The evolution of dewatering systems for CBM/CSG applications

The evolution of dewatering systems for CBM/CSG
applications – past, present and future: motivation for a
new ESPCP design
Lyon van der Merwe and Attie Jonker
Don Brown
Franklin Electric SA (pty) ltd
South Africa
13 Engwena Road, Sebenza, South Africa, 1610
[email protected]
Franklin Electric Inc.
USA
400 East Spring Street, Bluffton, IN, 46714
[email protected]
Abstract – The history of tight gas artificial lift systems
are discussed from a period and technology point of view.
Practical aspects of the particular dewatering process
(artificial lift process) are considered. The impact of new
pumping technologies and modern control gear and system
management principles are elaborated on. The advantages of
comprehensively designed system solutions with respect to the
particular application are discussed.
wells in (often) close proximity. Therefore, when
considering artificial lift requirements in such applications a
multiple well viewpoint should rather be considered, as
opposed to single well operation. Several advantages could
be obtained when operating from a more holistic point of
view.
Index Terms – Artificial lift, coal bed methane, coal seam
gas, dewatering, systems.
I. INTRODUCTION
While coal bed methane or coal seam gas (CMB/CSG)
operations are associated with the oil and gas industry,
several aspects of such operations justify viewing the
dewatering process or hydrostatic pressure reduction or
artificial lift operation from a more conventional ground
dewatering perspective. The significant amount of
descriptive terms for the process is already a clue to the
overlap of the same functional requirement, albeit
approached from a different industry. At no time however,
should the requirements in the CBM/CSG production
industry with respect to safety, reliable operation be ignored.
In fact, additional effort should be considered to increase
safety, reliability, time between work overs and
serviceability.
A. Artificial lift
Artificial lift or the reduction of hydrostatic pressure is
required in cases where the natural gas pressure formed in
the coal seams cannot overcome the hydrostatic pressure. It
is also advantageous to reduce the hydrostatic pressure in
order to increase gas production.
1) Artificial lift process: The process of artificial lift
provides external energy to create additional drawdown on
the formation. This can be achieved with a rod pump, a
progressing cavity pump (surface driven – PCP or
submersible driven - ESPCP), an electrical submersible
pump (ESP) or gas compression.
2) Typical dewatering requirement: CBM/CSG
applications require (potentially) a widely varying range of
artificial lift or dewatering requirements – from several
hundreds of barrels of water per day to only a few barrels of
water per day. Irrespective of the rate of pumping, it should
always be under controlled conditions.
3) Multiple well environments: Another characteristic of
specifically CBM/CSG operations are the use of multiple
II. HISTORY OF CBM/CSG DEWATERING
The CBM/CSG industry found its origin in the oil and gas
industry. This is especially relevant since, notwithstanding
the nature of the oil and gas industry with respect to safety
and reliability, CBM/CSG application are associated with
deep settings, high pressures, and high powers and is based
on trusted and reliable product and long term experience.
A. Early days
During the early days of CBM/CSG the artificial lift or
dewatering equipment used, mostly stemmed from the oil
and gas industry to which the CBM/CSG industry belongs.
Fig. 1 Beam pump
Figure 1 is a picture of a beam pump. The use of oil and gas
industry equipment was due, mainly to the need for deep
settings, high operating pressures and large power levels. In
CBM/CSG applications the need to dewater relatively deep
coal seams (usually far below the useful groundwater level)
meant that the more conventional well or borehole
equipment could not easily meet the CBM/CSG dewatering
needs. Often the balance between operating power levels and
the need for high starting torque also influenced and biased
the use of oil and gas artificial lift equipment in the
CBM/CSG industry.
during initial the dewatering stage, the production phase
requires reduced power levels to pump lower volumes of
water.
C. Today
If history is a measure to go by, the CBM/CSG artificial
lift market, served by a mixture of traditional oil and gas
pumping equipment and more conventional water well
equipment, will see a continued gradual progressing towards
using more conventional water well pumping equipment.
One reason for the effective use of progressing cavity pumps
stem from the need for a very wide range of duty points with
respect to operating pressure, considering that the
CBM/CSG dewatering application requires pumping down
water levels, sometimes ranging from ground level to levels
of 500 to 1500m below surface.
Fig. 2 Surface driven progressing cavity pump (typically 2-3 meters off the
ground).
