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1.
BASICS OF PRODUCTIONTECHNOLOGY
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Density difference
Viscosity difference
Leads different shear stresses
Expansion of gas Leads Faster Velocity
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Since 1930, several Theories
Leads to Multiphase Vertical
Flow and Multiphase
horizontal flow
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1. Specific volume of fluid varies with pressure and
Temperature; small gas at the bottom & more at top
2. Energy loss due to Frictional, loss due to turbulence
& slippage loss due to specific weight difference.
Multiphase Vertical Flow-Distinguishing Features
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Affected by
1. ID, acceleration due to gravity, wetted angle on
pipewall, interfacial tension, etc.
2. Flow regime due to variation of press & temp.,
buoyancy, turbulence, inertia & surface tension.
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(i) Frictional loss varies inversely with ID.
(ii) Combined frictional losses of gas & liquid is morethan that of each phase individually.
iii) Varying heights of pipeline layout profile
iv) Flow pattern varies with pressure, temperature,flow velocity and rate.
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Multiphase Vertical Flow-Distinguishing Features
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Pf Ps
FIG -1.2
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Basics of Production Technology
Producing Oil WellsMainly oil, Multiphase Flow
Producing Gas WellsMainly gas, very high GOR
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A plumbing system connecting reservoir drainage
boundary to the first stage separator at surface.
Several Nodes are formed. Inflow Curve (IPR) Measures Reservoir Capacity to
Produce.
Outflow Curve (TIC) measures ability to lift fluid to
surface.
Inflow/outflow intersection provides solution point or
natural flowing point.
Wellbore Hydraulics (Nodal Analysis) means:
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Reservoir Drainage area
Path Sector 4
Separator
Liquid out let
PathSector
3
Tubing
Path Sector 2
Path Sector 1
Gas
Schematic Diagram of different
Path - Sectors of fluid
flow from Reservoir to surface
Well head
Beam
Fig 1.4a
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Liquid RateLiquid Rate
PP
Decreasing GLRDecreasing GLR
Inflow Vs Outflow CurvesInflow Vs Outflow Curves
IPRIPR
00
Keeping THP ConstantKeeping THP Constant
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Multiphase flow (Vertical/Inclined), known as Outflow or
Tubing Intake Curve (TIC) Vs. IPR, known as Inflow.
Liquid
Rate
Fig. 1.4 (c)
P
OperatingPoint
IPR
TIC
Pwf
QL
Pr
QL max0
KeepingGLR & THPconstant
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Q max for Straight P.I. >> Q max for IPR
FIG.1.4-1 : Actual Case For P I
Pwf
q
STRAIGHT P.I . AND IPR
STRAIGHT P.I.
Q maxQ max
IPR
Pwf = Pr
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PR
E
S
S.
P
I
G
O
R
CUMM. PROD.
P I
FIG. 1.4-2 : Typical Performance For an Active Water Drive Reservoir
GOR
PRESSURE
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CUMM. PROD.
FIG. 1.4-3 : Typical Performance For A Solution Gas Drive
Field Reservoir.
RESV.PRESS
GOR
PI
PI
GOR
RESV.
PRESS.
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.
CUMM. PROD.
RESV.
PRESS.
GOR
PIGOR
P.I
RESV.
PRESS.
FIG. -1.4-4 : Typical Performance For A Gas cap Expansion DriveReservoir.
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RATE.
PRESS .
00
Pwf
Pb
qqmaxqb
JPb/1.8
VOGEL
BEHAVIOR
CONSTANT J
Pr
FIG.1.4-5: Combination Constant PI and Vogel Behaviour Case,
when Pr>Pb
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FIG. - 1.4-6 : Computer Calculated Inflow Performance
Relationships For A Solution Gas Drive Reservoir- Pattern of
IPR with Cumulative Recovery.
