Geological Modeling and Sandbox Experiment of Dushanzi Anticline in Southern Junggar Foreland Thrust Belt, Western China

The Dushanzi anticline located at the western segment of Southern Junggar foreland thrust belt have been highly deformed and complex structures developed, which increases the difficulties of seismic gathering, processing and interpretation, as well as the structural mapping. Therefore, it will increase the risk of oil and gas exploration. Based on the interpretation of the seismic pre-stack depth migration profiles, we construct the preliminary model of the Dushanzi anticline with constrains of the surface observations and borehole data. Comparing the synthetic seismic section acquired from the wave equation forward modeling, we determine the forelimb dip and the structural configuration of the Dushanzi anticline. The geometric analysis and numerical modeling of fault related folds assist to construct the quantitative structural model of the Dushanzi anticline, which make the structural interpretation reasonable. The sandbox modeling reproduced the kinematic process of the Dushanzi anticline and validated the reasonableness of the structural modeling. The analyses show that the Dushanzi anticline underwent two periods of deformation events causing different types of fault-related folds. The deformation during Yanshan period is relative weak and the strata beneath Jurassic layer represent low amplitude anticline with a detachment located in the Jurassic coal-bearing strata. The structural deformation during Himalayan stage is intense and the structural pattern is dominated by shear-fault propagation fold. Its main detachment fault occurs in ductile bed of the Lower Cretaceous Tugulu Group and disappears in the Neogene Shawan Formation. The tip of the fault terminated in the Shawan formation. The forelimb of this anticline represents triangle ductile deformation with area conservation, length and thickness non-conservation. Through constructing the quantitative structural model, we improve the quality of the seismic refection profiles and increase the reliability of identification traps, which provide the basis of the implement of drilling targets.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California