Abstract: The characteristic and significance of well log activity curves that can be used to identify the interface of parasequence unit are analyzed. Example is taken from the regression system tract of No.2 sequence in the third middle member of Shahejie formation in T-715 Well of Sheng li oilfield. Integrating with the field core analysis, three parasequence units are classified and can be well identified by using three kinds of activity curves (SP, RT and GR), of which SP logs can be used to identify high-resolution sequence. The study shows that the method of weighting several activity curves for identification of parasequence units is of feasibility, applicability and good efficiency.

Key words: sequence stratigraphy, sequence, well logs, activity curve, identification