PRODUCING RATE , M3/D
Np/N = 0.1%
2 %
4 %
6 %
8 %
10 %
12 %
14 %
CUMM. REC.,
% OF
ORIGINAL OIL
IN PLACE
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INTRODUCTION ON ARTIFICIAL LIFT
CONCEPT OF PRODUCTIVITY INDEX
P.I = Q / ( Pr - Pwf )
Where ,
P.I = Productivity index.
Q = Total quantity of fluid.
Pr = Reservoir Pressure.
Pwf = Flowing bottom hole pressure.
Q Pr - Pwf
Q = K (Pr - Pwf)
K = Q / (Pr - Pwf)
Where K is a constant, known as PI
Pwf Pr
Pwf = Pr
Pwf
Pwf = 0
Q Qmax
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INFLOW PERFORMANCE
VOGELS WORK ON IPR :
From general IPR equation i.e.
J= qo/(Pr-Pwf)--------------- ( 1 )
WhenPwfis zero , theqobecomes maximum and denoted asqmax.
That is J = qmax / (Pr- 0)
or J= qmax /Pr----------------- ( 2 )
Contd.--------------
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VOGELS WORK ON IPR :
Dividing equation ( 1 )by ( 2 )
J / J = qo/(Pr-Pwf) * Pr/ qmax
or qo / qmax =(Pr -Pwf ) / Pr
or qo / qmax =( Pr / Pr )-(Pwf / Pr )
or qo / qmax =1-(Pwf / Pr )since IPR curve below bubble point is not a straight line , he
created a parabolic equation from the above.
Contd.----------------
INFLOW PERFORMANCE
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VOGELS WORK ON IPR :
He distributed {Pwf /Pr }in the following manner
20 % of{Pwf /Pr } & 80 % of {Pwf /Pr }
Therefore , the new equation is established as :-
qo / qmax = 1 - 0.2 {Pwf /Pr } - 0.8 {Pwf /Pr }
He then plotted dimensionless IPRs in two dimensional plane ,
where X- axisrepresents qo / qmax and Y- axisrepresents Pwf
/Pr Contd.----------------
INFLOW PERFORMANCE
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VOGELS WORK ON IPR :
The minimum and maximum values qo / qmax and Pwf /Prin each case is 0 and 1.0.
Inflow performance relationship for solution gas drive reservoirs (afterVogel).
00
0.20
0.40
0.60
0.80
1.00
1.000.800.600.400.20
Pwf/Pr
qo / qmax
INFLOW PERFORMANCE
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STANDINGS EXTENSION OF VOGELS IPR
FOR DAMAGED OR IMPROVED WELL :According to him, flow efficiency is defined as :
F.E = Ideal drawdown/Actual drawdown
=(Pr - P'wf) / (Pr - Pwf) ---(1)Where,
P'wf = Pwf + (DP)skin
(DP)skindefined by Van Everdingen is as below :
(DP)skin= S q / 2kh
Contd.-----
PrPwf
(DP) Skin
So, Pwf = Pwf + (DP) Skin
INFLOW PERFORMANCE
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PREPARATION OF FUTURE IPR -
For planning future requirement of
Artificial Lift, Surface and Downhole
equipment
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IPR of Gas Wells
Qg= C (P2r
P2
f)n
C is a constant and it includes reservoir thickness,
permeability, temp., wellbore & drainage radii etc.
n depends upon turbulent flow near the well bore.
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Fig. 1.4.9 : Inflow Performance Curve of a Gas Well
(in log-log graph)
qg
(Pr2 P
f2)
102
100
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FLOW PATTERNS
+ Multiphase Correlations
+ Usefulness of multiphase Correlations
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MULTIPHASE FLOW
Number of flow regimes may be divided into two broad
divisions :
Where one phase is continuous.
Ex: Bubble , Spray & Froth flow.
Liquid is the continuous phase in bubble flow and gas is the
continuous phase in the other two.
Where both phases are continuous.
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SINGLE PHASE FLOW
Refers to one fluid medium only
MULTIPHASE FLOW
Refers to more than one fluid medium , for example
Oil , Water and Gas.
