8th Middle East Artificial Lift Forum (MEALF) Technical ... · Therefore, in addition to contribute...
Transcript of 8th Middle East Artificial Lift Forum (MEALF) Technical ... · Therefore, in addition to contribute...
8th
Middle East Artificial Lift Forum
3-5 February 2015
Ritz Carlton Hotel, Doha -Qatar
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8th Middle East Artificial Lift Forum (MEALF)
Technical Paper Proceedings
3-5 February 2015
Doha
Qatar
8th
Middle East Artificial Lift Forum
3-5 February 2015
Ritz Carlton Hotel, Doha -Qatar
2
Copyright Statement
The views expressed in the papers are those of the authors and do not
necessarily represent the views of MEALF.
This publication is protected by copyright law. All rights reserved. No part of
this publication may be reproduced, stored in a retrieval system, or
transmitted in any form or by any means, electronic, mechanical,
photocopying, recording or otherwise, without the permission of MEALF
and/or the author.
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Middle East Artificial Lift Forum
3-5 February 2015
Ritz Carlton Hotel, Doha -Qatar
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Operating Electric Submersible Pumps: How to achieve long life-time in
challenging reservoirs?
B. Viguerie (TEP Qatar); E. Toguem, P. Lemetayer, P. Perusat, (Total S.A);
Abstract
Artificial lifting with ESP contributes to accelerate and increase recovery. However,
occurrence of short runs can strongly reduce MTTF and economical cut-off. This paper
focuses on mitigating such failures.
Firstly, a statistical analysis derives the instantaneous failure rate. The curve shape includes
the failure contribution from early failures, event driven failures and finally normal or long
wear-out failures. Developing a cause tree identifies the most efficient preventive solution.
Several field cases are presented with challenging wells producing with a high gas fraction. It
shows how ESP run life involves the whole production system from surface to Bottom Hole.
Two examples illustrate how well dynamics or furtive conditions can be the root cause of
severe wear leading to short runs especially for challenging reservoir. A third field example
quantifies gains from active automation. Statistical analysis shows the reduction of short runs
and the effect of water cut. A new tool quantifies run life increase and OPEX reduction when
corrective actions lead to very few failures. Technical improvements can strongly extend the
run life depending on long term wear out failures. However, mastering both the production
system design and active control of the operational system is key to fully addressing the
various root causes of short runs allowing the operator to benefit from the full effect of
modern ESP designs.
Introduction
The artificial lift technologies are becoming more and more important today and all the major
companies are careful to news R&D project about ESP. Since the beginning of the utilization
of ESP for oil and gas industry the applications has significantly expanded. Manufacturers
focus mainly on innovation to improve ESPs run-life and range of application. Since the early
1980’s, TOTAL EP (TEP) has been involved in developing and testing new ESP technology.
Indeed, TEP has been operating challenging offshore fields requiring improved technology to
extend the economic limit. Due to the challenging reservoir conditions, attention should be
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Middle East Artificial Lift Forum
3-5 February 2015
Ritz Carlton Hotel, Doha -Qatar
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given to each ESP to improve their run-life to challenge costs. Challenging reservoir
conditions mainly combine medium temperature, gassy or viscous fluids and strong transient
due to reservoir heterogeneities. Therefore, in addition to contribute to new ESP design,
TOTAL has developed a mastering of ESP driving. No doubt that a good design is not
enough to achieve good run-life in challenging conditions.
This paper explains how TOTAL has transformed the difficulty imposed by challenging
reservoirs in various fields from Middle East, Europ and Wet Africa to a really mastering of
ESP driving.
Material and Method
The following part details three points:
- Example of gas lock with developing cause tree to make difference between fatal or
aggravating parameter
- Analysis of a number of challenging reservoirs using ESPRIFTS tool to extend the
understanding further from cause tree analysis
- To end with results of new active automation for a true dynamic control
Cause tree to make difference between fatal or aggravating parameter
One of the major objectives to understand the behavior of an ESP is to identify the cause of
failure. In almost all cases of ESP failure there are not one causes of failure but a sequence of
events which is leading to the failure through a cascade. It is important to break down this
sequence because a problem can be masking others. For that, in addition to the tear down, it
is very interesting to analyze the operating conditions and ESP behavior before the ESP
failure. In other terms, the analysis should not be limited to observe the failed equipment but
it should include the detail of all the events during the ESP runlife. The usage of tools as a
“cause tree” allows tracking the origin of the problem and determining which parameter is the
root cause and the degree of criticity of others parameters.
