生油阶段湖相泥页岩孔隙演化特征及其与页岩油富集关系

The program aims at pore types and distribution of pore size of low mature to mature shale and their influence factors. The basic geological and geochemical experiments (TOC, pyrolysis, XRD, etc.), high resolution scanning electron microscope (FIB-SEM and ESEM) , Nano-CT and measuring technique for pore size distribution (MICP, LPA of CO2, N2 and SAXS) are used to study on natural evolution shale and artificial mature shale. The experiments results are used to quantitative describe the pore morphology, type, distribution of pore size and their contribution to total pore space. During the research the influence of organic type, maturity, clay type and content on pore characteristics of different pores (micro-pore, meso-pore and macro-pore), types (organic pore, inorganic pore) will be discussed. At last, the pore type plates, evolution patterns of mudrock during the oil generation stage will be established, the shale oil accumulation state and the effect of various type pores on shale oil enrichment will be studied. This program will provides important help on the understand of the shale oil occurrence state, quantity and flow characteristics.

本项申请对处于生油阶段的湖相泥页岩孔隙类型、大小、孔径分布、影响因素及其与页岩油富集关系进行研究。拟综合利用基础地质与地化实验（TOC、热解、XRD等）、高分辨率扫描电镜（如FIB-SEM/ESEM）、纳米CT、孔径分布测试技术（MICP/CO2/N2/SAXS）对低熟-成熟自然演化系列泥页岩及人工熟化系列泥页岩样品进行测试分析，定量刻画生油阶段泥页岩孔隙形态、分类、大小、孔径分布与各类孔隙贡献，定量表征有机质丰度、成熟度、粘土矿物种类与含量等地质因素对不同尺度（微孔、介孔、宏孔）、不同类型（有机、无机）孔隙特征的影响，建立成油阶段泥页岩孔隙类型图版、演化模式，揭示页岩油赋存状态及各类孔隙在页岩油赋存中的作用。研究结果对于揭示烃类的赋存状态、赋存量及渗流特征有重要帮助。

本项目采用孔径表征、孔隙观察、分子动力学模拟等手段对湖相生油阶段泥页岩进行了孔隙形态、大小、孔径分布及其影响因素，以及页岩油赋存状态和可动性方面的研究。结果显示：①松辽盆地青山口组泥页岩发育碎屑颗粒边缘孔、粘土矿物间孔、有机质颗粒边缘孔、粒间孔及少量有机质孔；数量上看，大孔并不发育，以孔径小于10nm的孔隙为主；②随成熟度/埋深增加，粒内孔隙度变化不明显，粒间孔隙度和有机孔隙度受埋深压实和有机质生烃/酸/二次生烃的双重影响，孔隙体积变化复杂；③TOC过高或过低对页岩油富集不利，在3%附近最为合适。当页岩油含量较低时，主要富集在微孔和孔径小于4nm的介孔中，当页岩油含量较高时，原油主要分布在孔径介于2~90nm之间的介孔和宏孔；④ 推算了页岩油的可动下限（40nm），页岩油可动下限评价公式：S1>1.247×TOC-1.8916。⑤ 石英和石墨烯表面有四个吸附层，单层厚度~0.44nm；在石英狭缝（8.57nm）中吸附相体积所占比例为41.1%，有机质狭缝（7.92 nm）中为42.4%。通过本项研究揭示了湖相页岩孔隙演化模式及页岩油赋存/可动下限，对于丰富页岩油赋存机理有重要帮助。