Drag Reduction

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Drag Reducing Agents in Multiphase Flow Pipelines:Recent Trends and Future NeedsB. A. Jubran a; Y. H. Zurigat b; M. F. A. Goosen ca Department of Aerospace Engineering, Ryerson University, Toronto, Ontario,Canadab University of Jordan, Amman, Jordanc School of Science and Technology, University of Turabo, Puerto Rico

Online Publication Date: 01 November 2005To cite this Article: Jubran, B. A., Zurigat, Y. H. and Goosen, M. F. A. (2005) 'DragReducing Agents in Multiphase Flow Pipelines: Recent Trends and Future Needs',Petroleum Science and Technology, 23:11, 1403 - 1424To link to this article: DOI: 10.1081/LFT-200038223

URL: http://dx.doi.org/10.1081/LFT-200038223

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Petroleum Science and Technology, 23:1403–1424, 2005Copyright © Taylor & Francis Inc.ISSN: 1091-6466 print/1532-2459 onlineDOI: 10.1081/LFT-200038223

Drag Reducing Agents in Multiphase FlowPipelines: Recent Trends and Future Needs

B. A. JubranDepartment of Aerospace Engineering, Ryerson University,

Toronto, Ontario, Canada

Y. H. ZurigatUniversity of Jordan, Amman, Jordan

M. F. A. GoosenSchool of Science and Technology, University of Turabo, Puerto Rico

Abstract: In this paper, recent work on drag reducing agents in single and multiphaseflow pipelines is reviewed. Focus is placed on theories of drag reduction, the influenceof drag reduction agent types, and hydrodynamic and heat transfer characteristics offlows in the presence of drag reducing additives. Questions are raised, shortcomingsare assessed, and future research needs are outlined.

Keywords: drag reducing agents, heat transfer, multiphase flow, flow conditioner

INTRODUCTION

Drag reduction in pipe flow using polymeric drag reduction agents (DRAs)is a problem of great practical engineering interest because DRAs reducepumping power and increase piping system capacity. DRAs have been usedin several engineering systems, such as district heating and cooling, oil pro-duction and transportation pipelines, and others. Its first commercial use wasin the 1.2 m diameter Trans-Alaskan Pipeline in 1979, where a 50% dragreduction was achieved, thereby increasing the capacity of the pipeline from1.45 to 2.1 MBPD (Burger et al., 1982). This resulted in eliminating theneed for installing two pumping stations, which were planned to achieve the

Received 4 March 2004; accepted 23 April 2004.Address correspondence to B. A. Jubran, Department of Aerospace Engineering,

Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada, M5B 2K3. E-mail:[email protected]

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1404 B. A. Jubran et al.

mentioned increase in capacity. Since that time, the DRAs have been usedin many petroleum product pipeline installations, such as the Iraq-Turkey oilpipeline and Oseberg Field in the North Sea (Berge and Solvik, 1996). Thus,the use of DRAs has the following advantages:

1. Increased pipeline capacity (throughput).2. Savings in pumping power.3. Pressure reduction with the associated reductions in pipe thickness and

pressure surge.4. Reduction in pipe diameter in the design phase as well as the number or

size of pumping facilities.

The result of DRA application is a reduction in systems’ overall costs.One further advantage of using drag reducing agents is that the DRAs canbe implemented immediately or temporarily, giving high operational flexibil-ity. Typical dosage rates for 10–30% flow improvement in oil pipelines are1–2 ppm of polymer per injection site. Berge and Solvik (1996) found thatthe required DRA-injection rates for multiphase flows were four times higherthan those needed for stabilized crude oil. This was attributed to the highershear degradation that resulted from the higher degree of flow turbulencein the multiphase system. The performance of DRAs is measured using theeffectiveness defined by:

effectiveness (ε) = �Pwithout DRA − �Pwith DRA

�Pwithout DRA(1)

The performance of DRAs is affected by several factors, such as pipediameter, temperature, fluid viscosity, and the presence of paraffin and/orwater. Comparisons of effectiveness and costs for new and conventional DRAsare shown in Figures 1, 2, and 3 (Berge and Solvik, 1996). Over a 14-yearperiod (between 1980 and 1994) the effectiveness of drag reducing agentshad increased 14 times.

The aim of this paper is to review recent work on drag reduction insingle and multiphase flow in pipelines. Focus is placed on theories of dragreduction, the influence of drag reduction types, and hydrodynamic and heattransfer characteristics of the flows in the presence of DRAs. Questions areraised, shortcomings are assessed, and future research needs are outlined.

THEORIES OF DRAG REDUCTION

Drag reducing agents (DRAs) are applied in pipelines with turbulent flow,hence, they are not effective in laminar flows. The reduction is achieved by theinteraction between the polymer molecules and the turbulence componentsof the flow. Polymers tend to stretch in the flow and absorb the energy in thestreak, which in turn stops the burst that produces the turbulence in the coreand results in a reduction in turbulence (Lester, 1985; Mizunuma et al., 1996).

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Drag Reducing Agents in Multiphase Flow Pipelines 1405

Figure 1. Comparison of conventional gel-type DRA and new generation type.

Figure 2. Performance comparison of new generation type and conventional gel-typeDRA.

Figure 3. Cost comparison of conventional gel-type DRA with new generation typeDRA.

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Thus, the principal effect of DRAs is to reduce the velocity fluctuations inthe normal direction and Reynolds stresses thereafter. Cationic surfactants areanother class of DRA which form rod-like micelles. Under shear stress, mi-celles line up in the direction of flow and build the so-called shear-inducedstate, which leads to a damping of radial turbulence and a subsequent re-duction in pressure loss. The various theories used to explain drag reductionphenomena are summarized by Kostic (1994) (see Table 1).

The existence of multiphase flow (oil/gas and oil/water/gas mixture) inpipelines is common in the oil and gas industry. This is due to the fact that oiland gas wells are drilled far away from the separation site, which necessitatestransport by multiphase pipeline flow. Drag reducing agents have been usedfor a long time to lower the friction component of the pressure in a single-phase flow during the transport of oil or gas in pipelines. However, recentlyit has been shown that DRAs are also effective in multiphase flow and workvery well on all components of pressure drop: frictional, accelerational, andgravitational (Dass et al., 2000). This is because of the DRA’s ability tomodify the flow pattern, which will be discussed later in this paper.

Drag reduction phenomena in multiphase flow are still far from beingwell understood in spite of the numerous investigations. This is due to thedependence of such phenomena on a large number of parameters, such as oilviscosity; pipe diameter; liquid and gas velocities; composition of oil, suchas the wax content, pipe surface roughness, water cut, pipeline inclination,DRA concentration, types of DRA; shear degradation of DRAs, temperature,and pH (Kang and Jepson, 2000).

DRAG REDUCING AGENTS

Drag reducing agents (DRAs) are high molecular weight, long chain poly-mers, such as polymethacrylate (PMMA), polyethyleneoxide (PEO), andpolyisobutylene (PIB). DRA polymers commonly used are x-olefin polymersand copolymers of very high molecular weight. A new generation of dragreduction agents is now available commercially. In general, the new DRAis characterized by high polymer content. The active component is still apolyalphaolefin polymer with a fast dissolution rate and a slow degradationrate. Moreover, they are characterized by low viscosity and are much easierto handle. Berge and Solvik (1996) reported field results in crude oil and mul-tiphase flows using the new generation DRA, which is an emulsified powderproduct with a polymer content of 20–25%, as compared to conventionalgel-type product with polymer content of 5–8%. They reported that the newDRA tends to be four times more effective than the conventional gel-typeDRA, with cost savings of 25%. Table 2 summarizes drag reducing additivesand their properties, while Table 3 lists the drag reduction and heat transferbehavior as reported by Kostic (1994).

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Tabl

e1.

The

orie

sof

drag

redu

ctio

nph

enom

ena

The

ory

Des

crip

tion

Shea

rth

inni

ngO

rigi

nally

itw

assp

ecul

ated

that

near

-wal

l-la

yer,

byvi

rtue

ofsh

ear-

thin

ning

,m

ayha

veex

trem

ely

low

erfr

ictio

nco

effic

ient

than

pure

solv

ent.

Lat

erth

isth

eory

was

disc

ount

edsi

nce

itw

aspr

oved

that

shea

r-th

inni

ngfr

ictio

nis

som

ewha

tlo

wer

,bu

tno

tne

arly

that

ofdr

ag-r

educ

tion

fric

tion.

Vis

co-e

last

icity

and

norm

al-s

tres

ses

Thi

sm

ayw

ell

beth

em

ost

unfo

rtun

ate

theo

ry.

Dra

g-re

duci

ngpo

lym

erso

lutio

nsar

evi

scoe

last

ican

dsh

owth

eno

rmal

-str

ess

diff

eren

ces,

but

for

conc

entr

atio

nsex

trem

ely

high

bydr

ag-r

educ

tion

stan

dard

s.V

ery

dilu

teso

lutio

nsdo

not

exhi

bit

any

mea

sura

ble

elas

ticity

,no

rch

ange

ofvi

scos

ityfr

ompu

reso

lven

t,st

illth

eyar

eve

ryst

rong

drag

redu

cers

.A

lso,

visc

oela

stic

,cr

oss-

linke

dpo

lyac

rylic

acid

(Car

bopo

l)so

lutio

nsdo

not

show

any

drag

-red

uctio

n,ex

cept

for

shea

r-th

inni

ngef

fect

.It

may

wel

lbe

that

visc

oela

stic

itydo

esno

tpl

ayan

ym

ajor

role

indr

agre

duct

ion,

but

ism

erel

yan

acco

mpa

nyin

gpr

oper

tyof

som

edr

ag-r

educ

tion

fluid

s.It

iskn

own

that

both

visc

oela

stic

and

non-

elas

ticflu

ids

may

prod

uce

drag

-red

uctio

n.M

olec

ular

“str

etch

ing”

Gre

atly

exte

nded

linea

rm

acro

mol

ecul

esin

shea

rdi

rect

ion

inte

rfer

ew

ithtu

rbul

ence

,pr

ovid

ing

ast

iffe

ning

effe

ct,

thus

redu

cing

fric

tion

drag

.O

ther

spo

stul

ate

that

mol

ecul

aren

tang

lem

ents

are

resp

onsi

ble

for

inte

rfer

ing

with

and

enla

rgin

gth

esu

blay

ered

dies

.So

me

have

argu

edth

atm

acro

mol

ecul

es’

elas

ticpr

oper

ties

and

cont

inuo

usde

form

atio

n,lik

ea

“yo-

yo”

effe

ct,

are

resp

onsi

ble

for

dam

ping

smal

ltu

rbul

ent

eddi

es,

stor

ing

and

reco

veri

ngot

herw

ise

diss

ipat

edtu

rbul

ent

ener

gy.

How

ever

,fo

rex

trem

ely

dilu

teso

lutio

nsit

seem

sun

likel

yth

atsu

cha

hypo

thes

isco

uld

beva

lid.

Dec

reas

edtu

rbul

ence

prod

uctio

nSo

me

rese

arch

ers

sugg

est

that

poly

mer

addi

tives

inte

rfer

ew

ithth

epr

oduc

tion

oftu

rbul

ence

,an

dth

atth

ere

duct

ion

phen

omen

aar

eno

tdu

eto

turb

ulen

cedi

ssip

atio

n,bu

tar

edr

iven

byre

duce

dge

nera

tion

oftu

rbul

ence

.Si

nce

the

two

have

tobe

inba

lanc

e,th

eir

role

sm

aybe

easi

lym

ista

ken.

(con

tinu

ed)

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Tabl

e1.

(Con

tinu

ed)

The

ory

Des

crip

tion

Dec

reas

edtu

rbul

ence

diss

ipat

ion

Tur

bule

nce

ener

gydi

ssip

atio

nvi

afin

est

eddi

esis

grea

tlyre

duce

d(s

uppr

esse

d)by

addi

tives

inte

rfer

ence

,to

anex

tent

equa

lto

the

drag

-red

uctio

n,w

hile

larg

ered

dies

and

larg

e-sc

ale

flow

inst

abili

tyar

epr

esen

t(s

till

turb

ulen

tflo

w),

but

with

diff

eren

tan

dm

ore

favo

rabl

est

ruct

ure.

Vor

tex

stre

tchi

ngIt

ispo

stul

ated

that

resi

stan

ceto

vort

exst

retc

hing

redu

ces

the

mix

ing

and

ener

gylo

sses

.It

isfu

rthe

rsh

own

that

dilu

tepo

lym

erso

lutio

nsm

ayha

veth

ousa

nds

oftim

eshi

gher

exte

nsio

nal

visc

osity

than

the

stea

dy-s

tate

visc

osity

,w

hich

may

have

ast

rong

influ

ence

ondr

ag-r

educ

tion

mec

hani

sm,

belie

ved

topl

aya

maj

orro

lein

are

gion

just

outs

ide

the

lam

inar

subl

ayer

(5<

y+

<50

).N

on-i

sotr

opic

prop

ertie

san

dtu

rbul

ence

Sinc

evi

scos

ityis

shea

r-ra

tede

pend

ent

and

the

shea

r-ra

teis

dire

ctio

nal,

the

solu

tion

stru

ctur

ebe

com

esan

isot

ropi

c;he

nce

visc

osity

(inc

ludi

ngdy

nam

ican

dhi

gher

-ord

erst

ress

coef

ficie

nts)

has

tobe

anis

otro

pic:

for

shea

rth

inni

ngflu

ids,

itis

low

erin

the

flow

dire

ctio

nan

dhi

gher

incr

oss-

flow

dire

ctio

ns,

thus

supp

ress

ing

cons

ider

ably

the

cros

s-flo

wflu

ctua

ting

velo

city

com

pone

nts

(esp

ecia

llysm

all-

scal

eed

dyflu

ctua

tions

).L

amin

ariz

atio

nof

turb

ulen

tflo

wT

urbu

lenc

eis

the

“was

tefu

l”di

ssip

atio

nof

fluid

ener

gyvi

ath

efin

est

turb

ulen

ted

dies

,th

usit

dire

ctly

incr

ease

sfr

ictio

ndr

ag.

The

refo

re,

drag

redu

ctio

nis

adi

rect

mea

sure

ofpa

rtia

lflo

wla

min

ariz

atio

n.B

yde

finiti

on,

turb

ulen

ceim

plie

sra

ndom

fluct

uatio

nsan

den

ergy

diss

ipat

ion,

othe

rwis

eflo

win

stab

ility

will

have

som

eor

derl

yse

cond

ary

(and

unst

eady

)flo

wpa

ttern

s.U

nans

wer

edqu

estio

ns:

•D

oes

visc

oela

stic

ityha

vean

ydi

rect

rela

tion

with

turb

ulen

tdr

agre

duct

ion?

