Abstract: The Jiergalangtu sag is one of the important oil production bases in the Erlian Basin. In the early Cretaceous, the Lower
Cretaceous Tenggeer and Saihantala formations experienced two intense uplifts and denudations. The recovery of denudation amount o
sedimentary strata has a great significance for the evaluation of hydrocarbon accumulation. Based on data of mudstone sonic log
interval and vitrinite reflectance, the denudation thickness of the Tenggeer and Saihantala formations in the Jiergalantu sag is
calculated, and the original sedimentary thickness and burial process were restored. Results show that the denudation of the Tenggeer
and Saihantala formations has undergone different degrees under the control of structural inversion. The denudation thickness of the
Tenggeer Formation is about 243-1933 m, and that of the Saihantala Formation is about 95-290 m. The distribution of denudation
thickness is obviously affected by the differential activity of faults in different directions and scales during the tectonic inversion. The
denudation of the Hanni structural belt near the northwestern boundary faults is relatively large, and gradually decreases to the
southeastern gentle slope zone. The difference of denudation amount in different structural parts of the area has a direct impact on
hydrocarbon accumulation. Fault depression area and later inversion controlled large sedimentation and strong denudation area have a
long hydrocarbon generation time of source rock. The denudation and pressure relief of uplift zone formed by structural inversion along
the structural strike are beneficial to the vertical and lateral migration of oil and gas along NE fault plane and the formation of reservoir
in favorable traps on both sides of the fault plane.

Key words: Jiergalangtu sag, Saihantala Formation, Tenggeer Formation, mudstone sonic log interval, denudation thickness;
depositional thickness