1_Drag Reducing Agents in Multiphase Flow

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Drag Reducing Agents in Multiphase Flow Pipelines: Recent Trends and Future Needs  Article

Petroleum Science Scie nce and Technology · February F ebruary 2005

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DOI: 10.1081/LFT-2000382 10.1081/LFT-200038223 23

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Bassam Ali Jubran

 Yousef Zurigat

Ryerson University

American University of Sharjah

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

Drag Reducing Agents in Multiphase Flow Pipelines: Recent Trends and Future Needs B. A. Jubran Department of Aerospace Engineering, Ryerson University, Toronto, Ontario, Canada

Y. H. Zurigat University University of Jordan, Jordan, Amman, Amman, Jordan

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

Abstract: In this paper, recent work on drag reducing agents in single and multiphase multiphase flow pipelines pipelines is reviewed. reviewed. Focus is placed on theories of drag reduction, the influence of drag reduction agent types, and hydrodynamic and heat transfer characteristics of  flows in the presence of drag reducing additives. Questions are raised, shortcomings are assessed, and future research needs are outlined. Keywords: drag reducing agents, heat transfer, multiphase multiphase flow, flow, flow conditioner conditioner

INTRODUCTION

Drag reduction in pipe flow using polymeric drag reduction agents (DRAs) is a problem problem of great great practica practicall engineeri engineering ng interest interest because DRAs reduce reduce pumping power and increase piping system capacity. DRAs have been used in several engineering systems, such as district heating and cooling, oil production and transportation pipelines, and others. Its first commercial use was in the 1.2 m diameter Trans-Alaskan Pipeline in 1979, where a 50% drag reduction was achieved, thereby increasing the capacity of the pipeline from 1.45 to 2.1 MBPD (Bur (Burger ger et al., al., 1982). 1982). This resulted resulted in eliminat eliminating ing the need for installing two pumping stations, which were planned to achieve the Received 4 March 2004; accepted 23 April 2004. Address Address correspondenc correspondencee to B. A. Jubran, Department Department of Aerospace Aerospace Engineering, Ryerson University, 350 Victoria Street, Toronto, Ontario, Canada, M5B 2K3. E-mail: [email protected] 1403

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mentioned increase in capacity. Since that time, the DRAs have been used in many petroleum product pipeline installations, such as the Iraq-Turkey oil pipeline 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 can be implemented immediately or temporarily, giving high operational flexibility. Typical dosage rates for 10–30% flow improvement in oil pipelines are 1–2 ppm of polymer per injection site.  Berge and Solvik (1996)   found that the required DRA-injection rates for multiphase flows were four times higher than those needed for stabilized crude oil. This was attributed to the higher shear degradation that resulted from the higher degree of flow turbulence in the multiphase system. The performance of DRAs is measured using the effectiveness defined by: effectiveness (ε)

=

P without DRA

−

P with DRA

P without DRA

(1)

The performance of DRAs is affected by several factors, such as pipe diameter, temperature, fluid viscosity, and the presence of paraffin and/or water. Comparisons of effectiveness and costs for new and conventional DRAs are shown in Figures 1, 2, and 3 (Berge and Solvik, 1996). Over a 14-year period (between 1980 and 1994) the effectiveness of drag reducing agents had increased 14 times. The aim of this paper is to review recent work on drag reduction in single and multiphase flow in pipelines. Focus is placed on theories of drag reduction, the influence of drag reduction types, and hydrodynamic and heat transfer characteristics of the flows in the presence of DRAs. Questions are raised, 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 the interaction between the polymer molecules and the turbulence components of the flow. Polymers tend to stretch in the flow and absorb the energy in the streak, which in turn stops the burst that produces the turbulence in the core and results in a reduction in turbulence ( Lester, 1985; Mizunuma et al., 1996).

Drag Reducing Agents in Multiphase Flow Pipelines

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

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

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

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Thus, the principal effect of DRAs is to reduce the velocity fluctuations in the normal direction and Reynolds stresses thereafter. Cationic surfactants are another class of DRA which form rod-like micelles. Under shear stress, micelles line up in the direction of flow and build the so-called shear-induced state, which leads to a damping of radial turbulence and a subsequent reduction in pressure loss. The various theories used to explain drag reduction phenomena are summarized by  Kostic (1994)  (see Table 1). The existence of multiphase flow (oil/gas and oil/water/gas mixture) in pipelines is common in the oil and gas industry. This is due to the fact that oil and gas wells are drilled far away from the separation site, which necessitates transport by multiphase pipeline flow. Drag reducing agents have been used for a long time to lower the friction component of the pressure in a singlephase flow during the transport of oil or gas in pipelines. However, recently it has been shown that DRAs are also effective in multiphase flow and work  very well on all components of pressure drop: frictional, accelerational, and gravitational (Dass et al., 2000). This is because of the DRA’s ability to modify the flow pattern, which will be discussed later in this paper. Drag reduction phenomena in multiphase flow are still far from being well understood in spite of the numerous investigations. This is due to the dependence of such phenomena on a large number of parameters, such as oil viscosity; pipe diameter; liquid and gas velocities; composition of oil, such as 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 polymers, such as polymethacrylate (PMMA), polyethyleneoxide (PEO), and polyisobutylene (PIB). DRA polymers commonly used are x-olefin polymers and copolymers of very high molecular weight. A new generation of drag reduction agents is now available commercially. In general, the new DRA is characterized by high polymer content. The active component is still a polyalphaolefin polymer with a fast dissolution rate and a slow degradation rate. Moreover, they are characterized by low viscosity and are much easier to handle. Berge and Solvik (1996) reported field results in crude oil and multiphase flows using the new generation DRA, which is an emulsified powder product with a polymer content of 20–25%, as compared to conventional gel-type product with polymer content of 5–8%. They reported that the new DRA tends to be four times more effective than the conventional gel-type DRA, with cost savings of 25%. Table 2 summarizes drag reducing additives and their properties, while Table 3 lists the drag reduction and heat transfer behavior as reported by Kostic (1994).

