新疆油页岩升温过程中孔隙结构演化特征  

Study on the Evolution of Pore Structure Characteristics of Xinjiang Oil Shale During the Heating Progress

作　　者：张文[1] 蓝升 马文良 王佳 Zhang Wen;Lan Sheng;Ma Wenliang;Wang Jia(College of Construction Engineering,Jilin University,Changchun 130026,China)

机构地区：[1]吉林大学建设工程学院,长春130026

出　　处：《吉林大学学报(地球科学版)》2023年第6期1689-1705,共17页Journal of Jilin University:Earth Science Edition

基　　金：国家重点研发计划项目(2019YFA0705504);国家自然科学基金优秀青年科学基金项目(42022053)。

摘　　要：孔隙结构是油页岩描述的重要特征,直接影响页岩油气的储存和运移。因此,研究孔隙结构演化对指导油页岩原位开采具有重要意义。本文以新疆巴里坤油页岩为研究对象,利用热重(TG)、低温氮气吸附(LTNA)与压汞(MIP)等试验,结合LTNA-MIP联合精确表征方法,揭示巴里坤油页岩热解失质量规律及升温过程中孔隙发育特征,并对孔隙结构演化过程和机理进行研究。结果表明:新疆油页岩热重可分为低温缓慢失质量阶段(20~360℃)、中温快速失质量阶段(360~500℃)和高温缓慢失质量阶段(500~600℃),由于该油页岩具有低挥发分、高含油率、高灰分的特点,中、高温阶段是主要的失质量阶段;巴里坤油页岩内部孔隙类型复杂,升温过程中,微、小孔由狭缝形演变为导管状,中、大孔始终以墨水瓶状为主。墨水瓶状孔隙在300~400℃和500~600℃这2个温度区间集中发育,有效孔隙则在400~500℃大量发育。低温段以原生大孔为主,在自由水蒸汽压、矿物热膨胀和沥青质软化共同影响下,孔隙结构变化较小;中温段有机质集中热解,产生扩孔效应,单位孔隙体积大幅增加,孔隙类型以中孔为主;高温段黏土矿物失水、石英相变产生膨胀压力,大孔、中孔进一步扩展。Pore structure is an important feature of oil shale,which directly affects the storage and transport of shale oil and gas.Therefore,studying the evolution of pore structure is of great significance to guide the in-situ exploitation of oil shale.In this paper,taking Balikun oil shale as the research object,based on thermogravimetric(TG),low-temperature nitrogen adsorption(LTNA)and mercury intrusion porosimetry(MIP)tests,combined with LTNA-MIP joint accurate characterization methods,to reveal the law of pyrolysis weight loss and pore development characteristics of Balikun oil shale during heating,and study the evolution process and mechanism of pore structure.The results show that the thermal weight of Xinjiang oil shale can be divided into low temperature slow weight loss section(20-360℃),medium temperature rapid weight loss section(360-500℃),and high temperature slow weight loss section(500-600℃).The internal pore types of Balikun oil shale are complex,and during the heating process,the micro and small pores evolve from slit type to conduit shape.The medium and large holes are always mainly inkbottle-shaped.The inkbottle-shaped pores developed intensively in the two temperature ranges of 300-400℃and 500-600℃,and the effective pores developed in large quantities at 400-500℃.Native macropores dominated the low-temperature section,and the pore structure changed little under the combined influence of free water vapor pressure,mineral thermal expansion,and asphaltene softening.The concentrated pyrolysis of organic matter in the middle temperature section produces a pore expansion effect,the pore volume is significantly increased,and the pore type is mainly mesoporous.The expansion pressure is generated by the water loss of clay minerals and the phase change of quartz in the high temperature section,and the large pores and middle pores are further expanded.

关 键 词：油页岩 孔隙结构演化 压汞 低温氮气吸附 联合表征 新疆 

分 类 号：P618.12[天文地球—矿床学] TU45[天文地球—地质学]