ANALYSIS OF HIGH-RESOLUTION SEQUENCE STRATIGRAPHY AND STUDY OF DEPOSITIONAL SYSTEMS IN THE MALING OIL FIELD, ORDOS BASIN

Based on the theory of base-level cycles, two long-term, six medium-term and twenty-seven short-term cyclic sequences can be distinguished in the Jurassic Yan'an Formation and Fuxian Formation in the Maling oil field, Ordos basin.This paper introduces in more detail the controls of the base level on sedimentary facies.The change in base level of the long-term cycles may affect and control the types, development scales and facies association patters of streams, and the ascending half and descending half of the medium-term cycle may give rise to the same type of fluvial facies.On the basis of an analysis of cores, well records, well logs and single-well facies, three types of sediments, namely, the sediments of braided streams, meandering streams and anastomosed streams, are distinguished in this area.