Discrete Element Modeling Of Influence Of Subsalt Faults On Deformation Of Salt-overlying Beds In Tarim Basin

Cambrian subsalt formation in Tarim basin is an important new area for oil and gas exploration.In the thesis,based on the analysis of seismic profiles in Tarim Basin and the investigation of previous literatures,we have summarized the structural styles of subsalt faults in Tarim basin,including horst,graben and half-graben.We have studied the influence of subsalt faults on the deformation of salt-overlying beds in Tarim basin by discrete element method.The thesis mainly focuses on the influence of structural styles of subsalt faults,thickness of the salt layer,thickness of salt-overlying beds,displacement of subsalt faults,and horizontal distance between the two subsalt faults on the structural deformation evolution of salt-overlying beds.Model results show that subsalt faults control the location of salt-related structures within the salt-overlying layers,and the subsalt fault is inverted more easily when it is closer to the shortening boundary.The factors such as thickness of the salt layer,the thickness of the salt-overlying beds and the displacement of the subsalt faults,significantly affect the geometry of the fold within the salt-overlying beds as a result of the inversion of the subsalt faults.With increasing the thickness of the salt layer,the wavelength(horizontal scale)of the salt-overlying fold increases,whereas the amplitude(uplift)of the fold decreases.The subsalt fault is more easily inverted in models with thinner salt-overlying beds,and the larger displacement of the subsalt fault.As a result,a fold with a smaller wavelength and a larger amplitude of the fold develops in the salt-overlying layers.In models with a relatively small horizontal distance between the subsalt faults,only one of the subsalt faults is inverted,which directly affects the geometry of the salt-overlying fold.Finally,the reliability of the simulation is verified by comparing the model results with typical seismic profiles of salt structures in Tarim Basin.