天然气提高采收率理论基础、技术方法与发展方向

Enhanced gas recovery:Theory,technology and prospect

中国大部分主力气田相继进入开发中后期且整体采收率不高,天然气提高采收率研究与实践形势迫切。为了促进天然气提高采收率理论技术进步和开发水平提高,建立了统一、具有普遍适用性的天然气采收率评价模型,分析了影响天然气采收率的关键因素,明确了天然气提高采收率发展前景与方向。研究结果表明:①储量利用程度、压降波及系数和压力衰竭效率是影响天然气采收率的3个关键因素,天然气采收率是3个关键因素对应系数的乘积;②结合安岳气田龙王庙组气藏、克拉2气田、苏里格气田和川南页岩气等开发实践,针对常规水驱气藏、致密气和页岩气等非常规气,通过提高储量利用程度、压降波及系数和压力衰竭效率预计可提高采收率6~15个百分点;③提出了天然气提高采收率理论技术攻关方向,包括明确气藏提高采收率机理、研发提高采收率新方法、加强提高采收率技术现场试验。结论认为,研究结果奠定了天然气提高采收率理论基础,系统形成了不同类型气藏提高采收率技术方法,为已开发气田提高采收率和持续稳产提供了技术支持,并可促进我国天然气产业持续健康快速发展,对保障国家能源安全具有重要指导意义。

Research on the enhanced gas recovery(EGR)technology is urgently needed in most of China’s major gas fields due to low recovery in their late development stages.To promote progress in ERG theory and technology,this paper establishes a unified and universal model for gas recovery evaluation,analyzes the key factors affecting the gas recovery,and expects the prospect of EGR.The results are obtained as follows.First,the production degree of reserves,pressure drawdown sweep efficiency and pressure depletion efficiency are key factors affecting the gas recovery,which is the product of the coefficients corresponding to these factors.Second,according to the development practice of Anyue Longwangmiao gas reservoir,Kela 2 gas field,Sulige gas field and Southern Sichuan shale gas,it is estimated that the recovery of conventional water-driven gas reservoirs and unconventional gas reservoirs(incl.tight gas and shale gas)can be improved by 6–15 percentage points by increasing the production degree of reserves,the pressure drawdown sweep efficiency and pressure depletion efficiency.Third,it is proposed that clarifying the EGR mechanism,developing new EGR methods,and promoting the field test of EGR technologies are directions for theoretical and technical researches.The study results provide a theoretical foundation for EGR.The EGR methodologies for different types of gas reservoirs provide technical support for improving gas recovery and stable production of existing gas fields,promote healthy and rapid development of natural gas industry in China and provide guidance for guaranteeing national energy security.