Quantitative Characterization of Rock Microstructure of Digital Core Based on CT Scanning

doi:10.19657/j.geoscience.1000-8527.2020.044

Abstract

Abstract:

Rock microstructure is a key parameter that determines the macro-physical reservoir properties. CT core scanning technology can perform three-dimensional (3D) visualization and fine quantitative characterization of rock microstructures. In this paper, rock cores of the Huagang Formation (Fm.) from north of the central inversion zone of the Xihu Sag (East China Sea Basin) are used as an example. Firstly, 3D digital core images were established by CT scanning. Secondly, the image processing algorithm and the “maximum ball” algorithm were used to analyze the samples. The grain size distribution and pore structure are spatially and quantitatively analyzed. The Huagang Fm. rock grain size is mainly 100-300 μm, belonging to fine sandstone. Different grain sizes lead to differences in pore structure, and the reservoir pore connectivity and structural parameters are quite different. Non-connected pores are mainly isolated. The pore radius ranges mainly 20-60 μm, whilst the throat radius and length is 3-15 μm and 15-45 μm, respectively. The pore-throat coordination numbers are quite different (mostly from 0 to 4), and the pores and throats are largely triangular. This study enhances the quantitative evaluation of reservoir micro-parameters, and provides strong technical support for visualizing and quantitative characterizing rock microstructures.

Key words: CT, digital core, grain size analysis, pore structure, pore network model, Xihu Sag

CLC Number:

TE122.2

ZHAO Jianpeng, CUI Likai, CHEN Hui, LI Ning, WANG Ziliang, MA Yao, DU Guichao. Quantitative Characterization of Rock Microstructure of Digital Core Based on CT Scanning[J]. Geoscience, 2020, 34(06): 1205-1213.

Figures/Tables 14

References 25

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岩样号	深度/m	岩性	孔隙度/%	渗透率/(10^-3μm²)	扫描分辨率/(μm/像素)	计算孔隙度/%	计算渗透率/%
岩样A	3 725.50	细砂岩	11.65	1.734	3.87	9.13	1.012
岩样B	3 745.00	细砂岩	12.95	10.310	3.68	10.21	7.639
岩样C	3 765.00	细砂岩	8.47	0.504	4.00	7.96	0.193
岩样D	3 798.05	细砂岩	16.86	75.860	3.68	15.20	55.421

岩样号	深度/m	岩性	孔隙度/%	渗透率/(10^-3μm²)	扫描分辨率/(μm/像素)	计算孔隙度/%	计算渗透率/%
岩样A	3 725.50	细砂岩	11.65	1.734	3.87	9.13	1.012
岩样B	3 745.00	细砂岩	12.95	10.310	3.68	10.21	7.639
岩样C	3 765.00	细砂岩	8.47	0.504	4.00	7.96	0.193
岩样D	3 798.05	细砂岩	16.86	75.860	3.68	15.20	55.421

样品号	最小粒径 /μm	最大粒径 /μm	平均粒径 /μm	中值粒径 /μm	偏度	峰度
岩样A	27.6	679.0	246.0	241.3	0.326	-0.120
岩样B	23.3	557.5	205.1	206.6	0.173	0.253
岩样C	30.4	511.7	190.5	179.0	0.977	1.276
岩样D	26.5	477.6	199.7	191.6	0.426	0.155

样品号	最小粒径 /μm	最大粒径 /μm	平均粒径 /μm	中值粒径 /μm	偏度	峰度
岩样A	27.6	679.0	246.0	241.3	0.326	-0.120
岩样B	23.3	557.5	205.1	206.6	0.173	0.253
岩样C	30.4	511.7	190.5	179.0	0.977	1.276
岩样D	26.5	477.6	199.7	191.6	0.426	0.155

样品号	孔隙特征参数			喉道特征参数			迂曲度
样品号	最小孔隙半径/μm	最大孔隙半径/μm	孔隙半径均值/μm	最小喉道半径/μm	最大喉道半径/μm	喉道半径均值/μm	迂曲度
岩样A	12.776	141.894	41.825	4.209	89.123	13.120	3.156
岩样B	11.271	139.923	38.976	3.781	84.646	13.582	3.212
岩样C	4.401	88.332	17.907	4.169	65.000	10.866	3.576
岩样D	13.504	152.585	42.805	3.979	93.205	14.989	2.539