The following example shows the importance of cause tree utilization to determine the
criticism of each parameter. With this approach it has been demonstrated that the high
reservoir temperature is not a root cause of failure but a parameter which reduces the
tolerance of temperature excursion.
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Ritz Carlton Hotel, Doha -Qatar
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Example: Field in West Africa with a reservoir temperature 90°C, ESP run life : 467 days
Fact:
When the ESP was restarted we observed a no flow rate at the well head and the temperature
motor was unreasonably high (102°C). At the stop of the ESP the temperature motor quickly
rose to 130°C. Then, it was impossible to restart the ESP. The equipment which failed was
the cable.
Analysis :
This cause tree shows that the root cause of the failure was a slug of gas. When this slug
passed through the pump, it locked the flow-rate through the pump which is well known as
gas-lock mechanism. As a result, there was a no-flow rate situation over a significant period.
Therefore the motor could not be cooled and the motor
temperature rose. But the most important fact was
invisible: the fluid locked in the pump could not be
evacuated. As the pump was still running, these fluids
trapped in the pump were heating up. A too long
duration of no flow rate period has resulted in a severe
heat up. At the stop of ESP, these fluids fell back and
burnt all the components below the pump intake over
Pump power
Gas lockNo flow rate
no cooling
Temperature fluid
reservoir
Unsufficient
mitigation by
operating
Very hot
fluids in the
pump
Too Long heating up of motor and pump
Critical isolation
damage
ELECTICAL SHORT
Time
Hot motor
Back
flow
Pump
stop
P
M
S
Cable
At the stop of the
pump, back flow of fluid > 170°C
Motor temperature :
102°C 130°C
Restart and stop due to insulation fault
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less than one minute (Motor temperature rose to 130°C). Particularly, the power cable
insulation has been seriously damaged. The temperature of this fluid was estimated above
170°C because the melting point of the insulation material has been exceeded. However the
consequence is only caught when restarting up.
This case was observed a number of times again
in fields in Middle East. However as the reservoir
fluid temperature is lower in the field in Middle
East (60°C) than the previous case 90°C there was
not the same level of consequence. The right
graph shows the difference in margin when the
reservoir temperature increases.
This analysis shows many conclusions: for TOTAL the clarification of this type of problem
allows to develop knowledge to master the operation of ESP. The protection by motor
temperature trip is not enough. Thus, the duration of no flow conditions can be significant
due to delay between round surveys. Moreover, it permits to make the difference between
fatal situation such as a long no flow period and an aggravating parameter. As example, the
reservoir temperature reduces the tolerance of temperature excursion
Extending understanding further from cause tree analysis
The aim of all these investigations is to understand all the failure modes. It is valuable to use
statistic analysis to account for the large variations of the operating conditions or of the
characteristics of produced fluids at a particular time from the reservoir.
The software used for this analysis is ESP-
RIFTS®. This tool gives users the possibility to
carry out reliability analysis. Theses analyses
bring out some category of failure mode and
their weight to determine areas of ESP run-life
improvement. In fact, failures can be divided
in tree classes: early failure, event driven
failure and long term wear out failure.
With courtesy from ESP-RIFTS
Temperature (°C)
Time
T° réservoir 90°C
T° max coaling
170°C
Gas-lock Back Flow
T° réservoir 60°C
Motor temp
TCHM103 Congo
120°C
100°C
Estimation of pump
fluid temp CHM103
Congo
Motor temp
ALK 46 Qatar
130°C
Estimation of pump
fluid tempALK46
Qatar
Cum
ula
tive failu
re%
Time
Long term wear
out failure
« Random »
or eventdriven failure
Early
failure
1
2
3
Short runs Long runs
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Ritz Carlton Hotel, Doha -Qatar
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Let us review these three families of failure causes which practically will be divided into two
groups of root causes.
The first group concerns short runs or long runs. It relates to completion from engineering or
deployment aspects. Engineering aspects include architecture, type or grade of equipment,
design of components. It concerns the families of early and long term wear out failures.
The first family (early failure) represents the part of the short run failures which result from
manufacturing or deployment problem. The long term wear out failure represents the failures
due to the normal wear of equipment. This first family of failures is quickly and easily fixed
because problems of manufacturing or deployment are usually clearly identifiable. For the
third family, failure is due to old age equipment. Increasing this family of run life also
depends on the quality of equipment. Thus, these two families are not the major concern for
this paper.
The second group is related to failures at any time. The root cause is linked to operating and
called “event-driven failures”.
This type of failure cannot be always anticipated by a
good design. Indeed, the design accounts for operating
margins. However, a severe transitional period associated
with inappropriate transient operating conditions will
exceed the design margins and may seriously damage the
ESP.
