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De artment of of Petroleum En En ineerin Univ Un iver ersi sity ty of of St Stav avan ange gerr Seminar Seminar at Aker Solutions, Solutions, Stavanger Stavanger – May 31st, 2011
ut ine an time sc e u e
8.30 – 9.15
Flow regimes and impact on phase slippage, fluid concentrations and pressure drop in
9.25 – 10.15
Hydrates, wax and asphaltenes
10.25 -11.00
Multiphase Multip hase flow – influen influence ce from interf interfaces, aces,
2 Seminar at Aker Solutions, Solutions, Stavanger Stavanger - May31st, 2011 2011
Flow re imes and im act on hase sli a e, fluid concentrations and pressure drop in pipelines QG
Gas
QL
Liquid
• Stratified liquid and gas – is there a flow? How to decide? • Some concepts are needed: • • Fluid fractions • Flow patterns (” regimes” )
3 Seminar at Aker Solutions, Stavanger - May31st, 2011
QUIZ: A simple(st) case of two-phase flow Equal inflow QL = QG
Horizontal pipeline
Gas
3 1
Stabilized interface ?
qu
• • Any guideline principles?
4
Basic uantities and definitions: - Superficial velocities and fluid fractions GS
q G
A
uG uL
q L
AG
ULS
U LS U GS
Apparent liquid ” ”
qL
qG
q L q L qG
Mixture velocity :
U mix
U LS U GS
ULS ULS UGS
Seminar at Aker Solutions, Stavanger - May31st, 2011
5
Basic uantities and definitions: - True velocities and Slip q G
A
uG uL
q L
AG
u L
uG
True (phase) velocities :
p ve oc y : u S u G u L and uG
q L A L G
AG
NOSLIP condition: uL = uG = Umix
u L
= 6
Seminar at Aker Solutions, Stavanger - May31st, 2011
Basic uantities and definitions: - True liquid fraction versus noslip fraction GS
q G
A
uG uL
q L
AG
ULS
True real volume fraction L
AL L
A arent (”noslip”):
L
U LS
G
q L q L qG
U LS
S
U GS
S = Slip ratio
U LS U LS U GS
Seminar at Aker Solutions, Stavanger - May31st, 2011
7
True fraction noslip fraction (S = 1) as mixture velocity increases
1
L
U
U LS 1
S
Flow regime U
n o i t c
( Keeping constant
r f d i u q i L
L Segregated flows
Mixed flows
U LS U LS
U GS
0 Umix 8 Seminar at Aker Solutions, Stavanger - May31st, 2011
Flow regimes in horizontal pipes Flow d rect on y t i c o l e v
d e e p s w o l f g n i s a e r c n I
o L
y i c o l e v e t a i d e r e t n I
y t i c o l e v h g i H
Stratified smooth flow (SS)
Stratified wavy flow (SW)
Elongated bubble flow (EB)
Slug flow (I)
Dispersed bubble flow (DB)
nnu ar wavy flow (A-AW)
9 Seminar at Aker Solutions, Stavanger - May31st, 2011
ow regime map – orizonta pipes Dispersed bubble (DB) 10
Slug flow (I)
Elongated u e ow (EB/I)
s m S L
a e an u er 2.5 cm i.d. Pipe air-water flow at atmospheric conditions Mandhane Annular annular wavy annular mist flow
0.1 Stratified smooth
Stratified wavy flow
Flow direction y t i c o l e v w o L
y t i c o l e v e t a i d e m r e t n I
y t i c o l e v h g i H
0.01 0.1
10
1
Stratified smooth flow (SS)
Stratified wavy flow (SW)
Elongated bubble flow (EB)
Slug flow (I)
Dispersed bubble flow (DB)
Annular (wavy) flow (A-AW)
100
UGS (m/s)
10 Seminar at Aker Solutions, Stavanger - May31st, 2011
Flow regimes and map – vertical pipes Flow regime map
Flow regimes - types
(small)
flow Slug – churn ow
11 Seminar at Aker Solutions, Stavanger - May31st, 2011
