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SAND MANAGEMENT
CENTRAL AZERI CASE STUDY
HEMRAJ GAIDHANI, PhD
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Agenda
Introduction
Flow Scheme & Design Basis
Overview of Test Runs
Results of Test Runs
Solutions to be reviewed
- Sand Removal from Separators
- Sand Separation Package Performance
- Sand Jetting Pump
- Changes to Sand Separation Package Flow Scheme
- Sand Jetting Control
Combination of TORE Desanders with Conventional sand Jetting- Feasibility Study proposal
- Previous Investigations by BP/KBR
Questions
SAND MANAGEMENT
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INTRODUCTION
The primary objectives of the Sand Management Study for CA, was to:
- Identify the root causes of the Sand Jetting pump failure.
- Propose short, medium and long term solutions that will enable the sand
removal / separation systems to function per design intent.
- Identify potential modifications to minimise Operations involvement in
the sand jetting process.
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Why is Sand Removal Important?
Reduces separation
efficiency due to the
reduced volume available
for fluid separation
Potential to erode the
downstream LCV,
Pipes, etc
Microbial Induced
Corrosion (MIC) of
Separator cladding may
occur
INTRODUCTIONS
Sand production is
expected to increase
with increased water cut
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Flow Scheme of CA Sand Separation Package
SEPARATORS
TORESCRUB
HYDROCYCLONE
SURGEVESSEL
MAIN JETTING PUMP
Oil
Sand FC580151
PDC
580144
Jetting Header
Slurry Return
Jetting Water Supply
Vent
Water
Gas
Oil
SandCyclones
LC
580151
PC
580154
Makeup(intermittent)
PackageTopsides
XXV
580152
Excess Water Dump(not in use)
XXV
580145
SAND BAGGINGOR CUTTINGREINJECTIONTANK
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Sand Separation Package Performance Specifications:
10% of particles from the separators are less than 30 microns.
(based on produced sand with 75% less than 200 microns, D50 = 130 microns)
Jetting water circulation flow rate of 81m3/h.
Designed for a maximum slurry concentration of 50 wt% (i.e. 27 vol%.)in the outlet stream from the separators
Designed for maximum 1000 ppmv free oil in water to the
hydrocyclone
Remove 95% of sand particles greater than 30 microns in the sand
slurry to the Torescrub
DESIGN INTENT
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FACTS AND EXPECTATIONS
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RESULTS OF TEST RUNS
May 2005 (Trial-1):
Train 2 HP separator was sand jetted online.
The jetting pump 1D-P58011 discharge pressure dropped from 69 bargto 60 barg in 6 minutes.
This suggested sand erosion of the Pitot Tube in the pump and wasthought to be due to sand carryover to jetting pump without effectiveremoval in the Torescrub 1D-V58014.
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RESULTS OF TEST RUNS
Oct 2005 (Trial -2):
Installed an up-stand pipe inside the surge vessel 1D-V58015 to attemptto limit sand carryover to the jetting pump.
To reduce sand concentration in the slurry entering the Torescrub dilutedthe slurry by partially bypassing jetting water around the HP Separator.
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RESULTS OF TEST RUNS
Oct 2005: LP Separator Sand Jetting
A very small quantity of sand was recovered
The concentration of sand to sand jetting pump was 0.06 wt%, less thanthe pump design tolerance of 0.1 wt%.
Sample Downstream of Main Pump
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RESULTS OF TEST RUNS
Oct 2005: HP Separator Sand Jetting
- 600 litres of sand was collected from the Torescrub in 10 minutes
- Oil carryover with sand (like Porridge)
- 70% of the solids particles are larger than 200 micron in size
Sample from Sand Bagging
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RESULTS OF TEST RUNS
Oct 2005: HP Separator Sand Jetting
- 70% of the solid particles are larger than 30 micron in size
- Torescrub Design Criteria: 95% removal efficiency for particles 30
microns or larger.