This group of failures is ‘major’ for ESP run-life in
challenging reservoir conditions because the fluid is not
always mono-phase. As the gas and water fractions are changing at the pump intake, the ESP
is exposed to large fluctuations of load.
Early failureeasy to correct Long term wear out failure
Improvement of Materiel(manufacturer)
Cum
ula
tive failu
re%
Cum
ula
tive failu
re%
TimeTime
Event driven failure
(environment and operationcondion)Good ESP driving
Cum
ula
tive failu
re%
Time
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The two extremely critical cases are the emulsion and the gas lock.
These two critical cases generate mechanical wear out for the pump (shaft, impeller, torque)
and the seal-section. It contributes to damaging temperature excursions due to bad cooling
(small flow rate).
The consequences for these two cases are similar but the causes are opposite. While, the
emulsion lock is characterized by a significant charge and so an over current, the gas lock is
characterized by zero load and intensity fall.
This type of case can be fatal for ESP or at least damaging. In challenging reservoirs, it is
possible to have a succession of “small damage” conditions. It generates a quick wear which
is no easily identifiable.
This type of event driven damaging condition
is called “furtive condition”. Mastering these
furtive conditions is the major objective to
improve ESP run-life in challenging reservoirs.
The right graph confirms the two effects of gas
fraction and WCT on the run life of ESP’s
systems.
Developing an efficient solution from advanced understanding
The strength and the occurrence of all the fluctuations of fluid properties at pump intake
cannot be anticipated. As example, the time and duration of all the gas slugs cannot be
predicted.
Difficult and furtive conditions are hardly fully predictable in the wells. It is similar to
driving a car during a bad weather such as a sand storm. The occurrence, the strength and the
position of sand dune movements are not fully predictable. Moreover wells are not always
easy to access quickly enough (Offshore, weather conditions …). Therefore it is crucial to use
automated and stand-alone system to continuously drive properly the ESP.
Total has developed a new dynamic control system which mitigates the furtive damaging
condition in the aim to improve the ESP run life. This tool, FCW (Full Control of Well) is
based on two key aspects: to detect and to avoid exposure to furtive damaging conditions.
1,4
1,9
2,1
2,5
2,12,3
3,5
3,7
0,0
0,5
1,0
1,5
2,0
2,5
3,0
3,5
4,0
0 - 12.50 12.50 - 25 25 - 37.50 37.50 - 50 50 - 62.50 62.50 - 75 75 - 87.50 87.50 - 100
Run-life (years)
Water Cut (%)
Run-life VS water cutCONGO
Run Life versus Water Cut
Fields in West Africa
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Ritz Carlton Hotel, Doha -Qatar
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Detection is the first and the most important aspect of a good dynamic control because that
permits to setting up early enough the good corrective action to limit the damage. Faster the
detection is, better will be the correction.
In addition, an advanced understanding is crucial to develop and to apply the most efficient
corrective action.
Results and discussion
1) The result of the utilization of FCW,
since 2008, is impressive. The
number of failures per year are been
devised by three in 4 year. This result
confirms that the FCW is a true active
automation for dynamic control of
ESP.
Therefore the reduction of operating cost is significant. This tool has been successfully
experienced in West Africa fields since 2008 and it is currently expending in other assets.
2) In addition to standard existing tools in ESP-RIFTS, a new module has been developed
using the Total software WellTeller. It uses the instantaneous failure rate to predict ESP
failures and to optimize planning of ESP change-out. Called “yearly failure rate”, it
allows quantifying the gain in run-life improvement from one year to the other even with
a limited number of failures.
Conclusion and recommendations:
Due to this understanding of damaging conditions of ESP, it was possible to setting up
automatism system (FCW) to operating the ESP in the better condition which avoid
damaging conditions.
Today, the utilization of this FCW reduces considerably the operating cost with ESP with an
increased run-life. In addition to this cost reduction, a real know-how has been demonstrated
which allows to extend the limit imposed by challenging conditions in a mature field. ESP’s
reaches larger volumes and lower pressure. Allowing ESP’s at lower cost in challenging
reservoirs contribute to increase the recovery factor.
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Ritz Carlton Hotel, Doha -Qatar
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Acknowledgments
The teams in various Total affiliates in Middle East, Europe and West Africa are
acknowledged for the input and contributions to this paper.