On the other hand the CBM market in the USA has been
using centrifugal submersible pumping systems for a
significant number of years. To support this market the
continuous improvement in the electric motors and
centrifugal pumps to address this need has led to the
development of dedicated submersible motors and pumps
for the CBM/CSG market.
However, these products were trusted and had long term
records of reliability and were technologies that was well
understood, meaning that expertise were available to operate
and service the equipment. In fact that is still true for today.
The confluence of the latter with effectively 40-50 years’
experience in the progressing cavity pumping industry has
resulted in an exciting new development that will make a
substantial contribution to the CBM/CSG market.
B. Later development
Eventually the products used in conventional water well
pumping applications found its way into the CBM/CSG
industry – including the necessary modifications with respect
to materials, robustness and adaption of pressure and flow
characteristics.
III. PRACTICAL ASPECTS OF THE ARTIFICIAL LIFT PROCESS
Fig. 3 Electrical submersible pump (ESP), typically used in the
conventional water well industry, applied to a CBM/CSG application
(typically 0.5 meters off the ground).
During the 1990’s the USA CBM/CSG market started to us
conventional water well pumping equipment extensively.
Figure 3 is a picture of such an ESP installation. It became
apparent that while higher power levels may be required
In CBM/CSG dewatering applications several aspects,
contrary to conventional water well pumping need to be
dealt with. Solids handling is an important issue. The
CBM/CSG application does not deal with clean water
pumping. Hence a suitable pump needs to be able to manage
especially fracture sand, coal fines and even larger coal
particles. Additionally, one needs to deal with gas entrained
water when dewatering coal seams. The level of gas-cut is
often unpredictable and variable. Thirdly, unknown water
conditions (varying pressure conditions and flow rates) make
it difficult to size pumps and control it. Water quality and
chemical composition also complicate the application. It is
also important to consider the surface impact of the pumping
equipment. Since multiple wells (vertical or horizontal) are
often required a reduction in surface impact will always be
welcome. Another significant consideration with artificial
lift systems for CBM/CSG would be operating cost per well,
as cost can add up rapidly when considering a multitude of
wells.
A. Solids handling
Possibly one of the most important design features in the
Franklin Electric pump is the exclusive heavy duty ball
check valve. See figure 4. This feature prevents any possible
backspin and if any sand is present in the rising main, it will
settle on top of the check valve. The PC pump is designed to
produce enough pressure with the next start-up that it will
discharge the sand to the surface.
A further consideration for any installation is to use the
smallest diameter pipe possible with the correct
specifications to ensure that the highest water velocity
possible is achieved, to move any frac sand and/or coal fines
through the discharge. Features such as these contribute
substantially to the success of the ESPCP design, as has been
proven in case studies. See later on. Pumps pulled for
routine inspection contained up to 10m of pipe above the
pump filled with frac sand and coal fines.
Fig. 5 ON/OFF control – the saw tooth bold line shows the water level.
Figure 5 also illustrates the possibility of controlling the
maximum pump speed (high flow rate pulses in the first half
of the graph) to ensure sufficient fluid velocity thereby
transferring suspended solids to surface. The ON/OFF mode
of operation is made possible by the heavy duty ball check
valve design.
One parameter that influences the pump selection is the
minimum flow characteristics. Conversely, the selected
pump minimum flow may be chosen based on critical tubing
velocity. As discussed in [3], if the tubing flow velocity is
less than the critical transport velocity of the sand/coal
particles, it will settle out in the tubing above the pump. In
the case of the new ESPCP design the settling will take place
on top of the check valve, preventing particles from settling
in the rotor stator. Particle accumulation can also create a
partial or complete blockage 9as experienced in case studies
undertaken) in addition to increasing the overall fluid
density. Any of these situations will cause higher pump
discharge pressures.
Fig. 4 Electrical submersible progressing cavity pump (ESPCP)
construction
The case studies also revealed that ON/OFF operation of the
pumps could be implemented (maintaining a reasonable
cycle time to avoid motor damage) without any noticeable
start-up difficulty. This mode of operation, together with the
normal continuous mode of operation over the complete
speed range makes a large turndown ratio in volume pumped
possible. See Figure 5. [1]
In the example below the graph represents the critical tubing
rate for various U.S. standard sheave sizes. See figure 6. If
tubing flow rates fall below this line, there is a strong
possibility that the velocity will not be sufficient to transport
that particular particle size to surface. Therefore, as the
required dewatering needs drop to below this minimum
continuous rate of pumping, an ON/OFF mode of operation
may prove useful and in fact desirable, given that the ON
time makes provision for at least one tube volume being
displaced per cycle.
