气田采出水回注协同二氧化碳地质封存分析

Discussion on Coordination of Gas Field Produced Water Reinjection and Carbon Dioxide Geological Storage

天然气上产与CO_(2)减排是我国实现“双碳”目标的重要战略举措,与之密切相关的气田采出水回注与CO_(2)地质封存已成为能源环境领域的热点话题.目前,地下水环境保护政策趋紧,气田采出水地下回注一定程度受限,CO_(2)地质封存规模化发展缓慢,二者均需探寻新的实施路径和效益路径.本文系统分析了气田采出水回注与CO_(2)地质封存在场地选址、建井与注入、运行监控与环境监测以及流-固相互作用与运移影响等方面的异同.结果表明:①储层可注性与盖层封闭性均为二者选址的核心,井筒完整性与材质同是保护地下水的关键,过程控制与风险监测均为保障工程长期安全的重要手段,流-固相互作用与地层响应及流体时空分布均是两类工程的关键科学问题.②CO_(2)强化卤水/咸水资源开采协同气田采出水回注、CO_(2)强化天然气开采协同气田采出水回注是实现二者协同的潜在效益路径.研究显示,气田采出水回注协同CO_(2)地质封存,在充分利用地层空间、注入井及监测等基础设施的同时,能提升采出水回注能力,促进CO_(2)矿化封存,是推进减污降碳协同、实现环境效益与气候效益及经济效益多赢的潜在重要途径.

Natural gas production and CO_(2)emission reduction are important strategic measures to achieve the dual carbon goals in China.The gas field produced water reinjection and CO_(2)geological sequestration have become hot topics in the field of energy and environmental protection.At present,groundwater environmental protection policies are becoming increasingly strict,the gas field produced water reinjection is limited to a certain extent,and large-scale development of carbon dioxide geological storage is slow.Both limitations need to explore new implemental beneficial paths.This study systematically analyzed the similarities and differences between gas field produced water reinjection and CO_(2)geological storage in terms of site selection,well construction and injection,operation monitoring and environmental monitoring,fluid reaction and migration,etc.The results shown that:(1)Reservoir injectability and caprock sealing are the core concerns in site selection.Wellbore integrity and material quality are the keys to protect groundwater resources.Process control and risk monitoring are important means to ensure long-term safety.Fluid-solid interaction,formation response,and fluid spatiotemporal distribution are key scientific issues.(2)CO_(2)enhanced water recovery and gas field produced water reinjection,CO_(2)enhanced gas recovery and gas field produced water reinjection are the potential economical methods to achieve coordination of gas field produced water reinjection and CO_(2)geological storage.The research show that gas field produced water reinjection with CO_(2)geological storage can improve the reinjection capacity of produced water,promote the mineralization and storage of CO_(2),and reuse the infrastructure including formation space,injection wells,and monitoring.It is a potential method to promote the coordination of pollution and CO_(2)emission reductions,and to achieve environmental,climate and economic benefits at the same time.