Gas – concentration profiles Pipe
Gas fraction
G
Up
Leads to vertical differences: • Gas- liquid wetting (evt. water) • Asymmetric corrosion (”6’oclock”) • Shear stress & Erosion rates • Heat transfer rates 12 Seminar at Aker Solutions, Stavanger - May31st, 2011
Particle slurries in multiphase flow
D:\BACKUP 2009 - DET ASTRONOMISKE ÅRET 2009\Åpent Hus 17mars09\Utvalg te hi gh-
13 Seminar at Aker Solutions, Stavanger - May31st, 2011
Particle slurry regimes - dunes Suspended particles in liqud
Rabenjafimantsoa and Time ( UIS) - project with Statoil 2000-2005
14 Seminar at Aker Solutions, Stavanger - May31st, 2011
Oil-water-gas flow regime map
http://www.iceweb.com.au /Flow/multiphase_1.htm
15 Seminar at
Aker Solutions,
Stavanger - May31st, 2011
Importance of flow regimes Much more than just ”flow appearance”: Field plan and development • Multiphase simulation, pressure and fluid fraction determination • Slip ratio and fluid transport rates in long pipelines • • Decisive for quality of multiphase metering
Flow assurance, safety • Process stability and control • Pipeline and equipment vibration and fatigue • Erosion •
16 Seminar at Aker Solutions, Stavanger - May31st, 2011
The challenge of calculating pressure drop in long traverses T e pressure gra ient varies a ong t e pipe due to variation in pipe diameter, inclination and mixture density (pressure dependent)
Pout
in
Pressure at exit:
Pou
Pn P
Sum of pressure drop in all pipe segment
Challenge in multiphase flow: • The pressure profile depends on the pressure ! 17 Seminar at Aker Solutions, Stavanger - May31st, 2011
Robust – ”homogeneous” pressure drop model for two-phase flow x UGS
Pressure gradient versus UGS for contant ULS 12000
ULS
Friction factor dp Friction : f (Re) m U mix 2 dx D 2
4
1
f
*
) 10000 m / a P ( 8000 t n e i d 6000 r g e r 4000 u s s e r P 2000
Constant Uls= 3m/s
Total
0
5
10
15 20 Ugs (m/s)
25
30
Hydrostatic: dp m g sin dx h
Acceleration: dp dU mix m U mix dx a
dx
EXCEL version 18
Seminar at Aker Solutions, Stavanger - May31st, 2011
Two-phase pressure drop model – Excel version
UGS Quantity as ens y Liquid density Kinematisk gas viscosity Dynamic gas viscosity Liquid viscosity Pipe diameter
Symbol rog rol nyg myg myl D
Pipe inclination Acc eleration of gravity
g
20,0 deg 9,81E+00 m/s^2
Slip ratio
S
1,2
Superficial gas velocity Mixture velocity Gas fraction Liquid fraction
UGS Umix epsg epsl
2 dx D C Re m 2 m U mix f
Mixture density Mixture viscosity
rom mym
dp m
Reynolds number Friction factor
Re f
2,40E+05 3,86E-03
Friction pressure drop
dPdx_f dPdx_h dPdx_a dPdx
9,08E+02 Pa/m 2,57E+03 Pa/m Pa/m 3,48E+03 Pa/m
LS
p
n
g sin
dp U dUmix m mix dx dx a
Hydrostatic pressure drop Accelerational pressure drop Total pressure drop
Value 1000 1,50E-06 1,50E-05 3,00E-03 1,50E-01
Unit gm kg/m^3 m^2/s Pa*s Pa*s m 3,49E-01 rad
, 1,3 m/s 4,8 m/s 0,236363636 0,763636364 766 kg/m^3 2,29E-03 Pa*s
19
The World is Dynamic! – need for Measurement an ontro does not mean that the individual flowrates (G,L) are constant ! - Need for multiphase metering for survey and control !
Separation approach Weatherford
Mixing approach MPM
20