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(1)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

SURFACE PROCESSING

A – CRUDE OIL TREATMENT

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-SEPARATION – Contents

1- Well effluents Generalities

2- Gas/liquid separation

-equilibrium calculations

-influence of the process recovery rate

3- Separator sizing principles

-diphasic vertical separator

-diphasic horizontal separator

4- Gas/Liquid Separator different types

5- Foaming (difficult gas/liquid separation)

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-WELL HEAD EFFLUENTS

WELLHEAD

WELLHEAD

EFFLUENTS

EFFLUENTS

GAS

GAS

OIL

OIL

WATER

WATER

FORMATION SAND AND SILT

FORMATION SAND AND SILT

COLLOID STATE CLAY

COLLOID STATE CLAY

CORROSION PRODUCT

CORROSION PRODUCT

WAXES

WAXES

ASPHALTENES

ASPHALTENES

MINERAL CRYSTALS

MINERAL CRYSTALS

NaCl

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

SEPARATION CHAIN

EMULSION EMULSION INTERMINGLED WATER/OIL INTERMINGLED WATER/OIL FOAMS FOAMS LIQUID DROPLETS LIQUID DROPLETS IN GAS IN GAS WELLHEAD EFFLUENTS WELLHEAD EFFLUENTS CONDENSATE CONDENSATE FREE WATER FREE WATER GAS

GAS--LIQUIDLIQUID SEPARATION SEPARATION GAS TREATMENT GAS TREATMENT DEHYDRATION DEHYDRATION CONDENSATE CONDENSATE RECUPERATION RECUPERATION EMULSION EMULSION TREATMENT TREATMENT WATER WATER EMULSION EMULSION GAS GAS WATER WATER OPERATIONS SOMETIMES OPERATIONS SOMETIMES CARRIED OUT CARRIED OUT export crude OIL

OIL--WATERWATER

SEPARATION

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-SOURCE OF WATER

WATER AND OIL ZONES IN RESERVOIR

WATER AND OIL ZONES IN RESERVOIR

OIL

OIL

OIL

OIL

* Active Water Reservoir

* Active Water Reservoir

* Water Injection : Injection of 1

* Water Injection : Injection of 1

-

-

2 volumes of water

2 volumes of water

Production of 1

Production of 1

-

-

5 volumes of water per oil volume

5 volumes of water per oil volume

* Faulty Cementing Job

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

SOURCE OF SALT

SALT SALT RESERVOIR WATER RESERVOIR WATER

INJECTED WATER (SEA WATER)

INJECTED WATER (SEA WATER)

*If Salt Content>10mg/l , Reservoir Water INGRESS

*If Salt Content>10mg/l , Reservoir Water INGRESS

Produced Water Not Detected; only salt content is measured

Produced Water Not Detected; only salt content is measured

*HASSI MESSAOUD : CAMBRIEN WATER 370g/l

*HASSI MESSAOUD : CAMBRIEN WATER 370g/l

Low Water Cut

Low Water Cut HIGH SALT CONTENTHIGH SALT CONTENT 0,1%

0,1% SALT CONTENT 370 mg/lSALT CONTENT 370 mg/l

*Sometimes HIGH SALT CONTENT without Water EAST BAGDAD As much as 265ppm of salt *** * Same for Hassi Messaoud - Fateh - ABK -Zadco This Phenomenon is limited in Time

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-OIL , BSW and GOR EVOLUTION WITH TIME

Production 106 m3 / an 3 2 1 GOR GOR OIL OIL BSW % 30 30 20 20 10 10 300 300 200 200 100 100 YEARS BSW BSW 1 1 22 33 44 55 66 77 88 99 1010 1111 1212 GOR   

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

CONTRACTUAL WATER AND SALT CONTENTS

TRANSPORTERS

TRANSPORTERS

: LIMITATION FOR WATER CONTENT

: LIMITATION FOR WATER CONTENT

*PIPELINE

*PIPELINE

-

-

PIPE OVER LOADING

PIPE OVER LOADING

BSW <= 0.5%

BSW <= 0.5%

--

CORROSION ( WATER + SALT )

CORROSION ( WATER + SALT )

