Study On The Method Of Digital Core Extraction Of Carbonate Rock

Carbonate reservoirs are classified as unconventional reservoirs because of their complexity.At present,the proven carbonate reservoirs in the world account for more than half of the world's total reserves.Core is the most direct,effective and reliable data for the analysis of petrophysical characteristics.In recent years,digital core technology has developed rapidly and been widely used.The basis of digital core research is to extract the components of two-dimensional image and reconstruct three-dimensional digital core.The research contents and innovations of this paper are mainly reflected in the following aspects:(1)Electrical imaging image preprocessing: When the electrical imaging logging tool scans the borehole wall,its coverage rate is not 100%.Therefore,some blank bands will appear in the generated electrical imaging logging image.In this paper,image restoration technology is used to fill the blank bands,so that the generated image is complete,in order to achieve better visual effect,and the reconstructed image is filtered to denoise and smoothly restore the boundary information.(2)Research on the extraction methods of each component in electro-imaging image: Most scholars have only completed the classification of voids and skeletons in the extraction of electro-imaging components.In this paper,gray histogram method and traditional two-class variance method are used to segment the rock skeleton,voids and connected parts.The results are not satisfactory.The improved two-class variance method is used to extract the rock skeleton,voids and connected parts.(3)Research on core micro-fracture extraction method: In order to extract micro-cracks from core images with complex background accurately,firstly,Otsu segmentation algorithm is used to segment core images by threshold,and the background is preliminarily filtered to get binary images.For the segmented images,median filtering is used to eliminate smaller noise points,and then eight-neighborhood labeling algorithm is used to further eliminate the interference of noise and small holes,so as to extract microfracture.