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Drag Reducing Agents in Multiphase Flow Pipelines

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Generally, higher molecular weight polymers perform much better than identical but lower molecular weight polymers. A major drawback of polymer solutions is the degradation in high shear flows. This degradation is caused by the pump and piping system. Injecting the polymers downstream of the pipeline booster pumps can minimize this effect.  Choi and Kasza (1989) reported the dependency of degradation on the flow temperature. They found that dilute polymer solutions tend to degrade rapidly at 87.8 C while no degradation was experienced at 7.2 C. Moreover, they reported a drag reduction of 50% for one month of circulation. Kwack and Hartnett (1982) investigated the effect of degradation on the friction factor and heat transfer in a recirculating flow system. They observed no effect of DRA degradation on the friction factor, but there was an effect on the heat transfer. The degree of degradation was presented using the critical Weissenberg number. High concentrations were used to make up for the degradation. The effectiveness obtained was very much dependent on the type of drag reducing agent used. Sitaramaiah and Smith (1969) reported experimental results on drag reduction in turbulent flow using several acrylamide based polymers. They compared their effectiveness with that of polyethylene oxides and found that drag reduction increased with higher molecular weight, concentration and flow rate for all polymers approaching values of 70–80%. The main conclusion was that low-salt content solvents should be used for better efficiencies when polymers with ionic groups are used as fluid-friction reducers. The selection of the drag reduction agent was very much related to the application under consideration and the cost. Virk (1975a, 1975b) and Hoyt (1984) identified two asymptotic, additiveintensive flow regimes of zero and maximum drag reduction that envelope a third polymeric regime wherein additives’ properties exert certain influences. The polymeric regime, based on Prandtl-Karman (P-K) coordinates, consisted of two extremes of flow behavior called types A and B. Type A was a family of additive solutions that produced a “fan” of friction factor segments which radiated outward from a common “onset” point on the P-K law (Figure 4) (Virk et al., 1997). Type B included a variety of additives, such as polyelectrolytes and fibers, with a ladder of segments on the P-K law. Wahl et al. (1982)   reported field experimental results on two drag reducing agents to increase the capacity of crude oil pipelines. The pipelines tested 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 modified drag reducer that is a more viscous polymer solution. The performance of  the modified drag reducer increased by approximately 10-fold, that is, 2 ppm of the modified polymer gave the same level of performance as 20 ppm of  the standard drag reducer for a pipe of 8-in diameter and 4–5 fold for a 48-in diameter pipe. The most important conclusion of their work was that high performance, low concentration modified polymers were very attractive for offshore production operations where space and deck loading are critical factors. ◦

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B. A. Jubran et al.

 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.

Drag Reducing Agents in Multiphase Flow Pipelines

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The effect of surface roughness of the pipe on drag reduction using different types of DRAs was reported by Derrule and Sabersky (1974) and Bewersdoff and Berman (1987). Derrule and Sabersky observed that when polyethelyne oxide was used as the surface roughness of the pipe was increased, drag reduction also increased. Bewersdoff and Berman (1987) observed no change in the drag reduction effectiveness for rough pipe when polyacrylamide was employed for both smooth and rough pipes. A summary of effectiveness for different types of DRAs is shown in Table 4.