*BY SEA NO FIXED CONSTRAINTS

*BY SEA NO FIXED CONSTRAINTS

BUT

BUT

--

ACCIDENTAL CONTAMINATION

ACCIDENTAL CONTAMINATION

--

LOAD ON TOP CONTAMINATION

LOAD ON TOP CONTAMINATION

AGREEMENT

AGREEMENT

PRODUCERS

PRODUCERS

TRANSPORTERS

TRANSPORTERS

REFINERS

REFINERS

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-1 ELECTROSTATIC DESALTER

1 ELECTROSTATIC DESALTER

SALT CONTENT <5mg/l

SALT CONTENT <5mg/l

* SCALE DEPOSIT INSIDE EXCHANGERS

* SCALE DEPOSIT INSIDE EXCHANGERS

* DISTILLATION UNITS CORROSION

* RESIDUAL QUALITY DEGRADATION

* RESIDUAL QUALITY DEGRADATION

95 % EFFICIENCY

95 % EFFICIENCY

INLET SALT CONTENT < 100 mg/l

INLET SALT CONTENT < 100 mg/l

INLET SALT CONTENT < 100 mg/l

EUROPEAN REFINERIES

REFINERY : Salt...100 mg/l

REFINERY : Salt...100 mg/l

Water....0,2%

Water....0,2%

TRANSPORT : Salt...60 mg/l

TRANSPORT : Salt...60 mg/l

Water....0,5%

Water....0,5%

BSW in Production Fields < 0.5 %

BSW in Production Fields < 0.5 %

BSW in Production Fields < 0.5 %

PRODUCTION FIELD SPECIFICATIONS

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

DEHYDRATION

TO WITHDRAW WATER DISPERSED IN CRUDE STRESSING

THE WATER CONTENT

DESALTING

TO GET THE SALT SPECIFICATION WHEN THIS IS NOT THE

DIRECT RESULT OF COMPLYING THE WATER SPEC.

DESALTING IS A DEHYDRATION TRT SET

PREVIOUSLY WITH WASH WATER SOFTER

THAN RESERVOIR WATER

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-DEHYDRATION/DESALTING

With Reservoir Water at 350 g/l expressed as NaCl equivalent

0.1 % of Water Content

350 mg/l ( 123 PTB ) Salt Content

Salt Content < 60 mg/l

Water Content < 0.017 %

SALINITY IS THE MOST RESTRICTING SPECIFICATION

With Reservoir Water at 40 g/l expressed as NaCl equivalent

0.1 % of Water Content

40 mg/l ( 14 PTB ) Salt Content

Salt Content < 60 mg/l

Water Content < 0.15 %

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

2- Gas/liquid separation

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-GAS/LIQUID SEPARATION - Generalities

Hydrocarbon reservoir :

at reservoir conditions, generally one monophasic fluid

at surface conditions (P &T decrease), different components appear : monophasic  polyphasic (gas + liquid)

hydrocarbon gas  condensation of heavier hydrocarbons liquid water vapour  liquid water

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

TREATMENT UNIT

AIM OF A TREATMENT UNIT

to recover all the different constituents

 Process specific to each development to treat oil so that it is free of gas

to produce a gas as dry as possible (no water nor heavy hydrocarbons) to remove water (and solids) from oil

(16)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -Pr Pw Pf Pc Pr Reservoir Ps Storage Shipping Separation

Hydrocarbon production scheme

Pr: Reservoir pressure Pf: Bottomhole flowing pressure Pw: Wellhead pressure Pc: Choke pressure Ps: Processing pressure

(17)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Phase diagram

P Liquid Pr Vapour T 0 Pf 0 % 100 % Ps Pc Pw Bubble Point mole % liquid 30 % 15 % 5 % 1 %

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

(20)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -at Constant composition

1. Flash process

If T constant = flash liberation P1 V1 T1 P2 V2 T2 with P1 > P2 P1 V1 T1 P2 V2 T1 P1 > P2 P1 V1 T1 P2 V2 T2 P1 > P2 T1 > T2 If T varies = flash separation

G1 L1 P1 T1 G2 L2 P2 T2

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

total composition varies : there is draw off

2. Differential process

If T = constant = differential liberation P1 > P2 G1 L1 G2 L2 Gi Li GS P1 T1 P2 T2

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-3. Composite process : combination of the two

G L L G1L1 G2L2 GSLS PG TG PF TG P1 T1 P2 T2 Pa Ta Differential Liberation (T cst)

Flash Flash Flash

Reservoir Separators Storage

PG PF P1 P2 Pa Ta T2 T1 TG P T

(23)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

OPTIMAL SEPARATION PRESSURE IN HYDROCARBON PRODUCTION FIELDS IS AN APPLICATION OF PHASE EQUILIBRIUM IN

THERMODYNAMICS



AMOUNT OF LIQUID RECOVERED IS DEPENDENT OF THE COMPOSITE PROCESS



SEPARATION EFFICIENCY

YIELD (R) = final stock tank oil mass / mass of hydrocarbons entering the processing unit

