坳陷湖盆斜坡区深水重力流水道地震响应及沉积特征——以松辽盆地LHP地区嫩江组一段为例  

Seismic reflection and sedimentary characteristics of deep-water gravity flow channels on the slope of lacustrine depression basin:First member of Nenjiang Formation in LHP area,Songliao Basin

作　　者：刘化清[1] 冯明[1] 郭精义[1] 潘树新[1] 李海亮[1] 洪忠[1] 梁苏娟[1] 刘彩燕[1] 徐云泽[1] LIU Huaqing;FENG Ming;GUO Jingyi;PAN Shuxin;LI Hailiang;HONG Zhong;LIANG Sujuan;LIU Caiyan;XU Yunze(PetroChina Research Institute of Petroleum Exploration&Development-Northwest,Lanzhou 730020,China)

机构地区：[1]中国石油勘探开发研究院西北分院,兰州730020

出　　处：《岩性油气藏》2021年第3期1-12,共12页Lithologic Reservoirs

基　　金：国家重大科技专项“岩性地层油气藏成藏规律、关键技术及目标评价”(编号:2017ZX05001-003)资助。

摘　　要：松辽盆地湖盆深水区重力流沉积广泛发育,由于资料分辨率低的限制,以往对其时空演化、内部结构方面的认识不清。基于高精度三维地震资料,利用90°相位转换、地层切片、光照显示等技术,研究了LHP地区下白垩统嫩一段湖盆深水斜坡上发育的重力流水道的地震特征以及水道的内部结构。结果表明:①嫩一段沉积时期,本区坡降为0.5‰~1.0‰,发育早、晚2套共9条迥然不同的水道系统。早期水道E—I处于整个重力流水道系统的下游近末端,为非限制性水道,宽度小于40 m,广泛发育决口分流水道,对下伏早期沉积侵蚀弱。晚期水道A—D处于重力流水道系统的中段,为限制性水道,其宽度为50~370 m,在曲流环发育部位宽度可达500 m,这类水道的下切深度可达20 m,剖面形态为U或V型,局部发育2~5 m高的天然堤。发育早、晚2套不同的水道系统可能与构造持续沉降导致盆地斜坡区的坡降变化有关。②坡降与水道曲率、深度与宽度之间均呈良好的正相关关系。③水道中细砂岩、粉砂岩包裹在优质烃源岩当中,具有形成岩性油气藏的良好条件,是今后重要的勘探领域。Multiple deep-water slope channels have been observed within the lacustrine Songliao Basin,northeastern China.To understandthe spatial-temporal evolution and internal structures of these channels,techniques including 90°phase rotation,stratal slicing,opacity stacks and illumination were used to study the seismic characteristics and internal structure of gravity flow channels developed on the deep-water slope of lacustrine basin of Lower Cretaceous Nen 1 member in LHP area.The results show that:①Nine channels within the 50 km2 LHP area were developed in Nen 1 member of the Late Cretaceous Nenjiang Formation.The depositional setting was a sublacustrine slope characterized by a gradient of 0.5‰-1.0‰.②Based on morphology,the channels were grouped into two channel systems based on size and degree of associated erosion:small meandering channels characterized by sinuosity of 1.03-1.17,which developed early and were commonly less than 40 m wide.Erosional confinement was minimal and distal avulsions were common.These channels can be described as relatively unconfined,lying down-slope of large gravity-flow systems.③Larger meandering channels with sinuosity of 1.04-1.45 and widths up to 500 m,were characterized by greater erosion with maximum erosional valley relief of 20 m.These channels were sufficiently large so that cross profiles could be evaluated,revealing U/V shaped section morphology.Avulsions were uncommon and levees were observed locally.These channels likely lie within the central part of associated gravity-flow systems.(4)Morphological statistics suggest that channel slope and sinuosity,depth and width are positively correlated.(5)Well data from neighboring area indicate that the channel fills were characterized by predominantly silt/fine sandstones with thickness of 10-20 m.These reservoir-prone deposits were bracketed in good quality source rocks making them favorable hydrocarbon exploration targets.(6)The Late Cretaceous global anoxic event possibly caused the abnormal climate(frequent flooding ev

关 键 词：湖盆深水斜坡 重力流水道 地震沉积学 地震地貌学 水道结构参数 嫩江组 松辽盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]