•Is

influ

ence

ofw

all

cruc

ial

sinc

epo

lym

ers

may

prof

ound

lym

odif

yje

tsan

dfr

eetu

rbul

ence

?•

Wha

tis

the

influ

ence

ondr

agre

duct

ion

ofin

tern

alan

dex

tern

albo

unda

ryla

yers

and

how

can

conc

epts

beun

ified

?•

Why

is“O

nset

”of

drag

redu

ctio

npr

esen

tw

ithso

me

but

not

all

drag

-red

ucin

gflu

ids?

•W

hydo

addi

tives

prod

uce

the

max

imum

fric

tion

and

heat

-tra

nsfe

rre

duct

ion

asym

ptot

es,

but

cann

otfu

llyla

min

ariz

eflo

w(U

ltim

ate

Dra

gR

educ

tion)

?•

Why

isth

eas

ympt

otic

heat

-tra

nsfe

rre

duct

ion

stro

nger

and

occu

rsfo

rhi

gher

poly

mer

conc

entr

atio

nth

anfr

ictio

ndr

ag?

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Tabl

e2.

Dra

gre

duci

ngad

ditiv

esan

dth

eir

prop

ertie

s

Type

ofad

ditiv

eC

hara

cter

istic

prop

ertie

s

Hig

h-po

lym

ers

—Po

lyet

hyle

neox

ide

(the

best

)—

Poly

isob

utyl

ene

(oil-

solu

ble)

—Po

lyac

ryla

mid

e—

Car

boxy

met

hylc

ellu

lose

Mac

rom

olec

ules

—hi

gh-m

olec

ular

wei

ght

(106

orhi

gher

),lin

ear

stru

ctur

e,w

ithm

axim

umex

tens

ivity

,ex

celle

ntso

lubi

lity.

Soap

and

surf

acta

ntag

greg

ates

Low

-mol

ecul

ar-w

eigh

tal

kali-

met

alan

dam

mon

ium

soap

mol

ecul

esfo

rmag

greg

ates

or“m

icel

les”

inlo

ng-c

hain

s.Fi

bers

—A

sbes

ton

—N

ylon

—W

ood

pulp

Asb

esto

sfib

ers

are

extr

emel

ylo

ng(h

air-

like)

.N

ylon

fiber

sar

esh

orte

r(l

engt

h-to

-dia

met

erra

tioab

out

50).

Woo

dpu

lpsu

spen

sion

sin

wat

erre

duce

turb

ulen

tfr

ictio

n.D

rag

redu

ctio

nis

less

infib

er-g

assu

spen

sion

s.

Solid

-liq

uid

part

icle

s—

Tho

ria

—Sa

ndan

ddu

stpa

rtic

les

—D

ropl

ets

inga

ses

Pneu

mat

icsy

stem

sha

vehi

gher

flow

rate

sw

hen

dust

-lad

enth

anw

ithcl

ean

air

only

.Su

spen

sion

ofth

oria

inw

ater

show

drag

redu

ctio

n.E

ven

drop

lets

inga

ses

redu

cefr

ictio

n.

Oth

erna

tura

lso

urce

sN

atur

algu

ms

(lik

egu

ar),

alga

e,an

dba

cter

iaus

ually

prod

uce

copi

ous,

high

-mol

ecul

ar-w

eigh

tpo

lysa

ccha

ride

.Pr

inci

pal

prop

ertie

sof

drag

-red

ucin

gad

ditiv

es•

Ext

ende

dle

ngth

and/

orsu

ffici

ent

mas

s(i

nert

ia)

toin

terf

ere

and

supp

ress

turb

ulen

tflu

ctua

tions

,pa

rtic

ular

lytr

ansv

erse

ones

.•

Rig

idity

and/

orel

astic

ityto

supp

ress

and

abso

rbtu

rbul

ent

fluct

uatio

ns.

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Tabl

e3.

Kno

wn

fric

tion

and

heat

-tra

nsfe

rbe

havi

orof

drag

redu

cing

fluid

s Cha

ract

eris

ticph

enom

ena

Fric

tion

fact

orH

igh

fric

tion

drag

redu

ctio

nfo

rve

rysm

all

conc

entr

atio

nsgi

ves

afr

ictio

nre

duct

ion

of40

%,

whi

ch,

with

incr

ease

ofpo

lym

erco

ncen

trat

ion,

reac

hes

the

limiti

ngas

ympt

otic

valu

eup

to80

%.

Hea

ttr

ansf

erSt

rong

erhe

at-t

rans

fer

redu

ctio

nth

anfr

ictio

ndr

agre

duct

ion;

over

90%

ofco

rres

pond

ing

New

toni

anva

lues

for

the

limiti

ngas

ympt

otic

case

.G

ener

ally

,th

isph

enom

enon

isno

tus

eful

,as

incr

ude-

oil

pipe

lines

.In

cont

rast

,he

attr

ansf

eris

incr

ease

din

boili

ngan

din

lam

inar

flow

thro

ugh

non-

circ

ular

duct

s.E

ntra

nce

leng

ths

Muc

hlo

nger

than

the

corr

espo

ndin

gN

ewto

nian

valu

es,

onth

eor

der

of10

0an

d50

0hy

drau

licdi

amet

ers

for

hydr

odyn

amic

and

ther

mal

entr

ance

leng

ths,

resp

ectiv

ely.

Tra

nsiti

onto

turb

ulen

ceSm

ooth

ertr

ansi

tion

from

lam

inar

totu

rbul

ent

flow

,as

oppo

sed

toab

rupt

tran

sitio

nof

New

toni

anflu

ids.

Als

o,hi

gher

tran

sitio

nal

Rey

nold

snu

mbe

rva

lues

(muc

hhi

gher

than

2000

,of

ten

5000

orhi

gher

).In

som

eca

ses

the

“ons

et”

ofdr

ag-r

educ

tion

isen

coun

tere

d.M

ean

velo

city

profi

les

Flat

ter

velo

city

profi

les

(in

cent

ral

regi

on)

than

the

solv

ent

alon

e.T

hat

isqu

iteth

eop

posi

tefr

omth

ein

fluen

ceof

pipe

roug

hnes

son

the

profi

le.

Tur

bule

nce

stru

ctur

eFl

uctu

atin

gv′ v

eloc

ityco

mpo

nent

isre

duce

d,w

hile

axia

lco

mpo

nent

u′ i

sle

ssaf

fect

ed;

thou

ghso

me

resu

ltsar

eco

nflic

ting.

Spac

ing

betw

een

larg

e-sc

ale

slow

-str

eaks

ism

ore

than

doub

led,

and

time

betw

een

the

“bur

sts”

(flui

dlu

mps

)ej

ecte

dfr

omth

ew

all

regi

onis

incr

ease

dte

n-fo

ld.

Oth

erC

avita

tion

isof

adi

ffer

ent

char

acte

ran

dis

ofte

ngr

eatly

redu

ced.

Ext

ensi

onal

flow

sth

roug

hpo

rous

med

ia(a

nap

plic

atio

nin

enha

nced

-oil-

reco

very

)an

dje

tflo

ws

have

diff

eren

tch

arac

teri

stic

sth

anin

pure

solv

ent.

