Rapid prototype for extracting the pore skeleton of samples of drilling cores from X-ray Micro-CT.
Category: Oil Industry Applications
Technologies: Drilling core topology, MevisLab.
The original goal was to perform an skeletonization of the porous region of a cube which was extracted from a drilling core using X-ray micro-tomography. The initial purpose was to find the connectivity between two opposite faces of the cube.
MeVisLab was used to design a prototype for extracting the skeleton of the structure of the core pores. It was demonstrated that MeVisLab is an efficient tool for the production of prototypes.
Skeletonization is a simple tool to verify that there is an internal topology for transporting fluid. It also facilitates the visualization of the core empty spaces. It is a quick and simple way to know the internal topology of the core empty spaces before the simulation.
The figure below shows the simplified diagram of MeVisLab based application. MeVisLab is free for research, but you need a license for production. By having a license the prototype shown in the figure could be coded in C++, and relatively quickly we could produce the skeletonization module.
The module “IntervalThreshold” shown in the figure, was used to segment the region of pores, this module produces a binary image. The module “DtfSkeletonization” pulls the skeleton of the binary image, using a progressive erosion of the voxels, while preserving the topology. This process generates the median axis, and preserves the connectivity of the pore space.
One of the purposes of finding the skeleton is to analyze connectivity. To find for example the direction of maximum connectivity. This is equivalent to find the direction of maximum conductivity and high permeability.
The skeleton provides indications fluid behavior in the porous medium. In addition the skeleton provides a main flow direction and shows whether the medium is of homogeneous porosity. The connectivity is also linked to the permeability parameter since the latter depends on the length of the paths in the pores, the tortuosity and how well the pores are connected.
The upper video shows the skeleton obtained using our prototype. As database we use brique_02v2c300 cube with dimensions 300x300x300, obtained by micro-CT, with 2 micron resolution, this cube can be downloaded at the following link: