李勇, 王延斌, 孟尚志, 吴翔, 陶传奇, 许卫凯. 煤系非常规天然气合采地质基础理论进展及展望[J]. 煤炭学报, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.1305
引用本文: 李勇, 王延斌, 孟尚志, 吴翔, 陶传奇, 许卫凯. 煤系非常规天然气合采地质基础理论进展及展望[J]. 煤炭学报, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.1305
LI Yong, WANG Yanbin, MENG Shangzhi, WU Xiang, TAO Chuanqi, XU Weikai. Theoretical basis and prospect of coal measure unconventional natural gas co-production[J]. Journal of China Coal Society, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.1305
Citation: LI Yong, WANG Yanbin, MENG Shangzhi, WU Xiang, TAO Chuanqi, XU Weikai. Theoretical basis and prospect of coal measure unconventional natural gas co-production[J]. Journal of China Coal Society, 2020, 45(4). DOI: 10.13225/j.cnki.jccs.2019.1305

煤系非常规天然气合采地质基础理论进展及展望

Theoretical basis and prospect of coal measure unconventional natural gas co-production

  • 摘要: 煤层气、煤系页岩气和煤系致密气在国内外多个盆地中同时赋存,分别实现了勘探开发,但是多层/多种非常规天然气同井筒开发仍未系统实施。实现多气协同开发,将大幅提高地下资源可动用率和开发经济效益。本文系统总结国内外典型盆地煤系气生烃演化、气藏赋存、储层物性和产出机理方面的进展和认识,以期为非常规天然气多气合采提供理论和方法借鉴。主要进展包括:① 煤系生烃超压或微裂缝沟通是气体运移、聚集的必要条件;② 煤系含气系统呈现箱式封存、连续运聚、动态转化、定向聚散的特点;③ 岩层组合、应力场、温度场、含气性等静态地质参数决定可采性,单层/多层相渗、储层压力、供液能力等动态参数决定产出效果;④ 物理实验和数值分析可模拟理想地质条件下的合采干扰因素,储层压力和渗透率是影响排水期和气水同产期渗流的主要因素;⑤ 合理的排水采气工艺和科学控制采气速度,可适当避免或控制层间和井筒内的干扰。后续研究的核心是“地质+工程”甜点区优选,需要解决的关键问题包括:① 叠置多类型气藏在地质演化过程的动态运聚过程,优势储层的形成与界定准则;② 煤系内复杂的气水分布关系和流体压力系统,如何保证增产改造措施的有效性和科学监测;③ 多层合采排采控制制度及产能预测方法。在具体工作中查明“煤系沉积—储层演化—生烃运聚—气水赋存”的动态耦合过程,围绕“开发地质选区—钻完井与储层保护—增产改造—合采制度及产能预测”进行攻关。根据不同地区煤系非常规天然气的共生特点,选择合适的技术实现同井筒合采,有助于提高经济效益和资源动用率。

     

    Abstract: Coalbed methane,shale gas and tight gas within coal measures exist simultaneously in many basins world- wide,with the successful exploration and development of specific gas respectively. However,the multi-layer / multi-un- conventional natural gas development in the same wellbore has not yet been systematically implemented. The realiza- tion of multi gas collaborative development will greatly improve the availability of underground resources and economic benefits. This paper systematically summarizes the development and understanding of hydrocarbon generation evolu- tion,gas reservoir occurrence,reservoir physical properties and production mechanism of coal bearing gas occurrence in typical basins in order to provide theoretical and methodological reference for unconventional gas multi gas co-pro- duction. The main progresses include ① the overpressure or micro-fissure during hydrocarbon generation of coal meas- ures is the necessary condition for gas diffusion and migration continuously to adjacent layers;② coal bearing gas sys- tem presents the characteristics of box sealing,continuous migration and accumulation,dynamic transformation and di- rectional accumulation and dispersion;③ static geological parameters such as strata combination,stress field,tempera- ture field and gas bearing property determine the recoverability,and dynamic parameters such as single / multi-layer phase permeability,reservoir pressure and liquid supply capacity determine the production performance;④ physical experiment and numerical analysis can simulate the interference factors of combined mining under ideal geological con- ditions,and reservoir pressure and permeability are the main factors affecting the seepage in drainage period and gas water production period;and ⑤ a reasonable drainage gas production process and scientific control of gas production speed can properly avoid or control the interference between layers and in the wellbore. The key in co-production re- search is “geology+engineering” dessert area selection. The key problems needed to be solved include ① the dynamic migration and accumulation process of superimposed multi type gas reservoirs in the geological evolution process,and the formation and recognition criteria of dominant reservoirs;② the complex gas-water distribution relationship and flu- id pressure system in coal measures,and how to ensure the effectiveness and scientific monitoring of stimulation meas- ures;and ③ the multi-layer combined production and drainage control system and productivity prediction method. The detailed works are to clarify the dynamic processes of coal measures sedimentary,reservoir diagenesis,hydrocarbon generation and migration,and gas-water occurrence and flow state. The technical sequences are geological selection, drilling and completion and reservoir protection,stimulation and transformation technology,drainage system and pro- ductivity prediction. According to the coexistence characteristics of multi-layered unconventional natural gas in coal measures in different areas,choosing appropriate technology to realize co-production within one wellbore will signifi- cantly reduce development costs,improve economic benefits and resource utilization.

     

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