HYDRODYNAMICS OF PIPE FLOW IN THE PRESENCE OF DRAG REDUCING AGENTS

Drag reducing agent performance is very sensitive to any shear generated in the flow, as it results in the degradation of the agent. The hydrodynamic characteristics of the flow, such as turbulence, single pass or recirculatory flow, and single phase or multiphase flow have a significant impact on drag reduction effectiveness. Reddy (1986) observed a reduction in effectiveness in recirculatory flow compared to turbulent rheometer and single pass flows. This was attributed to the adverse effect of pipe fittings on the flow of polymer solution and the rapid degradation in recirculatory flow. This degradation was generated by the resulting shearing effects, which increased as the piping network became more complex. They further developed empirical correlations that could be used for the prediction of drag reducing effectiveness of  polymers in recirculatory flow systems. Gyr and Tsinober (1997)  concluded that drag reducing fluids are essentially non-Newtonian in the turbulent flow state and generally Newtonian in many laminar flows. They presented a critical discussion of the momentum deficit of drag reducing flows and a simple unequivocal demonstration for the claim that the drag reduction phenomena in a number of fluid systems are of rheological nature.  Berge and Solvik (1996)   reported that, in general, a higher degree of fluid turbulence resulted in a higher drag reduction. If this is to be related to the Reynolds number (Re), then this implies increasing velocity and decreasing viscosity. They reported that when the DRA dissolved rapidly 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 the calculation of the total pressure drop in perforated pipe flow as applied to horizontal wells. They divided the pressure drop into two components: reversible and irreversible. The reversible pressure drop was due to acceleration as more fluid entered the wellbore through perforations, while the irreversible pressure drop was due to friction and mixing effects. They computed the acceleration terms using both momentum and energy equations. Their computations showed that the acceleration terms were about one-third higher when the momentum equation was used compared to that obtained when the energy

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   m    p    p     0     0     5   –     0     1

   m    p    p     0     0     1   –     0     1

    k     i    v     l    o     S     d     )    n    a    6     9    e     9    g     1    r    e    (     B

    0     2  ,     0     1  ,     5

    %     0     2  ,     0     1

    %     2  ,     5

   m    p    p     0     0     5     1   –     0     5     2

   e    s    a     h    s     d    p     i    e    u     l     l    g     F     i    n    s  ,     l     i     O

   e    s    a     h    p    e     l    g    n     i    s  ,     l     i     O

   e    s    a     h    p    e     l    g    n     i    s  ,     l     i     O

   e    s    a     h    p    e     l    g    n     i    s  ,    r    e    t    a     W

   s    a    g     /     l     i    o  ,    e    s    a     h    p     i    t     l    u     M

    l     i    o    e     d    u    r    c    e     l    g    n     i     S

   w    o     l ,    fl     i    o   e    e    s     d    a    u     h    r    p    c    i    t    e    l     l    u    g    n   m     i     S

 ,     8  ,    r    e    e    n   t    e     i     l    m    e    a    p    i     i    p    d    n  ,     i     l    )       i     8    s    o    t    4   -    s     l    e    a    t    d    t    n     d   n    a    o  ,    e    2    z    l     i     fi    r     (     1    o     H

 ,     8  ,    r    e    e    n   t    e     i     l    m    e    a    p    i     i    p    d    n  ,    i     l    )       i     8    s    o    t    4   -    s     l    e    a    t    d    t    n     d   n    a    o  ,    e    2    z    l     i     fi    r     (     1    o     H

 ,    e    n     i     l    =    e    p   e     i    p    R    0    r  ,    0     0  ,    e    n    t     i    a    1   -    0     6    w   r    t    o     l    a    e    t    t    e    0    n     0    o    m  ,    z    i    a    0     i     0    r     d    o     2     H

   e    n     i     l    m    e    c      p     i     0     1   p    r     l    a    e    t    t    e    n    o    m    z    a     i     i    r     d    o     H

   m    c    s    e    n     0     i     l     1    e   –    p     5  .     i    p     2    r     l    e    a    t    t    e    n    o    m    z    a     i     i    r     d    o     H

 ,    a  ,     i    a     d     i     d    i    n    n    8     i       2     4  ,     1   s     l    e    s    e    a    l     i    l    t    n    m    i    m    o    z    5     i  .     5    r     9     7    o     H

    )    t    n    e    g    r    e    t    e     D     (

   a     h    t    f     i    w   o    r    e    t    n    e     d    t    w    n    o    p   o    c    r     d    e    e    %     fi   m    5     i    y    2    s    l   –     l     0    u   o    m   p    2     E

    M     E     G

    A     R     D    n    o     i    t    a    r    e    n    e    g    w    e     N

   s    n    o     i    t    a    c     i     l    p    p     A

 ,    r    e    e    n   t    e     i     l    m    e    a    p    i     i    p    d  ,     l    )     i    s    o    t      s     l    a    e    t    t    n     d    i    n     l    o      e    8    z     i     fi    r     (     4    o     H

   s    e     i    t    r    e    p    o    r     P

 ,  ,    3  ,    3  ,    4     %     %     %    t    t    t    t    t    t     1    m    m    n    n    n    c    c     8    w    i     i     /    w    i     /    w  .  ,    o  ,    o  ,    o    p    g    p    g    p    0    n  .    n  .    n  ,    s  ,    s  ,    o    h    y    o    o    a    a    y    y     i     i     h     i     h    t    P   t    s     i    t    P   t    s    i    t    t    s     i    a    a    a    s    s    s    a    a    a    r    fl    n    0    r    fl    n    0    r    fl   n    t    t    t    e    3    e    3    e    s    n    t    t     2    n     2    n  .     d     d     d    e    e    e    t    n    n    n    c    c    ;    =   n   e    ;    =   c    ;    a    e    e    n    n    v    C    o    l    v    C    o    l    v    C    P     l    o     ◦      K   c    o    ◦      K   c    o    ◦     0    c    o     8     0  ,    n   s    0    s     0  ,    n   s     2    n    ;     6    o    o   ;     6    o   ;    6  ,    4  ,     4  ,    =     i     i     i     1     1    t     %    t     %    t     %     8     8    c     M    c     M    c     M     0  .     0  .     0    e    1    P    0    j    e    1    P    0    j    e    1    P     K     j    n    n    n     I     I     I

