摘要
北部湾盆地涠西南凹陷页岩油资源丰富,主要发育基质型、纹层型、夹层型和互层型4种类型。但不同类型页岩油赋存特征和可动性尚不明确,制约了勘探开发进程。基于荧光薄片、激光共聚焦和多温阶热解等实验技术,深入剖析了涠西南凹陷流沙港组二段下层序—流沙港组三段上层序不同类型页岩油微观赋存状态,定量表征了其可动油质量分数和可动油占比,并在此基础上明确了页岩油可动性的主控因素。结果表明:1)页岩油主要有吸附态和游离态2种赋存形式,其中吸附油可动性差,主要富集于有机质残体内;游离油可动性好,主要富集于粒间孔和微裂缝。2)互层型页岩油可动性最好,纹层型次之,基质型和夹层型中等。3)页岩油可动性与有机质成熟度、有机质丰度、储层物性及矿物组成等因素密切相关。在生油窗内,油页岩成熟度越高,可动性越好;当TOC小于4%时,随着TOC增大,可动油质量分数增大,当TOC大于4%时,最大可动油质量分数趋于稳定;泥页岩中薄夹层砂岩甜点越发育,可动油越富集。
There are abundant shale oil resources in Weixi′nan Sag of Beibu Gulf Basin,which can be divided into four types of matrix type,laminar type,interlayer type and interbedded type.However,the occurrence characteristics and mobility of different types of shale oil are still unclear,which restricts the process of exploration and development.Based on the experimental techniques of fluorescence thin section,laser confocal and multi-temperature pyrolysis,the microscopic occurrence states of different types of shale oil from the lower sequence of the second Member to the upper sequence of the third Member of Liushagang Formation in Weixi′nan Sag were analysed,the movable oil mass fraction and proportion of the shale oil were quantitatively characterized,and the main controlling factors of oil mobility were determined.The results show that:(1)The shale oil in Weixi′nan Sag is dominated by adsorbed oil and free oil,of which the adsorbed oil has poor mobility and is mainly concentrated in organic residues.The free oil has good mobility,which is mainly concentrated in intergranular pores and microfractures.(2)Interbedded shale oil has the best mobility,followed by laminar types,with matrix and interlayer types having medium mobility.(3)Shale oil mobility is closely related to the maturity and abundance of organic matter,reservoir physical property and mineral composition.In the oil generation window,the higher the maturity of oil shale,the better the mobility.When TOC is less than 4%,the mass fraction of mobility oil increses with the increase of TOC.When TOC is greater than 4%,the mass fraction of maximum movable oil tends to be stable.The more the thin interbedded sandstone sweet spot developed in shale,the more the movable oil is enriched.
作者
胡德胜
游君君
孙文钊
白楠
周刚
HU Desheng;YOU Junjun;SUN Wenzhao;BAI Nan;ZHOU Gang(Zhanjiang Branch of CNOOC Ltd.,Zhanjiang 524057,China)
出处
《断块油气田》
CAS
CSCD
北大核心
2024年第1期26-33,共8页
Fault-Block Oil & Gas Field
基金
国家重点研发计划项目“中国东部非生物气富集与成藏机理”(2019YFA0708504)。
关键词
页岩油
赋存特征
可动性
流沙港组
涠西南凹陷
shale oil
occurrence characteristics
mobility
Liushagang Formation
Weixi′nan Sag