Seve

ral

othe

rbe

havi

ors

ofm

ore-

conc

entr

ated

poly

mer

solu

tions

,su

chas

die-

swel

l,W

eiss

enbe

rgro

d-cl

imbi

ngef

fect

,tu

bele

sssi

phon

,in

vers

ese

cond

ary

flow

,et

c.ar

em

arke

dly

diff

eren

tfr

omN

ewto

nian

flow

s.

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Generally, higher molecular weight polymers perform much better thanidentical but lower molecular weight polymers. A major drawback of polymersolutions is the degradation in high shear flows. This degradation is causedby the pump and piping system. Injecting the polymers downstream of thepipeline booster pumps can minimize this effect. Choi and Kasza (1989) re-ported the dependency of degradation on the flow temperature. They foundthat dilute polymer solutions tend to degrade rapidly at 87.8◦C while nodegradation was experienced at 7.2◦C. Moreover, they reported a drag reduc-tion of 50% for one month of circulation.

Kwack and Hartnett (1982) investigated the effect of degradation on thefriction factor and heat transfer in a recirculating flow system. They observedno effect of DRA degradation on the friction factor, but there was an effect onthe heat transfer. The degree of degradation was presented using the criticalWeissenberg number. High concentrations were used to make up for thedegradation. The effectiveness obtained was very much dependent on thetype of drag reducing agent used.

Sitaramaiah and Smith (1969) reported experimental results on drag re-duction in turbulent flow using several acrylamide based polymers. Theycompared their effectiveness with that of polyethylene oxides and found thatdrag reduction increased with higher molecular weight, concentration andflow rate for all polymers approaching values of 70–80%. The main conclu-sion was that low-salt content solvents should be used for better efficiencieswhen polymers with ionic groups are used as fluid-friction reducers. The se-lection of the drag reduction agent was very much related to the applicationunder consideration and the cost.

Virk (1975a, 1975b) and Hoyt (1984) identified two asymptotic, additive-intensive flow regimes of zero and maximum drag reduction that envelopea third polymeric regime wherein additives’ properties exert certain influ-ences. The polymeric regime, based on Prandtl-Karman (P-K) coordinates,consisted of two extremes of flow behavior called types A and B. Type Awas a family of additive solutions that produced a “fan” of friction factorsegments which radiated outward from a common “onset” point on the P-Klaw (Figure 4) (Virk et al., 1997). Type B included a variety of additives, suchas polyelectrolytes and fibers, with a ladder of segments on the P-K law.

Wahl et al. (1982) reported field experimental results on two drag re-ducing agents to increase the capacity of crude oil pipelines. The pipelinestested varied in diameter and length, and were in the range of 8–48 in and 12–167 km, respectively. Two DRAs were used: CDR drag reducer and a modi-fied drag reducer that is a more viscous polymer solution. The performance ofthe modified drag reducer increased by approximately 10-fold, that is, 2 ppmof the modified polymer gave the same level of performance as 20 ppm ofthe standard drag reducer for a pipe of 8-in diameter and 4–5 fold for a 48-indiameter pipe. The most important conclusion of their work was that high per-formance, low concentration modified polymers were very attractive for off-shore production operations where space and deck loading are critical factors.

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Figure 4. (a) Type A “fan” for collapsed conformation of B1120, in 0.3 N NaCL(b) type B “ladder for extended conformation of B1120, in 0.0003 N NaCl.

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The effect of surface roughness of the pipe on drag reduction usingdifferent types of DRAs was reported by Derrule and Sabersky (1974) andBewersdoff and Berman (1987). Derrule and Sabersky observed that whenpolyethelyne oxide was used as the surface roughness of the pipe was in-creased, drag reduction also increased. Bewersdoff and Berman (1987) ob-served no change in the drag reduction effectiveness for rough pipe whenpolyacrylamide was employed for both smooth and rough pipes. A summaryof effectiveness for different types of DRAs is shown in Table 4.

HYDRODYNAMICS OF PIPE FLOW IN THE PRESENCE OFDRAG REDUCING AGENTS

Drag reducing agent performance is very sensitive to any shear generatedin the flow, as it results in the degradation of the agent. The hydrodynamiccharacteristics of the flow, such as turbulence, single pass or recirculatoryflow, and single phase or multiphase flow have a significant impact on dragreduction effectiveness. Reddy (1986) observed a reduction in effectivenessin recirculatory flow compared to turbulent rheometer and single pass flows.This was attributed to the adverse effect of pipe fittings on the flow of poly-mer solution and the rapid degradation in recirculatory flow. This degradationwas generated by the resulting shearing effects, which increased as the pipingnetwork became more complex. They further developed empirical correla-tions that could be used for the prediction of drag reducing effectiveness ofpolymers in recirculatory flow systems.

Gyr and Tsinober (1997) concluded that drag reducing fluids are essen-tially non-Newtonian in the turbulent flow state and generally Newtonian inmany laminar flows. They presented a critical discussion of the momentumdeficit of drag reducing flows and a simple unequivocal demonstration forthe claim that the drag reduction phenomena in a number of fluid systemsare of rheological nature. Berge and Solvik (1996) reported that, in general,a higher degree of fluid turbulence resulted in a higher drag reduction. If thisis to be related to the Reynolds number (Re), then this implies increasing ve-locity and decreasing viscosity. They reported that when the DRA dissolvedrapidly in the fluid, it resulted in a modified structure of the turbulence and,hence, better performance.

Su and Gudmundsson (1994) presented the basic equations used for thecalculation of the total pressure drop in perforated pipe flow as applied tohorizontal wells. They divided the pressure drop into two components: re-versible and irreversible. The reversible pressure drop was due to accelerationas more fluid entered the wellbore through perforations, while the irreversiblepressure drop was due to friction and mixing effects. They computed the ac-celeration terms using both momentum and energy equations. Their compu-tations showed that the acceleration terms were about one-third higher whenthe momentum equation was used compared to that obtained when the energy

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Tabl

e4.

Perf

orm

ance

and

appl

icat

ions

ofva

riou

sty

pes

ofdr

agre

duci

ngag

ents

Con

cent

ratio

nD

rag

redu

cing

agen

tsPr

oper

ties

App

licat

ions

Flui

ds(p

pm)

Eff

ectiv

enes

sR

efer

ence

s

CD

Rpo

lym

er(w

ater

solu

ble

poly

mer

s)In

ject

ion

conc

entr

atio

n,w

t%10

%;

solv

ent

flash

poin

t,PM

,60

◦ C;

dens

ity,

g/cm

3

0.81

4,K

=23

0Pa

.s

Hor

izon

tal-

oil

pipe

line,

(fiel

dte

sts)

,di

amet

er48

-in

Oil,

sing

leph

ase

5,10

,20

6–23

%B

urge

ret

al.

