Sequence stratigraphic characteristics and hydrocarbon prospect of Mesozoic Formation in Suibin Depression, Sanjiang Basin

According to the detailed analysis of drilling data, together with the interpretation of seismic section, the Mesozoic of Suibin Depression is divided into four second-order sequences and eight third-order sequences. The third-order sequences at the bottom of second-order sequences develop low-stand systems tracts (LSTs), and the other sequences do not. The analysis result of the balanced section and Milankovitch cycle indicates that the Mesozoic sequences above third-order in the Suibin Depression are mainly controlled by structure, and that the Milankovitch cycle only controls high frequency sequences (systems tracts). Based on the above analyses, the second-order sequence stratigraphy model of the Mesozoic of Suibin Depression is established. The model is of typical tripartition, the early basin fill (LST), the middle basin expansion (TST) and the late basin abortion (HST). The transgressive systems tracts (TSTs) overlying the LSTs in the second-order sequences may be good seal and source rock, so the LSTs have the potential for oil and gas. Key words: Sanjiang Basin, Suibin Depression, sequence stratigraphy, Milankovitch cycl