Abstract:

In order to understand the volcanic rocks filling model in basin and explore favorable volcanic reservoir in less or no well area, the systematically study of seismic facies units, their reflection characteristics and geological interpretation is necessary. With volcanostratigraphy theory and seismic volcanostratigraphy method, the typical seismic facies of the volcanic rocks were studied based on wells and inter-well seismic profiles in the Songliao volcanic rifted grabens, Early Cretaceous. The facies can be divided into 4 types and 10 subtypes of typical seismic facies units, such as the volcanic dome unit, the volcanic platform unit, the volcanic filling unit and the cutting units. Based on wellseismic contrast and the references of volcanostratigraphy study in the field, the geological models of seismic units and their response relationship are described. Seismic facie units usually correspond to the volcanic rocks with the main filling type (facies and facies association) composition; the volcanic dome unit can be interpreted as the domeshaped extrusion dome, the acid simple lava flow, the acid compound lava flow and so on; the volcanic platform unit can be interpreted as the platform-shaped basic-intermediate simple lava flow and the pyroclastic flow; the volcanic filling unit can be interpreted as the simple lave flow and volcanic pyroclastic flow which fill in the preceding low-lying land;the cutting units can be interpreted as the sheet, dike. Besides the seismic facies, the analysis of geological attributes of seismic reflection characteristics are favorable to understand geological meaning much better.

Key words: rift sequences of Songliao basin, seismic volcanostratigraphy, seismic units, filling patterns of basin volcanic rocks, response relationship