Опыт исследования керна карбонатных отложений методом рентгеновской томографии

Abstract

Relatively new direction for geological properties study in petroleum geology nowadays is the use of X-ray tomography. The basis of this method is X-ray rock density study. This paper shows the results of possible X-ray tomography applications while studying petrophysical properties of carbonate reservoir plugs on example of several oil fields in Perm region. The microfocus system of X-ray control with computer tomography Nikon Metrology XT H 225 and software AvizoFire 7.0 were used. The cylinder samples with diameters of 30 and 10 mm and cubic samples with a side length of 5 mm were used in the study. The results of X-ray tomography represent 2D-slices of lengthwise and crosswise sample cross-section, 3D-model of cavities, consolidation areas and initial oil saturation distribution as well as graphs of pore and irreducible water saturation versus sample height and histograms of pore diameters. The study of cavities and consolidation areas distribution in the samples allowed to type core depending on its cavity structure. Analysis of porosity evaluation of the samples with different diameters that were made from the one pies of core showed that correlation coefficient was 0.77. Such relatively low coefficient could be explained by significant heterogeneity of core even in one lithotype. During the irreducible water saturation determination four radiographic solutions were tested. It was noticed that irreducible water does not exist in the large voids (cavities, cracks, big pores). Best results were obtained for NaI and LaCl3·3H2O solutions. Presented in this paper results allow obtaining most authentic 3D distribution of pore space and fluid saturation during futhure X-ray tomography study of carbonate deposits.