(GP/GT) for Additional Water Supply in the Lower Rio Grande

the eastern part of the study area, in Reservoir Area B, but the
extremely low salinity, moderate temperature, geopressured sands at
shallower depths (Table 4) make this an optimum area for production
of useable water.
Data for the quantity of entrained gas in the water are not
available. ~owever,
estimates based on comparisons of gas-to-water
ratios, using salinity of the water, would indicate ratios as high
as 25-30 SCF/BBI.
Reservoir Area C
Area C includes the area located between the McAllen fault to
the west, the Donna fault to the east, the transverse trending
Shepherd fault to the south, and extends northeast to a point of
limited well control (Fig. 2).
This outline defines a maximum
reservoir area of some 255 square miles.
A reservoir defined by
outlining the area within lines drawn between key wells results in
a reservoir of approximately 90 square miles (Fig. 2).
The Frio sediment pattern within this section is dominated by
the major growth fault to the west, the McAllen fault, and the
Donna fault to the east. The lower Frio sediments are cut by
numerous faults which dip toward the coast. This faulting dies
out in the shallower Frio section (Fig. 3). Rapid sedimentation of
the lower Frio resulted in sands thickening away from the coast
toward the McAllen fault, with a resultant reversal of dip.
Dip
angles increase toward the major fault and decrease, or flatten,
toward the northeast (Fig. 3). Although the lower Frio section is
cut by numerous faults, the thickness of the sands within this
11-8