Abstract:

Currently, most of the oil fields in eastern China are going into the development period of high water cut. In the period of high water cut, detailed subdivision of the reservoir is required before the technology of tertiary oil recovery is put into effect, and the thin and poor-quality layers become the aim of secondary infill and adjustment well. In fact, the recognition and interpretation of water encroaching in thin and poor-quality pay zones become a critical issue in the oil field development. Theoretically speaking, variations of lithological, petro-physical and oil-bearing property of the strata can be interpreted and identified with the log curves. As a result of small thickness of single thin-beds, high clay content and frequent intercalations of sandstones and clay-stones, however, it becomes difficult for log curves to reflect the characters of the single thin-beds. In this work, the log curves are preprocessed by using the response function to improve the discrimination accuracy of the well logs, so as to improve the accuracy in the interpretation of thin and poor-quality pay zones that are under water encroaching.

Key words: high water-cut, thin and poor-quality pay zones, water encroachment, response function, interpretation