苏北盆地溱潼凹陷古近系阜宁组二段页岩油富集高产主控因素与勘探重大突破

Main controlling factors for the enrichment of shale oil and significant discovery in second member of Paleogene Funing Formation,Qintong Sag,Subei Basin

在对苏北盆地溱潼凹陷古近系阜宁组二段泥页岩生烃特征、含油性、储集性研究的基础上,剖析页岩油富集的主控因素。溱潼凹陷阜二段泥页岩厚度大、有机碳含量(TOC)中等,具备页岩油富集的物质基础。深凹带阜二段泥页岩镜质体反射率(R_(o))为0.9%~1.0%,热演化程度适中,页岩油具有轻烃和气测全烃值高、流动性好的特点;断层不发育,保存条件好,地层压力高,有利于富集高产;脆性矿物含量较高,纹层和天然裂缝发育,可压性好。连续性大面积分布的优质泥页岩是油气富集的基础,保存条件是成藏的关键,热演化程度是含油性的决定因素,异常高压、纹层发育和较高脆性矿物是高产的重要因素。沙垛地区SD1井阜二段页岩油具有低TOC(1%)、低气油比(40~80 m^(3)/t)、高异常压力(1.25 MPa)的特征,该井的成功开发,降低了陆相页岩油评价标准的门限,拓展了页岩油的发展空间。

Based on the study of hydrocarbon generation features,oil bearing property and reservoir property of shale in the second member of Paleogene Funing Formation in the Qintong Sag of the Subei Basin,the main controlling factors of shale oil enrichment were analyzed.Shale of the second member of Funing Formation in the Qintong Sag was featured by large-scale thickness and medium TOC content,which provided a material basis for shale oil enrichment.The vitrinite reflectance(%R_(o))of shale in the second member of Funing Formation in the deep sag distributed between 0.9%-1.0%,indicating a moderate thermal evolution degree.Shale oil has the characteristics of light hydro-carbon,high gas-measured total hydrocarbon value and good fluidity.Few faults were developed,resulting in good preservation conditions and high formation pressure,which were conducive to hydrocarbon enrichment.High content of brittle minerals and well-developed lamella and natural fractures made formation fracturing easier.The continuous and large-area distribution of high-quality shale is the basis for oil and gas abundance.Preservation condition is the key factor to reservoir formation.The degree of evolution is a decisive factor of oil-bearing.High pressure,lamina development and high brittle mineral content are important factors for high yield.The shale oil in second member of Funing Formation in Shaduo area has the characteristics of low TOC content(1%),low gas oil ratio(40-80 m^(3)/t)and high pressure(1.25 MPa).The success of this well has reduced the shale oil evaluation standard and threshold,and expanded the development space of shale oil.