Pattern recognition is to subsume undetermined patterns with computer technologies based on study and classification of the known patterns.Pattern recognition can be performed in three steps.First

preprocess data through Fourier analysis

regression analysis and multi-point smoothing;then calculate frequency spectrum of the known wells' geological data by using cyclical strategraphy and perform feature study and extraction and pattern classification with Milankovitch cyclic components;and finally classify strata in other wells by using the established patterns.Strategraphic division has been performed in 40 wells in Dagang oilfield with the pattern recognition method and the results are in good agreement with the original ones and have better accuracy.