Fig. 6 Critical Sand Settling Rate for specific riser area (approximately 4
square inches) [3]
B. Entrained gas
Laboratory tests [2] conducted during the development
of the ESPCP show that a gas cut of up to 60% results in
only a 25% loss in flow rate and even less at maximum
operating pressure. See figure 7.
loop control to achieve control of the desired parameter
(water level or bottom-hole pressure or any other parameter
that is used to control the operation of the well) by
maintaining an average set value. This mode of run time
modulation can be used until the flow rate during the ON
time drops below the critical tubing velocity. It must also be
noted that the pump design needs to take starting
characteristics of the pump into consideration as well, to
make frequent starting possible without creating potential
high starting torque situations but at the same time maintain
high levels of efficiency. See figure 9.
Figure 9 Large turndown ratio operation
Fig. 7 Electrical submersible progressing cavity pump (ESPCP)
construction
C. Unknown water conditions
Widely varying water flow rate requirements and a large
variation in required pressure management make it difficult
to select one pump through-out the life of a CBM/CSG well.
However, during the initial stages of the well’s life it will be
helpful to reduce pump change-outs to a minimum. The new
ESPCP design, in combination with the necessary control
system can increase the dynamic range of the first pump
installed to reduce work-over requirements. Figure 8 shows
the range over which the required water production may
vary.
D. Surface impact
Since several wells may be required on a CBM/CSG
field, the surface impact will play an important part. Figure
10 is an illustration of a rather innovative way of
camouflaging large surface components, while figure 11
illustrates an installation of the latest ESPCP technology.
Figure 10 Rod pump in children’s play park
Fig. 8 Exponential decline of water in a typical well [4]
Since the pump design provides for ON/OFF operation (ball
check valve) this mode of operation can be used in closed
reliable start/stop operation and energy optimized solution,
based on the correct motor control applied over an extended
operating range, including full and partial load conditions.
B. Measuring equipment and telemetry
In CBM/CSG applications it is normally required to
report the amount of water pumped, the gas flow rate.
Additionally the water level needs to controlled, making it
necessary to obtain information on the down hole pressure
and casing pressure. Solutions are offered today that
integrate all the necessary measuring equipment, integrated
in such a way that all the information is readily available.
Figure 12 illustrates such a system offering. Reliable
measurements, accessibility, compatibility and serviceability
is possible without unnecessary capital outlay.
Figure 11 Reduced surface impact, incorporating significantly more
operating information
This installation incorporates telemetry, well control, data
concentration and communication, integrated into a single
system.
The correct control system will also reduce the need for
regular site visits and surface disturbance. Remote control
and data collection ensures that site visits are undertaken on
a need to basis only.
E. Well operating cost
While initial CBM/CSG artificial lift installations made
use of large (10’s kW) installations, the selection of the
correct pumping equipment can reduce both capital and
operating costs substantially.
Results obtained from recent installations show that typical
power levels can be as low a 600W- 3kW to maintain the
correct water levels at depths of 280m - 480m. Control
panels with drives and motors rated at 7.5kW are used in
these applications. Substantially oversized equipment will
result in poor efficiencies, higher input power levels and
increased operating cost.
Nevertheless provision should be made for the necessary
starting torque and control to ensure reliable operation. High
starting torque capability and high operating efficiencies can
be obtained with the correct pump design.
IV. IMPACT OF MODERN CONTROL GEAR AND SYSTEM
Figure 12 Complete CBM/CSG control system, incorporating control
panel, measuring equipment, telemetry and communication integrated on a
single skid.
Another aspect of the proposed measuring equipment that
may result in significant future advantages is based on the
fact that the proposed systems solution offers a per well
affordable measurement capability of gas and water flow
rates, making the detection of line leakages (in both water
and gas) at early stages possible. Additionally, water (total
dissolved solids – TDS) and gas (methane content or
Wobble index) quality can also be monitored.
MANAGEMENT
Modern control gear and system management capabilities, in
collaboration with the new ESPCP design make it possible
to operate CBM/CSG dewatering/artificial lift systems using
compact integrated solutions, ensuring component
compatibility, reliable operation and user friendly operation.
