付德亮,段中会,杨甫,等. 富油煤钻井式地下原位热解提取煤基油气资源的几个关键问题[J]. 煤炭学报,2023,48(4):1759−1772. doi: 10.13225/j.cnki.jccs.2022.0183
引用本文: 付德亮,段中会,杨甫,等. 富油煤钻井式地下原位热解提取煤基油气资源的几个关键问题[J]. 煤炭学报,2023,48(4):1759−1772. doi: 10.13225/j.cnki.jccs.2022.0183
FU Deliang,DUAN Zhonghui,YANG Fu,et al. Key problems in in-situ pyrolysis of tar-rich coal drilling for extraction of coal-based oil and gas resources[J]. Journal of China Coal Society,2023,48(4):1759−1772. doi: 10.13225/j.cnki.jccs.2022.0183
Citation: FU Deliang,DUAN Zhonghui,YANG Fu,et al. Key problems in in-situ pyrolysis of tar-rich coal drilling for extraction of coal-based oil and gas resources[J]. Journal of China Coal Society,2023,48(4):1759−1772. doi: 10.13225/j.cnki.jccs.2022.0183

富油煤钻井式地下原位热解提取煤基油气资源的几个关键问题

Key problems in in-situ pyrolysis of tar-rich coal drilling for extraction of coal-based oil and gas resources

  • 摘要: 富油煤是一种具有油气资源属性的特殊煤炭资源,开发富油煤所蕴含的煤基油气资源,实现煤炭这一高碳资源的低碳利用,对于保障国家能源安全、实现“双碳”目标具有重要意义。钻井式富油煤地下原位热解是在工程钻井的基础上,通过煤层人造裂缝,实现多口钻井的连通,然后利用电加热或气体热载体加热等技术加热煤层,使富油煤热解产生油气资源,并在抽采井完成油气采集。目前,煤层加热方式、煤层热解温度、储层改造技术、热解油气的高效抽采等问题亟待解决。① 反应热加热、传导加热、辐射加热等在富油煤地下原位加热应用中均存在不同缺陷,以气体热载体加热为主的对流加热方式更加适用,但是针对不同的地质条件,优选经济安全的载热流体,营造高效的热解氛围尚需要开展针对性的研究工作。多种加热方式相互配合,有望成为富油煤地下原位加热方法的突破方向。② 350~450 ℃是目前普遍较为认可的高效热解温度,但是不同煤质特征以及不同热解氛围,其相应的优势热解温度区间略有不同,富油煤热解的化学热力学和动力学研究是科学预测热解温度的有效手段。③ 在储层改造方面,水力压裂技术、超临界CO2压裂技术和液氮致裂技术,在富油煤地下原位热解应用中均具有一定的适应性,但同时也不同程度的存在一些缺陷,对于不同的地质条件而言,需要做具体客观的评价方可确定相适应的技术手段。可控冲击波技术在岩层致裂方面具有高效可控的优势,未来有望在本领域得到广泛应用。④ 富油煤热解产生的可燃气体以CH4、H2、CO为主,同时伴随较高含量的CO2,易于直接抽采,而热解油为高密度、高黏度的煤焦油,其凝结温度高,180 ℃以下便会大量凝结,存在井筒堵塞的风险,针对性的制定抽采井温压保持方案,是提高热解产物抽采效率的关键所在。此外,未来研究工作中,有关富油煤地下原位热解地质工程一体化综合评价、原位热解反应进程监测、全过程数值模拟等系统性问题同样需要重点关注。

     

    Abstract: Tar-rich coal is a special coal resource with the property of oil and gas resources. Developing the oil and gas resources contained in the tar-rich coal is of great significance for ensuring energy security and realizing the goal of "dual carbon". In-situ pyrolysis of tar-rich coal is a new coal resource development technology. Through some artificial cracks in coal seams, multiple wells can be connected. The coal seam is then heated using some technologies such as electric heating or fluid heating to generate oil and gas resources from the pyrolysis of tar-rich coal. At present, some problems such as coal seam heating mode, optimal pyrolysis temperature, reservoir reconstruction technology and efficient extraction of pyrolysis oil and gas need to be urgently solved. ① There are some defects in the application of reaction heating, conduction heating, and radiation heating in the underground in-situ heating of tar-rich coal. Convection heating based on injection fluid heating is more suitable for the in-situ heating of tar-rich coal. According to different geological conditions, it is still necessary to carry out targeted research work for optimizing the economical and safe heat carrying fluid and creating an efficient pyrolysis atmosphere. The combination of various heating methods is expected to be the breakthrough direction of the underground in-situ heating method of tar-rich coal. ② At present, 350−450 ℃ is generally recognized as the efficient pyrolysis temperature. With different coal characteristics and different pyrolysis atmospheres, the corresponding dominant pyrolysis temperature range is slightly different. The methods of chemical thermodynamics and kinetics for the pyrolysis of tar-rich coal are effective means to predict pyrolysis temperature scientifically. ③ Hydraulic fracturing, supercritical CO2 fracturing, and liquid nitrogen fracturing have some limitations for the in-situ pyrolysis of tar-rich coal. For different geological conditions, it is necessary to select the appropriate reservoir reconstruction scheme through specific objective evaluation. Controllable shock wave technology has the advantage of high efficiency and control in rock fracturing and is expected to be widely used in the in-situ pyrolysis process in the future. ④ The combustible gases produced by the pyrolysis of tar-rich coal are mainly CH4, H2, and CO, accompanied by a high content of CO2, which is easy to be directly extracted. The oil produced by pyrolysis is coal tar with high density and high viscosity, which will condense in large quantities below 180 ℃. There is a risk of wellbore clogging and the key to improving the extraction efficiency of pyrolysis products is to formulate the temperature and pressure maintenance scheme of the extraction well. In addition, the systematic issues such as integrated geological engineering evaluation, in-situ pyrolysis reaction process monitoring, and the whole-process numerical simulation of tar-rich coal should also be focused on in the future research work.

     

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