Abstract: The Wudun depression belongs to an area with a low degree of exploration. The oil source conditions in the Lower Jurassic outcrop area are good, and the oil and gas show well in many wells drilled. However, the sequence stratigraphic framework of the basin, the sequence spatial evolution characteristics and sedimentary distribution rules are not clear, which restricts the later exploration deployment, which restricts the next exploration deployment. The research on the sequence stratigraphic division and regional sequence stratigraphic framework of  Middle and Lower Jurassic in Wudun depression is carried out by comprehensively applying the data of logging, seismic, core, and analysis data. At first, the spectrum-attribute-trend analysis of logging, time-frequency analysis, geochemical analysis and other methods are used to divide the sequence, and six third-order sequences and 28 fourth-order sequences are divided. Then, the matching wavelet decomposition and reconstruction method is used to improve the resolution of seismic data, and the seismic multi-attribute dimensionality reduction fusion technology and multi-scale matching with well-seismic joint are used for sequence analysis, and then the Jurassic sequence stratigraphic framework is established in this area. At the same time, the logging sequence division results and seismic multi-attribute fusion analysis results are cross-verified to clarify the spatial evolution characteristics of the sequence. At the same time, the logging sequence division results and seismic multi-attribute fusion analysis results are cross-verified to clarify the spatial evolution characteristics of the sequence. On the basis of high-precision sequence analysis, under the constraints of fine structural interpretation and sedimentary palaeogeomorphology, the distribution characteristics of sedimentary facies belts at key horizons are finally determined by using the results of sequence interpretation at different levels. A set of ideas and methods for the establishment of regional high-precision sequence stratigraphic framework and the study of sedimentary laws in areas of low exploration degree have been formed.

Key words: low exploration area, spectrum attribute analysis, multi-scale matching comparison, sequence stratigraphic framework, sedimentary law