页岩油岩心孔隙度测量的若干问题

Issues in shale oil core porosity measurement

张金晴 陶国亮 黄代 罗翠娟 刘凌波 仰云峰

HANG Jinqing TAO Guoliang HUANG Dai LUO Cuijuan LIU Lingbo YANG Yunfeng

1. 中国科学院 地质与地球物理研究所 公共技术中心, 北京 100029; 2. 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; 3. 中国石化 油气成藏重点实验室, 江苏 无锡 214126; 4. 中国石化 经纬有限公司 胜利地质录井公司, 山东 东营 257000; 5. 苏州冠德能源科技有限公司, 江苏 苏州 215163; 6. 苏州中科地星创新技术研究所, 江苏 苏州 215163

1. Institutional Center for Shared Technologies and Facilities, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; 2. Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China; 3. SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms, Wuxi, Jiangsu 214126, China; 4. Shengli Geologging Company, SINOPEC Jingwei Co., Ltd., Dongying, Shandong 257000, China; 5. Suzhou Grand Energy Technology Ltd., Suzhou, Jiangsu 215163, China; 6. Suzhou Zhongke Dixing Innovation Technology Research Institute, Suzhou, Jiangsu 215163, China

页岩孔隙度的测试方法主要分为流体侵入法和电子/射线辐射法两大类。其中，辐射法因存在一定的局限性，目前应用范围不广。由于页岩孔隙结构具有纳米级特征，氦气凭借其分子小、化学性质稳定、渗透性优异，成为测量页岩孔隙度最常用的流体介质。氦气流体在侵入页岩内部时，其渗透效果受样品尺度和孔隙连通性的影响。块状样品因其复杂的孔隙迂曲度而需要较长的压力平衡时间，而颗粒样品能够显著改善页岩纳米孔隙的连通性，探测到更多的孔隙空间，因此所测孔隙度更加真实可靠。为了明确何种粒径具有最佳的样品代表性，并探明在页岩油岩心中复杂的可溶有机质—有机溶剂—纳米孔隙相互作用机制下溶剂抽提对孔隙度的影响，从样品尺度和溶剂抽提两个关键因素出发，系统综述了近年来页岩孔隙度测试方面的进展，并对松辽盆地白垩系青山口组页岩油岩心孔隙度进行了实测分析。研究表明，采用块样视密度和颗粒氦气孔隙度相结合的方法测试页岩油岩心孔隙度效果最佳。建议选用粒径为主体孔径的3～4个数量级的样品，这样既能保证样品的代表性，又能提高实验效率。不建议对页岩油岩心进行溶剂抽提，推荐采用低温真空干燥方法尽可能清除孔隙中含有的可溶有机质，从而提高孔隙度测量的准确性。

The primary methods for shale porosity measurement are the fluid invasion method and the electron/X-ray radiation methods. Among them, radiation methods, due to certain limitations, are currently not widely applied. Since shale pore structures have nanometer-scale characteristics, helium gas, with its small molecular size, stable chemical properties, and excellent permeability, has become the most commonly used fluid medium for shale porosity measurement. The penetration of helium gas into shale is influenced by core sample size and pore connectivity. Bulk samples require a long time for pressure equilibrium due to their complex pore tortuosity, while grain samples exhibit improved nanopore connectivity in shale with more pore space detected, making the measurement more accurate and reliable. This study aims to determine the sample with the optimal particle size and explore the impact of solvent extraction on porosity under the complex interaction mechanisms of soluble organic matter, organic solvent, and nanopores in shale oil cores. Recent progress in shale porosity measurement is systematically reviewed, focusing on sample size and solvent extraction, and experimental analyses of the shale oil core porosity in the Cretaceous Qingshankou Formation in Songliao Basin are conducted. The research indicates that the combination of bulk sample apparent density with grain helium porosity achieves the best measurement result for shale oil core porosity. It is recommended to use samples with particle sizes that cover 3 to 4 orders of magnitude larger than the main pore diameter to ensure both sample representativeness and experimental efficiency. It isn’t recommended to perform solvent extraction on shale oil cores and use low-temperature vacuum drying to remove soluble organic matter in pores, thereby improving the accuracy of porosity measurements.

https://doi.org/10.11781/sysydz2025020433