Field Evaluation of an Offshore Pumping System
Transcript of Field Evaluation of an Offshore Pumping System
Field Evaluation of an Offshore Pumping System
Jeffrey A. Bennett1, Augusto Garcia-Hernandez1, Marco Antonio Muñoz Prior2
Moisés León Dorantes2, 1 - Southwest Research Institute®
2 - PEMEX Exploración y Producción
Jeffrey A. Bennett (Presenter)• Research Engineer, Southwest Research Institute• Experienced in thermal fluid network modeling• MSc – Turbomachinery Aeromechanics, KTH/Université de Liège • BS – Mechanical Engineering, Virginia Tech
Augusto Garcia-Hernandez• Group Leader, Pipeline Simulation, Southwest Research Institute• 12 years experience modeling pipelines and associated machinery• MS – Petroleum Engineering, University of Tulsa• BS – Mechanical Engineering, Universidad Central de Venezuela
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Slide 2: Presenter/Author Bios
Marco Antonio Muñoz Prior• Mechanical Engineer Electrician, Design and Optimization of
Crude Oil Infrastructure, PEMEX Exploración y Producción• Mechanical Engineering, Instituto Politecnico Nacional
Moisés León Dorantes• Former superintendent in the Coordination of Transport and Oil
Distribution, PEMEX Exploración y Producción• Mechanical Engineering, Instituto Politecnico Nacional
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Slide 3: Presenter/Author Bios
An evaluation was performed on one of the largest offshore facilitiesbelonging to PEMEX Exploration and Production due to forecasts predictingthat future crude oil production will contain heavier oils. The primary functionof the evaluation was to assist PEMEX in determining if the facility’s pumpsneeded to be upgraded. In addition, several of the centrifugal pumps of theplatform had been recently replaced with screw pumps. Therefore, theevaluation was performed in three parts: first, the remaining centrifugalpumps were evaluated in the field at available testing conditions; second, ahydraulic analysis of the network was conducted to predict the systemperformance with heavier oils; and third, an interactive pump simulator wasdeveloped to train operators on the new screw pump equipment. Thispresentation/paper will focus on the first step, the field evaluation of thecentrifugal pumps, and the remaining steps will be discussed briefly.
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Short Abstract
Presentation Overview
• Field Evaluation– System Background– Performance Testing
Approach– Pipeline Modeling Results– Field Testing Results
• Hydraulic Modeling• Simulator Development
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Presentation Overview
• Field Evaluation– System Background– Performance Testing
Approach– Pipeline Modeling Results– Field Testing Results
• Hydraulic Modeling• Simulator Development
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Background
• PEMEX Exploration and Production’s off-shore pumping system transports approximately 50% of Mexican crude oil production
• Complex interconnected platform network where different crude oils are mixed
• Historically has operated with 19 API oil, however, forecasts predict mixtures of approximately 16 API oil
• Screw pumps recently installed to help transport heavier oil
• Aging centrifugal pumps require a performance evaluation
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TERMINAL MARITIMA DOS BOCAS
Cayo Arcas
Rebombeo
FSO Ta’Kuntah
Nohoch-A
POL-A
Akal-N
L-1
L-1
L-4
L-2
L-2
Akal-B
36"
Akal-L
Akal-J
L-2L-1
L-3
ABK-ARMSO
L-3
Akal-C
36"36"
36"36"
36"
36"
24"
24"
30"
20"20"
24"36"
36" 36"
AIKMZ
FPSOYùum
K'ak'náab
36"36"
Rebombeo Platform
• The booster platform “Rebombeo” is located in the Gulf of Mexico approximately 25 miles off-shore
• Two 36-inch sub-sea pipelines travel 52 miles
• Platform has 10 pumps connected in parallel– 6 centrifugal– 4 screw (new)
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TB-A TB-C TB-DTB-BTB-01 TB-02 TB-03 TB-04 TB-05 TB-06
LINE 2 INLET
LINE 2 OUTLET
REBOMBEO PLATFORM
LINE 1 INLET
LINE 1 OUTLET
FILTERS FILTERS
CENTRIFUGAL PUMPS
SCREW PUMPS
Performance Testing
• Goal: Traverse entire pump curve at a given speed (follow ASME PTC-8.2 Standard)
• This test requires the system pressure difference to decrease as the flow rate increases
• Platform’s 6 centrifugal pumps come in 2 varieties – high capacity and low capacity
• Can we take advantage of the different pump types?
