An Image Processing Approach to Measuring the Sphericity and Roundness of Fracturing Proppants

Before being applied in oil fields, it is necessary to evaluate the quality of the fracturing proppants, for which sphericity and roundness are the two important parameters. In this paper, we propose a new approach to the sphericity and roundness measurement of proppants based on an image processing method. First, the OTSU method is introduced to binarize proppant image, and the statistical analysis is performed to divide the image into proppant regions and non-proppant regions. Second, after filling small holes, edge curves of all proppants were obtained by the Canny operator. Third, for all 20 images in the standard template, according to their corresponding sphericity and ratios between the radius of maximum inscribed circle and the radius of the minimum circumscribed circle, a fitting curve with maximum coefficient of determination was obtained, which could determine any proppant’s sphericity. Fourth, the edge curve of any proppant was divided into several segments and curve fitting method was used to obtain a curve function for each segment. Finally, the roundness of any proppant was obtained based on curvature radius of all points in the edge curve and radius of its minimum circumscribed circle. Actual proppant’s evaluation experiments showed that our approach was closest to the artificial determination using a standard template in terms of precision