A Research On Three-dimensional Reconstruction Method Of Three-dimensional Digital Core

Log interpreter will obtain the porosity,permeability and some other geological parameters exactly with rock core,which is the important real geological material.The coring cost and geological limitations help to develop the 3D digital core reconstruction technology.Much effort has been made on this research in our country.Most of the time,the reconstructed core is cubic or cuboid,which is not close to the reality,cylinder.In this thesis,the 3D cylinder digital core has been constructed based on the electrical imaging log image and core material.The cylinder core will show the 2D electrical imaging log image around the borehole and the 3D cylinder into the borehole,which will greatly improve the development of electrical imaging log interpretation.An electrical imaging logging tool cannot cover the borehole 100%,so the blank paths exit on the image.In order to obtain a more accurate 3D digital rock core,two methods are implemented to reconstruct log image.One method is a repair algorithm based on FMM which can repair the small blank paths.The problem is that blurring and stepping will occur after repairing the large paths.The other is a repair algorithm based on MPS.This method will repair paths of all scale.Also,the reconstructed result is good and gives a good overall look of the image.Due to the large difference and the incompatible gray values between the target area and the background area in the electrical imaging log image,the simple threshold segmentation method is applied based on marker finishing in this paper,which will invert the image into binary image involved the pore and matrix.The MPS method and the core sheet image are used to reconstruct the 3D digital core.Then the reconstructed data is superimposed into a cylindrical shape.In processing,the K-D tree method is applied to optimize the efficiency of the K-means fuzzy clustering algorithm.And the 3D reconstruction efficiency has been greatly improved.In order to test the feasibility of the reconstruction algorithm,the core data of the three depth segments in the electrical imaging log image are selected as reference.The porosity values of the three depth segments are calculated and then compared with the porosity calculated by reconstructed 3D digital core.Finally,the result shows that the relative porosity error is within 10%,and the average porosity is almost the same.It is obvious that the cylinder digital core reconstruction algorithm based on electrical imaging log images is reliable and effective.