(198

0)

CD

Rpo

lym

ers

Inje

ctio

nco

ncen

trat

ion,

wt%

10%

;so

lven

tfla

shpo

int,

PM,

60◦ C

;de

nsity

,g/

cm3

0.81

4,K

=23

0Pa

.s

Hor

izon

tal-

oil

pipe

line,

(fiel

dte

sts)

,di

amet

er8,

12,

and

48-i

n

Oil,

sing

leph

ase

10,

20%

14–2

3%W

ahl

etal

.(1

982)

Mod

ified

CD

RIn

ject

ion

conc

entr

atio

n,w

t%10

%;

solv

ent

flash

poin

t,PM

,60

◦ C;

dens

ity,

0.81

4,K

=28

0Pa

.s

Hor

izon

tal-

oil

pipe

line,

(fiel

dte

sts)

,di

amet

er8,

12,

and

48-i

n

Oil,

sing

leph

ase

5,2%

23–4

6%W

ahl

etal

.(1

982)

Gua

rgum

(GM

),X

anth

angu

m(X

M),

Poly

acry

lam

ide

(PA

M),

Car

boxy

met

hylc

ellu

lose

(CM

C),

and

asbe

stos

fiber

(AF)

Hor

izon

tal

wat

erpi

pelin

e,di

amet

er1-

in,

Re

=20

,000

to60

,000

Wat

er,

sing

leph

ase

250–

1500

ppm

17%

for

CM

C,

37%

for

GM

,40

%fo

rX

M,

33%

for

PAM

,and

28%

for

AF

Red

dy(1

986)

Oil

solu

ble

DR

AH

oriz

onta

l10

-cm

diam

eter

pipe

line

Mul

tipha

se,

oil/g

as20

and

50pp

m82

%fo

rsl

ugflo

wan

d47

%fo

ran

nula

rflo

w;

slug

freq

uenc

yde

crea

sed

sign

ifica

ntly

with

addi

tion

ofD

RA

Kan

gan

dJe

pson

(200

0)

GE

M(D

eter

gent

)H

oriz

onta

l2.

5–10

cmdi

amet

erpi

pelin

esSi

ngle

crud

eoi

l10

–500

ppm

10%

(2.5

and

5cm

dia.

),35

%(7

.5cm

dia.

)an

d50

%(1

0cm

dia.

)

Man

sour

and

Asw

ad(1

989)

New

gene

ratio

nD

RA

Em

ulsi

fied

pow

der

with

apo

lym

erco

nten

tof

20–2

5%

Hor

izon

tal

14-i

ndi

a,9.

5m

iles,

28in

dia,

75m

iles

Sing

lecr

ude

oil,

mul

tipha

seflo

w10

–100

ppm

70%

,ne

wge

nera

tion

DR

A;

50%

,co

nven

tiona

lD

RA

Ber

gean

dSo

lvik

(199

6)

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equation was used. Moreover, they conducted experimental investigations ona perforated pipe with 144 perforations, geometrically similar to the wellborecasing. They found that the total pressure drop consisted of 80% wall friction,15% mixing effects, and 5% pressure drop due to acceleration.

It is interesting to note here that most of the work carried out so far onperformance of horizontal wells only considered the friction component ofthe total pressure (Dikken, 1990; Landman, 1994). Little work has been doneon drag reduction other than that used by friction (Dass et al., 2000). Themain outcome of this work was that the semi-empirical relationship developedfor pipe junction in hydraulics cannot be used for flow in horizontal wellsbecause the flow ratio and perforation diameters are different.

The effect of pipe diameter on the performance of the drag reducing agentis an important parameter which cannot be accounted for through Reynoldsnumber (Re) as was done for Newtonian fluids. A good account of the effectof diameter on drag reduction fluids was shown in the work reported by Sellinand Ollis (1983) and Matthys (1991). Matthys pointed out that the effect ofthe diameter must be included in an additional parameter that is necessary forthe prediction and characterization of friction in the non-asymptotic regime.However, Re may be used provided the viscosity of the solvent rather thanthe viscosity of the actual solution is used in the calculation of Re. Therationale behind this is that very dilute solutions tend to have a viscosity thatis independent of the shear rate in the high shear rate regime. However, if theviscosity is much larger than that of the solvent, then the approximation usingsolvent-based Re will be justifiable, particularly when the drag reductionobtained is small (Matthys, 1991). It was also reported that using smallerdiameter pipes to predict the performance of drag reduction in larger diameterpipes would not result in an accurate prediction (Jepson and Taylor, 1993).

Mansour and Aswad (1989) conducted an experimental investigation onthe effect of pipe diameter on DRA using a detergent called GEM in a re-circulating system. They reported that increasing the pipe diameter increaseddrag reduction, which was contrary to the findings of Lester (1985), whofound that increasing the pipe diameter decreased drag reduction. Jubranet al. (1992) conducted an experimental investigation on the effect of pipediameter on drag reduction of GEM in a recirculating system. They foundthat as the diameter of the thermoplastic pipe was increased, the drag re-duction decreased. Gasljevic and Matthys (1993) investigated the effect ofdrag-reducing surfactant additives on heat transfer exchangers. Their resultsindicated that increasing the diameter of the pipe from 2 to 52 mm resultedin a decrease in the drag reduction effectiveness. This effect was diminishedas Re increased beyond 105. The general consensus was that increasing thediameter of the pipe tends to decrease drag reduction effectiveness.

Another focus research area for drag reducing agents is their influenceas flow conditioners for two-phase flow in pipelines (i.e., effects on flowstructure). Again, the effect depends on the type of DRA used. Rosehartet al. (1972) investigated the presence of DRAs on the structure of single and

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two-phase flow in horizontal pipes using visual observation. The addition ofDRAs to the flow did not change the slug transitional velocity and the slugfrequency at low polymer concentration. It was found to be the same forthe air/water system, but decreased at higher polymer concentration. Kanget al. (1998) investigated DRA in three-phase flow and oil/water/gas flow.They concluded that DRA was effective in reducing drag for different flowpatterns, such as stratified, slug, and annular flow. DRA was found to changethe flow patterns in horizontal pipes. Their results agreed well with those ofRosehart (1972) which showed that for three-phase flow DRA concentrationdid not affect the slug transitional velocity. The amount of drag reductionobtained is very much dependent on the type of flow regimes, as can be seenin Table 5.

Kang et al. (1999) conducted an experimental investigation on usingdrag reducer agents in multiphase flow in vertical pipes. In addition to theperformance of drag reduction, they reported flow conditioning due to DRAs.Adding DRAs shifted the transition to slug flow to higher superficial liquidvelocities. No effect was reported on the superficial gas velocity for theflow to remain in transition. The effectiveness of DRAs tended to decreasewith increasing superficial liquid velocity at the same superficial gas velocity(Table 5). Kang and Jepson (2000, 1999) reported experimental investigationson using drag reduction as a flow conditioning agent in multiphase pipe flows.They reported that DRAs did not change the slug transitional velocity, butdecreased the slug frequency and the height of the liquid film.

The effect of DRAs in two-phase flow in annular flow was investigatedexperimentally by Al-Sarkhi and Hanratty (2001, 2001a) and Soleimani et al.(2002). In air-water flow in a horizontal 9.53 cm diameter pipe the DRAinjection resulted in drag reduction of 48% with only 10–15 ppm DRA con-centrations (Al-Sarkhi and Hanratty, 2001). It was noted that the DRA’s ef-fectiveness is sensitive to the method of injection as well as the concentrationof polymer in the injected solution (maser solution). At maximum drag re-duction the annular flow became stratified with smooth interface. Also, forthe same DRA concentration in the flow there is an optimum concentration ofthe master solution that maximizes the effectiveness. A master solution con-centration of 1000 ppm of Percol 727 was suggested (Al-Sarkhi and Hanratty,2001). In the work of Al-Sarkhi and Hanratty (2001), two injection locationsalong the pipe were used: one 0.6 m upstream of the air-water mixing teein the liquid line and one 5.5 m downstream of the tee where two-phaseflow exists. It was observed that when the DRA is injected in the upstreaminjection location its effectiveness decreased with increasing the gas velocity,while it was insensitive when injection took place in the downstream injec-tion location. Thus, in annular flow the injection of DRAs should be in theliquid film.

