煤岩CT图像的孔隙度和比表面积测量方法

(中国矿业大学(北京)力学与建筑工程学院,北京 100083)

煤岩; CT图像; 孔隙度; 比表面积; MATLAB; Avizo;

Measurement of porosity and specific surface area of coal rock using CT images
JIN Zhi-min,ZHOU Hong-wei,XUE Dong-jie

(School of Mechanics and Civil Engineering,China University of Mining and Technology(Beijing),Beijing 100083,China)

coal rock; CT image; porosity; specific surface area; MATLAB; Avizo

备注

为实现基于CT图像的煤岩孔隙度和比表面积快速测量,提出了一种基于MATLAB图像处理的测量方法。以平煤十二矿深部采集的煤岩为研究对象,应用Nano CT技术对样品进行了扫描,并分别借助Avizo和MATLAB软件计算孔隙度和比表面积,研究了Avizo三维建模和MATLAB图像处理2种方法的优缺点。发现2种方法计算出的结果误差仅在10%左右,且以复合Cotes公式的误差估计最小,孔隙度和比表面积的误差分别为9.392%和8.247%.结果表明:传统的基于Avizo三维建模的测量方法精确度较高,同时还能获取样品的三维孔隙网络模型和孔隙的形状、走向及孔径分布,但计算过程复杂,对于复数个试样必须进行多次计算,且对CT图像有较高的质量要求。基于MATLAB图像处理的测量方法则通过简单的数值积分实现了快速计算煤岩的孔隙度和比表面积,避免了三维建模,极大地降低了计算复杂度,且能够一次性处理复数个试样,较好地满足了实际工程需要。且对于CT图像具有更高的容错率,每次计算仅需其中数张扫描质量效果较好的CT图像即可。

In order to realize the rapid measurement of porosity and specific surface area of coal using CT images,a measurement method based on MATLAB image processing is proposed.Taking the coal rock obtained from the deep part of Pingdingshan Coal Mine Group 12 as the research object,the sample was scanned by Nano-CT,and the porosity and specific surface area were calculated by Avizo and MATLAB software respectively.The advantages and disadvantages of Avizo 3D modeling and MATLAB image processing were studied.It is pointed that the errors calculated by the two methods are only about 10%,with the error done by the composite Cotes formula the smallest.The errors of porosity and specific surface area are 9.392% and 8.247%,respectively.The results indicate that the traditional measurement method based on Avizo 3D modeling is more accurate,and the 3D pore network model and the shape,orientation and size distribution of pores can be obtained.However,the calculating process is comparatively complicated,and it is necessary to perform multiple calculations for a plurality of samples,with high quality requirements for CT images.The measurement method based on MATLAB image processing proposed in this paper realizes the rapid calculation of porosity and specific surface area of coal by simple numerical integration,which avoids 3D modeling,reduces the computational complexity greatly,and processes multiples at a time.The sample satisfies the engineering needs well.Moreover,for CT images,there is a higher fault tolerance rate,and only a few CT images with better scanning quality effects are needed for each calculation.