页岩油岩心样品洗油实验效率对比分析  

Comparison of Washing Oil Experiment of Core Samples from Shale Oil Reservoir

作　　者：王志昊 赵建华 蒲秀刚[3] 刘可禹 李俊乾 程斌 WANG Zhihao;ZHAO Jianhua;PU Xiugang;LIU Keyu;LI Junqian;CHENG Bin(Shandong Provincial Key Laboratory of Deep Oil and Gas,Qingdao,Shandong 266580,China;School of Geosciences,China University of Petroleum(East China),Qingdao,Shandong 266580,China;Exploration and Development Research Institute,Dagang Oilfield Company,PetroChina,Tianjin 300280,China)

机构地区：[1]山东省深层油气重点实验室,山东青岛266580 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]中国石油大港油田公司勘探开发研究院,天津300280

出　　处：《现代地质》2022年第5期1304-1312,共9页Geoscience

摘　　要：页岩储层中的裂缝和微纳米级孔隙是页岩油的主要赋存空间。岩心样品高效无损洗油是页岩孔隙结构表征和页岩油赋存研究的关键,但是目前的实验方案并不统一。通过调研总结常用的洗油方法,针对现行广泛使用的浸泡抽提法、快速萃取法以及气驱+索氏抽提法对大港油田沧东凹陷孔二段页岩(块样,1 cm×1 cm×1 cm)进行洗油测试,利用Rock-Eval热解仪和气相色谱仪对洗油前后的样品以及萃取出的可溶有机质进行了实验效果对比和三种方法之间的优劣性分析。研究结果表明,随着实验时间的延长萃取物中重烃含量逐渐增加,且低孔低渗的页岩岩心在常温常压下难以达到理想的洗油效果。升温和增压可以提高洗油效率,但长时间的高温作用会使部分重烃和吸附组分裂解,当裂解的速度大于轻烃组分被萃取的速度时,S_(1)值会出现随着洗油时间上升的现象;合适的压力条件可以有效促进洗油速率,但如果条件控制不好会造成样品破碎或者内部孔隙被破坏。建议在洗油过程中采用较低的压力、常温或者稍微加温以加快实验速度,驱替法和抽提法结合会有更好的效果。Fractures and micro-/nano-scale pores in shale reservoirs are the main occurrence space of shale oil.Efficient and non-destructive washing oil of core samples is the key to the characterization of shale pore structure and shale oil occurrence,yet there is no unified scheme currently.In this study,we investigated and summarized the common“washing oil”schemes,and selected Soxhlet extraction,rapid extraction and gas flooding+Soxhlet extraction to compare their effects on shale block samples(1 cm×1 cm×1 cm)from the Kongdian Formation(Ek_(2),2^(nd) member)in the Cangdong depression.Rock-eval pyrolysis instrument and gas chromatograph were used to compare the experimental results and the pros and cons of the three methods,by analyzing the samples before and after washing oil and the extracted soluble organic matter.The results show that the heavy hydrocarbon components in the extract increase gradually with time.It is difficult for low-porosity/-permeability shale cores to achieve ideal washing oil effect under room temperature and pressure.Heating and pressurization can improve experimental efficiency,but heavy hydrocarbons and adsorbed components would partially break down into light hydrocarbons due to prolonged high temperatures,and the S_(1) value would rise when the rate of decomposition is higher than that of extraction.Appropriate pressure conditions can effectively promote the washing oil rate,but the samples or its pore structures may be destroyed under the unstable pressure.We suggested to use lower pressure,room temperature or slightly higher temperature in washing oil to speed up the process,which would produce better results when combining the displacement and extraction methods.

关 键 词：页岩 孔隙 岩心洗油 索氏抽提 洗油效率 

分 类 号：P618.1[天文地球—矿床学] TE34[天文地球—地质学]