致密油/页岩油富集模式及资源潜力——以黄骅坳陷沧东凹陷孔二段为例

Enrichment patterns and resource prospects of tight oil and shale oil:A case study of the second member of Kongdian formation in the Cangdong sag,Huanghua depression

为了进一步明确黄骅坳陷沧东凹陷孔二段致密油和页岩油富集条件及资源潜力,基于铸体薄片、扫描电镜、地化数据及其他资料,利用沉积学、构造地质学和石油地质学的分析方法,阐述并建立孔二段致密油和页岩油的富集条件、控制因素和富集模式,采用小面元法和体积法评价出孔二段致密油和页岩油资源量.研究结果表明:1)黄骅坳陷沧东凹陷古近纪经历坳-断两期盆地叠置,导致沧东凹陷北部构造反转型-南部构造继承型差异构造演化;2)孔二段致密油和页岩油分布在构造反转型、继承型2类斜坡带和次级凹陷内成熟富有机质泥页岩附近,具有明显的"源控"、"储控"和"带控"特点,即成熟富Ⅰ型和Ⅱ型干酪根的泥页岩提供油气来源,致密砂岩和泥页岩储层提供油气储集空间,2类斜坡带、次级凹陷内成熟富有机质泥页岩控制页岩油的空间分布,而致密油分布受控于成熟富有机质泥页岩和构造活动双重因素;3)建立了以致密油和页岩油为核心的"源控"、"储控"和"带控"3种因素约束下的层区带油气富集模式;4)以孔二段层区带油气富集模式为指导,采用小面元法和体积法评价出孔二段致密油资源量为4.2×108 t和页岩油资源量为18.2×108 t.

The paper aims to explicit the enrichment conditions and resource prospects of the second member of Kongdian formation in the Cangdong sag,Huanghua depression.Based on the data analysis of casting thin section,scanning electron microscopy,geochemical and other material,and the analytic procedure of sedimentology,structural geology and petroleum geology,the enrichment conditions,controlling factors and enrichment patterns of tight oil and shale oil in the second member of Kongdian formation were elaborated and established.Then,the inferred resource of the two types of oil were evaluated by facet method and volumetric method.The results show that:1)The Cangdong sag of Huanghua depression experienced depressed-rifted basin superimposition in Paleogene,which leads to the different tectonic evolution of northern section inversion type and southern section succession type.2)The tight oil and shale oil in the second member of Kongdian formation distributed near the mature organic shale in the secondary depression and the slope belts of the structural inversion type and succession type,with obvious characteristics of "source control","reservoir control"and "belt control".Namely,the mature shale rich in Type I and II kerogen provides the source for oil and gas;tight sandstone and shale reservoirs provide the reservoir space for oil and gas;the mature organic shale controls the spatial distribution of shale oil in the two types of slope belts and secondary depression,while the distribution of tight oil is controlled by mature organic shale and tectonic activity.3)The enrichment patterns taking tight oil and shale oil as the core,with constraints of"source control","reservoir control"and"belt control",were established.4)Taking the enrichment patterns of the second member of Kongdian formation as the guidance,according to the facet method and the volumetric method,the tight oil and shale oil resource in the second member of Kongdian formation are 4.2×108 t and 18.2×108 t respectively.