Preservation of accumulated petroleum in the traps is the last, but not least, step in the maintenance of a viable petroleum system in a sedimentary basin. The collaborative action of two important factors controls the preservation of petroleum accumulations in the ZFTB: (i) intense structural deformation and (ii) faulting. Both factors are regionally variable throughout the ZFTB, and therefore different levels of hydrocarbon preservation can be expected in different areas. Intense structural deformation often results in the breaching and complete loss of petroleum accumulations. Salt domes piercing through small-scale traps can also result in complete loss of the trapping capacity. In contrast, the activity of faults usually results in partial loss of petroleum accumulations in the ZFTB (e.g., due to thinning of the evaporite seal rocks or due to juxtaposition of reservoir layers with more permeable thief zones). Structural tilting can also cause partial loss or remigration of existing petroleum accumulations. The present-day boundary of the maximum hydrocarbon loss in the ZFTB coincides with the ZMFF. This boundary is characterized with intense deformation/faulting and most of the surface hydrocarbon seeps are clustered around this important structural element.