湖相“白烟型”喷流岩——新型的致密油储层类型——以准噶尔盆地西缘乌尔禾地区风城组为例

Lacustrine “white smoke type” exhalative rock——A new type of tight oil reservoir: A case study from Lower Permian Fengcheng Formation in Urho area, western margin of Junggar Basin

下二叠统风城组为准噶尔盆地西缘乌尔禾地区重要的原油产层,储层岩性为云质岩类,具有典型的致密储层性质,为一类成因尚不为人们所熟悉的、但具备巨大油气勘探开发潜力的新型湖相"白烟型"喷流岩。以岩心观察描述、薄片鉴定、扫描电镜观察、X射线衍射和物性分析资料为基础,以热水沉积学理论为指导,探讨了此类致密油储层的成因特征,提出同期火山喷发-湖底热液喷流-"内、外源"碎屑掺合的混合沉积模式,确定储层发育和分布受4种因素控制:1半深湖—深湖环境为湖底喷流岩致密油储层的发育奠定了物质基础;2构造破裂和溶蚀是改善储层物性和在致密油储层中形成"甜点"的主要作用方式;3区域构造格局和断裂构造的继承性活动,控制了喷流岩致密油储层的区域分布,提供了同期火山喷发、热液喷流、成岩期流体溶蚀改造及油气运移成藏的通道;4半深湖—深湖相"白烟型"喷流岩聚集区中具备多期次构造破裂和热液溶蚀作用的叠合部位,是有利的致密油储层"甜点"分布位置,也是致密油藏的预测目标。

As the representative of tight oil reservoir of Lower Permian Fengcheng Formation in Urho area, western margin of Junggar Basin, dolomitized rocks has great potential for oil and gas exploration and development of the ＂whitesmoke type＂ exhalative rock tight oil reservoir. Based on core observation and description, thin section analysis, scanning electron microscope, X ray diffraction and property analysis data, under the guidance of hot water sedimentary theory, this paper discussed the causes of these characteristics of tight oil reservoir, proposed mixed sedimentary model of volcanic eruption-sublacustrine hydrothermal jet flow--＂internal and external sources＂. The development and distribution of reservoir are controlled by four factors： （1）the semi deep lake-deep lake environment laid material foundation for the development of sublacustrine exhalative rock tight oil reservoir; （2）tectonic disruption and dissolution improwd reservoir and the formation of ＂sweets＂ in tight oil reservoir; （3）the regional distribution of exhalative rock light oil reservoir is controlled by regional tectonic framework and tectonic inheritance ac, tivities, provides the volcano hydrothernml fluid, diagenetic dissolution anti alteration and migration of oil and gas accumulation in channel; （4）the semi-deep to deep lacustrine facies ＂white smoke type＂ exhalative rock areas with multi-phase tectonic fracture and thermal dissolution is favorable tight oil reservoir ＂sweets＂ location, but also for the prediction of target of dense reservoir.