Lithofacies and reservoir characteristics of Late Carboniferous-Permian volcanic rocks in Niudong block, Santanghu Basin

The rock types, lithofacies and reservoir characteristics of Late Carboniferous-Permian volcanic rocks in Niudong block of Santanghu Basin are analyzed. The main volcanic rocks are pyroclastic rocks and lavas. The volcanic pyroclastic rocks are composed oftuff, volcanic breccia and volcanic agglomerate, while the lavas are composed of basalt and basaltic andesite. Vesicular basalt and basaltic andesite mainly distributed in roof and floor of the flow unit. It is amygdaloidal basalt and basaltic andesite in the middle and upper part, and dense basalt in the middle and lower part. The primarypore in the roofand floor ofamygdaloidal lava belt developed well, which is the favorable reservoir.