests and suggestions for industrial development

  • 摘要: 在实现碳达峰碳中和(“双碳”)目标和保障国家能源安全的双重需求驱动下,我国煤炭地下气化(UCG)迎来了新的历史发展机遇期。为科学制定技术攻关路线、加快产业化发展,按时间顺序梳理了煤炭地下气化试验历程,将其分为矿井式气化、直井/定向井气化、水平井气化3个发展阶段,探究了不同阶段推动气化技术革新的底层逻辑,从技术和非技术两个方面分析了未能产业化的原因并提出产业化发展建议。研究表明:(1)水平井+可控注入点后退气化工艺不仅能够有效规避浅层气化在地表沉降、淡水污染方面的风险,而且在扩大煤炭纵向开发范围、提高单井控煤量、提升粗煤气品质、保障连续气化方面具有优势,是当前和今后一个时期的主流技术路线。(2)我国是现场试验时间最长的国家,长期处于矿井式气化阶段,虽然我国中深层煤炭地下气化攻关试验刚起步,但是由于该技术攻关难度大、技术成熟度低,主要富煤国家在技术研发上基本属于同一起跑线,有希望成为我国钻井式气化技术弯道超车的新赛道。(3)技术适用性不强是造成矿井式、直井式气化产业化困难的主要技术原因,技术成熟度较低是制约水平井气化产业化的主要技术原因,长期稳产高产问题尚未得到彻底解决。(4)常规天然气低成本开发和页岩气革命的冲击,民众对浅层气化诱发环境污染的担忧,政府对煤炭地下气化的政策转向,是导致国外试验终止的主要非技术原因;发展规划长期空白、科研试验主体相对单一、科研投入不足、产业扶持政策未出台、联合创新机制未建立是阻碍我国气化产业化的非技术原因。提出我国UCG产业化建议:新时期要充分认识煤炭地下气化技术的复杂性和挑战性,按照“干成”“干好”两个维度,破解“长期稳产”和“高产优产”两个核心问题,通过同步推进科研攻关和现场试验不断提高技术成熟度,在生产端采用“先物理采气后化学气化”的梯级开发方式避免与煤层气开发竞争,在利用端积极探索与油气、新能源、煤化工融合发展模式以提高经济效益。作为一种“人造气藏”的颠覆性开发方式,煤炭地下气化攻关成功后能为其他矿产资源的流态化开发提供技术借鉴,助推我国化石能源非常规开发技术实现新跨越。

     

    Abstract: China's underground coal gasification has entered a new historical development opportunity period, driven by the dual requirements of realizing the "carbon peaking and carbon neutrality goals" and ensuring national energy security. This paper analyzes the history of underground coal gasification in chronological order in order to scientifically formulate a technological breakthrough route and promote industrial development. The history is divided into three stages of development: mine type gasification, straight/directional well type gasification, and horizontal well type gasification. The underlying logic of promoting gasification technology innovation at different stages is explored. The reasons for the failure of industrialization are analyzed from the two aspects of technology and non-technology, and the countermeasures for industrialization are proposed. The findings of the study are as follows: (1)Horizontal well & controlled retracting injection point gasification process can not only effectively avoid the risks of shallow gasification in terms of surface subsidence and freshwater pollution, but also has the advantages of expanding the scope of vertical coal resource development, increasing the amount of coal control within two wells, improving the quality of crude gas, and ensuring continuous gasification. In the current and future period, this method is the mainstream technical route.(2)China has the longest field test period and has been in the stage of mine-type gasification for a long time. Although China's underground gasification of medium-deep coal test research is in the early stage, but due to the difficulty and low maturity of technology research, the major coal-rich countries in the medium-deep coal gasification technology research and development basically falls into the same pace. This technology has the potential to become a new track for China's drilling-type gasification technology to overtake the other countries. (3)Analysis shows that the poor applicability of technology is the main technical reason for the difficulty in industrialization of mine and vertical well gasification, and the low maturity of technology is the main technical reason that restricts the industrialization of horizontal well gasification. The long-term safety and high production issues have not been completely solved.(4)The low-cost development of conventional natural gas and the impact of the shale gas revolution, public concerns about environmental pollution caused by shallow gasification, and the government's policy shift towards underground coal gasification are the main non-technical reasons for the termination of foreign experiments; The long-term lack of development planning, relatively single scientific research and experimental subjects, insufficient scientific research investment, lack of industrial support policies, and lack of establishment of joint innovation mechanisms are non-technical reasons that hinder China's industrialization. The industrialization suggestion of UCG in China is put forward: it is necessary to fully understand the complexity and challenges of underground coal gasification technology in the new period. According to the two levels of “full accomplishment” and “high-quality accomplishment”, the core issues of "longterm stable production" and "high yield and excellent production" should be solved. Through synchronous promotion of scientific research and on-site experiments, the technological maturity should be continuously improved. On the production side, the cascade development method of "physical gas extraction followed by chemical gasification" should be adopted to avoid competition with the development of coalbed methane. On the utilization side, actively exploring the integration development mode with oil and gas, new energy and coal chemical industries to improve economic benefits.⑥As a subversive “artificial gas reservoir” development method, the success of underground coal gasification can provide technical reference for fluidization development of other mineral resources, and push China's unconventional fossil energy development technology to a new level.

     

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