Geostatistics applied to the distribution of clays, lower c reservoir, west of Venezuela

Abstract

The study was carried out at the Lagomar Production Unit, in the Urdaneta Lama Field, in the reservoir C-5-X-18. The research work is projective and divided in six phases, establishing a methodology that allowed compiling, analyzing and interpreting information of the petrophysical property called shale volume (Vsh), through the application of geostatistical methods, to generate a model of distribution in the area. This research was carried out through X-ray diffraction (XRD) laboratory analysis on channel samples of the 13 selected wells, allowing interpreting the data, to determination of diferents clay types content (percentage). That form the Vsh present in the reservoir, obtaining four types of clay, such as: kaolinite as the largest contribution, then iIlite + esmectite, then the illite and finally the chlorite. At the same time, 25 wells that crossed the site were identified and they have conventional logs and a well that has special logs, allowing them to interpret them by means of the lithological charts of logs, with a predominance of clay such as montmorillonite, chlorite, illite and mix of these clays. The experimental variograms of each types of clay the XRD data were generated, adjusting all the curves with the potential theoretical variogram, in order to apply the Kriging estimation method, for the calculation of the percentages of each type of clay in wells with no XRD data. Finally generated the maps that represent the distribution of the clays of the C-5-X-18 reservoir.