Debottlenecking Water-Oil Separation with Increasing Water...
Transcript of Debottlenecking Water-Oil Separation with Increasing Water...
Debottlenecking Water-Oil Separation with Increasing
Water Flow Rates in Mature Oil Fields
Maher M. Shariff, Ph.D. and Lanre M. Oshinowo, Ph.D.
5th Water Arabia 2017 Conference and ExhibitionOctober 17 – 19, 2017
© Copyright 2017, Saudi Aramco. All rights reserved.
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• Background and Motivation
• Numerical Model and Test Matrix
• Results and Discussion
• Conclusions
Outline
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• Maturing fields with increasing water flow rates
• For certain GOSPs, water-oil separator (WOSEP) is the bottleneck
• WOSEPs are reaching capacity to process oily produced water
• Need solution to debottleneck gas-oil separation plant for forecast
rates
- Quantify separation performance
- Apply enhanced internal technology to improve separation at higher
throughputs
Background
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Produced Water Forecast
1X
1.5X
Produced
Water
Flow
Rate
Today +10 Years
Not to scale
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• Improving oil separation reduces lost production
• Improved produced water quality prevents formation damage
on reinjection to maintain reservoir pressure
• Avoid the need to build additional WOSEPs in the GOSP
Motivation
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• Use state-of-the-art multiphase CFD to model the oil-water
flow in the WOSEP vessel
• Develop debottlenecking solutions to increase water handling
capacity
Objectives
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Typical GOSP
LPPT
HPPT
WOSEP
Dehydrator
Production
Header
Desalter
Dry Oil
HP Gas
LP Gas
Water
Water
Produced Water Injection
HPPT
Water
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Water Oil Separation Vessel (WOSEP)
WaterWater OilOilInlet Distributor
(Water & Oil)
Gas
Oil Bucket
Water Baffle
Water Weir
`
Approximate dimensions: 180 ft Length; 14 ft diameter
160 MBD Throughput
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Multiphase Modeling
Separator CFD Modeling
Eulerian-Lagrangian Eulerian
Homogeneous Inhomogeneous
VOF Mixture N-Phase PopulationBalance
Explicit (Transient)
Implicit(Steady)
N-Phase PopulationBalance
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• N-Phase Eulerian multiphase model
- Water – primary phase
- Oil and gas – secondary phases
• Phase interaction
- Schiller-Naumann drag model
• Turbulence
- Standard 𝑘 − 𝜀 turbulence model with scalable wall functions
• Steady and incompressible
• High-resolution Computational mesh
- 2 million polyhedral cells/elements
Numerical Methodology
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• ANSYS Workbench for Pre-Processing – Geometry and Mesh
• ANSYS Fluent R18.0 for Solution
- Simulations run in parallel on an HPC cluster with 216 cores
• ANSYS CFD-Post 18.0 for Post-Processing
Solution Platform
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Run Flow (MBD) Oil Droplet Diameter (mm)
1 173 10
2 173 50
3 265 10
4 265 50
Numerical Test Matrix
Inlet Oil Fraction (OF) 0.01
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Geometry
Water Outlet
Inlet Distributor
(Water & Oil)
Oil Bucket
Water Baffle
Water Weir
Water Outlet
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Computational Mesh
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WOSEP Flow Field
Run 2
Streamlines (colored by time)
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WOSEP Flow Field
Run 1
Run 2
Run 3
Run 4Front view
Streamlines (colored by time)
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Velocity
Run 2
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Residence Time Distribution
0
2
4
6
8
10
12
14
16
18
0 500 1000 1500 2000 2500 3000 3500
Per
cen
tage
Time, seconds
173 MBD
265 MBD
Water Flow Rate {MBD} Mean of RTD {s} Retention Time (VC/Q) {s}
173 1142 1305
265 784 851
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Residence Time Distribution
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Oil Fraction
Run 2
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Oil Fraction
Run 2
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Effectiveness of Oil Separation
Run Flow (MBD) Oil Droplet
Diameter (mm)
Oil Removed
(%)
1 173 10 <1
2 173 50 9
3 265 10 <1
4 265 50 4
𝑆𝑒𝑝𝑎𝑟𝑎𝑡𝑖𝑜𝑛 𝐸𝑓𝑓𝑖𝑐𝑖𝑒𝑛𝑐𝑦 =𝐼𝑛𝑙𝑒𝑡 𝑂𝑖𝑙 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛 − 𝑂𝑢𝑡𝑙𝑒𝑡 𝑂𝑖𝑙 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛
𝐼𝑛𝑙𝑒𝑡 𝑂𝑖𝑙 𝐹𝑟𝑎𝑐𝑡𝑖𝑜𝑛× 100%
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• Successful CFD simulations of WOSEP under different conditions
• Flow patterns show adverse vortices induced by the inlet distributor that reduce ability to separate oil from water
• Very low oil separation obtained from separator design for base flow rate
• Increased water throughput further reduces separation performance
• Potential to increase primary stage produced water oil removal through improvements in WOSEP design:
- Inlet distributor
- Additional internals (perforated plate baffles or derivatives, coalescing plate packing)
- Vessel configuration
Conclusions
Dr. Regis D. Vilagines,
Dr. Ehab Elsaadawy, Dr. Fahad S. Al-Rashed
Oil and Gas Treatment Division, Saudi Aramco
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