231 / 2022-03-22 09:38:22

Seismic sedimentological characterization of lacustrine flooding sedimentary system in northern Songliao Basin

Songliao basin；Seismic sedimentology；Stratigraphic slice；Sedimentary system

The distribution characteristics of lacustrine flood sedimentary system affect the distribution law of reservoir. Using the key analysis techniques of seismic sedimentology such as phase conversion technology, stratigraphic slicing and frequency division interpretation, this paper analyzes the distribution characteristics of the first member of Nenjiang Formation sedimentary system in the central depression in the north of Songliao basin. The research shows that from Ⅱ2-2-n1sq1 to Ⅱ2-2-n1sq2 in the first member of Nenjiang Formation, the sedimentary base level rises continuously, the water body deepens gradually, the delta gradually regresses to the source direction, and the area of the lake basin is gradually expanding. During the  Ⅱ2-2-n1sq1 sedimentary period, sublacustrine fan deposits began to develop locally in the lacustrine environment. The lithology is mainly siltstone or argillaceous siltstone, and the sedimentary thickness varies from 0.5m to 5m. During the deposition period of Ⅱ2-2-n1sq2, the lake water area was further expanded. From the delta front in the north of the basin to the deep lake area, a large gravity flow channel and its end lake bottom fan were developed. The channel sand body was located in the middle of a large section of mudstone, with good oil content, porosity of 16% and permeability of 0.13×10-3μm2, easy to form lenticular reservoir.The research results deepen the understanding of the distribution law of oil and gas reservoirs in Nenjiang Formation and can effectively guide the oil and gas exploration of Saertu oil layer.