细粒沉积中内源组分的类型、分布及页岩油气甜点意义

Types and distributions of endogenetic components in fine-grained sediments and their implications for the evaluation of shale oil and gas sweet spots

施振生 周天琪 汪鹏飞

Zhensheng SHI Tianqi ZHOU Pengfei WANG

页岩油气高效勘探开发依赖于甜点分布的精准预测，细粒沉积中内源组分的时-空分异与耦合效应对甜点分布具有关键控制作用。通过国内外典型含油气页岩的深入分析，系统揭示了细粒沉积中内源组分的类型、分布及其对页岩油气甜点的控制机理。结果表明：① 细粒沉积中内源组分有生源硅、生源碳酸盐矿物、生源磷酸盐矿物、内源有机质和盆内颗粒，主要富集于陆源碎屑过路区、陆源碎屑难到达区、上升洋流发育区和近滨快速海侵区4个区域。② 内源组分中生源硅溶解再沉淀形成的自生石英通过氢键抑制有机质降解，生源碳酸盐矿物和磷酸盐矿物通过胶结降低孔隙水渗流速率来维持还原环境，从而有利于有机质的富集。③ 富内源组分页岩中生源硅与有机质协同成孔、生缝，产生独特的有机孔-微裂缝网络耦合结构。生源硅骨架提供刚性支撑与孔隙网络，有机质热演化产生膨胀应力与溶蚀作用共同驱动三维微裂缝网络的发育。④ 内源组分通过影响有机质富集、孔隙结构、气体吸附、渗流特征以及岩石脆性，来决定页岩油气甜点的分布。页岩油气的甜点一般具有高生源硅含量、高总有机碳含量、多纳米级孔隙及微裂缝和高脆性矿物含量的特征。目前，细粒沉积中内源组分的成因和富集机制、内源组分与储层物性和脆性指数的定量关系以及成岩过程中内源组分对有机质保存与孔隙演化的动态调控机制等方面的研究还需进一步深入。未来，需要进一步通过多尺度表征、人工智能和多学科融合等手段来识别和分析内源组分，从而为页岩油气高效开发提供支撑。

Efficient exploration and exploitation of shale oil and gas depend heavily on the accurate prediction of hydrocarbon sweet spot distribution. Meanwhile， the spatiotemporal differentiation and coupling of endogenetic components in fine-grained sediments produce a key effect on sweet spot distribution. Through an in-depth analysis of typical oil and gas-bearing shales both at home and abroad， we systematically reveal the types and distribution patterns of endogenetic components in fine-grained sediment， as well as the mechanisms by which these components control shale oil and gas sweet spots. The results indicate that the major endogenetic components include biogenic silica， biogenic carbonate minerals， biogenic phosphate minerals， authigenic organic matter， and intraclasts. These components are primarily concentrated in zones that terrigenous clastics pass by， zones that are difficult to reach for terrigenous clastics， areas influenced by upwelling ocean currents， and nearshore areas experiencing rapid transgression. The dissolution-reprecipitation process of biogenic silica， among others， leads to the formation of authigenic quartz， which inhibits organic matter degradation through hydrogen bonding. While the biogenic carbonate and phosphate mineral cementation maintains reducing environments by decreasing pore water mobility. All these are conducive to organic matter enrichment. The biogenic silica in endogenetic component-rich shales， through its synergy with organic matter， contributes to the development of pores and fractures， which in turn leads to the formation of a distinctive organic pore-microfracture coupling structure. Furthermore， the rigid support and pore networks provided by the biogenic silica frameworks provide， along with swelling stress and dissolution induced by the thermal evolution of organic matter， collectively drive the formation of a three-dimensional microfracture system. Endogenetic components play a determinant role in the distribution of shale oil and gas sweet spots by influencing organic matter enrichment， pore structure， gas adsorption， seepage characteristics， and rock brittleness. Accordingly， shale oil and gas sweet spots generally feature high endogenetic component content， elevated nano-scale porosity， abundant microfractures， and high brittle mineral content. Presently， there is a need for further investigation into the genesis and enrichment mechanisms of endogenetic components in fine-grained sediments， as well as the quantitative relationships of these components with the physical properties and brittleness index of reservoirs. Moreover， the mechanisms underlying the dynamic controlling effects of the endogenetic components on organic matter preservation and pore evolution during diagenesis warrant further exploration. In the future， it is necessary to further identify and analyze the endogenetic components using methods such as multi-scale characterization， artificial intelligence （AI）， and interdisciplinary integration， with a view to supporting the efficient exploitation of shale oil and gas.

10.11743/ogg20250305