- Oil carryover with sand
Sample from Surge Drum
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TEST RUN CONCLUSIONS
Expected Produced Sand:
-75% of the solids particles smaller than 200 micron in size
- Avg. particle size (D50) 130 microns
Design Criteria
Cumulative % Greater Than vs Size
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
110%
1 10 100 1000
Particle Size, microns
Cumulative%
Series1
GCA#1: Average of 5 Samples
M. Bothamley June/99
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TEST RUN CONCLUSIONS
Actual Produced Sand:
-75% of the solids particles are larger than 200 microns
- Average particle size (D50) is 240 microns
Q - Does it affect performance of Torescrub, effective fluidisation in Separator?
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Oil Loading :
Sand jetting Nozzles
Oil/Water Interface
Wax Formation (based on Nov 2006 Thermographs) :Temperature of the sand layer is approximately 42C which is thewax formation temperature of the production fluids.
Low temperature promotes wax formation in any oil retained in the
sand layer.
Slurry Concentration :
No Control available
RESULTS OF TEST RUN
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Main Jetting Pump: Rotojet/Pitot Tube Type Pump
Sand separation package is designed to handle 50 wt% sand slurry
(and 23% on EA/WA).
10% of total particles were expected to be less than 30 microns (i.e. 5 wt%).
Torescrub is designed to remove 95% of particles greater than 30 microns.
i.e. 5% particles greater than 30 microns carry through to downstream equipment
Carry over Sand from Torescrub = 5%+ 2.25% = 7.25 wt%.
These solid particles accumulate in the Surge Vessel up to the stand pipe and wouldbe carried through to the jetting pump suction.
The design solid loading for the main jetting pump is only 0.1 wt%
RESULTS OF TEST RUN
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1. Sand Removal from Separators
2. Sand Separation Package Performance
Sand Loading Oil Loading/Wax Formation
3. Main Sand Jetting Pump
4. Sand Jetting Control and Changes to Sand Separation Package FlowScheme
Solutions to be reviewed
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1. Sand Removal from Separators
Replacement of Jetting nozzles with Tore or
Combination of Existing Jetting with Tore system
Jetting nozzles
1. Start of jetting
2. End of jetting
Original sand layer
Fluidised sand particles
Suction point
Nozzle fluidisation flow
Nozzle
Nozzle
Tore system
Solutions to be reviewed
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2. Sand Separation Package Performance
Sand Loading
Short Term : Limit Sand build up Dilute the Slurry flow Surge vessel stand pipe modification
Medium Term : Change in Torescrub Internals/Cyclones
Long Term : Change in jetting internals of separators
Increase in circulation rate Dilute the Slurry flow (high capacity pump) Torescrub Replacement
Solutions to be reviewed
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2. Sand Separation Package Performance
Oil Loading/Wax Formation
Short Term Solutions:
Maintain water level in separators Chemical Injection
Medium Term Solutions:
Hot water circulation (WA Trials)
Long Term Solutions:
Increase Separator Sand Weir Height
Solutions to be reviewed
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3. Main Sand Jetting Pump Modifications
Short Term :
Internals Modification
Medium Term :
Add Pump Suction Strainer
Long Term :
Replace Pump
Additional Sand Filtration
Solutions to be reviewed
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Combination of Tore Desanderswith Conventional Sand Jetting
Jetting nozzles
1. Start of jetting
2. End of jetting
Original sand layer
Fluidised sand particles
Suction point
Nozzle fluidisation flow
Nozzle
Nozzle
Tore system
- Feasibility Study proposal
- Previous Investigations by BP/KBR
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Feasibility Study proposal Compatibility check of TORE with Sand Skid
Operating Philosophy
Process Control around Separator to maintainSand Slurry Concentration
Vendor Evaluation
Increase in Weir height in HP separator
Previous Investigations by BP/KBR
Combination of Tore Desanderswith Conventional Sand Jetting
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Thank You
&
We Welcome Your Comments and Questions