摘要
济阳坳陷低演化页岩油资源潜力巨大,是继中高成熟页岩油成功突破后的重要领域之一。为了明确低演化陆相页岩孔缝特征及对页岩油赋存的意义,以济阳坳陷外围青南洼陷沙河街组沙三下-沙四上纯上亚段为例,综合运用薄片观察、有机碳测试、X射线衍射(XRD)分析、溶剂抽提、低温N 2吸附、高压压汞、扫描电镜、能谱元素等多种技术,在划分页岩岩相基础上,探讨了低演化页岩孔隙类型、大小、分形特征及影响因素,明确了裂缝发育特征,阐明了页岩孔缝对页岩油赋存的重要意义。结果表明:研究区页岩总有机碳质量分数w(TOC)多在1.0%~4.0%,矿物组分以长英质矿物为主,其次为黏土矿物和碳酸盐矿物。孔隙类型以墨水瓶孔、平板狭缝孔为主,包括石英粒间孔、黏土矿物片间孔、白云石晶间孔等,孔径多小于200 nm,呈多峰分布,主要集中在2~50,50~80,100~200 nm。页岩储层发育较多的水平层理缝、高角度缝和网状缝,多被沥青充填或浸染,裂缝有利于页岩油的赋存和运移。富长英质矿物岩相通常比富黏土矿物岩相具有更高的孔体积和比表面积,长英质矿物对孔隙有积极贡献,且随热演化程度的增加,孔体积和比表面积呈先降低后增加的趋势。当镜质体反射率R_(o)>0.6%时,页岩油含量显著增加,主要与有机质开始大量生烃有关。水平层理缝、石英颗粒粒间孔、白云石和方解石晶间孔是页岩油有利的储集和赋存空间。
Low-maturity shale oil has great resource potential in Jiyang Depression and has become an important field after the successful breakthrough of medium-to high-maturity shale oil.[Objective]The purpose of this paper is to clarify the pore and fracture characteristics of low-maturity continental shale and their significance to shale oil occurrence.[Methods]By studying the E s x 3 and E s scs 4 members in Qingnan Depression,Jiyang Depression,this study combines thin section observation,TOC content,XRD analysis,solvent extraction,low-temperature N 2 adsorption,high-pressure mercury injection,scanning electron microscope observation and EDS analysis to classify the shale lithofacies,characterize the pore and fracture development,and illustrate the importance of shale pores and fractures for shale oil occurrence.[Results]The TOC content is mostly in the range of 1.0%-4.0%,and the mineral composition mainly includes felsic minerals,followed by clay and carbonate minerals.The major pore types are ink-bottle-shaped pores and plate-parallel-shaped pores,including quartz intergranular pores,clay mineral interlamellar pores,and dolomite intercrystalline pores.The major pore sizes are mostly less than 200 nm and exhibit a multipeak distribution,which is concentrated in the ranges of 2-50 nm,50-80 nm and 100-200 nm.Horizontal bedding fractures,vertical fractures and network fractures developed in the studied shales and were mostly filled or contacted by bitumen.Felsic-rich shale lithofacies usually have a greater pore volume and specific surface area than clay-rich lithofacies,and felsic minerals positively contribute to pore development.The pore volume and specific surface area first decreased and then increased with increasing thermal maturity.When R_(o)>0.6%,the shale oil content increases significantly,which is mainly related to the large amount of hydrocarbon generation in organic matters.[Conclusion]Horizontal bedding fractures,quartz intergranular pores,and dolomite and calcite intercrystalline pores are favourable storage and occurrence spaces for shale oil.
作者
王伟庆
王学军
李政
王玉环
冯鲁川
李朋波
WANG Weiqing;WANG Xuejun;LI Zheng;WANG Yuhuan;FENG Luchuan;LI Pengbo(Exploration and Development Research Institute,SINOPEC Shengli Oilfield Company,Dongying Shandong 257015,China;SINOPEC Key Laboratory of Shale Oil/Gas Exploration and Production,Dongying Shandong 257015,China;Shandong Provincial Key Laboratory on Exploration and Development for Unconventional Oil and Gas(Preparation),Dongying Shandong 257015,China)
出处
《地质科技通报》
CAS
CSCD
北大核心
2024年第3期94-107,共14页
Bulletin of Geological Science and Technology
基金
中国石油化工股份有限公司项目“济阳坳陷及周缘页岩油资源分级分类评价与优选”(P22083)。
关键词
青南洼陷
沙河街组
低演化页岩
孔缝特征
赋存空间
Qingnan Sag
Shahejie Formation
low-maturity shale
pore and fracture characteristic
occurrence space