   s    t    n    e    g    a    g    n     i    c    u     d    e    r    g    a    r     D

   r    e    )    t    r    a    s    w   e     (    m    y    r    e    l    o    p    m    y    e     l     l    o    p    b    u     l     R   o     D   s     C

   s    r    e    m    y     l    o    p     R     D     C

    R     D     C     d    e     fi     i     d    o     M

 ,    e     )    s    o   s     M  ,    A    l    o    u   t     )     l     l    s     P     (    e    e     M    c     b     l     X    e     (    y   s  ,     i     d    h    a     A     )    t     R    m    e    d     M   m    n    u    a     )    D     l    a    m     G    g     F     (    n   r    y     )    e  ,     A    l    a    c    y    x     b    m     h    o    C    (    a    u    t    r     l    u     b    y    n    r     l    e    o     M    g    a    r    a    s    o     b     C    a    u    X    P    C    (    fi    l     i     G     O

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Drag Reducing Agents in Multiphase Flow Pipelines

1415

equation was used. Moreover, they conducted experimental investigations on a perforated pipe with 144 perforations, geometrically similar to the wellbore casing. 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 on performance of horizontal wells only considered the friction component of  the total pressure (Dikken, 1990; Landman, 1994). Little work has been done on drag reduction other than that used by friction ( Dass et al., 2000). The main outcome of this work was that the semi-empirical relationship developed for pipe junction in hydraulics cannot be used for flow in horizontal wells because the flow ratio and perforation diameters are different. The effect of pipe diameter on the performance of the drag reducing agent is an important parameter which cannot be accounted for through Reynolds number (Re) as was done for Newtonian fluids. A good account of the effect of diameter on drag reduction fluids was shown in the work reported by Sellin and Ollis (1983) and Matthys (1991). Matthys pointed out that the effect of  the diameter must be included in an additional parameter that is necessary for the prediction and characterization of friction in the non-asymptotic regime. However, Re may be used provided the viscosity of the solvent rather than the viscosity of the actual solution is used in the calculation of Re. The rationale behind this is that very dilute solutions tend to have a viscosity that is independent of the shear rate in the high shear rate regime. However, if the viscosity is much larger than that of the solvent, then the approximation using solvent-based Re will be justifiable, particularly when the drag reduction obtained is small (Matthys, 1991). It was also reported that using smaller diameter pipes to predict the performance of drag reduction in larger diameter pipes would not result in an accurate prediction ( Jepson and Taylor, 1993). Mansour and Aswad (1989)  conducted an experimental investigation on the effect of pipe diameter on DRA using a detergent called GEM in a recirculating system. They reported that increasing the pipe diameter increased drag reduction, which was contrary to the findings of Lester (1985), who found that increasing the pipe diameter decreased drag reduction.   Jubran et al. (1992)  conducted an experimental investigation on the effect of pipe diameter on drag reduction of GEM in a recirculating system. They found that as the diameter of the thermoplastic pipe was increased, the drag reduction decreased. Gasljevic and Matthys (1993) investigated the effect of  drag-reducing surfactant additives on heat transfer exchangers. Their results indicated that increasing the diameter of the pipe from 2 to 52 mm resulted in a decrease in the drag reduction effectiveness. This effect was diminished as Re increased beyond 10 5 . The general consensus was that increasing the diameter of the pipe tends to decrease drag reduction effectiveness. Another focus research area for drag reducing agents is their influence as flow conditioners for two-phase flow in pipelines (i.e., effects on flow structure). Again, the effect depends on the type of DRA used.   Rosehart et al. (1972) investigated the presence of DRAs on the structure of single and

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B. A. Jubran et al.

