Sequence filling style and target selection of 3~(rd) member of Shahejie formation in Shuangbei area

Based on the theory of sequence stratigraphy, the seismic sequence analysis of 9 seismic profiles in Shuangbei area was carried out. The results show that the seismic reflection of high-level system domain has the characteristics of low frequency, medium amplitude and good continuity. Drilling data revealed that the lithologic combination was interbedded between sand conglomerate and mudstone, with good anisotropy and further lateral extension of sand bodies. The formation thickness of the water-entering system domain is obviously wedge-shaped thickening in the direction of depression, and the seismic reflection has the characteristics of high frequency, medium and low amplitude and poor continuity. The conical, lenticular, wedge-shaped reflected geological bodies and super-reflected seismic phases can be identified. Drilling data revealed that the sand and mudstone are mixed with high shale content and poor anisotropy, which is the cause of collapse. Combined with the sequence development characteristics, it is clear that the upper system tract of 3~(rd) member of Shahejie formation is targeted at lithology-structure traps under the control of micro-amplitude structure, while the upper system tract of water inflow is targeted at lithology traps of up dip pinch-out type sandstone and lenticular type sand body.