Study On The Sequence Stratigraphy And Sedimentary System Of Upper Jurassic Of ADM Area In South Turgai Basin

The South Turgai basin is located in the middle of Kazakhstan. Most of the basin has a high degree of exploration, and litho-stratigraphic traps have already become an important direction of increment in reserves. According to the integrated study on seismic data, well logging data and drilling cores, we established the sequence stratigraphic framework of ADM area. The upper Jurassic can be divided into three third-order sequences and six fourth-order sequences. We identified two types of sequence boundary. One was the boundary of SQ8 and SQ7, and it was truncated disconformity surface which represented stratigraphic denudation. The other one was angle disconformity surface, the boundary of SQ6 and SQ5, representing transformation of structural environment. We analyzed the sequence evolution and its constitution in depression period. We concluded the features of sequence filling, which was for local uplift and denudation, the distribution of sediments was confined, facies changed fast, with poor continuity and huge thickness.Based on previous study and exploration data, guided by sequence stratigraphy theory, we studied seismic facies, electrofacies and sedimentary facies carefully. On the basis of sequence stratigraphic framework of area and major wells, we discovered the distribution of sedimentary facies, and defined the identification marks of delta, fan delta and lacustrine. We also analyzed the spatial combination relationship of facies, defined the development characteristics of sedimentary system, and established sedimentary model.Using seismic attribute analysis and referring to study and analyses of fixed wells, we identified and forecasted traps in upper Jurassic. We discovered many types of lithostratigraphic traps, including unconformity surface-seal traps, lenticular sandstone traps, stratigraphic overlapping traps and sandstone updip pinch out traps. We evaluated and optimized these traps. At last we proposed three types of potential zone. It not only widened the exploration area and supplied with targets to be selected, but also added important experience for application of technique and method in lithostratigraphy traps exploration.