大庆油田古龙页岩油-CO_(2)高压相态及传质规律  

High-pressure phase behavior and mass transfer law of Gulong shale oil and CO_(2)in Daqing oilfield

作　　者：宋兆杰[1] 邓森[2,3] 宋宜磊 刘勇 鲜成钢[1] 张江 韩啸 曹胜[2,3] 付兰清 崔焕琦 Song Zhaojie;Deng Sen;Song Yilei;Liu Yong;Xian Chenggang;Zhang Jiang;Han Xiao;Cao Sheng;Fu Lanqing;Cui Huanqi(Unconventional Petroleum Research Institute,China University of Petroleum,Beijing 102249,China;Exploration and Development Research Institute,Daqing Oilfield Company Limited,Heilongjiang Daqing 163712,China;Heilongjiang Key Laboratory of Reservoir Physics and Fluid Mechanics,Heilongjiang Daqing 163712,China;China University of Petroleum-Beijing at Karamay,Xinjiang Karamay 834000,China)

机构地区：[1]中国石油大学(北京)非常规油气科学技术研究院,北京102249 [2]大庆油田有限责任公司勘探开发研究院,黑龙江大庆163712 [3]黑龙江省油层物理与渗流力学重点实验室,黑龙江大庆163712 [4]中国石油大学(北京)克拉玛依校区,新疆克拉玛依834000

出　　处：《石油学报》2024年第2期390-402,共13页Acta Petrolei Sinica

基　　金：国家自然科学基金项目“页岩油储层纳微米孔喉中油-CO_(2)-水多元体系相行为与流动机制研究”(No.52074319);黑龙江省揭榜挂帅科技攻关项目“古龙页岩油提高采收率关键问题研究”(DQYT-2022-JS-761);中国石油大学(北京)科研基金项目(2462021QNXZ008)资助。

摘　　要：大庆油田古龙页岩油轻质油带分布广泛,具有与CO_(2)形成混相的有利组分、温度和压力条件,注CO_(2)前置压裂和吞吐提高采收率潜力较大,但目前对于古龙页岩油-CO_(2)高压相行为的认识尚不充分。在状态方程和气液两相相平衡理论的基础上,通过与页岩油恒质膨胀实验、细管实验等结果校验,构建了考虑纳米限域效应的古龙页岩油-CO_(2)两相相平衡热力学模型和基于相平衡模型的油气最小混相压力计算方法。以古页2HC井和古页9HC井页岩油为研究对象,阐明了成熟度、油/CO_(2)比例、压力、纳米限域效应等因素影响的页岩油-CO_(2)相间传质规律。研究结果表明,随着CO_(2)摩尔分数的增加,古页2HC井和古页9HC井页岩油的饱和压力逐渐降低。在储层温度和压力条件下,古页2HC井和古页9HC井页岩油能够与CO_(2)混相。在相同的CO_(2)注入量条件下,古页2HC井页岩油的分子量和黏度更高,降幅也更大,饱和压力和膨胀系数更小,变化幅度也更小。注CO_(2)多级接触过程显示,CO_(2)在古页2HC井和古页9HC井页岩油中的溶解能力和抽提效果较为接近。在充分接触后,古页2HC井和古页9HC井注气后缘油相中C_(1)—C_(6)组分全部被抽提到气相中,油相中CO_(2)的摩尔分数分别攀升至86.63%和87.35%。纳米限域效应的存在,减小了纳米孔内油气间组成差异,导致了界面张力和最小混相压力的降低,有利于CO_(2)与页岩油相溶、混相。纳米限域效应对古页2HC井和古页9HC井页岩油的影响无明显差异,当孔隙半径由100 nm降低到10 nm时,古页2HC井和古页9HC井页岩油与CO_(2)的最小混相压力分别降低20.90%和21.31%。通过明确页岩油藏流体相态变化规律,可为注CO_(2)开发优化设计提供理论指导。The light oil from Gulong shale is widely distributed,with favorable components and temperature-pressure conditions for miscibility with CO_(2).Pre-fracturing with CO_(2)injection and huff-and-puff can offer significant potential to enhance oil recovery.However,there is a lack of sufficient understanding of the high-pressure phase behavior of Gulong shale oil.Based on the equation of state and two-phase equilibrium theory,through verifying the results of constant mass expansion experiment and slim tube experiment for shale oil,the paper establishes a thermodynamic oil-CO_(2)two-phase equilibrium model considering the nano-confinement effect,and also a calculation method for the minimum miscibility pressure based on the two-phase equilibrium model.This paper is a case study of Gulong shale oils in Well Guye 2HC and Well Guye 9HC,and elucidates the interphase mass transfer behavior of Gulong shale oil and CO_(2),which is influenced by the factors such as maturity,oil/CO_(2)ratio,pressure,and nano-confinement effect.The results show that with an increase in CO_(2)mole fraction,the saturation pressure of Well Guye 2HC and Well Guye 9HC shale oils gradually decreases.Under reservoir temperature and pressure conditions,both Well Guye 2HC and Well Guye 9HC shale oils can be miscible with CO_(2).Under the same amount of CO_(2)injection,Well Guye 2HC shale oil exhibits a higher molecular weight and viscosity with a greater drop,and a lower saturation pressure and expansion coefficient with a smaller variation than Well Guye 9HC shale oil.The multilevel contact process of CO_(2)injection shows that the dissolution capacity and extraction effect of CO_(2)are similar in both Well Guye 2HC and Well Guye 9HC shale oils.After sufficient contact,C_(1)-C_(6)components in the oil phase of Well Guye 2HC and Well Guye 9HC shale oils at the far end opposite to injection gas front are all extracted into the gas phase,and the mole fractions of CO_(2)in the oil phase increase to 86.63%and 87.35%,respectively.The presence of nano-confine

关 键 词：古龙页岩油 注CO_(2)提高采收率 油气相态 最小混相压力 纳米限域效应 

分 类 号：TE311[石油与天然气工程—油气田开发工程]