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Hea
d [F
t]
Flow [GPM]
Pump Curves
Low Capacity PumpHigh Capacity Pump
Pipeline System Curves
• Dissimilar to the pump curve, the pipeline system curve requires an increasing pressure difference for high flow rates
• For standard operation this is great -> stable operating point
• For testing a means to vary flow conditions is necessary to follow the testing standard
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A]
Flow [GPM]
Pipeline System Curves
Pipeline to PlatformPipeline from Platform
Sample Test Point
• Pumps are in parallel, thus equal head across each
• Test pump kept at constant speed
• Speed of other pumps varied to change flow through test pump
• Pipeline simulations used to prove approach and determine necessary test conditions
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Flow [GPM]
Sample Test Point
Test Pump @ 5,200 RPMFlow - Test PumpLow Capacity Pump @ 5,210 RPMFlow - Low Cap. PumpHigh Capacity Pump @ 3,100 RPMFlow - High Cap. PumpHead Level
Pipeline Network and Machinery Model
• 1-D pipeline fluid model of the existing facility including L1, L2, and L3 lines
• Used previous pump field measurements to represent pump curves
• Various emulsion of water-in-oil up to 30% water-cut
• Flow, pressure, and temperature field data was previously used to validate the hydraulic model within 1.12%
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REBOMBEO
NH-AAKAL-C
L-1L-2
20” ∅AKAL-J
24” ∅
36” ∅
36
” ∅
L-3
TMDB
INT-26INT-52
INT-27
L= 5.2 km
L= 8.6 km
L= 5.3 km
L-3
Crude Oil Pipeline System from the Production Platforms to TMDB
Modeling Results
• Modeling demonstrated that test approach of varying speed of adjacent pumps is able to vary flow through the test pump
• However, unable to traverse entire pump curve with this approach
• Traverse of entire pump curve requires a change in platform operation conditions
• Limitation primarily due to platform pressure limits
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Hea
d [f
t]
Flow [GPM]
Predicted Pump Performance
Test RPM - Corrected with Affinity LawsTest RPM - Corrected for ViscosityBEPTest Point 1: 1,846 GPMTest Point 2: 2,615 GPMTest Point 3: 3,650 GPMTest Point 4: 4,600 GPM
Test Set-up: Flow Measurements
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Ultrasonic Flow Meter
Test Set-up: Pressure Measurements
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Differential Pressure
Suction Pressure Discharge Pressure
Pump Speed
Measured Pump Performance
• Only one platform flow condition available for testing – limited to current production
• Performance test was able to traverse a portion of pump curve
• Results used to estimate the pump degradation
• Testing was performed on 3 of the 6 centrifugal pumps
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ead
[ft]
Flow [GPM]
Measured Pump Performance
Test RPM - Corrected with Affinity Laws
Test RPM - Corrected for Viscosity
Test RPM - Corrected for Degradation
Test RPM - Corrected for Degradation and Viscosity
Measurements
BEP
Presentation Overview
• Field Evaluation– System Background– Performance Testing
Approach– Pipeline Modeling Results– Field Testing Results
• Hydraulic Modeling• Simulator Development
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Hydraulic Modeling Evaluation
• After performance testing complete, additional simulations performed to predict scenarios that are undesirable for experimentation at an operating platform either due to expense or safety
• Water hammer scenarios used to predict worst-case pressure spikes
• Also simulated changes to system valve configurations
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Flow
Rat
e (G
PM)
Pres
sure
(Kg/
cm^2
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Time (min)
SDV-3101closed
Valve beginsclosingValve beginsclosingValve beginsclosing
Valve Closed
Valve Starts to Close
Presentation Overview
• Field Evaluation– System Background– Performance Testing
Approach– Pipeline Modeling Results– Field Testing Results
• Hydraulic Modeling• Simulator Development
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Purpose of Developing a Training Simulator
• Safely train operators to use newly installed screw pumps
• Helps platform operators comply with API 1120, ASME B31Q, RP 1161 and RP T-2
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Training on the Simulator
• Simulator has screens that mimic control screens and a computational engine that predicts system response to trainee actions
• Additional screens added to provide operators with insight into the system hydraulics
• Ability to simulate complex procedures such as start-ups and shutdowns
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• Field evaluation of offshore pumps was performed
• Pipeline simulations were used to provide insight into test conditions necessary to perform a full sweep of pump curve
• Limited flow conditions in the field resulted in a limited range of the pump curve being tested
• Pump degradation was estimated from the field testing and adopted in the model
• Hydraulic system evaluation used to estimate worst-case water hammer scenarios
• Training simulator was developed to train operators to use newly installed screw pumps
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Conclusions
Centrifugal Pump with Shaft Guard On
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Thank you for your attention!
I will be happy to address any questions.
Jeffrey A. BennettResearch Engineer
Augusto Garcia-HernandezGroup Leader