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Abstract:

Differential interlayer deformation and structural coupling are the major characteristics of tectonic deformation in the Tazhong area. In this paper, the geometric characteristics and deformation mechanisms of faults in the Tazhong area were analyzed through a detailed interpretation of seismic sections, analysis of rock mechanical tests and application physical analog methods to gain a better understanding of the pattern of structural deformation in the Tazhong area. The deformation mechanism revealed in this paper also provides insights that will benefit the exploration of large hydrocarbon reserves in this area. It is proposed that the structural coupling effect in the area has typical “superimposed” characteristics. Deformation in the deep and intermediate layers and in the shallow layers is independent but exhibits certain similarities. The sandbox model of the study area revealed that there is a strong correlation between preexisting basement structures (basement uplifts and faults) and faults in the overlying layers. Because of the combined effects of basement structures and decollement layers, a fault is more likely to slip above the preexisting basement structures, thereby forming “superimposed” faults. Although the structural coupling effect can improve the diversity of trap styles and contributes to vertical hydrocarbon migration, the faulting associated with structural coupling also destroys the cap rocks, which is detrimental to hydrocarbon preservation.