A. Harmonious motor, pump and control system selection
The new pump design, together with the appropriate
control system ensure an optimized system, capable of the
necessary starting torque, high operating efficiencies,
V. FIELD EXPERIENCE
Several systems have been installed over the past 2 years,
with the bulk number of installations taking place during the
period March to November 2011. The results to date are
summarized in Appendix 1.
A. Background
The core development (based on several years’ pump
and motor experience) was focused on the close-coupling of
the pump and motor. Laboratory tests confirmed designs.
Production models were fabricated and installed in several
wells with a broad spectrum profile, including production
phase wells and pilot wells.
Complete systems were installed, including control panels,
measuring and telemetry equipment as well as
communication equipment. Data was collected on a
continuous basis to facilitate the evaluation of well, pump
and system performance, thereby eliminating the need to
extract pump for evaluation purposes. This made it possible
to obtain early life cycle performance data from various
pumps.
B. Pump and motor performance
Motor performance did not show any significant
unexpected results. The CBM motor is an improved
(materials and minor construction details) version of a
design that has been used extensively in CBM wells in North
America.
Pump performance results indicate and confirm progressing
cavity pump behavior where non-ideal sandy and solids
conditions prevail. High levels of solids impact observably
on pump performance. To estimate pump life after two
years’ of field installations, continuous speed versus flow (at
constant pressure) performance (where available) was
recorded as a measure of wear. The table below shows the
results. Since pressure loss is the main contributor to
performance failure and since the pump speed can be varied
(continuously) over a 2:1 range a representative life time can
be estimated, based on the assumption that a decrease of
performance of 40% will be equivalent to pump end-of-life.
Table 1 Estimated pump life
Assuming a linear wear pattern for the present sample it can
be said that pump life varies between 1.28 years and 9.4
years. These numbers need to be tested over time. In actual
terms, given real time operation, the average run time to date
per pump is approximately 10 -11 thousand hours. This is
the time during which the data was collected and the
projections are based.
The performance results of the new ESPCP development in
the field is positive and indicates a sufficient degree of
success to warrant implementation of the current pump
design.
C. System, data and communication
The value of real time continuous data collection is clear
when considering the results obtained from the field
installations where data was available. Challenges associated
with communication, measurement of multiphase media and
other system characteristics were identified and solutions
implemented. Reliable systems operation and management
was illustrated through the successful operation of two 5spot sites, included in the field data presented.
Several installations in North America (USA) produced
positive results in production wells, including shale wells.
Stripper well applications are also envisaged.
REFERENCES
[1]
[2]
[3]
Solids content and size will always play a dominant role in
this estimation. Additional, observations have indicated that
some wear characteristics include non-linear wear patterns,
meaning that wear may set in initial but be arrested at a
particular point in time. This may be attributable to wear
caused by particles /solids of a specific size reaching a final
or limiting wear characteristic, once tolerances between
rotor and stator reach levels sufficient to pump particles of
a particular size. This observation does make the present
linearized model conservative and it is conceivable that
longer pump life times may be experienced once sufficient
real time data becomes available.
Another important observation, pertaining to pump
performance, is the increased accumulation of solids in the
rising main/tubing where critical fluid velocities (velocities
capable of ejecting solids at the surface) are not met. Solids
accumulating and increasing in the riser/tubing will impede
pump performance by creating an increasing restriction on
the pump, resulting in reduce performance, not because of
pump wear but because of an external restriction placed on
the pump in the form of an increased outlet pressure
condition.
[4]
A. Jonker, Exploring ESPCP (Electric Submersible Progressing
Cavity Pumps) as a dewatering method in Coal Bed Methane gas
fields, Internal report, franklin Electric SA, May 2012.
Laboratory tests – ESPCP development, Franklin Electric Inc.
Bluffton Indiana, 2010
Gas Well Deliquification, 2nd Edition, James F. Lea, Henry V.
Nickens, Mike R. Wells, ISBN: 9780750682800, 2008
Halliburton, Coalbed methane principles and practices, 2008,
Halliburton Company.
