SEPARATION&PROCESSING

PNGE470

WELLSTREAM

NaturalGasWaterVaporLiquidHydrocarbonsLiquidWaterSolids

BASICOPERATIONS Separation

SeparationofSolids SeparationofFreeLiquidsRemovaloftheHeavyHydrocarbons

ProcessingRemovaloftheWaterVaporRemovaloftheAcidGases

EngineeringObjectives

MaximizeRecoveryattheLowestCost

SEPARATION

PNGE470

SeparationofGasfromFreeLiquids

ComponentsofaSeparator Causeaprimaryphaseseparation

ACentrifugalDevice

Removeentrainedliquidmistfromthegas ALargeSettlingSection

Removeentrainedgasfromtheliquid AMistExtractor

Dischargegasandliquidwithnoreentrainment AdequateControl

TYPES

VERTICAL:LowGORRequireLimitedSpace

Expensive

HORIZONTAL:HighGORMostCommonforGasWells

LessExpensive

SPHERICAL3PhaseSeparation

CompactVeryLimitedSurgeSpace

SEPARATORS

HORIZONTALSEPARATOR

HORIZONTALSEPARATOR

VERTICALSEPARATOR

SPHERICALSEPARATOR

SeparatorGasCapacity

0.5

L gG

g

G

L

g

v K

v =Superficial Gas Velocity, ft/s =Liquid Density =Gas DensityK Empirical Factor

SeparatorKValues

SeparatorGasCapacity0.5

2L g

g

o

2.4D KpqzT

q=Flow Rate, MMscf/dD=Diameter, ftp=Operating Pressure, psiaT= Operating Temperature, Rz= Gas Deviation Factor

SeparatorLiquidCapacity

LL

L

L

1440 Vqt

q Liquid Capacity, bbl/dayV Settling Volume, bblt Retention time, min

RetentionTimes

VerticalSeparatorSettlingVolumes

HorizontalSeparatorSettlingVolumes

SphericalSeparatorSettlingVolumes

Example Sizeastandardverticalseparatorforthefollowingconditions:

GasRate=5MMcfdGasGravity=0.7

LGR=20bbl/MMCFAPIGravity=60o

P=800psigT=80oF

Solution

0.52

L g

g

3L

g 3

0.5 0.5g2

L g

2.4D KpqzT

141.562.4 46.11 lb/ft131.5 60

2.7 P 2.7 0.7 800 = 3.38 lb/ftz T 0.828 80 460

qzT 5 0.828 540 3.38D2.4Kp 2.4 K 800 46.11 3.38

K 0.06 D 28" K 0.3

5 D 11" K 0.205 D 15"

Solution

LL

L

16" 5'

Liquid Rate 20 5 100 bbl/d1440 Vq

t

Table 7-3 V= 0.271440 0.27q 389 bbl/d

1

LowPressureVerticalSeparator

GasCapacity

HighPressureVerticalSeparators

GasCapacity

LowPressureHorizontalSeparators

GasCapacity

HighPressureHorizontalSeparators

GasCapacity

SphericalSeparators

Example

Sizeastandardverticalseparatorforthefollowingconditions:

OilRate=2500bbl/dayGOR=1000SCF/bbl

P=50psig

Solutiong

L

L

g L

q 2500 1000 2,500,000 scfd 2.5MMcfd@50psig q 2.9MMcfd

1440 1.61V 1.61 q 2318 25001

Next Size1440 2.06V

36" 5

2.06 q 2969 25001

'

30" 10'

30"q 3.75MMcfd q 2969 bbl / da

1y

0'

Fig. 4.6

Table 7 4

ExampleSizeastandardverticalseparatorforthefollowingconditions:

GasRate=5MMcfdLGR=20bbl/MMCF

P=800psig

Solution

g

L

20" 7',6"Liquid Rate 20 5 100 bbl/dFig 4.7 @800 psig q 5.4MMcfdTable 7-3 V= 0.65

1440 0.65q 936 bbl/d1

Example

Sizeastandardhorizontalseparatorforthefollowingconditions:

GasRate=5MMcfdLGR=20bbl/MMCF

P=800psig

Solution

g

L

Liquid Rate 20 5 100 bbl/dFig 4.10 @800 psig q 5.1MMcfdTable 7-5 V= 0.61

1440 0.61q 878 bbl/d

'

1

16" 5

Example

Sizeastandardhorizontalseparatorforthefollowingconditions:

GasRate=10MMcfdCondensateRate=500bbl/dWaterRate=100bbl/d

P=800psig

Solution

g

L

L

Fig 4.10 @800 psig q 10.2MMcfdTable 7-5 V= 1.80

1440 1.80q 518 bbl/d< 500+100 bbl/d5

Next Size:Table 7-5 V= 2.63

1440 2.63q 757

20" 10'

24" 10'

bbl/d5

SeparationoftheCondensableHydrocarbons

VaporLiquidEquilibrium(VLE)

StageSeparation

PandTReduction Compression

VaporLiquidEquilibrium(VLE)

FlashCalculations

c

ii

i

Ni i

i 1 V i

i i ii i

L i V L i V

ykxz 1 k

0n k 1 1

z z kx , yn k n n k n

ix

iy

iz

StandingMethod

LPFlash LP-Flash.xslThis spreadsheet performs flash calculations at low pressures and temperatures.(pressure < 1,000 psia, temperature < 200 oF)

Input Data:Pressure: 600 psiaTemperature: 200 oFSpecific gravity of stock tank oil: 0.90 water = 1Specific gravity of solution gas: 0.70 air = 1Gas solubility (Rs): 500 scf/STB

Composition

Compound Mole Fraction (zi)

C 1 0.6599C 2 0.0869C 3 0.0591i-C 4 0.0239n-C 4 0.0278i-C 5 0.0157n-C 5 0.0112C 6 0.0181C 7+ 0.0601N 2 0.0194CO 2 0.0121H 2S 0.0058

1.0000

Instructions:1) Update input data in blue;2) Run Macro Solution;3) Enter a value for z-factor in the "Flash Calculation" section;4) View results.