two-phase flow in horizontal pipes using visual observation. The addition of  DRAs to the flow did not change the slug transitional velocity and the slug frequency at low polymer concentration. It was found to be the same for the air/water system, but decreased at higher polymer concentration.   Kang et al. (1998)   investigated DRA in three-phase flow and oil/water/gas flow. They concluded that DRA was effective in reducing drag for different flow patterns, such as stratified, slug, and annular flow. DRA was found to change the flow patterns in horizontal pipes. Their results agreed well with those of  Rosehart (1972) which showed that for three-phase flow DRA concentration did not affect the slug transitional velocity. The amount of drag reduction obtained is very much dependent on the type of flow regimes, as can be seen in Table 5. Kang et al. (1999) conducted an experimental investigation on using drag reducer agents in multiphase flow in vertical pipes. In addition to the performance of drag reduction, they reported flow conditioning due to DRAs. Adding DRAs shifted the transition to slug flow to higher superficial liquid velocities. No effect was reported on the superficial gas velocity for the flow to remain in transition. The effectiveness of DRAs tended to decrease with increasing superficial liquid velocity at the same superficial gas velocity (Table 5). Kang and Jepson (2000, 1999) reported experimental investigations on using drag reduction as a flow conditioning agent in multiphase pipe flows. They reported that DRAs did not change the slug transitional velocity, but decreased the slug frequency and the height of the liquid film. The effect of DRAs in two-phase flow in annular flow was investigated experimentally 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 DRA injection resulted in drag reduction of 48% with only 10–15 ppm DRA concentrations (Al-Sarkhi and Hanratty, 2001). It was noted that the DRA’s effectiveness is sensitive to the method of injection as well as the concentration of polymer in the injected solution (maser solution). At maximum drag reduction the annular flow became stratified with smooth interface. Also, for the same DRA concentration in the flow there is an optimum concentration of  the master solution that maximizes the effectiveness. A master solution concentration of 1000 ppm of Percol 727 was suggested (Al- Sarkhi and Hanratty, 2001). In the work of Al-Sarkhi and Hanratty (2001), two injection locations along the pipe were used: one 0.6 m upstream of the air-water mixing tee in the liquid line and one 5.5 m downstream of the tee where two-phase flow exists. It was observed that when the DRA is injected in the upstream injection location its effectiveness decreased with increasing the gas velocity, while it was insensitive when injection took place in the downstream injection location. Thus, in annular flow the injection of DRAs should be in the liquid film. To investigate the effect of diameter size on drag reduction in annular flow Al-Sarkhi and Hanratty (2001a) used a smaller diameter (2.54 cm) and achieved drag reductions of 63% compared with 48% for the 9.53 cm pipe

   e    m     i    g    e    r    w    o     fl    t    n    e    r    e     f     f     i     d    r    o     f    t    n    e    g    a    n    o     i    t    c    u     d    e    r    g    a    r     d     f    o    t    c    e     f     f     E   .       5     e       l       b     a       T

   e    c    n    e    r    e     f    e     R

    )     )     8     8     9     9     9     1    9     1     (     (  .     l .     l    a    a    t    e    t    e    g    g    n    a    n    a     K    K

   s    n    o     i    t     i     d    n    o    c    w    o     l     F

   s    s     /    a    g    m     3     3     l     5    a     0     0     2  .     0  .     i  .     0    c     0    s     fi     /    r    y    y    y    ;    t    t    e    t     i     i    m    s     i    p    c    c    e    4    c     i    u    o    o    t    o     l     l    s     i    n     l    e    e  ,    c    e    v     /    a    s    o    h    v    v     l    :    :    :    t    e     d     d    m     d    v    e     i     i     i    r    u    u     5     l    u    s    i  .     l    o    q    /    q     0    q    i    a     i     l     l     l     l    m    l    :    s    :    m     l    y     /    y    a    7    a     i    y    t    t     i    a    i    t     i   –    i    c    4    c    c    m    i    c    c    fi    c     fi    o    o    s     fi     4    o     l     l    r    r     /    r    s     l    e    e    e    e    e    e    n    m   v    a    v    e     i    p    p    p    v    t    u    u     h     7    d     d    s    i    s    c    t    s    u     i     i    a    s    u    s    u    s    o  ,     /  ,  ,     l    g    q    s    q    l    e    m    m    m     i     i    m    e    v     l     l    p    p     l    p    a     i    p    1     l     l    p    p    s    c    y    a    i    a    fi    a     1    t     i     i  .     0     5     0    c    c    c    r     7    0    fi     1    1    g  ,    e    o    fi    :    :    s    :     d    r     l    r    p    e    e    e    n     A    A    /     A    u    p    v     R    R   m    R   a    p    u    u    s     D    D     D     S     S

   n    o     i    t    e    a    p     i     i    n     P    l    c    n     i

   e    e    p    i    p     i    p    p     l     l    a    a    t    t    n    n    o    o    z    z     i     i    r    o    r    o     H    H

    )     8     9     9     1     (  .     l    a    t    e    g    n    a     K

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   e    p     i    p     l    a    c     i    t    r    e     V

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    %     1     8   –     %     %     7     6     0     9     0     5