To investigate the effect of diameter size on drag reduction in annularflow Al-Sarkhi and Hanratty (2001a) used a smaller diameter (2.54 cm) andachieved drag reductions of 63% compared with 48% for the 9.53 cm pipe

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Tabl

e5.

Eff

ect

ofdr

agre

duct

ion

agen

tfo

rdi

ffer

ent

flow

regi

me

Dra

gPi

peFl

owre

gim

eef

fect

iven

ess

incl

inat

ion

Flow

cond

ition

sR

efer

ence

Full

pipe

flow

(100

%oi

l)42

%H

oriz

onta

lpi

peD

RA

:10

ppm

,sup

erfic

ial

liqui

d:ve

loci

ty0.

25m

/sK

ang

etal

.(1

998)

Stra

tified

flow

Mor

eth

an40

%H

oriz

onta

lpi

peD

RA

:10

ppm

,su

perfi

cial

liqui

d:ve

loci

ty0.

03m

/s,

gas

velo

citie

s4–

7m

/sK

ang

etal

.(1

998)

67–8

1%H

oriz

onta

lpi

peD

RA

:75

ppm

,su

perfi

cial

liqui

d:ve

loci

ty0.

03an

d0.

11m

/s7

m/s

Kan

get

al.

(199

8)

90%

Ver

tical

pipe

Supe

rfici

alliq

uid

velo

city

:0.

5m

/s,

supe

rfici

alga

sve

loci

tyle

ssth

an4

m/s

Kan

get

al.

(199

9)

Slug

flow

50%

Ver

tical

pipe

Supe

rfici

alliq

uid

velo

city

:al

lve

loci

ties;

supe

rfici

alga

sve

loci

tym

ore

than

4m

/sK

ang

etal

.(1

999)

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used previously (2001). However, they found that compared with the largediameter pipe, a larger concentration of polymer is required in the smallerdiameter pipe to achieve the maximum drag reduction (10 ppm in 9.53 cmpipe and 30 ppm in 2.54 cm pipe). Differences in the resulting flow patternwere also observed. At the large diameter pipe the resulting flow pattern wasstratified with smooth interface while at the smaller diameter pipe the patternwas characterized by stratified-annular.

The study of Soleimani et al. (2002) investigated the effect of DRAs onthe transition form stratified to slug flow in a horizontal 2.54 cm pipe. It wasfound that at gas superficial velocities greater than 4 m/s the DRAs delaythe transition to slug flow; i.e., transition occurs at larger liquid holdup. AsDRAs are added into a stratified flow, a higher thickness of the liquid layeris required to initiate the slugging. In view of these findings, the additionof DRAs to multiphase flow has potential in flow conditioning. In general,limited work has been done on the role of DRAs as a flow conditioner andmore comprehensive work is needed.

Dass et al. (2000) reported a model to predict the components of pressuredrop in slug flow in a horizontal pipe. The aim of their work was to shedlight on the contributions of the frictional and acceleration components tototal pressure drop in horizontal slug flow in the presence of drag reducingagents. The predicted and experimental results showed good agreement. TheDRA was active in reducing both components of the pressure drop. It wasfound that the acceleration component was dominant and contributed morethan 80% of the total pressure. This increased significantly as the superficialgas velocity was increased. Both components of the pressure were reducedby 67% and 78% at DRA of 20 and 50 ppm, respectively. However, dragreduction was decreased as the superficial gas velocity was increased. It isinteresting to note in their study that the drag reduction obtained was mainlyin the acceleration component, indicating that the DRA was effective in themixing zone of the slug flow. Fan and Hanratty (1993) developed a model topredict the pressure drop across a stable slug flow. They treated the slug as ahydraulic jump and assumed that the pressure change takes place at the rearof the slug, where the change could be positive or negative.

Dukler and Hubbard (1975) developed a model to predict the frictionaland acceleration components of total slug pressure drop in an air-water sys-tem. The model assumed that the two phases within the slug body werehomogeneously mixed with negligible slip. The frictional component of thepressure was predicted using an equation similar to that used in a single phaseflow after modifying the density of the mixture and the friction factor. Theacceleration contribution was found by assuming a stabilized slug flow bodythat is receiving and losing mass at equal rates. The acceleration pressure dropwas then calculated from the force required to accelerate the liquid to slugvelocity. Vlachos and Karabelas (1999) investigated shear stress circumfer-ence in stratified flow. They used the momentum equations for both phasesto predict the liquid holdup, axial pressure gradient, and average liquid to

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wall shear stress, for the wavy stratified and stratified/atomization gas/liquidflow in a horizontal pipe.

HEAT TRANSFER IN PRESENCE OF DRAG REDUCING AGENTS

Drag reduction and heat transfer phenomena associated with drag reducingfluids are far from being well understood. Certain applications for the uti-lization of drag reduction agents necessitate a closer look at the heat transferprocess as well as the hydrodynamics process involved. However, it is inter-esting to note that in the case of using drag reduction in crude oil pipelines,the effect of these agents on the heat transfer process can be useful in keep-ing the loss of heat to the atmosphere to a minimum, while keeping the oilflowing at a lower pumping power. Moreover, in certain cases it brings downthe cost of thermal insulation of the pipelines.

Matthys et al. (1987) reported local and heat transfer measurements incircular tubes for suspensions of betonite and for a combination of betoniteand polyacrylamide in water for both laminar and turbulent flow. It was foundthat a viscosity model based on rheological measurements could represent theresults with a Newtonian relationship. It was also found that combining clayand polymer in a fluid produced viscoelastic solutions that were very sen-sitive to mechanical degradation. The local heat transfer results were wellcorrelated using the Colburn and Reynolds analogies, regardless of the con-centration of bentonite. Yoo et al. (1993) investigated experimentally the heattransfer characteristics of drag reducing polymer solutions in the thermal en-trance region of circular tube flows. The tests were conducted in two stainlesssteel tubes with length to diameter ratios of 710 and 1100. The fluids usedwere aqueous poly-acrylamide solutions of Separan AP-273 with a concen-tration range of 300 to 1000 wppm. The main finding of this investigationwas that the order of magnitude of the thermal entrance length of the maxi-mum drag reducing polymer solutions was much higher than that of turbulentNewtonian fluids in tube flows.

Gasljevic and Matthys (1994) reported local heat transfer results andfriction in the entry region of a circular pipe in the presence of a drag re-duction surfactant. Two entrance arrangements were used: a cone contractionand a wire mesh plug fitted to flatten the velocity profile. The main findingsof this work were the restructuring of the fluid itself due to high local en-ergy dissipation in the inlet region, and the stronger coupling between thehydrodynamic and thermal field development in the case of surfactant so-lutions than in the case of polymer solutions. The Reynolds analogy andthe direct relation between the friction and heat transfer coefficients werenot valid for drag reducing fluids; i.e., the Reynolds and Colburn analogieswere not valid for this type of flow. The reasoning behind this is still notclear and further research is needed (Matthys, 1991; Matthys and Sabersky,1987).