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Influence of the Process Recovery rate

Separation P Pb 1 3 15° TG T Liberation 2 1 Rs P Flash Differential Pb Rs = V gas produced V oil at Pb

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

QUANTITIES OF FREE GAS ARE MORE IMPORTANT IN FLASH LIBERATION THAN IN DIFFERENTIAL LIBERATION

SIMILARLY, VOLUME OF LIQUID IS GREATER IN A DIFFERENTIAL PROCESS THAN IN A FLASH PROCESS

THE RELATIVE DIFFERENCE BETWEEN THE TWO CURVES DEPENDS ON THE NATURE OF THE OIL : SLIGHT FOR HEAVY OILS AND

GREATER FOR VOLATILE OILS



the higher the number of separation stages, the greater the liquid recovery



but P at 1st stage is governed by well head P (i.e. reservoir P)



number of stages is a compromise between costs of installation and liquid recovery

(26)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -G L G L Pi T1 Ps T1 Flash liberation

max gas & min liquid

One stage Application / Field Several stages P1 T1 P2 T1 L P3 T1 L Ps T1 G Separators Storage G L L G G

Influence of the process Recovery rate

in each separator : flash liberation

but the whole chain of separators represents a differential separation

(27)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Rule of thumb

Separation pressure at the different stages

n = number of stages + storage Examples GOR < 20 m3/m3 1°: 3-7 bara 2°: Storage GOR < 150 m3/m3 1° :10-20 bara 2°: 2-6 bara 3°: Storage P sep. HP P storage n - 1

R =

GOR > 200 1°: 20-40 bara 2°: 5-15 bara 3°: 2-5 bara 4°: Storage

(28)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-PALANCA FIELD (ANGOLA)

Separation efficiency = final stock tank oil mass / mass of hydrocarbons entering the processing unit

at P = 25, 20, 15 & 10 bar

at T = 105°C, 90°C, 75°C

Determination of the optimal P & T and number of separation stages to get the higher separation efficiency

(29)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Sep. Efficiency (%) 74 73.5 73 72.5 0 10 20 105 Pressure (bars) 25 90 75° C 75 74.5 75.5 76 76.5 5 15

(30)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -Sep. Efficiency (%) 74.5 74 73.5 73 0 6 12 105 Pressure (bars)15 90 75° C 75.5 75 76 76.5 77 3 9

Low pressure separator pressure 77.5

(31)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Sep. Efficiency (%) 75.5 75 74.5 0 6 12 105 Pressure (bars) 15 90 75° C 76.5 76 77 77.5 3 9

Medium pressure separator pressure

(32)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -Pressure (bar) Output (%) 76.5 76 75.5 0 10 20 25 4 stages 77.5 77 78 5 15 3 stages 2 stages

PALANCA separation – output T=

75°C

significant gain between 2 & 3

less gain between 3 & 4     ECONOMICS COMPROMISE

(33)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Influence of separation temperature

Temperature

+

-Low Average High Liquid Economy Water Gas H2S treatment Gas Price EFFECT ON RECOVERY ( )

in general, the lower the T the higher the liquid recovery

(34)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -ASHTART Gas 13b - 110 °C 1b - 85 °C Gas Oil Gas 5b - 40 °C 1b - 35 °C Gas Oil

GAIN 9 % OIL at

lower T

(35)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri BREME Flare 4b 40° C 1b Gas Oil Flare 4b 40° C 1b Gas Oil

GAIN 2.6 % OIL

from flare gas recovery

3.5 b 30° C

(36)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-3- Separator sizing

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Sizing of a separator

INCREASING COMPLEXITY OF FIELD INSTALLATIONS WITH THE AIM TO MAXIMISE RECOVEY AND OPTIMISE ALL PRODUCTION UNITS

INTRODUCTION TO GENERAL PRINCIPLES AND METHODS OF SIZING AND TYPICAL VALUES

SPECIFIC INSTALLATIONS AS HEATER-TREATER, CYCLONIC SEPARATORS, etc. ARE DETERMINED BY MANUFACTURERS

(38)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Sizing of a separator

DIMENSIONS FOR GAS AND LIQUID FLOWRATES ARE CALCULATED SEPARATELY

FOR GAS FLOWRATE, SPEED LIMITED TO PREVENT GAS FROM ENTRAINING DROPLETS OF LIQUID  smallest diameter possible

