Abstract：
By applying electric imaging logging equipment for different kinds of fractured-vuggy carbonate oil reservoirs, we can
get high resolution images of the borehole wall. However, it is hard to acquire the information of the fractures, solution pores and
cavities accurately on the account of the lithology distribution randomness, the media heterogeneity around the borehole and the
intertwining and adhesion of fractures. Based on the incomplete path opening and tolerance operators that remain flexible enough to
fit rectilinear and slightly curved structures since they do not depend on the choice of a structural element shape and the advantage
of a sinusoidal database that can fit the fractures precisely, this paper proposes a new method to intelligently identify and extract
discontinuous fractures solution pores and cavities from the original electric logging image data by using multi-scale incomplete
path opening and tolerance operators, a sinusoidal database and a second-order moment ellipse fitting method. First, the opening and
closing operation of mathematical morphology is adopted to eliminate the noise of the electric imaging logging data. Then formulas
of incomplete path opening and a density clustering method are deduced and analyzed. The incomplete path opening parameter
sets and tolerance operators in different directions are applied to trace and separate fractures and the density-based clustering of
applications with noise is introduced to classify these separated parts of fractures that are in continuous or intermittent bending linear
structures. After the comparation of results of bending linear structures fitting in a Hough transform and a sinusoidal database, we
find that the Hough transform is only appropriate to match the low angle fractures while the sinusoidal database method is more
accurate for high angle fractures or in fragmentary condition. Apart from that, we can get the phase, amplitude and depth information
of these fractures by the sinusoidal database method. Finally, the second-order moment method is used to determine the equivalent
ellipse of the remaining vugs and the vertical-horizontal ratios of vugs are obtained. In order to illustrate the application of the pro
posed method, examples of numerical simulation data and oil well field data have been tested. According to the result, intertwining
fractures and vugs are separated successfully, which demonstrates the effectiveness and adaptability of our method in application
of electric imaging logging data. So the proposed method offers practical support for the precise evaluation of fractured-vuggy
carbonate oil reservoirs and helps to raise the level of recognition to the distribution of fractures and vugs of the target layers.
Key words：electric imaging logging; identification and separation of fractures and vugs; incomplete path opening operation; sinusoidal database; DBSCAN; second moment ellipse fitting
Corresponding Authors： shenjinsongcup@163.com
Cite this article：WANG Lei, SHEN Jinsong, HENG Hailiang, WEI Shuaishuai. Automatic fractured-vuggy identification and extraction from electric imaging logging data based on an incomplete path opening operation and a sinusoidal database. Petroleum Science Bulletin, 2021, 03: 380-395.