SINGLE & MULTIPHASE FLOW
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MULTIPHASE FLOW
HORIZONTAL FLOWVERTICAL /
INCLINED FLOW
STRATIFIED INTERMITTENT ANNULAR DISPERSED BUBBLE
SMOOTH WAVY SLUG ELONGATED BUBBLE
BUBBLE SLUG CHURN ANNULAR
MULTIPHASE FLOW
MULTIPHASE FLOW
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STRATIFIED SMOOTH FLOW(LOW GAS & LIQUID RATES - PHASES SEPARATED BY GRAVITY)
STRATIFIED WAVY FLOW(SAME AS ABOVE WITH RELATIVELY HIGH GAS FLOW RATE)
HORIZONTAL FLOW Fig2.2A
Fig-2.2B
MULTIPHASE FLOW
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INTERMITTENT SLUG FLOW(INTERMITTENT FLOW OF LIQUID AND GAS - GAS POCKETS DEVELOPES)
ELONGATED BUBBLE FLOW(SAME AS ABOVE ; EARLIER THAN SLUG FLOW, WHEN GAS RATES ARE
LOWER)
HORIZONTAL FLOW Fig-2.2C
Fig2.2D
MULTIPHASE FLOW
MULTIPHASE FLO
W
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ANNULAR FLOW
GAS OCCUPIES CENTRAL PORTION LIKE A
CYLINDER AND LIQUID REMAINS NEAR THE
PIPEWALL; CENTRAL PORTION ENTRAINSLIQUID DROPLETS. OCCURS AT VERY HIGH
GAS FLOW RATE.
HORIZONTAL FLOWFig-2.2E
MULTIPHASE FLOW
MULTIPHASE FLO
W
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DISPERSED BUBBLE FLOW
AT VERY HIGH LIQUID FLOW RATE, LIQUID
PHASE IS CONTINUOUS & GAS PHASE IS
DISPERSED ALL AROUND LIQUID IN THE FORMOF DISCRETE BUBBLES.
HORIZONTAL FLOW
Fig2.2F
MULTIPHASE FLOW
MULTIPHASE FLO
W
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BUBBLE FLOW
VERTICAL / INCLINED FLOW
OCCURS AT RELATIVELY
LOW LIQUID RATES.
MULTIPHASE FLOW
MULTIPHASE FLO
W
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SLUG FLOW
VERTICAL / INCLINED FLOW
Symmetric about the pipe axis.
Gas phase -like a large bullet
shaped gas pocket with a diameter
almost equal to pipe diameter.
Gas pocket is termed
as Taylor Bubble.
MULTIPHASE FLOW
MULTIPHASE FLO
W
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CHURN FLOW
VERTICAL / INCLINED FLOW
Similar to slug flow, though it is
chaotic with no clear boundaries
between the two phases.
Flow pattern is characterised
by oscillatory motion.
Occurs at high flow rates; liquidslugs become frothy.
MULTIPHASE FLOW
MULTIPHASE FLOW
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ANNULAR FLOW
VERTICAL / INCLINED FLOW
Liquid film thickness is almost
uniform around pipe wall.
Characterised by a fast moving
gas core.
Liquid film is highly wavy due tohigh interfacial shress.
MULTIPHASE FLOW
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Effect of variables Line Size
Flow Rate
Gas-Liquid Ratios
WaterCut
Viscosity
Slippage
Kinetic energy term
MULTIPHASE FLOW
HORIZONTAL MULTIPHASE FLOW
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Effect of Variables - I
Pipe DiameterPressure loss (dP) decreases
rapidly with increase in Pipe Diameter.
Flow RateHigher flow rate increases dP
GLRIncreased GLR increases friction,
hence more dP, unlike to vertical flow.
HORIZONTAL MULTIPHASE FLOW
HORIZONTAL MULTIPHASE FLOW
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Effect of Variables - II
ViscosityViscous crude offers more
problem in horizontal flow mode.