APPENDIX 1 - FIELD DATA
Well 1
Well Type
CBM/CSG
Pump type
ESPCP
Motor type
Submersible CBM
Cable
Permatrail 10 round
Rising main/tubing
J 55 2"
Pressure transducer
4-20mA
Well head
Modified
Gas flow meter
DP Pitot
Water flow meter
Mag flow
Control panel
CBM skid mounted
VSD
7.5kW
Controller
RTU IP
Communication local
2.4GHz
Communication remote
GSM
Water line pressure -operating (bar)
<3
Casing pressure max. (bar)
<5
Total vertical depth (m)
286
Total insertion length (m)
286
Angle of pump from vertical (Deg)
0
Target flow (bbl/d)
150
Actual flow (bbl/d)
160
Water quality TDS ppm
<4000
Solids %
Low
Solids type
Sand
Solids size
Fine
Was a shroud used
No
Well construction
Close cased
Flow rate/Freq
57
Flow rate/Freq (150 days' operation)
55
Initial install date
Mar-11
Total recorded run time (h)
10658
Number of Days in Operation
534
2nd Unit Install date
Total recorded run time (h)
Number of Days in Operation
Power supply
Mains
Comments
Running
Well 2
CBM/CSG
ESPCP
Submersible CBM
Flexible 10 round
Flexible CBM Lay Flat
4-20mA
Modified
DP Pitot
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
GSM
<3
<5
280
280
0
150
120
<6000
High
Sand & Fines
Coarse
No
Close cased
57
56
Oct-10
181
Mar-11
9725
405
Mains
Severe scaling
present. Pump
replaced Feb 2012.
Pump removed May
2012.
Well 3
CBM/CSG
ESPCP
Submersible CBM
Flexible 10 round
J 55 2"
4-20mA
Modified
DP Pitot
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
GSM
<3
<5
274
274
0
150
100
<4000
Low
Sand
Fine
No
Close cased
39
34
Mar-11
11894
535
Mains
Running.
Well 4
CBM/CSG
ESPCP
Submersible CBM
Flexible 10 round
J 55 2"
4-20mA
Modified
DP Pitot
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
GSM
<3
<5
286
286
0
150
75
<4000
Low
Sand
Fine
No
Close cased
Mar-11
7810
356
Feb-12
-7810
179
Mains
Running. Pump
replaced with lower
flow rate.
Well 5
CBM/CSG
ESPCP
Submersible CBM
Flexible 10 round
Bore Quip (synthetic)
4-20mA
Modified
DP Pitot
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
GSM
<3
<5
280
280
0
150
70
<4000
Low
Sand
Fine
No
Close cased
19
18.5
Mar-11
11795
535
Well 6
CBM/CSG
ESPCP
Submersible CBM
Flexible CBM 10 Flat
J55 2"
4-20mA
1500psi
DP/Ultrasonic
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
Satellite/GSM
<3
<5
490
490
0
300
110
<3000
Low
Sand & Fines
Fine
No
Close cased
Nov-11
3670
157
Well 7
CBM/CSG
ESPCP
Submersible CBM
Flexible CBM 10 Flat
J55 2"
4-20mA
1500psi
DP/Ultrasonic
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
Satellite/GSM
<3
<5
484
484
0
300
80
<3000
Low
Sand
Fine
No
Close cased
Nov-11
3710
155
Well 8
CBM/CSG
ESPCP
Submersible CBM
Flexible CBM 10 Flat
J55 2"
4-20mA
1500psi
DP/Ultrasonic
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
Satellite/GSM
<3
<5
480
480
0
300
40
<3000
Low
Sand
Fine
No
Close cased
Nov-11
676
88
Mains
Generator
Generator
Generator
Running.
Well 9
CBM/CSG
ESPCP
Submersible CBM
Flexible CBM 10 Flat
J55 2"
4-20mA
1500psi
DP/Ultrasonic
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
Satellite/GSM
<3
<5
490
490
0
300
70
<3000
Very high
Sand
Coarse
No
Close cased
Nov-11
3102
158
Aug-12
36
Generator
Well 10
CBM/CSG
ESPCP
Submersible CBM
Flexible CBM 10 Flat
J55 2"
4-20mA
1500psi
DP/Ultrasonic
Mag flow
CBM skid mounted
7.5kW
RTU IP
2.4GHz
Satellite/GSM
<3
<5
475
475
0
300
270
<6000
Low
Sand
Fine
No
Close cased
May-11
204
Nov-11
3770
158
Generator
Well 11
CBM/CSG
ESPCP
Submersible CBM
Armoured Flat
4-20mA
Ultrasonic
Mag flow
CBM skid mounted
11kW
RTU IP
GSM
690
800
78
74
Yes
Mar-12
0
Generator
Running. Casing
101mm ID - restricted
Running. Casing
space. Extreme sand
Running. Pump
101mm ID - restricted
content. Pump
Running. Casing 101
replaced. Casing
Abandoned. Casing
space. Pump and
replaced once.