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Toh and Ghajar (1988) and Matthys (1991) observed that the thermalentrance and hydrodynamic lengths for drag reducing solutions were morethan that observed for Newtonian fluid flow with values of more than 20 and100 diameters, respectively.

Matthys (1991) carried out a comprehensive survey on the most impor-tant results and the current research needs of heat transfer, drag reduction,and fluid characterization for turbulent flow of polymer solutions in pipes.He investigated the problem of the reduction in convective heat transfer inthe presence of a drag reducing agent. It was pointed out that the reductionproduced by the addition of the agent was upset by the greater reduction pro-duced in the convection heat transfer. He attributed the lack of investigationson heat transfer of polymer solutions to the complexity of viscoelastic flows.This required a more demanding experimental set up to accurately record thedata. Matthys (1991) indicated the availability of macroscopic and correla-tion work for purely viscous non-Newtonian fluids, but not for viscoelasticnon-Newtonian fluids that cover flows with drag reduction agents.

Gasljevic and Matthys (1991) investigated the thermal and hydrodynamiccharacteristics of drag-reducing surfactant solutions in the entry region of thepipe, as well as after fittings. In addition, they provided an excellent literaturereview on the subject. It was reported that for surfactant solutions the frictioncoefficient and the Nusselt number were varying at the same rate beyond 300diameters. Heat transfer downstream of an elbow tended to increase over thatobtained for fully developed flow, but it did not degrade the fluid.

Gasljevic et al. (1993) conducted a comprehensive experimental investi-gation on the performance of various types of heat exchangers in the presenceof drag reducing surfactants in the working fluid. The working fluid used wasa solution of 2300 ppm of Ethoquad T/13 and 2000 ppm of NaSal in deionizedwater. Pressure and heat transfer measurements were taken at an operatingtemperature in the range of 312–319 K and fluid velocities of 0.2–3 m/s.They compared their results with those obtained when tap water was used asthe working fluid and concluded that the thermal and hydrodynamic charac-teristics are very much dependent on the geometry and flow conditions in theheat exchanger. It was also noted that a significant drag reduction could beachieved in heat exchangers with little penalty in the heat transfer process.

Gasljevic and Matthys (1993, 1991) reported an investigation to explorethe use of surfactant drag reducing additives to reduce the pumping powerin hydronic heating and cooling systems. Various issues were investigated,namely the matching of the additives with system characteristics, drag reduc-tion in fittings and valves, and the heat transfer process in the presence ofreduction agents. It was concluded that the use of drag reducing agents inheating and cooling systems can be implemented at a small cost and wouldlead to significant energy savings.

Kostic (1994) carried out a critical review on turbulent drag, heat transferreduction phenomena, and laminar heat transfer enhancement in non-circularduct flow of non-Newtonian fluids. The review outlined peculiar behaviors

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and applications of DRAs. Kostic reported that the underlying mechanismthat produces drag and heat reduction is far from being understood. He notedthat this should keep researchers busy for many years to come. Despite thelimited research to date on the heat transfer aspects of viscoelastic fluids,there was enough evidence to conclude that such fluids tend to enhance heattransfer in laminar non-circular duct flow. Moreover, he reported that flowlaminarization, due to flow-induced anisotropic fluid structure and properties,was the predominant factor for the reduction phenomena rather than fluidelasticity. On the other hand, fluid elasticity was responsible for laminar heattransfer augmentation. Hartnett and Kwack (1986) reported that for a polymersolution the reduction in friction was not accompanied by a reduction in heattransfer. For a comprehensive review of research work related to heat transferin the presence of drag reducing agents, see studies by Dimant and Poreh(1976) and Cho and Hartnett (1982).

CONCLUDING REMARKS

This paper has highlighted research conducted on drag reduction in single andmultiphase flows with particular reference to the oil industry. It has examinedwork related to theories of drag reduction, the influence of drag reductiontypes, and hydrodynamic and heat transfer characteristics of the flows in thepresence of a drag reducing agent. Moreover, it has raised questions andshortcomings that need answers, as well as pin-pointing potential areas thatneed further research.

Drag reduction phenomena and theories related to multiphase flow arestill far from being well understood. More work is needed in the areas ofshear degradation, and the effect of wax content, water cut, and pipe incli-nation on the performance of drag reduction in smooth and perforated pipeswith emphases on oil wells. Most of the work carried out on the performanceof horizontal wells consider only the friction component of the total pressurewithout taking into consideration the acceleration component. Limited workhas been done on the role of drag reducing agents as a flow conditioner, espe-cially for large pipe inclinations with a high water cut. Further fundamental,experimental, and analytical investigations are needed to better understandthe heat and hydrodynamic processes associated with drag reduction in sin-gle and multiphase flows, since the Reynolds and Colburn analogies are notvalid for drag reducing fluids.

REFERENCES

Al-Sarkhi, A., and Hanratty, T. J. (2001). Effect of drag-reducing polymeron annular gas-liquid flow in horizontal pipe. Int. J. Multiphase Flow27:1151–1162.

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Al-Sarkhi, A., and Hanratty, T. J. (2001a). Effect of pipe diameter on the per-formance of drag-reducing polymers in annular gas-liquid flows. TransIChemE Part A 79:402–408.

Berge, B. K., and Solvik, O. (1996). Increased pipeline throughput using dragreducer additives (DRA): Field experiences. SPE 36835, 203–208.

Bewersdorff, H., and Berman, N. A. (1987). Effect of roughness on dragreduction for commercially smooth pipes. J. Non-Newtonian Fluid Me-chanics 24:365–370.

Burger, E. D., Munk, W. R., and Wahl, H. A. (1980). Flow increase in the transAlaska pipeline using a polymeric drag reducing additive. 55th AnnualFall Technical Conference and Exhibition of the Society of PetroleumEngineers, Dallas, Texas, Sept. 21–24, SPE 9419.

Burger, E. D., Munk, W. R., and Wahl, H. A. (1982). Flow increase in transAlaska pipeline through use of polymeric drag-reducing additive. JPT377–386.

Cho, Y. I., and Hartnett, J. P. (1982). Heat transfer in flows with drag reduc-tion. Adv. Heat Transfer 15:59–139.

Choi, U. S., and Kasza K. E. (1989). Long-term degradation of dilute poly-achrylamide solutions in turbulent pipe flow. Drag Reduction in FluidFlows, Ellis Horwood Limited, 163–169.

Dass, M., Kang, C., and Jepson W. P. (2000). Quantitative analysis of dragreduction in horizontal slug flow. SPE Annual Technical Conference andExhibition, Dallas, Texas, 1–4 October, SPE 62944.

Derrule, P. M., and Sabersky, R. H. (1974). Heat transfer and friction coef-ficient in smooth and rough tubes with dilute polymer solutions. Int. J.Heat and Mass Transfer 17:529–540.

Dikken, B. J. (1990). Pressure drop in horizontal wells and its effects onproduction performance. JPT 1426–1433.

Dimant, Y., and Poreh, M. (1976). Heat transfer in flows with drag reduction.Adv. Heat Transfer 12:77–113.

Dukler, A. E., and Hubbard, M. G. (1975). A model for gas-liquid slug flowin horizontal and near horizontal tubes. Ind. Chem. Fundam. 14(4).

