CA Sand Management

8/3/2019 CA Sand Management

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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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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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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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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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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



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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



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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



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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



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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



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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

Documents

CA Sand Management