Results

Flash Calculation:

nv = 0.8791

Compound zi ki zi(ki-1)/[nv(ki-1)+1]C 1 0.6599 6.5255 0.6225C 2 0.0869 1.8938 0.0435C 3 0.0591 0.8552 -0.0098i-C 4 0.0239 0.4495 -0.0255n-C 4 0.0278 0.3656 -0.0399i-C 5 0.0157 0.1986 -0.0426n-C 5 0.0112 0.1703 -0.0343C 6 0.0181 0.0904 -0.0822C 7+ 0.0601 0.0089 -0.4626N 2 0.0194 30.4563 0.0212CO 2 0.0121 3.4070 0.0093H 2S 0.0058 1.0446 0.0002

0.0000

nL = 0.1209

Compound xi yi xiMWi yiMWiC 1 0.1127 0.7352 1.8071 11.7920C 2 0.0487 0.0922 1.4633 2.7712C 3 0.0677 0.0579 2.9865 2.5540i-C 4 0.0463 0.0208 2.6918 1.2099n-C 4 0.0629 0.0230 3.6530 1.3356i-C 5 0.0531 0.0106 3.8330 0.7614n-C 5 0.0414 0.0070 2.9863 0.5085C 6 0.0903 0.0082 7.7857 0.7036C 7+ 0.4668 0.0042 53.3193 0.4766N 2 0.0007 0.0220 0.0202 0.6156CO 2 0.0039 0.0132 0.1709 0.5823H 2S 0.0056 0.0058 0.1902 0.1987

Apparent molecular weight of liquid phase: 80.91Apparent molecular weight of vapor phase: 23.51Specific gravity of liquid phase: 0.76 water =1Specific gravity of vapor phase: 0.81 air = 1Input vapor phase z-factor: 0.958Density of liquid phase: 47.19 lbm/ft

3

Density of vapor phase: 2.08 lbm/ft3

Volume of liquid phase: 0.04 bblVolume of vapor phase: 319.66 scfGOR: 8659 scf/bblAPI gravity of liquid phase: 56

Example

Solutionnv = 0.8791

Compound zi ki zi(ki-1)/[nv(ki-1)+1]C1 0.6599 6.5255 0.6225C2 0.0869 1.8938 0.0435C3 0.0591 0.8552 -0.0098i-C4 0.0239 0.4495 -0.0255n-C4 0.0278 0.3656 -0.0399i-C5 0.0157 0.1986 -0.0426n-C5 0.0112 0.1703 -0.0343C6 0.0181 0.0904 -0.0822C7+ 0.0601 0.0089 -0.4626N2 0.0194 30.4563 0.0212CO2 0.0121 3.4070 0.0093H2S 0.0058 1.0446 0.0002

0.0000

SolutionnL = 0.1209

Compound xi yi xiMWi yiMWiC1 0.1127 0.7352 1.8071 11.7920C2 0.0487 0.0922 1.4633 2.7712C3 0.0677 0.0579 2.9865 2.5540

i-C4 0.0463 0.0208 2.6918 1.2099n-C4 0.0629 0.0230 3.6530 1.3356i-C5 0.0531 0.0106 3.8330 0.7614n-C5 0.0414 0.0070 2.9863 0.5085C6 0.0903 0.0082 7.7857 0.7036C7+ 0.4668 0.0042 53.3193 0.4766N2 0.0007 0.0220 0.0202 0.6156

CO2 0.0039 0.0132 0.1709 0.5823H2S 0.0056 0.0058 0.1902 0.1987

SolutionApparent molecular weight of liquid phase: 80.91Apparent molecular weight of vapor phase: 23.51Specific gravity of liquid phase: 0.76 water =1Specific gravity of vapor phase: 0.81 air = 1Input vapor phase z-factor: 0.958Density of liquid phase: 47.19 lbm/ft3Density of vapor phase: 2.08 lbm/ft3Volume of liquid phase: 0.04 bblVolume of vapor phase: 319.66 scfGOR: 8659 scf/bblAPI gravity of liquid phase: 56

STAGESEPARATION

STAGESEPARATION

LowTemperatureSeparation IncreasedLiquidHCRecovery WaterVaporRemoval

TemperatureReductionisAchievedbySuddenPressureReduction.RequiresHighPressure

H

TJoul-Thompson Coefficeint: =P

Constant H Sudden ExpansionFor Natural Gas 0 P T

EffectofTemperatureonLiquidRecovery

Example

High pressure gas condensate well:Gas Rate = 10 MMcfd

P = 800 psigLiquid Rate= 200 bbl/day

Temperature =85oF

If T is lowered to 20oF, what additionalrecovery could be expected?

Solution

o

200 bblLiquid to Gas Ratio 2010 MMcf

bbl@ 20 F Liquid to Gas Ratio 25.7MMcf

Additional Recovery ( 25.7 20 ) 10 57 bbl / day