Aquifer Airlift Testing

26 Pages·2016·1.38 MB·English

by  Chris Lang

Aquifer Airlift Testing
Presentation for the CWWCA Annual Meeting 2008

by Hank Baski

Colorado Springs

January 12, 2008
Overview Aquifer Airlift Testing
Ground Water: Fallacies & Forecasts
• Commonly believed fallacies hinder optimal development of water wells:
– The use of clear water as drilling fluid results in the “best” well
– Artificial gravel pack is needed for sand-free, high-efficiency wells
– Step pumping aquifer tests can determine well efficiency
– Air-lifting cannot be trusted for reliable aquifer pumping tests
and can air-bind a well
• New technologies and innovations will impact the water well industry
over the next decade:
– Horizontal wells will play a greater role in water recovery and injection
– Pricing for larger sedimentary wells will be based on
well efficiency instead of footage
– Unique, new methods for well development will arrive
– Energy savings will drive widespread adoption of
aquifer thermal energy storage
• Case Study: Development of the Denver Basin Aquifers
• Question & answer session
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Experience Aquifer Airlift Testing
“Hank’s Guide to Wellness” Builds on 40 Years Of:
• Drilling
– Started in water well business while in high school
– Helped to build a cable tool drilling rig for the family drilling
business in Northern Minnesota
– Moved business to Pueblo, Colorado
• Consulting in Ground Water Hydrology
– Based in Denver, Colorado
– Projects nationwide
• Manufacturing
– Recognized need for ground water tools
– Decided to develop products: pitless units, inflatable packers, and
downhole flow control valves (currently seven patents on these)
My Motto (I’m not an easy boss…): “question everything &
everyone - including yourself - and be willing to change”
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Experience Aquifer Airlift Testing
My Experience with Air Lifting
• First used in 1959 with Ingersoll-Rand down-the-hole hammer
rig in Northern Minnesota
• Aquifer testing
– 1968 to 1974 with Wright Water Engineers
– 1976 to 1987 as self-employed hydrologist
– 1978 to present in “free” consulting to various customers
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Basics Aquifer Airlift Testing
How & Why Does Airlifting “Pump” Water
- and Related Facts
• Column of water in a well is replaced with an air-water mixture
that “weighs” less
• In most cases airlift aquifer testing is more reliable than other
methods as casing and nearby fracture storage effects are
minimized
• Pumping rates and pumping levels are easy to obtain
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Basics Aquifer Airlift Testing
Example
air
air-water mixture
0
static water level
300
pumping
water level
600
end of air pipe
1,000
non-aerated water
1,200
Aquifer
1,600
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Basics Aquifer Airlift Testing
Air-lifting: Principles, Definitions & Example
Principles of Operation:
1. Aerated column is lighter than submergence
(think of a lake and then progress to a well)
2. Aerated column during pumping + friction loss = submergence
3. Empirical relationships are “state-of-the-art”. Probably, it’s
impossible to derive and/or calculate accurate formulas describing
requirements and performance of all air-lift operations.
Key Definitions: Example Specifications:
• Pumping Submergence • 8 inch borehole or well pipe I.D.
PS % = (APD - PWL) / APD • 2 inch air pipe I.D.
APD = Air Pipe Depth • 40% pumping submergence
PWL = Pumping Water Level • 1900 cfm air compressor delivery
• Static Submergence • 450 gpm air-lift pumping capacity
SS psi = APD - SWL
APD = Air Pipe Depth
SWL = Static Water Level
Sources: Why Air-lift Pumping Tests by Hank Baski (Feb’79), Baski Inc. Catalog #6
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Basics Aquifer Airlift Testing
Approximate Air-lift Pumping Capacities
Borehole Air Air Compressor Requirements
or Compressor
• Pressure rating [psi] must be 20%
well Air Pipe Pumping Submergence % Delivery greater than the Static Submergence
Pipe Tube [psi].
Nominal Actual • Volume rating [cfm or cubic feet per
Size OD 10% 20% 40% 60% 80% minute] must approximate values from
(inch) (inch) (gpm) (gpm) (gpm) (gpm) (gpm) (cfm) this table for hydrology testing:
3/8 1/8 0.08 0.3 0.5 0.7 7.4 – If the water production surges, i.e.
1/2 3/16 0.17 0.6 1 1.4 12 varies in gpm rate, then a
3/4 1/4 0.4 1.4 2.4 3.4 20 GREATER cfm is needed.
1 3/8 1 3 5 7 31
– On the other hand, well
1-1/2 1/2 3 8 13 18 77 development by air-lift pumping is
enhanced by surging; therefore, a
Pipe Pipe
LOWER cfm is desired for part of
Nominal Nominal
the development period.
Size Size
– Do not significantly exceed the
2 1/2 0.5 5 15 25 35 120
listed air delivery rate [cfm] as this
3 3/4 2.5 15 40 65 90 270
will dramatically increase the
4 1 5 28 75 125 175 470
friction loss in the annular area,
5 1-1/4 7.5 50 140 230 320 740
causing the water production to
6 1-1/2 12 80 225 370 520 1100
decrease to the point where if too
8 2 25 150 450 720 1000 1900
much air is introduced, no water will
10 2-1/2 50 300 800 1300 1800 3000
be produced.
12 4 75 450 1200 1950 2700 4000
14 4 90 600 1700 2900 4000 5100 NOTE: 1 foot of water = 0.433 psi
1 psi = 2.31 feet of water
16 5 100 800 2400 3900 5500 6600
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How To Aquifer Airlift Testing
Airlift Set-up For Aquifer Testing
• Maximize water production by using 1/3 of casing I.D for the air
pipe O.D.
• Calculate air compressor volume requirement for 6,000 feet/min.
velocity in annulus
• Pressure requirement for “unloading” is submergence (in PSI)
plus 10 to 20% more
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How To Aquifer Airlift Testing
Things To Consider For Aquifer Airlift Testing In
Mountain Wells
• During drilling the drill cuttings “load” in the annulus reduces
water production
• 4-1/2” drill pipe also reduces water production in a 6” hole: the
optimum air pipe O.D. for testing would be 1-1/2” nominal
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