FOR LIQUID FLOWRATE, RETENTION TIME  SIZE TO ENSURE THAT

THE GAS IS COMPLETELY RELEASED FROM IT DEPENDS ON OIL CHARACTERISTICS

(39)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Basic data

Sizing of a separator

Gas : Flow rate - composition - specific mass Oil : Flow rate - composition - specific mass Retention time

1

Sizing for gas Sizing = passage cross-section

Passage cross-section = f (limit velocity gas) Limit velocity gas = liquid not drawn with it 2

Sizing for liquids Sizing = f (retention time)

Retention time = time needed for degassing Retention time = f (oil characteristics)

(40)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Vertical separator GAS

Aim : PREVENT WATER BEING DRAWN ALONG P T P = ΠΠΠΠD3 6 Lg Condition : P > A + R fixed D limit = 20 µm A = ΠΠΠΠD 3 6 Vg R = K ΠΠΠΠD2 4 V2 V V < K D L - V V 1 GOR L V ) = m/s Kv = f ( at D (Ø) L Liquid V V (velocity) Gas A R P

Sizing of a separator

weight aerodynamic force buoyancy liquid

max speed not to carry over D

(41)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Calculation of V (P and T) from M • Let M = 30 (0° C - 1013 mb) o = 22.430 Kg/m3 = MP ZRT • If T = 50° C and P = 20 bar V = o x P P0 x T0 T x 1 Z A few values of Kv

• Flare drum (horizontal) 0.04 m/s • Column head separator (horizontal) 0.07 m/s • Compressor suction (vertical) 0.04 m/s

= 22.430 x 1.01320 x 273323 x 0.931 = 24 kg/m3 Vertical separator GAS

(42)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

(43)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Vertical separator LIQUID Transit time through the vessel

Concerns water and oil (Gas : pm) T = V Q = Π ΠΠ Π D2 4 x h Q

Sizing of a separator

T:transit time

(44)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -Gas Outlet GAS Oil outlet Water outlet OIL WATER Feed Water droplet Gas bubble Oil droplet

VERTICAL Separator / Liquid : liquid sizing

(45)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Vertical separator LIQUID Decantation time

STOKES' law

D=O.1 mm (around 20 to 30 µm in general) V = g D

2 ( L - V)

18 µµµµ

Sizing of a separator

V = settling velocity of the liquid droplet D = diameter of the droplet

L = specific gravity of droplet

V = specific gravity of the gas at P&T g = gravitational acceleration

µ = viscosity of the continuous phase

note : Decantation time is very dependant of the crude and water characteristics ( emulsions)

(46)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Vertical separator LIQUID Retention time (practical reference)

Sizing of a separator

corresponds to the value obtained by taking the volume

measured between the mean level and the low level, where the mean level usually is located in the middle of the drum

Often varies with the crudes from 2" to 5" in most cases

but can reach 10" or even 30" or 60" for "problematic" crude, i.e. heavy oils or acid crudes

(47)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Vertical separator

• Gas passage velocity :

V critical = 0.048 in m/s Common practices L - G G • Internal diameter : D = D in m Q in m3/h V in m/s Q 900. ΠΠΠΠ . V • Height of separator : 1.5 < Height/Diameter < 3 • Max. oil level :

Hoil < 0.65 D • Low oil level :

at 10 inches from the bottom • Retention time

Oil + water = 2" to 5"

If foaming or high viscosity : 10"

(48)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -Horizontal separator

Sizing of a separator

Demister Flow straightened cross section

Gas Liquids Secondary chamber Decantation chamber A R P liquid Horizontal separator Gravity Gravity Vertical separator Resultant Entrainment Entrainment Resultant Kv horiz. = 1.25 Kv vertical

(49)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri L l Vh h D Water

h = continuous water height (water)

vh = decantation velocity of an oil droplet (rising)

vwater = displacement velocity of the continuous water phase (horizontal)

l = minimum decantation length

t = decantation time.

