深部煤层CO2地质存储与CH4强化开采的有效性理论研究

Laying the independent development experimental devices to simulate geochemical interaction between supercritical CO2/H2O system and coals and to imitate permeability change of coal reservoir with CO2 injection as fundamental innovation platforms, and considering anthracite reservoir basic geological model under conditions of temperature, fluid pressure,moiture and crustal stress in the deep of Qinshui basin as case study background, the applicants attempt to study geochemical interaction effect and volume and stress effect when CO2 injected into deep anthracite reservoirs, sorption, containment, fluid migration and displacement jointly controlled by both the effects, and geological and mathmetical models relating to the continuous process from CO2 injection, sorption, containment, fluid migration and displacement to CH4 output;to develop numerical modelling software for CO2-ECBM with independent intellectual property; to establish a methodological system of CO2-ECBM simulation and assessment; to generate CO2-ECBM theoritical model and technical mode of deep anthracite; to found validation theory of CO2-ECBM mainly aiming at CO2 storage in deep coal seams; and to scientifically answer the question on CO2-ECBM validation of deep anthacite represented by Qinshui basin. Consequently,the research will provide scentific evidence for China to carry out CO2-ECBM engineering exploration of deep coal seams, and lay the theoritical foundation for greenhouse gas emission reduction and its environmental effect for atmosphere.

以自主开发的“模拟超临界CO2/H2O体系与煤岩地球化学反应实验装置”和“模拟CO2注入煤层渗透性变化实验装置”为实验模拟研究平台，基于沁水盆地示范工区及其深部温、压、水、地应力条件下无烟煤储层基本地质模型，探索深部无烟煤储层条件下超临界CO2注入煤层体积应力效应和CO2/H2O/煤岩地球化学反应效应本质，煤储层结构演化、吸附解吸、渗透性变化和流体运移规律，吸附解吸-扩散-渗流-驱替耦合关系及其物理化学过程连续性等关键科学问题，研究构建深部煤层CO2注入-吸附解吸-流体运移-CH4产出地质模型、数学模型，开发数值模拟技术；揭示深部无烟煤储层CO2-ECBM有效性机理，形成CO2-ECBM有效性评价方法，科学回答以沁水盆地为代表的深部无烟煤储层CO2-ECBM有效性问题；为我国实施深部煤层CO2-ECBM工程探索提供科学依据，发展CO2-ECBM温室气体减排及其大气环境效应评价的关键理论。

CO2-ECBM面临挑战的主要理论和技术问题中有效性是基础和前提，CO2-ECBM有效性涵盖煤层CO2可注性、CO2封闭、CO2存储容量与CH4增产效果关键要素。以最值得关注的沁水盆地为主要工区，以山西组3#无烟煤层为主要模拟研究对象，以地层条件、煤储层特征和基本地质模型为实验模拟设置条件、数值模拟边界条件和参数，探索研究了深部无烟煤储层条件下超临界CO2注入煤层体积应力效应和CO2/H2O/煤岩地球化学反应效应，煤储层结构演化、吸附解吸、渗透性变化和流体运移规律，吸附解吸-扩散-渗流-驱替耦合关系及其物理化学过程连续性等关键科学问题。项目研究取得的创新结果集中表现为系统揭示了深部无烟煤储层CO2-ECBM有效性机理，发现深部无烟煤储层CO2可注性变化受控于煤储层特征差异性及其煤岩应力应变（负）效应与地球化学反应（正）效应，CO2注入煤层后的竞争吸附-CO2置换CH4-CH4解吸是深部煤层CO2封存的主要机制，基于储层地质模型和CO2封存机理本构模型建立了CO2封存容量计算评价模型和煤储层流体连续性过程模型；探索建立了深部无烟煤储层CO2-ECBM有效性评价方法体系，研创了模拟CO2/H2O与煤岩地球化学反应、模拟CO2-ECBM煤岩应力应变效应等5台实验装置，深部煤层CO2-ECBM实验模拟、流体连续性过程建模与数值模拟等3项技术，建立了深部煤层CO2存储容量计算评价、CO2可注性与CH4增产效果评价预测2个评价方法；评价结果表明沁水盆地CO2-ECBM有效性较好。发表学术论文101篇，其中SCI论文39篇；出版学术专著2部，主编专刊1期；授权国家发明专利7项，授权软件著作权4项。研究结果科学回答了以沁水盆地为代表的深部无烟煤储层CO2-ECBM的有效性问题，为我国实施深部煤层CO2-ECBM工程探索提供了科学依据，发展了CO2-ECBM温室气体减排的关键理论。