A hydrodynamic study of several stratigraphic units in the Permian Basin shows a regional west to east dip of the potentiometric surface. The Ellenburger and Devonian have closed lows against a part of the Ft. Stockton uplift and against some faults in the general area. The Devonian has a steeper dip of the potentiometric surface in New Mexico than in Texas. The Mississippian has too sparse data to show significant features other than east dip. The Strawn potentiometric surface has steeper east dip on the east flank of the Midland Basin and approaches hydrostatic conditions around the Central Basin Platform. The dip of the Wolfcamp is to the east and north in New Mexico and east and northeast in Texas. The San Andres shows east dip. The Delaware Mountain group has general east dip, but anomalous conditions are suggested in central Reeves County.

The potentiometric surface of all units mapped is approximately the same regionally, in spite of the wide differences in elevation and location of the outcrops and subcrops. However, locally there are many variations. Tilting of the hydrocarbon accumulations is a significant factor in a few fields. Vertical and horizontal pressure relationships around faults and subcrops, vertical and lateral continuity of oil, relative permeability to oil, and other hydrodynamic conditions can be critical factors to be considered in exploration in the Permian Basin.

The quality of drill-stem-test instrumentation and programming in the Permian Basin needs to be improved to furnish the pressure data that should be available to the industry.

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