页岩油可动性分子地球化学评价方法——以济阳坳陷页岩油为例

Molecular geochemical evaluation of shale oil mobility: a case study of shale oil in Jiyang Depression

蒋启贵 黎茂稳 马媛媛 曹婷婷 刘鹏 钱门辉 李志明 陶国亮

JIANG Qigui LI Maowen MA Yuanyuan CAO Tingting LIU Peng QIAN Menhui LI Zhiming TAO Guoliang

1. 中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126; 2. 页岩油气富集机理与有效开发国家重点实验室, 江苏 无锡 214126; 3. 国家能源页岩油研发中心, 江苏 无锡 214126; 4. 中国石化 油气成藏重点实验室, 江苏 无锡 214126

1. Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China; 2. State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Wuxi, Jiangsu 214126, China; 3. State Energy Center for Shale Oil Research and Development, Wuxi, Jiangsu 214126, China; 4. SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms, Wuxi, Jiangsu 214126, China

目前，对于页岩油的可动性评价还没有规范的方法和标准，常使用热解S1、S1/w（TOC）及中值孔喉半径等多参数的组合并结合勘探开发实际来进行综合表征，相关地质解释理论依据相对缺乏。通过对济阳坳陷页岩油岩心样品的实验分析及研究，利用页岩油分子组成与页岩含油性及页岩油赋存空间的耦合关系，建立了表征页岩油可动性的分子地球化学评价参数模型。研究表明，当∑nC20-/∑nC21+比值小于1时，页岩孔喉中值半径一般大于20 nm，此时，热解S1一般大于3 mg/g，S1/w（TOC）>100 mg/g，且随S1、S1/w（TOC）及页岩孔喉中值半径的增大，∑nC20-/∑nC21+比值基本不变，反映了页岩孔喉半径达到一定级别后，喉道中大、小烃类分子扩散运动不受扩散能垒的影响，孔喉道中页岩油分子组成相对均质，页岩油可动性强；当∑nC20-/∑nC21+比值大于1时，页岩孔喉中值半径一般小于20 nm，此时热解S1一般小于3 mg/g，S1/w（TOC）<100 mg/g，且随S1、S1/w（TOC）及页岩孔喉中值半径的减少，∑nC20-/∑nC21+比值快速升高，反映了页岩孔喉半径小于一定级别后，大分子烃类组分在喉道中扩散运动受到扩散能垒的抑制，页岩油可动性差，易流动的主要是低分子量烃，此时页岩游离油含量也较低。济阳坳陷页岩油流动孔喉下限半径在20 nm左右。

Shale hydrocarbon potential, shale oil mobility and shale compressibility are three important factors of geological evaluation for shale oil exploration and development. Among them, shale oil mobility is constrained by the pressure system, shale hydrocarbon potential, shale oil composition and occurrence space. Since there were no standardized methods or criteria for shale oil movability evaluation, a combination of multiple parameters (pyrolysis parameter S1, S1/w(TOC) and median pore-throat radius) together with exploration and development practice have been used for comprehensive characterization. Based on the experimental analysis of a large number of core samples for shale oil exploration in the Jiyang Depression, a coupling relationship among shale oil molecular composition, shale hydrocarbon potential and shale oil occurrence space was found, and a molecular geochemical evaluation model for shale oil mobility was established. The study revealed that when the ratio of ∑nC20-/∑nC21+ was<1, shale pore throat radius was generally>20 nm. Under this condition, pyrolysis S1 was usually>3 mg/g and S1/w(TOC) was>100. The ratio of ∑nC20-/∑nC21+ basically remained constant with the increase of S1, the ratio S1/w(TOC) and shale pore throat radius. This indicated that when shale pore throat radius is large, hydrocarbon molecular diffusion is not affected by diffusion energy barriers, and shale oil molecule occurrence in pore throats is relatively homogeneous, so shale oil has a good fluid mobility. When the ratio of ∑nC20-/∑nC21+ was>1, shale pore throat radius was usually<20 nm, pyrolysis S1 was commonly<3 mg/g, and the ratio of S1/w(TOC) was<100. The ratio of ∑nC20-/∑nC21+ was increasing quickly with the decrease of S1, S1/w(TOC) and shale pore throat radius. It indicated that when the shale pore throat radius becomes small, diffusion energy barriers limited the diffusion of macromolecular hydrocarbon components in pore throats, thus shale oil has a poor fluid mobility and low molecular weight hydrocarbon is the main constituent to flow easily. In such a condition, shale has a poor content of free oil. The lowest limit of pore-throat radius for shale oil flow in the Jiyang Depression is approximately 20 nm.

国家科技重大专项“大型油气田及煤层气开发：中国典型盆地陆相页岩油勘探开发选区与目标评价”（2017ZX05049001）资助。

https://doi.org/10.11781/sysydz201806849