Where is oil found within a salt-dome-related petroleum trap?

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salt dome Figure 1: Interrelationships of salt structures (see text)

In a salt-dome-related petroleum trap, oil is found within the sedimentary strata that have been deformed by the upward movement of the salt mass. These accumulations typically occur along the folded or faulted flanks of the salt plug or within the sediments draped over the top of the plug.123

Because petroleum is less dense than the water typically saturating subsurface rock formations, it migrates upward until it is blocked by an impermeable barrier. In these structural traps, the salt dome acts as a seal, causing the oil and natural gas to accumulate in the highest available portions of the porous reservoir rock, often arranged with natural gas at the top, followed by oil, and then water at the bottom.45