Oil droplet Vwater

Horizontal separator

Sizing of a separator

Decantation time with Stokes law

(50)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Sizing of a separator: Summary

GAS IS THE PRIORITY PARAMETER TAKEN INTO ACCOUNT IN THE DESIGN OF SEPARATORS

LIQUID TRANSIT TIME (often referred as Retention time) IS MORE EMPIRIC AND IS MORE BASED ON EXPERIENCE WITH SAFETY MARGINS MORE OR LESS IMPORTANT

DECANTATION TIME FOR LIQUIDS IS GENERALLY BASED ON LAB EXPERIMENTS

(51)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

4- Gas/Liquid Separator

different types

(52)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Vertical 2 phase separator

Drainage duct Pressure valve Safety seal Mist extractor Pressure gauge Déflector Oil and gas inlet Primary chamber Visual level monitor Decantation chamber Base Purge Oil outlet Manhole Isolation partition Centrifugal effect in a vertical separator Gas flow Liquid flow 3 2 1 1. body of separator 2. gas outlet (high point) 3. fluid input

Deflector action

well adapted for low GOR

(53)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Horizontal 2 phase separator

Mist extractor Settling section Secondary chamber Primary chamber Diffuser Gas + liquids inlet Decantation chamber Separation partition Purge Anti-wave partition Chassis Oil outlet Gas Liquid Gas outlet well adapted for high GOR

(54)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-gas outlet Inlet

liquid outlet

High-pressure horizontal separator with liquid retention capacity

large capacity high P

(55)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Spherical 2 phase separator

Fluids inlet Gas outlet Oil outlet Level regulation Scrubber Deflector rare

(56)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Cyclone effect separator

Gas outlet

Gas + Liquid inlet

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Multi-cyclone separator

Multi-cyclones Gas outlet Liquid outlet Diffuser Gas inlet

Liquid level Secondary drain Retention

volume

Liquid outlet

(58)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Other types

of gas/liquid separators

(59)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Gas SCRUBBER

Mist extractor Sifter

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-VAPE SORBER

Absorbent material Porous filters

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Components

of a gas/liquid separator

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Horizontal 2 phase separator components/internals

Mist extractor Settling section Secondary chamber Primary chamber Diffuser

Gas + liquids inlet

Decantation chamber Separation partition Purge Anti-wave partition Chassis Oil outlet Gas outlet

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

5- Foaming

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Foaming

Origin

• Gas expansion + oil / gas surface tension

• Pure liquids do not foam A surfactant is needed

Mixtures of isomers in hydrocarbons are surfactants • Foams are unstable (state of least energy)

• The internal viscosity of the oil stabilises the foam, leading to drawing along of the gas (foaming)

(65)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

FOAMS

FOAMS are oil + gas "emulsions"

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© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-–

INCONVENIENTS :

oil entrainments in gas (affecting scrubbers, flares,

compressors protection, gas treatment solvents ...),

and gas entrainments in oil ( pump cavitation, later

degassing...)

loss of control of levels in separators

(67)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri GAZ

• the speed of drainage is

dependant of the viscosity of

the oil

•the max width is dependant

of the liquid interfacial

tension

INTERFACIAL FILM

(68)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -•

NATURAL SURFACTANTSNATURAL SURFACTANTS

ADDED SURFACTANTS (PRODUCTION CHEMICALS)ADDED SURFACTANTS (PRODUCTION CHEMICALS)

SOLID PARTICULESSOLID PARTICULES

WATER DROPLETSWATER DROPLETS

(69)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Foaming is dependant on crude characteristics

BUT

• If asphaltene content > 1 %, higher foaming and stability

• if acid index >0.2 mg KOH/l, lower quantity of foam & higher stability

• The % of water and additives (anticorrosion etc… ) do not appear to have any effect on the phenomenon

Tendency to foam

API 40 = .825 API 30 = .876 Increase in % vol.

Foam breaking in seconds

API > 40 30 < API < 40 API < 30

10 - 20 20 - 40 > 50 30 30 - 60 > 60

(70)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-• THE VERTICAL SPEED OF GAS BUBBLES IS HIGH DUE TO THE

HIGH DENSITY DIFFERENCE WITH THE OIL (STOKES LAW)

GAS BUBBLES FLOCCULATE AT THE SURFACE AND CREATE A

"MATTRESS"

COALESCENCE BECOMES THE LIMITING FACTOR

THE LIQUID IS DRAINED OUT OF THE INTERFACIAL FILM

DECREASING ITS WIDTH UNTIL A MINIMUM VALUE IS REACHED WHERE IT BREAKS

BREAKING WIDTHS ARE MUCH THINNER THAN FOR EMULSIONS

(71)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

IT IS POSSIBLE TO :

