Figure 3. Pressure-Depth Plots Showing Two Continuous Gas Column Scenarios. a) Pressure distribution in the case of a continuous gas phase over water in equilibrium. The top of the gas represents the point of maximum overpressure. The observed pressure gradient within the gas is consistent with the low density of gas (smaller delta-p vs. depth compared to water). The point of normal pressure is at the base of the gas. b) Observed pressure distribution in the continuously gas-saturated Williams Fork section in the Picenace basin. The pressure gradient is consistent with either a non-equilibrium flow of gas from deep to shallow, or a manystacked reservoirs with systematically smaller sealing-pressure thresholds versus depth. The depth of normal pressure is at the top of the gas.