松辽盆地北部嫩江组中-低成熟页岩油地质特征及勘探突破

Geological characteristics and exploration breakthroughs of the middle to low mature shale oil of Nenjiang Formation in northern Songliao Basin

松辽盆地嫩江组发育陆相湖盆页岩,其分布面积广,烃源岩品质好,页岩油潜在资源规模大。以往的研究主要关注青山口组中-高成熟页岩储层,对于嫩江组的中-低成熟度典型湖相页岩鲜有涉及。基于全岩矿物分析、有机地球化学分析、场发射扫描电镜分析和氮气吸附实验等测试资料,结合区域构造背景和沉积特征,对嫩江组页岩的分布和烃源岩特征、含油性、储集性进行综合分析,揭示了嫩江组页岩油的地质特征及资源潜力。研究结果表明:嫩江组一段和嫩江组二段广泛发育页岩,其厚度大且分布稳定;嫩江组在纵向上发育3套有机质含量高的页岩层段,其有机质类型以Ⅰ型和Ⅱ1型为主,有机质演化程度主体处于中等成熟-低成熟阶段;页岩以发育粒间孔、粒内孔和黄铁矿晶间孔等多类型纳米级储集空间为主,孔径主要分布在64~128 nm;嫩江组温暖湿润的古环境奠定了页岩有机质发育的物质基础,同时优质的烃源岩与多类型纳米级储集空间的耦合共同制约了页岩油的富集。综合评价表明:纵向上,嫩江组二段为最优质的“甜点层”,嫩江组一段的中部次之;初步估算嫩江组的石油资源量超过100×10^(8)t。2021年,大庆油田有限责任公司在嫩江组部署了NY1H井,累积产油量为2160 t,实现了嫩江组中-低成熟页岩油在初期相对高产阶段的稳产,证实了嫩江组具备良好的页岩油资源基础和动用潜力。

The continental lacustrine shale is developed in Nenjiang Formation of Songliao Basin,and characterized with wide distribu-tion area,good quality of source rocks and large-scale potential shale oil resources.Previous studies mainly focused on the medium-high mature shale reservoirs of Qingshankou Formation,and rare attention is paid on the medium-low mature lacustrine shale in Nen-jiang Formation.Based on whole-rock mineral analysis,organic geochemical analysis,as well as test data of field emission scanning electron microscopy and nitrogen adsorption,in combination with the regional tectonic background and sedimentary characteristics,the paper comprehensively analyzes the distribution of shale and the characteristics of source rocks,shale oil content and reservoir property of Nenjiang Formation,and discovers the geological characteristics and resource potential of shale oil in Nenjiang Forma-tion.The results show that the shale is widely developed in Member 1 and 2 of Nenjiang Formation,with large thickness and stable distribution.Vertically,there are three sets of shale reservoirs with high organic matter in Nenjiang Formation,dominated by the organic matter of Type I and Il,in the medium-low mature stage.The nano-scale reservoir space of shale is dominated by intergranu-lar pores,intragranular pores and pyrite intercrystalline pores,and the pore size is mainly distributed in the range of 64 nm to 128 nm.The paleoenvironment provides a material basis for the development of organic matter,and the enrichment of shale oil is jointly controlled by the coupling of high quality source rocks and multi-type nano-level reservoir space.The comprehensive evaluation shows that the best sweet spots are developed in Member 2 of Nenjiang Formation,followed by the middle section of Member 1 of Nenjiang Formation.The oil resources are preliminarily estimated to be more than 100×10^(8)t.Well NY1H in Nenjiang Formation was deployed and drilled in 2021 by Daqing Oilfield Company Limited,with a cumulative oil production of 2160 t,achieving stable production of medium-low mature shale oil in Nenjiang Formation,which confirmed that Nenjiang Formation has a good resource base of shale oil and utilization potential.