Deep brine aquifers of the Palo Duro Basin, Texas Panhandle, ranging in depth from about 1,000 to 3,000 m below land surface, are underpressured compared with the shallow Ogallala aquifer. Two-dimensional simulations of flow in an east-west regional cross-sectional model through the basin permitted us to characterize regional ground-water flow, to investigate causes of underpressuring below the Evaporite aquitard, and to evaluate mechanisms of recharge and discharge to and from the Deep-Basin Brine aquifer.

Sandstone in the Travis Peak (Hosston) Formation has been extensively modified by burial diagenesis. Permeability in much of the formation has been reduced to less than 0.1 md as a result of compaction, extensive precipitation of authigenic minerals, and minor pressure solution. Thin zones of higher porosity and permeability occur mainly near the top of the formation; porosity and permeability decrease with depth below the top.

Permeability in a vuggy carbonate sequence can be related to particle size, separate-vug porosity, and interparticle porosity. Total porosity can be determined from neutron, acoustic, and density logs, but the distinction made between interparticle and separate-vug porosity using log responses has never been quantifiable. As a result, such distinction has never been integrated into permeability estimates drawn from log analysis.

Ground water that moves downward from aquifers in clastic rocks of the Triassic Dockum Group and Neogene Ogallala Formation dissolves bedded halite and anhydrite in the Upper Permian evaporite section along the perimeter of the Southern High Plains in the Texas Panhandle. Ground-water velocity in salt-dissolution zones beneath the Canadian River valley and Rolling Plains may be greater than ground-water velocity in salt-dissolution zones beneath the Southern High Plains because of greater hydraulic conductivity and greater hydraulic-head gradient.