Tectonic evolution and its controlling over sequence filling pattern of Paleogene in Beitang sag

Key words:  Beitang sag  Paleogene  tectonic evolution  episodic rifting  sequence pattern

Abstract:

The tectonic evolution regularity of Tertiary in Beitang sag was illustrated by using back-stripping technology. According to the recognization of tectonic units in the basin, Beitang sag can be divided into four type tectonic units ； fault-ter~ race abrupt slope belt, gentle slope belt, buried hill abrupt slope belt and multi-stage slope belt. The tectonic evolution character and its controlling effect on the sequence pattern in different evolution stages were analyzed. The research results show that the sag experienced rifting stage in Eogene and depression stage in Neogene. The rifting stage also can be divided into three rifting period. Fault-terrace abrupt slope belt, low uplift gentle slope belt and multi-stage slope belt sequence pattern mainly developed in rifting I period. However, gentle slope belt and multi-stage slope belt sequence pattern mainly developed in rifting II and III period. In rifting I period, fault-lithologic hydrocarbon reservoir developed in the fault-terrace abrupt slope belt，updip pinchout reservoir developed in the gentle slope belt and fault-block hydrocarbon reservoir developed in the multi-stage slope belt. In rifting II and III period, updip pinchout reservoir mainly developed all over the area，and the fault-block hydrocarbon reservoir developed in the multi-stage slope belt.