References
F.J.S Alhanati (C-FER Technologies), S.C Solanki (C-FER Technologies), T.A Zahacy (C-
FER Technologies), 2001, ESP Failures : Can we talk the same language?, SPE 148333,
presented at the SPE Electrical Submersible Pumps Workshop, Houston, 25-27April, 2001.
Lawrence A.P. Camilleri (Schlumberger), John Macdonald (Schlumberger Artificial Lift),
2010, How 24/7 real time surveillance increases ESP run life and uptime, Society of
petroleum Engineers, SPE-134702-MS, presented at the SPE annual technical conference and
Exhibition held in Florence, Italy, September 2010.
Claudio Lima (Petrobras), Alok Kumar (Schlumberger), Gustavo Sobreira (Petrobras S.A),
Luciano Lopez Diniz (Schlumberger), David J. Rossi (Schlumberger), Integrating predictive
surveillance with remote control operation, SPE 128761, presented at the SPE Intelligent
Energy Conference and Exhibition, Utrecht, The Netherlands, 23-25 March 2010
Abdualmonam Al Maghlouth (Saudi Aramco), Matt Cumings (Saudi Aramco), Majed Al
Awajy (Saudi Aramco), Abdulrahman Amer (Saudi Aramco), 2013, ESP Surveillance and
optimization solutions: ensuring best performance and optimum value, SPE-164382-MS,
presented at the SPE Middle East Oil and Gas Show and Conference, Manama, Bahrain, 10-
13 March.
Donald G. Thornhill (Baker Hughes), David Zhu (Baker Hughes Centrilift), 2009, Fuzzi
analysis of ESP performance, SPE-123684-MS, presented at the SPE Annual Technical
Conference and Exhibition, New Orleans, USA, 4-7 October 2009.
Paper No. #194
Operating Electric Submersible Pumps:
How to achieve long life-time in challenging
reservoirs?
B. Viguerie (TEP Qatar); E. Toguem,
P. Lemetayer, P. Perusat, (Total S.A);
Is Reservoir Temperature the Key Factor
for ESP Run-life ?
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Run-life for challenging conditions
• Artificial lift with ESP contributes to increasing recovery factor
• Challenging reservoirs induce operating conditions which damage ESP
• Short run-life impact OPEX thus economical cut-off
How to increase ESP run-life in challenging reservoirs ? ?
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Scattering of ESP run life
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Observed furtive conditions
- Références, date, lieu
100°C
122°C
75°C
45 min without flow rate
Motor heating
85% efficiency
Pump heating
60% efficiency
= Pump damaged
Motor heating up following a slug of gas
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Pump Intake Pressure
Motor Temperature
Cause tree Pump power
Gas lockNo flow rate
no cooling
Temperature fluid
reservoir
Unsufficient
mitigation by
operating
Very hot
fluids in the
pump
Too Long heating up of motor and pump
Critical isolation
damage
ELECTICAL SHORT
Time
Hot motor
Back
flow
Pump
stop
A Cause tree allows to understand correctly the failure and to correct it efficiently
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Damaged Elec. insulation
Short circuit
Temperature excursions
Temperature (°C)
Time
T° réservoir 90°C
T° max coaling
170°C
Gas-lock Back Flow
T° réservoir 60°C
Motor temp
TCHM103 Congo
120°C
100°C
Estimation of pump
fluid temp CHM103
Congo
Motor temp
ALK 46 Qatar
130°C
Estimation of pump
fluid tempALK46
Qatar
• The excursions of temperature matter more than reservoir temperature.
• Backflow induce strong excursion.
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Classes of ESP failures
S(t) Survival
H(t) Cumulative Hazard
Typical shape
Event driven failure at any time
Cum
ula
tive failu
re%
Time
Long term wear
out failure
« Random »
or eventdriven failure
Early
failure
1
2
3
Short runs Long runsWith courtesy from ESP-RIFTS
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Risk of damaging conditions
Occurrence of fluctuations in Gas or Water-cut increase the impact of damaging situations
Are Carbonated Reservoirs homogeneous and predictable ?
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Dynamic well driving
Driving efficiently the power
… especially
when
unexpected events Plenty horse power available
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Full Control of Wells Results
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30%
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50%
60%
70%
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Yearly ESP failure ratio(Number of failures
/ number of wells with ESP)Number of wells
with ESP
FCW
implementation
A good dynamic control do limit the exposition of damaging conditions thus the occurrence of failures.
Year
Failures
Number of wells
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Optimization
Root cause analysis
Detection
Knowledge
ESP run life
Paper #194 • Operating ESP’s: How to achieve long life-time in challenging reservoirs • P. Lemetayer
Acknowledgements / Thank You / Questions