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used previously (2001). However, they found that compared with the large diameter pipe, a larger concentration of polymer is required in the smaller diameter pipe to achieve the maximum drag reduction (10 ppm in 9.53 cm pipe and 30 ppm in 2.54 cm pipe). Differences in the resulting flow pattern were also observed. At the large diameter pipe the resulting flow pattern was stratified with smooth interface while at the smaller diameter pipe the pattern was characterized by stratified-annular. The study of   Soleimani et al. (2002)  investigated the effect of DRAs on the transition form stratified to slug flow in a horizontal 2.54 cm pipe. It was found that at gas superficial velocities greater than 4 m/s the DRAs delay the transition to slug flow; i.e., transition occurs at larger liquid holdup. As DRAs are added into a stratified flow, a higher thickness of the liquid layer is required to initiate the slugging. In view of these findings, the addition of 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 and more comprehensive work is needed. Dass et al. (2000) reported a model to predict the components of pressure drop in slug flow in a horizontal pipe. The aim of their work was to shed light on the contributions of the frictional and acceleration components to total pressure drop in horizontal slug flow in the presence of drag reducing agents. The predicted and experimental results showed good agreement. The DRA was active in reducing both components of the pressure drop. It was found that the acceleration component was dominant and contributed more than 80% of the total pressure. This increased significantly as the superficial gas velocity was increased. Both components of the pressure were reduced by 67% and 78% at DRA of 20 and 50 ppm, respectively. However, drag reduction was decreased as the superficial gas velocity was increased. It is interesting to note in their study that the drag reduction obtained was mainly in the acceleration component, indicating that the DRA was effective in the mixing zone of the slug flow.  Fan and Hanratty (1993) developed a model to predict the pressure drop across a stable slug flow. They treated the slug as a hydraulic jump and assumed that the pressure change takes place at the rear of the slug, where the change could be positive or negative. Dukler and Hubbard (1975) developed a model to predict the frictional and acceleration components of total slug pressure drop in an air-water system. The model assumed that the two phases within the slug body were homogeneously mixed with negligible slip. The frictional component of the pressure was predicted using an equation similar to that used in a single phase flow after modifying the density of the mixture and the friction factor. The acceleration contribution was found by assuming a stabilized slug flow body that is receiving and losing mass at equal rates. The acceleration pressure drop was then calculated from the force required to accelerate the liquid to slug velocity. Vlachos and Karabelas (1999) investigated shear stress circumference in stratified flow. They used the momentum equations for both phases to 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/liquid flow in a horizontal pipe.

HEAT TRANSFER IN PRESENCE OF DRAG REDUCING AGENTS

Drag reduction and heat transfer phenomena associated with drag reducing fluids are far from being well understood. Certain applications for the utilization of drag reduction agents necessitate a closer look at the heat transfer process as well as the hydrodynamics process involved. However, it is interesting 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 keeping the loss of heat to the atmosphere to a minimum, while keeping the oil flowing at a lower pumping power. Moreover, in certain cases it brings down the cost of thermal insulation of the pipelines. Matthys et al. (1987) reported local and heat transfer measurements in circular tubes for suspensions of betonite and for a combination of betonite and polyacrylamide in water for both laminar and turbulent flow. It was found that a viscosity model based on rheological measurements could represent the results with a Newtonian relationship. It was also found that combining clay and polymer in a fluid produced viscoelastic solutions that were very sensitive to mechanical degradation. The local heat transfer results were well correlated using the Colburn and Reynolds analogies, regardless of the concentration of bentonite.  Yoo et al. (1993) investigated experimentally the heat transfer characteristics of drag reducing polymer solutions in the thermal entrance region of circular tube flows. The tests were conducted in two stainless steel tubes with length to diameter ratios of 710 and 1100. The fluids used were aqueous poly-acrylamide solutions of Separan AP-273 with a concentration range of 300 to 1000 wppm. The main finding of this investigation was that the order of magnitude of the thermal entrance length of the maximum drag reducing polymer solutions was much higher than that of turbulent Newtonian fluids in tube flows. Gasljevic and Matthys (1994) reported local heat transfer results and friction in the entry region of a circular pipe in the presence of a drag reduction surfactant. Two entrance arrangements were used: a cone contraction and a wire mesh plug fitted to flatten the velocity profile. The main findings of this work were the restructuring of the fluid itself due to high local energy dissipation in the inlet region, and the stronger coupling between the hydrodynamic and thermal field development in the case of surfactant solutions than in the case of polymer solutions. The Reynolds analogy and the direct relation between the friction and heat transfer coefficients were not valid for drag reducing fluids; i.e., the Reynolds and Colburn analogies were not valid for this type of flow. The reasoning behind this is still not clear 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 thermal entrance and hydrodynamic lengths for drag reducing solutions were more than that observed for Newtonian fluid flow with values of more than 20 and 100 diameters, respectively. Matthys (1991) carried out a comprehensive survey on the most important 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 in the presence of a drag reducing agent. It was pointed out that the reduction produced by the addition of the agent was upset by the greater reduction produced in the convection heat transfer. He attributed the lack of investigations on heat transfer of polymer solutions to the complexity of viscoelastic flows. This required a more demanding experimental set up to accurately record the data. Matthys (1991) indicated the availability of macroscopic and correlation work for purely viscous non-Newtonian fluids, but not for viscoelastic non-Newtonian fluids that cover flows with drag reduction agents. Gasljevic and Matthys (1991)  investigated the thermal and hydrodynamic characteristics of drag-reducing surfactant solutions in the entry region of the pipe, as well as after fittings. In addition, they provided an excellent literature review on the subject. It was reported that for surfactant solutions the friction coefficient and the Nusselt number were varying at the same rate beyond 300 diameters. Heat transfer downstream of an elbow tended to increase over that obtained for fully developed flow, but it did not degrade the fluid. Gasljevic et al. (1993) conducted a comprehensive experimental investigation on the performance of various types of heat exchangers in the presence of drag reducing surfactants in the working fluid. The working fluid used was a solution of 2300 ppm of Ethoquad T/13 and 2000 ppm of NaSal in deionized water. Pressure and heat transfer measurements were taken at an operating temperature 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 as the working fluid and concluded that the thermal and hydrodynamic characteristics are very much dependent on the geometry and flow conditions in the heat exchanger. It was also noted that a significant drag reduction could be achieved in heat exchangers with little penalty in the heat transfer process. Gasljevic and Matthys (1993, 1991) reported an investigation to explore the use of surfactant drag reducing additives to reduce the pumping power in hydronic heating and cooling systems. Various issues were investigated, namely the matching of the additives with system characteristics, drag reduction in fittings and valves, and the heat transfer process in the presence of  reduction agents. It was concluded that the use of drag reducing agents in heating and cooling systems can be implemented at a small cost and would lead to significant energy savings. Kostic (1994) carried out a critical review on turbulent drag, heat transfer reduction phenomena, and laminar heat transfer enhancement in non-circular duct flow of non-Newtonian fluids. The review outlined peculiar behaviors

