Saturation Calculation Method Study Of Complex Reservoir For Oil Fields In Kazakhstan

In terms of the problems existing in the low coincidence rates of saturation calculation only with Archie's formulas for reservoirs of ADM field, Zhanazhol field and Suprasalt field in Kazakhstan, a series of studies has been conducted to improve the saturation calculation accuracy in this paper. First of all, two types of saturation calculation models, i.e. argillaceous sandstone model, cation exchange saturation model have been discussed in this paper, theoretically. Two saturation calculation models, mixed liquor conductivity model and modified Archie's saturation calculation model, which are deduced and developed according to respective geology features, have been practically applied to calculate the saturations of the above stated complex reservoirs.Based on the geology characteristics of ADM field, and by the use of the log data, plot converging technology and fuzzy cluster analysis technology have been employed to classify the reservoir into fine siltstone, sandstone, conglomerate and fundamental metamorphic reservoir. The saturation calculation method for fine siltstone and conglomerate has been studied, as for the saturation calculation for the high resistivity water layers in conglomerate reservoir, the modified Archie's formula, which is developed in this study, has been employed. As for the reservoir which is characterized with low resistivity oil layers existing in fine siltstone, the normalized Wickman-Smith equation has been used in water saturation calculation, and the saturation interpretation accuracy has been greatly improved, the absolute error has been decreased 17.4%. The carbonate reservoir of Zhanazhol field is characterized with fissure and matrix dual porosity. The fissures can be effectively recognized and the porosity can be calculated by the use of conventional log data and FMI data, therefore, the water saturation calculation formula for matrix and fissure has been established, and compared with the results of core analysis data, the absolute error has been decreased 7.2%.The reservoir of Suprasalt field is characterized with shallow buried depth and heavy oil properties, and water broke through earlier prevalently. Due to the low salinity of the formation water, Indonesia saturation equation, which is suitable for these kinds of reservoirs, has been selected, and the interpretation coincidence rate has been improved 21.1%.In terms of the different geology features, by means of selecting or establishing saturation interpretation models, good practical application effects have been achieved in ADM field, Zhanazhol field and Suprasalt field of Kazakhstan.