Water CutIts effect is not pronounced.
SlippageIts effect is not pronounced.
Kinetic EnergyFor High flow rates & low
density it is considered for computation.
HORIZONTAL MULTIPHASE FLOW
HORIZONTAL MULTIPHASE FLOW
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Effect of variables Tubing Size
Flow Rate, Density
Gas-Liquid Ratio
Water Cut
Viscosity
Slippage ,Kinetic Energy term
Inclination Angle
HORIZONTAL MULTIPHASE FLOW
VERTICAL / INCLINED MULTIPHASE
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Effect of Variables - I
Tubing SizeIt has pronounced effect in
deciding FBHP requirement..
Flow RateIt establishes the required
FBHP, which influences tubing size selection.
GLRIncrease GLR reduces FBHP requi-
rement, after a point reversal takes place.
FLOW
MULTIPHASE FLOW
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FLOWCORRELATIONS
HORIZONTAL
FLOW
VERTICAL
FLOW
INCLINED
FLOW
MULTIPHASE FLOW
VERTICAL / INCLINED MULTIPHASE
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Effect of Variables - II
DensityHigher density increases dP.
ViscosityHigher viscosity increases dP.
Water CutHigher watercut increases dP.
SlippageIt is observed during unstable flow region.
Kinetic EnergyFor High velocity & low density it is
considered for computation.
FLOW
MULTIPHASE FLOW
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VARIOUS ASSUMPSIONS TAKEN FOR
DIFFERENT CORRELATIONS :Fluid must be free from emulsion.
Fluid must be free from scale / paraffin build up.
Mashed or kinked joints should not exist.
Flow patterns should be relatively stable.
No severe slugging should occur.
Oil should not be very viscous.
U S OW
HORIZONTAL MULTIPHASE FLOW
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CORRELATIONS
FOR
HORIZONTAL
MULTIPHASE FLOW
Lockhart & Martinelli Baker
Andrews
et al.
Dukler
et al.
Eaton et al. Beggs & Brill
HORIZONTAL MULTIPHASE FLOW
MULTIPHASE FLOW
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VERTICAL FLOW
CORRELATIONS
Duns & Ros
Orkiszewski
Hagedorn Brown
Winkler &
Smith
Beggs &
BrillGovier
& Aziz
MULTIPHASE FLOW
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INCLINED FLOWCORRELATIONS
FLANIGAN
CORRELATION
BEGGS & BRILL
CORRELATION
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P
Decreasing GLR
Horizontal Multiphase Flow Gradient Curves
Flow line
Length
0
Min. Gradient Curve
Vertical / Inclined l Multiphase Flow Gradient Curves
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P
Increasing GLR
Vertical / Inclined l Multiphase Flow Gradient Curves
Depth
0
Min. Gradient Curve
Well Depth
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Vertical Flowing Pressure Gradients
(Courtesy: The Technology of Artificial Lift Methods By K.E. Brown)
FIG. 1.4-21(a)
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Horizontal Flowing Pressure Gradients
(Courtesy: The Technology of Artificial Lift Methods By K.E. Brown)
FIG. 1.4-21(b)
MULTIPHASE FLOW
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USEFULNESS OF VARIOUS CORRELATIONS :
Selecting tubing sizes.Predicting when the well will cease to flow.
Designing of artificial lift.
Determining flowing bottom hole pressures from the
wellhead pressures.
Determining the flowing bottom hole pressure, which
in turn help in determining P.I. of the well.
Predicting maximum flow rates possible.
Predicting whether the well is able to flow as per thepresent & future profile.
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Vertical/Horizontal Gas Flow
Mostly gas with little oil.
Basically flow of gas offers resistance to flow
in both vertical and horizontal conduits & in
that respect it differs from that with oil flow.
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Assumptions
Acceleration is negligible
Flow is steady & isothermal
No work done by gas
Equations are developed, like Weymouth equation for
horizontal flow, Hagedorn & Brown for Vertical Flow.
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