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and applications of DRAs. Kostic reported that the underlying mechanism that produces drag and heat reduction is far from being understood. He noted that this should keep researchers busy for many years to come. Despite the limited research to date on the heat transfer aspects of viscoelastic fluids, there was enough evidence to conclude that such fluids tend to enhance heat transfer in laminar non-circular duct flow. Moreover, he reported that flow laminarization, due to flow-induced anisotropic fluid structure and properties, was the predominant factor for the reduction phenomena rather than fluid elasticity. On the other hand, fluid elasticity was responsible for laminar heat transfer augmentation. Hartnett and Kwack (1986) reported that for a polymer solution the reduction in friction was not accompanied by a reduction in heat transfer. For a comprehensive review of research work related to heat transfer in 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 and multiphase flows with particular reference to the oil industry. It has examined work related to theories of drag reduction, the influence of drag reduction types, and hydrodynamic and heat transfer characteristics of the flows in the presence of a drag reducing agent. Moreover, it has raised questions and shortcomings that need answers, as well as pin-pointing potential areas that need further research. Drag reduction phenomena and theories related to multiphase flow are still far from being well understood. More work is needed in the areas of  shear degradation, and the effect of wax content, water cut, and pipe inclination on the performance of drag reduction in smooth and perforated pipes with emphases on oil wells. Most of the work carried out on the performance of horizontal wells consider only the friction component of the total pressure without taking into consideration the acceleration component. Limited work  has been done on the role of drag reducing agents as a flow conditioner, especially for large pipe inclinations with a high water cut. Further fundamental, experimental, and analytical investigations are needed to better understand the heat and hydrodynamic processes associated with drag reduction in single and multiphase flows, since the Reynolds and Colburn analogies are not valid for drag reducing fluids.

REFERENCES

Al-Sarkhi, A., and Hanratty, T. J. (2001). Effect of drag-reducing polymer on annular gas-liquid flow in horizontal pipe.   Int. J. Multiphase Flow 27:1151–1162.

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Al-Sarkhi, A., and Hanratty, T. J. (2001a). Effect of pipe diameter on the performance of drag-reducing polymers in annular gas-liquid flows.   Trans  IChemE Part A  79:402–408. Berge, B. K., and Solvik, O. (1996). Increased pipeline throughput using drag reducer additives (DRA): Field experiences. SPE 36835, 203–208. Bewersdorff, H., and Berman, N. A. (1987). Effect of roughness on drag reduction for commercially smooth pipes.   J. Non-Newtonian Fluid Mechanics  24:365–370. Burger, E. D., Munk, W. R., and Wahl, H. A. (1980). Flow increase in the trans Alaska pipeline using a polymeric drag reducing additive. 55th Annual Fall Technical Conference and Exhibition of the Society of Petroleum Engineers, Dallas, Texas, Sept. 21–24, SPE 9419. Burger, E. D., Munk, W. R., and Wahl, H. A. (1982). Flow increase in trans Alaska pipeline through use of polymeric drag-reducing additive. JPT  377–386. Cho, Y. I., and Hartnett, J. P. (1982). Heat transfer in flows with drag reduction.  Adv. Heat Transfer   15:59–139. Choi, U. S., and Kasza K. E. (1989). Long-term degradation of dilute polyachrylamide solutions in turbulent pipe flow.   Drag Reduction in Fluid  Flows, Ellis Horwood Limited, 163–169. Dass, M., Kang, C., and Jepson W. P. (2000). Quantitative analysis of drag reduction in horizontal slug flow. SPE Annual Technical Conference and Exhibition, Dallas, Texas, 1–4 October, SPE 62944. Derrule, P. M., and Sabersky, R. H. (1974). Heat transfer and friction coefficient 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 on production 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 flow in horizontal and near horizontal tubes.  Ind. Chem. Fundam.  14(4). Fan, Z., and Hanratty, T. J. (1993). Pressure profiles for slug flow in horizontal pipelines.   J. Multiphase Flow  19(3):421–430. Gasljevic, K., and Matthys, E. F. (1991). Feasibility study of the use of  drag-reducing additives to reduce pumping power in hydronic thermal distribution systems. Winter Annual Meeting of the American Society of  Mechanical Engineers ASME, Fluids Engineering Division, FED, 132: 57–65. Gasljevic, K., and Matthys, E. F. (1993). Saving power in hydronic thermal distribution systems through the use of drag-reducing additives.  J. Energy and Buildings  20(1):45–56. Gasljevic, K., and Matthys, E. F. (1994). Hydrodynamic and thermal field development in the pipe entry region for turbulent flow of drag-reducing surfactant solutions. Proceedings of the International Mechanical Engi-

