摘要
为了研究表面活性剂对页岩储层渗吸驱油效果及影响渗吸效果的主控因素,以苏北某油田页岩储层的岩心为研究对象,利用TOC分析、电镜扫描技术表征了岩心孔隙结构特征,利用核磁共振技术开展了多因素影响下的渗吸实验,评价了润湿性、裂缝、孔隙度、渗透率、表面活性剂浓度及类型等因素对页岩储层渗吸效率的影响,明确了渗吸过程中不同孔隙内原油分布特征及动用情况。结果表明:页岩渗吸分为前期、中期和后期3个阶段,前期渗吸速度大,渗吸效率迅速上升,中期时间占比最长,后期渗吸速度缓慢,渗吸效率趋于稳定;对比不同因素对渗吸的影响,岩心越水湿、裂缝越多,渗吸速度越大,渗吸效率越高;孔隙度越大、渗透率越小,渗吸效率越高;随表面活性剂浓度降低,渗吸效率呈上升趋势。核磁共振实验结果表明,页岩渗吸过程中,微小孔隙的原油动用情况大于大孔隙,改变渗吸条件可提高各类孔隙动用效率。
Cores from shale reservoirs in Subei Oilfield were taken as sample to study the effects of surfactants on the oil displacement efficiency and the main controlling factors of imbibition in shale reservoirs.The TOC analysis and scanning microscope technique(SEM)were used to characterize the pore structure of the core samples.Imbibition experiments under the influence of multiple factors were conducted using nuclear magnetic resonance(NMR)technology.Then the effects of factors were evaluated such as wettability,fractures,porosities,permeability,surfactant concentrations,and types on the imbibition efficiency of shale oil reservoirs,and the distribution characteristics and producing conditions of the oil in different pores were clarified during the imbibition process.The results showed that shale imbibition could be divided into three stages:early stage,middle stage,and late stage.The imbibition rate was high in the early stage,and the imbibition efficiency increased rapidly.The middle stage accounted for the longest period,and the imbibition rate slowed down in the late stage,with the imbibition efficiency tending to be stable.By comparing the effects of different factors on imbibition,it was found that a wetter core indicated more fractures and higher imbibition rate and efficiency.Moreover,a higher porosity and lower permeability led to higher imbibition efficiency.The imbibition efficiency showed an increasing trend with the concentration of surfactants decreasing.The NMR experimental results demonstrated that in the process of shale imbibition,the produced oil of micro-pores was more than that of macro-pores,and changing the imbibition conditions could improve the producing percentage of oil in various pores.
作者
王彪
李太伟
虞建业
戴志鹏
朱杰
WANG Biao;LI Taiwei;YU Jianye;DAI Zhipeng;ZHU Jie(Petroleum Engineering Technology Research Institute of SINOPEC Jiangsu Oilfield Company,Yangzhou City,Jiangsu Province,225009,China)
出处
《油气地质与采收率》
CAS
CSCD
北大核心
2023年第6期92-103,共12页
Petroleum Geology and Recovery Efficiency