Pump replaced due to
mm ID - restricted
101mm ID - restricted 101mm ID - restricted
Maximum frequency motor replaced once
silting. Flow sleeve
space. Well shut down
space. Well shut
space. Well
reached after 154 days due to scaling. Well
design changed.
for rehabilitation Mar
down for
abandoned - not
and coloumn (3 meter
shut down for
2012 - Aug 2012.
rehabilitation Mar
viable.
length) filled with
rehabilitation Mar
2012 - Aug 2012
sand. Well shut down
2012 - Aug 2012
for rehabilitation Mar
2012 - Aug 2012
Figure 13a Field data. During the operational period in cases where changes were made to pumps or motors data averaging was used to obtain meaningful results. Pump wear information provided was obtained on a continuous basis by
comparing flow rate versus frequency for constant pressure duty points. Pumps were only removed and tested once operational requirements could not be met. In these cases pump tests confirmed loss of performance to below useful duty.
Well Type
Pump type
Motor type
Cable
Rising main/tubing
Pressure transducer
Well head
Gas flow meter
Water flow meter
Control panel
VSD
Controller
Communication local
Communication remote
Water line pressure -operating (bar)
Casing pressure max. (bar)
Total vertical depth (m)
Total insertion length (m)
Angle of pump from vertical (Deg)
Target flow (bbl/d)
Actual flow (bbl/d)
Water quality TDS ppm
Solids %
Solids type
Solids size
Was a shroud used
Well construction
Flow rate/Freq
Flow rate/Freq (150 days' operation)
Initial install date
Total recorded run time (h)
Number of Days in Operation
2nd Unit Install date
Total recorded run time (h)
Number of Days in Operation
Power supply
Comments
Well 12
CBM/CSG
ESPCP
Submersible CBM
Armoured Round
2 3/8" EUE
4-20mA
0
150
Well 13
CBM/CSG
ESPCP
Submersible CBM
Armoured Round
2 3/8" EUE
4-20mA
Well 14
CBM/CSG
ESPCP
Submersible CBM
Armoured Round
2 3/8" EUE
4-20mA
Well 15
CBM/CSG
ESPCP
Submersible CBM
Armoured Round
2 3/8" EUE
4-20mA
Well 16
Shale
ESPCP
Submersible CBM
Well 17
Shale
ESPCP
Submersible CBM
2 3/8" EUE
4-20mA
2 3/8" EUE
4-20mA
0
150
146
146
0
75
483
483
0
300
302
302
0
30-35
335
335
0
30-35
Well 18
CBM/CSG
ESPCP
Submersible CBM
Armoured Round
2 3/8" EUE
4-20mA
0
150
Well 19
CBM/CSG
ESPCP
Submersible CBM
Armoured Round
2 3/8" EUE
4-20mA
0
75
Well 20
CBM/CSG
ESPCP
Submersible CBM
Well 21
CBM/CSG
ESPCP
Submersible CBM
2 3/8" EUE
4-20mA
2 3/8" EUE
4-20mA
0
150
389
389
0
75
Very High
Sand
Very High
Sand
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
28-Jun-11
28-Jun-11
29-Jun-11
08-Sep-11
17-Nov-11
09-Jan-12
Jun-11
Jun-11
Jun-11
11-Sep-11
453
453
452
381
311
258
7
7
98
Nov-11
30
16
Running
Running
Running
Running
Running
Running
Initial Install - Sand
wore hole in motor
shell
Pump not sized right
High sand content
2nd Install - Tubing
well. Initial ESP
for well. Removed to broke severing cable.
Pump failed - Run Dry
Shroud filled with installed into this well
be placed in another
sand around motor
lasted 7 days.
well
and up to intake of
pump. Still running
OK at time of removal.
Figure 13b Field data. During the operational period in cases where changes were made to pumps or motors data averaging was used to obtain meaningful results. Pump wear information provided was obtained on a continuous basis by
comparing flow rate versus frequency for constant pressure duty points. Pumps were only removed and tested once operational requirements could not be met. In these cases pump tests confirmed loss of performance to below useful duty.