The Well / Aquifer Model (Initial Test Results) - 26
The correlation analysis shows an unexplained variation of only 35,
indicating a high degree of correlation. As can be seen in the Figure, very high
efficiencies were attained with relatively low percentage open areas. For example,
well efficiencies of 98% and above were achieved with screens having open area
percentages of 3% and higher, and entrance velocities up to 2.5 ft/ sec. The
significance of these results is apparent in the design of wells where high percentage
open areas were thought to be the dominant factor in reducing frictional head losses.
In fact, most of the results seen in Figs. 24 through 48 show either directly or
indirectly that, above a minimum percentage of open area (3-5%), with entrance
velocities less than 2.5 ft/ sec, the results are independent of open area.
The results from the initial series of tests using the well / aquifer
model have proven to be not only encouraging but have provided answers to specific
questions relating to basic well design. Most of the objectives as outlined under
section 1.2 of this report were met and basic groundwork was laid to satisfy the
remainder. Several of the original objectives relating to Peterson’s work could not
be achieved due to the nature of initial testing procedures. Realizing these objectives
required variation of both model well discharge and screen length during a specific
test. In this initial testing, both well discharge and screen length were held
constant. Therefore, no data were available to check Peterson’s findings as outlined
under objectives 3, 4, and 5 of section 1.2 of this report. However, this area will
be covered in subsequent investigations using the well/ aquifer model.
The Santa Barbara and Silverado formations were wise choices of
aquifer materials because their different hydrogeologic properties resulted in important
test results. This first series of test not only established some basic guidelines and
methodology for the testing procedure itself, but has provided insight into important
areas for continued research.
Improving techniques developed with each subsequent test were
apparent in later test data. Combinations of screens, gravel packs, and aquifers have
led to understanding of the importance of the concept of "effective area of
opening". The distortion of model aquifer (1/6 of circumference) to model well (1/2
of circumference) was overcome in the later series of tests by selectively masking
screen apertures.
The analogy between the model and the theoretical flow equations was
verified in every test. Basic theoretical relationships between significant model
parameters were also verified using regression and correlation analysis. Thus the
correctness of test procedures was confirmed. Specifically, the following conclusions
were drawn from results obtained from the initial tests on the Santa Barbara and
Silverado aquifers:
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