Study on Petrophysical Evaluation Method of Water Flooded Zones in Zhetybai Oilfield, Kazakhstan

Abstract

The logging evaluation of the water-flooded layer is an important problem confronted in the middle and late stages of oilfield development. Aimed on the large variation of the formation water resistivity in the water-flooded layer and the limited accuracy of the saturation evaluation, the optimized dual water model was used to successfully realize the formation water resistivity values pickup automatically. It can greatly reduce the manual workload and improves the accuracy of logging evaluation. In view of the high salinity formation water in the Zhetybai area, the formation resistivity value is low and the logging qualitative identification is difficult. To establish sensitivity factor to characterize the flooded state of the formation more accurately. The physical experiment was designed for Zhetybai core sample, and the reasons why the formation resistivity increased with the increase of saturation in the later stage of freshwater flooding were preliminarily analyzed. Aiming at the water output problem of some high resistivity layers at the bottom of the reservoir, according to the curve response, the conclusion is drawn that the water output caused by the thickening of the crude oil in the formation, which is confirmed by the actual situation of regional water injection. The above technologies are well applied in the Zhetybai oilfield in Kazakhstan. The interpretation results have been verified by the production of nearly 200 wells, and the log interpretation coincidence rate of the water-flooded layer has been achieved at 89%.

Copyright 2022, IFEDC Organizing Committee.

This paper was prepared for presentation at the 2022 International Field Exploration and Development Conference in Xi’an, China, 16–18 November 2022.

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