Fan, Z., and Hanratty, T. J. (1993). Pressure profiles for slug flow in horizontalpipelines. J. Multiphase Flow 19(3):421–430.

Gasljevic, K., and Matthys, E. F. (1991). Feasibility study of the use ofdrag-reducing additives to reduce pumping power in hydronic thermaldistribution systems. Winter Annual Meeting of the American Society ofMechanical Engineers ASME, Fluids Engineering Division, FED, 132:57–65.

Gasljevic, K., and Matthys, E. F. (1993). Saving power in hydronic thermaldistribution systems through the use of drag-reducing additives. J. Energyand Buildings 20(1):45–56.

Gasljevic, K., and Matthys, E. F. (1994). Hydrodynamic and thermal fielddevelopment in the pipe entry region for turbulent flow of drag-reducingsurfactant solutions. Proceedings of the International Mechanical Engi-

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[Eco

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t: 15

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neering Congress and Exibition, Chicago, ASME, Fluids EngineeringDivision, FED, 206:51–61.

Gasljevic, K., Nan, X. M., and Matthys, E. F. (1993). Effect of drag-reducingsurfactant additives on heat exchangers. Proceedings of the 1993 ASMEWinter Annual Meeting, ASME Applied Mechanics Division, AMD,175:101–108.

Gyr, A., and Tsinober, A. (1997). On the rheological nature of drag reductionphenomena. J. Non-Newtonian Fluid Mechanics 73:153–162.

Hartnett, J. P., and Kwack, E. K. (1986). Prediction of friction and heattransfer for viscoelastic fluids in turbulent flow. Int. J. Thermophys. 7(1):53–63.

Hoyt, J. W. (1984). Some highlights in the field of polymeric drag reduction.Proceedings of International Conference on Drag Reduction. Sellin, R. J.(Ed.). England: University of Bristol, 1–11

Jepson, W. P., and Taylor, R. E. (1993). Slug flow and its transition in largehorizontal pipes. Int. J. Multiphase Flow 19:411–420.

Jubran, B. A., Hamdan, R., and Mansour, M. A. (1992). Some aspectsof drag reduction in thermoplastic pipes. Polym.-Plast. Technol. Eng.31(3&4):259–269.

Kang, C., and Jepson, W. P. (1999). Multiphase flow conditioning usingdrag-reducing agents. SPE Annual Technical Conference and Exhibition,Houston, Texas, 3–6 October, SPE 56569.

Kang, C., and Jepson W. P. (2000). Effect of drag-reducing agents in mul-tiphase oil/gas horizontal flow. SPE International Petroleum Conferenceand Exhibition in Mexico, 1–3 February, SPE 58976.

Kang, C., Jepson, W. P., and Gopal, M. (1999). Effect of drag-reducing agenton slug characteristics in multiphase flow in inclined pipes. J. EnergyRes. Technol. ASME Trans. 121:86–90.

Kang, C., Vancho Jr., R. M., Green, A. S., and Jepson, W. P. (1998). Theeffect of drag reducing agents in multiphase flow pipelines. ASME J.Energy Res. Technol. 120:15–19.

Kostic, M. (1994). On turbulent drag and heat transfer reduction phenom-ena and laminar heat transfer enhancement in non-circular duct flowof certain non-Newtonian fluids. Int. J. Heat and Mass Transfer 37(1):133–147.

Kwack, E. Y., and Hartnett, J. P. (1982). Effect of diameter on critical Weis-senberg numbers for polyacrylamide solutions in turbulent pipe flow. Int.J. Heat Mass Transfer 25:797–805.

Landman, M. J. (1994). Analytic modeling of selectively perforated horizontalwells. J. Petrol. Sci. Eng. 10(3):179–188.

Lester, C. B. (1985). The basics of drag reduction. Oil and Gas Journal Feb.,51–56.

Mansour, A. R., and Aswad, Z. A. R. (1989). A method to minimize costsor maximize flow rate of pumping crude oil inside pipelines using newdrag reducing additives. J. of Pipelines 7:301–305.

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[Eco

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l] A

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Matthys, E. F. (1991). Heat transfer, drag reduction, and fluid characteriza-tion for turbulent flow of polymer solutions: Recent results and researchneeds. J. Non-Newtonian Fluid Mechanics 38:313–342.

Matthys, E. F., Ahn, H., and Sabersky, R. H. (1987). Friction and heat trans-fer measurements for clay suspensions with polymer additives. ASMETransactions, J. Fluids Eng. 109:307–312.

Matthys, E. F., and Sabersky, R. H. (1987). Friction and heat transfer study ofa discontinuously shear-thickening antimisting polymer solution. J. Non-Newtonian Fluid Mech. 25:177–196.

Mizunuma, H., Ueda, K., and Yokouchi, Y. (1996). Synergistic effects inturbulent drag reduction by riblets and polymer additives. FED-Vol. 237,Fluids Engineering Conference, 2 ASME.

Reddy, G. V. (1986). Drag reduction by polymers in recirculatory flow. Chem.Eng. World 6:73–78.

Rosehart, R. G., Scott, D. S., and Rhodes, E. (1972). Gas liquid slug flowwith drag-reducing polymer solutions. AIChE Journal 18:744–750.

Sellin, R. H., and Ollis, M. (1983). Effect of pipe diameter on polymer dragreduction. Ind. Eng. Chem. Prod. Res. Dev. 22:445–452.

Sitaramaiah, G., and Smith, C. L. (1969). Turbulent drag reduction by poly-acrylamide and other polymers. SPE paper 2405.

Soleimani, A., Al-Sarkhi, A., and Hanratty, T. J. (2002). Effect of drag-reducing polymers on pseudo-slugs-interfacial drag and transition to slugflow. Int. J. Multiphase Flow 28:1911–1927.

Su, Z., and Gudmundsson, J. S. (1994). Pressure drop in perforated pipes:Experiments and analysis. SPE Asia Pacific Oil & Gas Conference,Melbourne, Australia, 7–10 November, SPE 28800.

Toh, K. H., and Ghajar A. J. (1988). Heat transfer in the thermal entranceregion for viscoelastic fluids in turbulent pipe flow. Int. J. Heat and MassTransfer 31(6):1261–1267.

Virk, P. S. (1975a). Drag reduction fundamentals. AIChE Journal 21:625–656.

Virk, P. S. (1975b). Drag reduction by collapsed and extended polyelec-trolytes. Nature 253:109–111.

Virk, P. S., Sherman D. C., and Wagger, D. L. (1997). Additive equivalenceduring turbulent drag reduction. AIChE Journal 43(12):3257–3258.

Vlachos, P., and Karabelas, P. (1999). Predictions of holdup, axial pressuregradient and wall shear stress in wavy stratified and stratified/atomizationgas/liquid flow. Int. J. Multiphase Flow 25:365–372.

Wahl, H. A., Beaty W. R., Dopper J. G., and Hass G. R. (1982). Drag re-ducer increases oil pipeline flow rates. Offshore South East Asia 1982Conference, 9–12 February, Singapore.

Yoo, S. S., Hwang, T. S., Eum, C. S., and Bae, S. C. (1993). Turbulent heattransfer of polyacrylamide solutions in the thermal entrance region ofcircular tube flows. Int. J. Heat and Mass Transfer 36(2):365–370.

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