Hydrodynamic flow in the Muddy aquifer is generally downdip to the west with an average gradient of 25 ft/mi (5 m/km). Flow patterns are controlled by the distribution of porous sandstone so that the regional patterns of flow reflect the total thickness of the Muddy aquifer. Local potentiometric highs appear to represent isolated areas of high pressure and downward flow from Mowry Shale (source rock) to the Muddy aquifer.

Lenticular Muddy sandstones form stratigraphic oil traps, but oil columns are determined largely by hydrodynamic flow. Calculations suggest that hydrodynamic flow accounts for 130 ft (40 m) of the total 150 ft (46 m) of the oil column at Recluse field; for 230 ft (70 m) of the total 250 ft (76 m) at Gas Draw field; and for 100 ft (30 m) of the total 150 ft (46 m) at Bell Creek field. Larger oil columns are the result of vertical flow. A potentiometric high of 6,000 ft (1,830 m) occurs at Kitty field, about 4,000 ft (1,220 m) in excess of the expected hydrostatic head, and the vertical pressure gradient probably accounts for a large part of the total 850 ft (259 m) of oil column. Vertical flow results in updip gradients and reduction of total oil column as at LX Bar field.

Potentiometric surface maps show that the Muddy aquifer is a dynamic system of both downdip and vertical, cross-formational flow. Observed oil columns are in equilibrium with present flow. Migration of oil downward from Mowry source rock has taken place in relatively recent time and is still occurring; it may result from montmorillonite dehydration at temperatures in excess of 200°F (94°C). The early history of fluid migration is obscured by present flow but may have been updip, eastward toward the basin flank. Flow of compaction waters may have been great enough to have prevented early oil accumulation. Exposure of the Muddy aquifer was post-Laramide and resulted in recharge by meteoric waters. Therefore Muddy oil fields are late accumulations as suggested by their present quilibrium with basinward flow.

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