基于多尺度X-CT成像的数字岩心技术在碳酸盐岩储层微观孔隙结构研究中的应用

doi:10.19657/j.geoscience.1000-8527.2019.03.17

摘要/Abstract

摘要：

为了更加直观、准确地刻画碳酸盐岩储集层的微观孔隙结构特征,分别选取裂缝发育的双孔介质碳酸盐岩储层样品与裂缝不发育的单介质碳酸盐岩储层样品,利用多尺度X-CT扫描成像技术建立不同级别的三维数字岩心,应用最大球算法与孔喉尺寸校正方法,提取并建立碳酸盐储层纳米级数字岩心孔隙网络模型,最后实现利用三维孔隙网络模型模拟储层物性参数、进汞曲线以及孔、喉分布曲线,并与常规高压压汞法结果进行平行对比。研究结果表明:利用数字岩心技术模拟得到的孔隙度、渗透率参数与实际测量结果相差较小;模拟得到的进汞曲线、孔喉分布曲线与室内压汞实验得到的曲线具有较高的一致性,数字岩心得到的模拟结果具有较高的可信度。数字岩心技术在碳酸盐储层微观孔隙结构的直观刻画与定量描述方面,具有明显优势。

关键词: X-CT扫描, 碳酸盐岩, 微观孔隙结构, 多尺度融合

Abstract:

In this paper, we analyzed two types of core samples from porous carbonate reservoir via X-CT imaging to better constrain their microscopic pore structural features. The two sample types are namely the double porosity medium with fracture development and single porosity medium with no fractures. Three dimensional (3D) digital cores of different levels are established via the multi-scale X-CT scanning imaging technology, using the maximal ball algorithm and the method for pore and throat size correction, and consequently the digital cores nanoscale pore network model in carbonate reservoirs are extracted and established. Finally, the 3D pore network model is used to simulate the reservoir physical parameters, mercury injection curves and the pore and throat distribution curves, and the results are compared with those generated by the conventional high-pressure mercury injection method. The results show that the porosity and permeability parameters obtained by using the digital core technology are smaller than the actual measurements. The simulated mercury injection curves and pore throat distribution curves are in good agreement with those obtained by the laboratory mercury intrusion experiment, demonstrating that this technique is reliable. Digital core technology has clear strengths in directly and quantitatively described the micro-pore structure of carbonate reservoirs.

Key words: X-CT scanning, carbonate rock, micro-pore structure, multiscale fusion

中图分类号:

TE122

盛军, 杨晓菁, 李纲, 徐立, 李雅楠, 王靖茹, 张彩燕, 崔海栋. 基于多尺度X-CT成像的数字岩心技术在碳酸盐岩储层微观孔隙结构研究中的应用[J]. 现代地质, 2019, 33(03): 653-661.

SHENG Jun, YANG Xiaojing, LI Gang, XU Li, LI Yanan, WANG Jingru, ZHANG Caiyan, CUI Haidong. Application of Multiscale X-CT Imaging Digital Core Technique on Observing Micro-pore Structure of Carbonate Reservoirs[J]. Geoscience, 2019, 33(03): 653-661.

图/表 10

图1 最大球算法提取孔隙网络模型过程

Fig.1 Extraction process of pore network model using maximal ball algorithm

图2 孔隙与喉道划分校正示意

Fig.2 Schematic diagram of division and correction of pore and throat

图3 选取进行实验的碳酸盐岩储层岩心样品照片

Fig.3 Photos of the selected core samples from the carbonate reservoirs for the experiment

图4 全岩心 CT 扫描图像及三维剖面((a)1号样品;(b)2号样品)

Fig.4 Whole-core CT scanned image and 3D profiles

图5 1号样品垂直方向剖面

Fig.5 Vertical cross-section of sample No.1

图6 2号样品局部精细CT扫描示意图

Fig.6 Fine CT scanned map for parts of sample No.2

图7 2号样品10 nm分辨率大面积背散射成像(分辨率:10 nm)

Fig.7 BSE image of sample No.2

图8 微米CT扫描分割后三维数字岩石模型与提取出的三维孔隙空间

Fig.8 3D digital rock model and extracted 3D pore space after segmentation by micron-scale CT scanning

图9 微米/纳米尺度融合后的三维数字岩石模型、三维孔隙空间以及三维孔隙网络

Fig.9 Three-dimensional digital model of rock, the pore space and 3D pore network after micro-/nano-scale fusion

图10 模拟进汞曲线、孔喉半径分布曲线与实测对比

Fig.10 Comparison between simulated mercury injection curve, pore throat radius distribution curve with the measured results

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