关井阶段CO_(2)作储气库垫层气的动态影响规律  

Dynamic influence law of CO_(2) used as cushion gas in gas storage during shut-in period

作　　者：曹洪源 柏明星[1,2] 杜思宇 张志超[1,2] 刘业新 CAO Hongyuan;BAI Mingxing;DU Siyu;ZHANG Zhichao;LIU Yexin(College of Petroleum Engineering,Northeast Petroleum University,Daqing,Heilongjiang,China;Key Laboratory of Enhanced Oil Recovery(Northeast Petroleum University),Ministry of Education,Northeast Petroleum University,Daqing,Heilongjiang,China)

机构地区：[1]东北石油大学石油工程学院 [2]东北石油大学提高采收率教育部重点实验室

出　　处：《石油与天然气化工》2024年第3期37-42,共6页Chemical engineering of oil & gas

基　　金：国家自然科学基金“枯竭油藏型储气库二氧化碳作垫层气机理及注采动态规律研究”(52174020);国家重点研发计划“二氧化碳提高油藏采收率与地质封存一体化关键技术及应用示范”(2022YFE0206700)。

摘　　要：目的为应对地下储气库中的垫层气损失,采用经济气体CO_(2)作为垫层气,目前,CO_(2)作垫层气在实际应用中存在各种条件限制,且对其在关井阶段的应用研究较少,有必要对在关井阶段CO_(2)作垫层气对天然气储气库的运行影响因素进行研究。方法利用有限元模拟CO_(2)作储气库垫层气时,研究关井阶段储气库动态参数(注气压力、注气速率和CO_(2)垫层气比例)对混气带的影响规律。结果注气压力对混气带的影响不大,将其控制在12 MPa左右最为合理,此时混气带占储气面积的比例为23.7315%;混气带面积占比随注气速率的增大而减小,但是在注气口附近会出现混合区域,导致回采天然气时出现大量的混合气体,所以注气速率控制在0.7×10^(8) m^(3)/d时最为合理,这时混气带面积占比为18.3246%;CO_(2)作垫层气的比例对天然气-CO_(2)之间的混合影响明显,当CO_(2)垫层气比例为20%时,混气带面积占比为7.2365%。结论根据实验结果设计针对混气带的控制措施,当注气压力控制为12 MPa时,注气速率为0.7×10^(8) m^(3)/d,当CO_(2)垫层气比例为20%时,能让储气库的运作更为经济,实验结果可为实际储气库的建设提供参考。Objective In order to deal with the loss of cushion gas in underground gas storage,CO_(2),an economical gas,is used as cushion gas.There are various restrictions in applying CO_(2) as cushion gas,and few studies on its application have been conducted during the shut-in period.Therefore,it is necessary to study the influencing factors of CO_(2) as cushion gas during the shut-in period in the operation of natural gas storage.Methods The influence of dynamic parameters of the gas reservoir(gas injection pressure,gas injection rate and CO_(2) cushion gas ratio)on the gas mixing zone is studied when CO_(2) is used as cushion gas by finite element simulation.Results The results show that the injection pressure has little effect on the mixing zone during the shut-in period.The injection pressure is controlled at about 12 MPa,which is the most reasonable,and the proportion of gas mixing zone in the gas storage area is 23.7315%.The proportion of the mixing zone decreases with the increase in gas injection rate,but the mixing zone near the gas injection port leads to a large amount of mixed gas when recovering natural gas.Therefore,it is reasonable to control the gas injection rate at 70×10^(6) m^(3)/d,and the proportion of mixing zone is 18.3246%.CO_(2) cushion gas ratio has an obvious effect on the mixing between natural gas and CO_(2).When the CO_(2) cushion gas ratio is 20%,the proportion of the gas mixing zone is 7.2365%.Conclusions According to the experimental results,the control measures for the gas mixing zone are designed.When the injection pressure is controlled to 12 MPa,the gas injection rate is 70×10^(6) m^(3)/d,and the CO_(2) cushion gas ratio is 20%,the operation of the gas storage can be more efficient,and the reference can be provided for the actual construction of the gas storage.

关 键 词：地下储气库 CO_(2) 关井阶段 注气压力 注气速率 垫层气比例 混气带占比 

分 类 号：TE972[石油与天然气工程—石油机械设备]