Method for determining spatial distribution and concentration of clay in a core sample

A method for determining spatial distribution and concentration of clay in a core sample, the method comprising:

• selecting a water-soluble salt of a metal with a high atomic weight as an X-ray contrast substance providing a selective ion-exchange reaction with the clay, the salt having a general formula R+M−, where R+ is selected from a group consisting of Ba2+;
• Sr2+;
• Tl+;
• Rb+ . . . , M− is selected from a group consisting of Cln;
• NOn;
• OHn;
• CH3COO, SO4;
• . . . in accordance with a standard table of inorganic substances' water solubility,
• injecting the X-ray contrast substance into a core sample,
• upon completion of the selective ion exchange reaction injecting a non-contrasting displacing agent into the core sample,
• scanning the sample by computer X-ray microtomography,
• obtaining a computer tomography image of the core sample,
• selecting an area of interest and a reference cross-section at the obtained computer tomography image of the core sample,
• obtaining grayscale histograms in cross-sections of the core sample and
• determining spatial distribution and concentration of the clay in the core sample by means of histogram analysis starting from the reference cross-section histogram.