Drag Reducing Agents in Multiphase Flow Pipelines

1423

neering Congress and Exibition, Chicago, ASME, Fluids Engineering Division, FED, 206:51–61. Gasljevic, K., Nan, X. M., and Matthys, E. F. (1993). Effect of drag-reducing surfactant additives on heat exchangers. Proceedings of the 1993 ASME Winter Annual Meeting, ASME Applied Mechanics Division, AMD, 175:101–108. Gyr, A., and Tsinober, A. (1997). On the rheological nature of drag reduction phenomena.  J. Non-Newtonian Fluid Mechanics  73:153–162. Hartnett, J. P., and Kwack, E. K. (1986). Prediction of friction and heat transfer 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 large horizontal pipes.   Int. J. Multiphase Flow  19:411–420. Jubran, B. A., Hamdan, R., and Mansour, M. A. (1992). Some aspects of drag reduction in thermoplastic pipes.   Polym.-Plast. Technol. Eng. 31(3&4):259–269. Kang, C., and Jepson, W. P. (1999). Multiphase flow conditioning using drag-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 multiphase oil/gas horizontal flow. SPE International Petroleum Conference and Exhibition in Mexico, 1–3 February, SPE 58976. Kang, C., Jepson, W. P., and Gopal, M. (1999). Effect of drag-reducing agent on slug characteristics in multiphase flow in inclined pipes.   J. Energy  Res. Technol. ASME Trans.  121:86–90. Kang, C., Vancho Jr., R. M., Green, A. S., and Jepson, W. P. (1998). The effect 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 phenomena and laminar heat transfer enhancement in non-circular duct flow of 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 Weissenberg 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 horizontal wells.  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 costs or maximize flow rate of pumping crude oil inside pipelines using new drag reducing additives.   J. of Pipelines  7:301–305.

1424

B. A. Jubran et al.

Matthys, E. F. (1991). Heat transfer, drag reduction, and fluid characterization for turbulent flow of polymer solutions: Recent results and research needs.  J. Non-Newtonian Fluid Mechanics  38:313–342. Matthys, E. F., Ahn, H., and Sabersky, R. H. (1987). Friction and heat transfer measurements for clay suspensions with polymer additives.   ASME  Transactions, J. Fluids Eng.  109:307–312. Matthys, E. F., and Sabersky, R. H. (1987). Friction and heat transfer study of  a discontinuously shear-thickening antimisting polymer solution.  J. Non Newtonian Fluid Mech.  25:177–196. Mizunuma, H., Ueda, K., and Yokouchi, Y. (1996). Synergistic effects in turbulent 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 flow with drag-reducing polymer solutions.  AIChE Journal  18:744–750. Sellin, R. H., and Ollis, M. (1983). Effect of pipe diameter on polymer drag reduction.  Ind. Eng. Chem. Prod. Res. Dev.  22:445–452. Sitaramaiah, G., and Smith, C. L. (1969). Turbulent drag reduction by polyacrylamide and other polymers. SPE paper 2405. Soleimani, A., Al-Sarkhi, A., and Hanratty, T. J. (2002). Effect of dragreducing polymers on pseudo-slugs-interfacial drag and transition to slug flow.   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 entrance region for viscoelastic fluids in turbulent pipe flow.  Int. J. Heat and Mass Transfer  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 polyelectrolytes.  Nature  253:109–111. Virk, P. S., Sherman D. C., and Wagger, D. L. (1997). Additive equivalence during turbulent drag reduction.  AIChE Journal 43(12):3257–3258. Vlachos, P., and Karabelas, P. (1999). Predictions of holdup, axial pressure gradient and wall shear stress in wavy stratified and stratified/atomization gas/liquid flow.   Int. J. Multiphase Flow  25:365–372. Wahl, H. A., Beaty W. R., Dopper J. G., and Hass G. R. (1982). Drag reducer increases oil pipeline flow rates. Offshore South East Asia 1982 Conference, 9–12 February, Singapore. Yoo, S. S., Hwang, T. S., Eum, C. S., and Bae, S. C. (1993). Turbulent heat transfer of polyacrylamide solutions in the thermal entrance region of  circular tube flows.  Int. J. Heat and Mass Transfer  36(2):365–370.