Analysis and Comparison of the Wells in the Pleasant Valley Area of Ventura County - 4
4.0 SUMMARY AND CONCLUSIONS
4.1 Summary
Well data from 34 wells in the Pleasant Valley area were analyzed
and production capabilities compared. The study area represents typical aquifer types
of the southwestern United States (i.e., interlayered sands, gravels, silts and clays).
Some local variation in aquifer properties between the wells was found and is normally
expected in such hydrogeologic environments.
Eleven of the wells were completed using wire wrap screen and
developed from 40 to 60 hours each using jetting and air lift pumping.
The remainder of the wells were completed using three other well
screen types, milled and punched slotted casing, and Shutter Screen. These wells were
developed using a simple bailing technique with an average development time of only
four hours per well.
As the specific capacity of each well is directly dependent on the
total length of well screen installed, it was necessary to "normalize" the specific
capacities in order that comparisons be made on an equal basis (i.e., some wells had
over 1000 ft of screen while others had only 200 feet).
Computer analysis of the data was made and results of the well and
aquifer properties compared.
Study results show that production capabilities of wells in the
Pleasant Valley area are a function of the length of well screen installed and the
water yielding properties of the aquifer. Specifically, the following conclusions
were reached:
- Length of well screen and type of aquifer penetrated are the major factors in
well production and specific capacity, not the percentage open area of the screen.
- Well drilled in areas where high yielding aquifers occur produce more water for
the same length of screen than do wells tapping aquifers with lower water yielding
properties. (Figure 4).
- The specific capacity of wells in the Pleasant Valley Ground-Water Basin is a
direct function of the total length of screen installed. (Figure 5).
- There is no relationship between high percentage open area screens and high
specific capacities. (Figure 3).
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