IT IS POSSIBLE TO :

increase the breaking width of the foam by adding a chemicalincrease the breaking width of the foam by adding a chemical

increase the speed of drainage by lowering the liquid increase the speed of drainage by lowering the liquid viscosity (HEAT)

viscosity (HEAT)

install separator internals acting on install separator internals acting on wettabilitywettability

use separators equipped with specific cyclonic inlet devicesuse separators equipped with specific cyclonic inlet devices

(72)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -Treatment • Mechanical - Washing

- longer time spent in installation • Chemical - anti-foam

(73)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Chemical Treatment Action:

• displace the foam stabilizing element from the bubble walls • or cause bubbles to burst locally

Necessary conditions:

• be soluble in the foaming system • disperse satisfactorily

• have surface tension < that of the foam

ANTI-FOAMS

(74)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-anti

anti

-

-

foam additives

foam additives

MOSTLY USED : SILICONE OILS ( POLYSILOXANES )

EFFICIENT AT 2/3 ppm (4 to 5 ppm if diluted )

HAVE TO BE INJECTED UPSTREAM THE SEPARATOR BUT THE

CLOSER FROM THE INLET

LOSS OF EFFICIENCY AFTER A CERTAIN PERIOD OF TIME)

LOOSE THEIR EFFICIENCY WHEN TOO MUCH MIXED WITH THE CRUDE

THESE PRODUCTS ARE REFINERY CATALYSTS POISONS their dosage have to be strictly controlled

(75)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

OTHER PRODUCTS

OTHER PRODUCTS

:

:

Heavy Alcohols, cheap but weak efficiency

fluoro-Silicones, very efficient but expensive

to be used in severe cases

Selection implemented in the Flash Foaming Test (Lab)

(76)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-CRUDE OIL FOAMING TENDENCIES

FLASH FOAMING TEST

FLASH FOAMING TEST

M

PI TR TR OIL STORAGE NITROGEN BUTANE TO WATER BATH CALIBRATED CYLINDER ADJUSTABLE CONTROL VALVE ( 35 L/H) PROCEDURE

P = 10 BARS with N2 / BUTANE T = 60 ° C

(77)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

Gutter separator

for foam treatment

Diffuser Oil Inclined plates Inlet Mist extractor Gas

(78)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

(79)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Section X-X

FOAMS TREATMENTS : mechanical

(80)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

-Foam treatment

by heating

in salt water bath

Mist extractor Inlet Burner LC (water) Water LC (water) oil Gas Gas PC (gas) Oil Heating Salt water

(81)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri

FOAMS ARE SIMILAR TO EMULSIONS

FOAMS ARE SIMILAR TO EMULSIONS

HEAVY OILS (viscous) OR ACID/NAPHTENIC CRUDES

HEAVY OILS (viscous) OR ACID/NAPHTENIC CRUDES

(natural surfactants) ARE CREATING STRONG FOAMS

(natural surfactants) ARE CREATING STRONG FOAMS

IF FOAMING HAS BEEN ANTICIPATED, OVERSIZING

IF FOAMING HAS BEEN ANTICIPATED, OVERSIZING

OF SEPARATORS OR SEPARATOR INTERNALS CAN

OF SEPARATORS OR SEPARATOR INTERNALS CAN

BE CHOSEN TO LIMIT INCONVENIENTS

BE CHOSEN TO LIMIT INCONVENIENTS

IF NOT, FOAM TREATMENT USUALLY REQUIRES

IF NOT, FOAM TREATMENT USUALLY REQUIRES

HEAT + CHEMICAL TREATMENT

HEAT + CHEMICAL TREATMENT

(82)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e

(83)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Pressure (bars) 300 250 200 150 100 50 0 0 50 100 150 200 100 % 98.4 97.2 96 94.4 91.7 88.9 85.1 80 T(° C) TG P1 Bubble curve 88.9 %

Flash liberation

Yield (R)

(84)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri e -Pressure (bars) 300 250 200 150 100 50 0 0 50 100 150 200 100 % 95.0 88.1 86.2 T(° C) TG P1 Initial bubble curve in the reservoir 83.7 92 % Elimination of gas Bubble curve at perforations

Differential liberation

Yield (R)

(85)

© 2 0 0 7 E N S P M F o rm a tio n In d u s tri Pressure (bars) 300 250 200 150 100 50 0 0 50 100 150 200 100 % 91.0 88.9 T(° C) P1 Initial bubble curve in the reservoir 84.7 90 % 1st stage separation gas elimination Perforations 86.7 Well head Bubble curve at perforations

Composite liberation

Yield (R)

References

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