Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua Essa L. Gross and John S. Gierke Department of Geological Eng. & Sciences Michigan Technological University Antoinette Kome SNV Nicaragua
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Characterization of seasonal effects on the specific capacity of rope-pump wells in a fractured rock-aquifer in Nicaragua Essa L. Gross and John S. Gierke.
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Characterization of seasonal effects on
the specific capacity of rope-pump
wells in a fractured rock-aquifer in
Nicaragua
Essa L. Gross and John S. GierkeDepartment of Geological Eng. & Sciences
Michigan Technological University
Antoinette KomeSNV Nicaragua
Outline
Problem Statement
Research Objectives
Study Area
Methodology
Results
Conclusions
Problem Statement
• Practically no information exists on the productivity of rural wells in developing countries.
• Policy makers have no information to base decisions or to develop water management plans.
• The lack of technical and economic resources prevents the collection of performance and monitoring data.
Design and test a method to characterize
the productivity of existing rope-pump
wells in rural areas of developing countries
Research Objectives
Monitor seasonal changes in SWLs
and specific capacities of rope-pump
wells in an area that experiences
distinct rainy and dry seasons.
Outline
Problem Statement
Research Objectives
Study Area
Methodology
Results
Conclusions
Santa Rita
Study Area
Regional Geology
Tpc - Coyol Group
Fractured ignimbrites,
tuff, andesite, basalt
X XX
X
Source: INETER
Rope-pump well
60’
Outline
Problem Statement
Research Objectives
Study Area
Methodology
Results
Conclusions
Testing and Monitoring Approaches
• Monthly manual pump tests in triplicate at 3 wells
• Each test conducted to attain pumping, equilibrium, and recovery phases
• A conventional step-drawdown test performed in one well
Pump test regime
• Pump 60 – 90 gal
• Approximate rate of 5 gpm
• Allow well to recover for an hour or more
• Triplicate tests
Well 2 - 2/10/07
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
0 20 40 60 80 100 120 140 160 180 200
Elapsed time (min)
Dra
wd
ow
n (
ft)
Well 2 - 2/10/07
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0.5
0 20 40 60 80 100 120 140 160 180 200
Elapsed time (min)
Dra
wd
ow
n (
ft)
Recuperation
Eq
uili
briu
m
dra
wd
ow
n
Pumping
ExplanationWell 2: 1/11/07
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
0 500 1000 1500 2000 2500 3000 3500
Elapsed Time (sec)
Dra
wd
ow
n (
ft) Test 1 levelogger
Test 2 levelogger
Test 3 levelogger
Test 3 sounder
Test 2 sounder
Test 1 sounder
Equilibrium drawdown Data analysis method
Pump and recovery curves Data analysis methods
SrTt
TsQ
2
3.0log264
Cooper-Jacob Approximation in “Conventional” Units: