99034 How Operating and Environmental Conditions Affect Erosion (51300-99034-Sg) (1)

8/10/2019 99034 How Operating and Environmental Conditions Affect Erosion (51300-99034-Sg) (1)

1/24


2/24

risk for personnel as well as equipment. Oil and gas producers need to be able to predict the severity of

erosion so that the service life of fittings susceptible to erosion can be determined. If the prediction tool

has the capability of accounting for parameters such as production rate or flow velocity, producers can

also determine the highest production capacity that keeps the erosion damage within tolerable limits,

maximizing the economic potential of the well.

Erosion is complex and depends on a multitude of factors such as the fluid and sand properties,

production rate of produced fluid and sand, pipe size, and sand size.

Therefore, developing predictive

tools for erosion poses a difficult task. Another factor that affects the severity of erosion is the type of

geometry. Most of the work that has been done on the development of erosion prediction models has

been for elbows and bends. This is a result of two primary factors.

First, the elbow is a relatively

simple geometry, and second, the elbow experiences a significant amount of erosion.

BACKGROUND

Erosion results from the impingement of sand, and the impingements occur due to the transfer of

momentum of the fluid to the particle in the direction of the wall, In some cases such as the elbow, the

inefficiency of the fluid to redirect (change the momentum of) the particles results in impingements.

Accounting for the efficiency of the exchange of momentum is a key factor in predicting erosion. Once

again, the efficiency of momentum transfer depends on many factors; some of the most important being

the ratio of density of the particle and fluid and the particle size. To illustrate the effect of the efficiency

of momentum transfer, sample particle trajectories are determined for representative air and water flow

in a 1 inch elbow with standard radius of curvature. For both cases, the initial particle velocities are set

equal to the bulk fluid velocity and the particle size is 150 microns.

Figure 1 shows the representative

particle trajectories in air at 50 psig with a bulk velocity of 50 ft/s. In air, the particles have sufficient

momentum to cross the streamlines and impinge the wall. The efficiency of exchange of momentum is

very low so the air does not alter the path of the particles, and the particles impinge with a velocity

similar to that of the bulk velocity of air. Figure 2 shows the representative particle trajectories for

water with a bulk velocity of 8 ft/s. For this case, the particles follow the streamlines much more closely

and only a few impingements occur. This behavior results since the density of the water is much larger

than the density of air and approaches the density of the particles.

Comparison of these figures also illustrates another important aspect of particle motion that

affects erosion. The particle trajectories for the water case demonstrate the effect of turbulence. The

particles are influenced by the instantaneous velocity of the fluid which is comprised of both the

fluctuating component resulting from turbulence and the mean component. There is also a fluctuating

velocity component associated with the air cases; however, due to the inefficiency of the transfer of

momentum the particles do not react to the fluctuations.

Some erosion such as in elbows occurs

primarily due to the mean component of velocity. The authors refer to this erosion mechanism as direct

impingement. However, in some geometries such as straight sections of tubing, particle impingements

only occur due to the fluctuating component of velocity. For these cases, the erosion mechanism is

random impingement. Under most conditions, the erosion resulting from direct impingement is more

severe than for the random impingements.

This is another reason that erosion damage in elbows is

studied.

Previous guidelines for avoiding erosional damage by limiting production rates were based

purely on empirical relations.

For example, the recommended velocity limitation described by the

American Petroleum Institute Recommended Practice 14E (API RP 14E) gives a limiting production

velocity by the formula (1)


3/24

c

ve=

JF

m

(1)

where pm is the fluid mixture density at flowing pressure and temperature, and in Equation (1) has the

units of lb/ft3; the units of the fluid velocity, Vc, is in ft/s. The API formula is very simple and easy to

use, but, as noted in the literature [2,3], the formula does not recognize many factors contributing to

erosiordcorrosion, and the use of this formula can result in unrealistically low production velocity limits

for preventing pipe damage in erosive service. The only physical variable accounted for in Equation (1)

is the fluid density. The formula suggests that the limiting velocity could be increased when the fluid

density is decreased. This does not agree with experimental observations for sand erosion, because sand

in gases with lower densities will cause higher erosion than liquids with higher densities.

Recent methods for predicting threshold velocities in producing wells are based on penetration

rates in an elbow geometry because this geometry is more susceptible to erosion damage than a straight

pipe section. A common procedure presented in the literature is to extrapolate a threshold flowstream

velocity relation from erosion rate data for an elbow geometry based on an allowable amount of erosion

(e.g., a penetration rate of 5 or 10 roils per year). Examples include work of Salama and Venkatesh [4],

Bourgo yne [5], Svedeman and Arnold [6]. Recently, some of these methods were also extended to

multiphase flow [3,7].

EROSION/CORROSION RESEARCH CENTER (E/CRC) MODEL

(Application to Single-phase and Multiphase Flow)

It is well recognized by many researchers that predicting erosion is a very complex problem.

Current methods for erosion calculation are based on semi-empirical correlations that relate solid

particle impact velocity to pipe wall material loss rate.

Thus, erosion calculation can be even more

complicated in multiphase flow systems where sand particles are entrained in a complex multiphase

flow and the particle impingement velocity and impingement location on the pipe wall must be

determined.

Recent models for predicting erosion do account for the flow effects and these models are

referred to as the generalized models because they can account for different pipe geometries. In the

generalized model, the erosion calculation is performed based on particle impingement angle and speed.

The generalized model requires significant flow modeling that are normally done by computational fluid

dynamics (CFD) codes which are still in their infancy for predicting multiphase flow. This approach is

also currently in progress at the E/CRC. The generalized model approach currently requires significant

computational effort and, in general, is not suitable for design calculations. Therefore, it is desirable to

devise simpler and more efficient mechanistic models, that are based on the generalized model and

empirical information, and do account for the important variables that affect erosion. Based on this idea,

a formula is proposed for computing penetration rates in elbows, tees and direct impingement

geometries. In this formula, an expression for computing the maximum penetration rate in steel material

is proposed of the form

w Vp

h = FM Fs Fp F,m

D2

(2)


4/24

where

h

= penetration rate, m/s (can be converted to mm/yr or mpy)

FM = an empirical constant that accounts for material hardness

For carbon steel materials, FM=

1.95 x 10-5/B-059(for VL in m/s) where B is the

Brinell hardness factor

5

= empirical sand sharpness factor

%

= penetration factor for steel (based on 1 pipe diameter), m/kg

r/D =

penetration factor for elbow radius

w

= sand production rate, kg/s

VL

= characteristic particle impact velocity, rrds

D= ratio of pipe diameter in inches to a one inch pipe

The relation was developed based on extensive empirical information gathered at the

Erosion/Corrosion Research Center and data gathered at the Texas A&M University [8,9]. A major

difference between the E/CRC model and the earlier work is that method was developed to find the

characteristic impact velocity of the particles on the pipe wall, VL. This characteristic impact velocity

of the particles depends on many factors including pipe geometry and size, sand size and density, flow

regime and velocity, and fluid properties.

Characteristic Impact Velocity of Sand Particles

A method for computing the characteristic impact velocity of the particles with the pipe wall for

a tee and an elbow geometry has been presented in previous work [10, 11]; a brief description is given in

this section. The characteristic impact velocity of the particles is obtained by creating a simple model of

the stagnant layer in a pipe geometry. This is done by relating the erosion rates of complex geometries

to erosion occurring in a direct, or normal, impingement situation. This procedure is presented

conceptual y in Figure 3. In order to impinge the target wall, the sand particles must penetrate the fluid

layer (so called stagnation zone) for each of the geometries that are shown in Figure 3. The behavior of

the particles in the stagnation region strongly depends on the pipe fitting geometry, fluid properties, and

sand properties.

For two phase flow, this region can be assumed to be composed of gas and liquid

phases according to the flowing volumes of gas and liquid. Thus, the impact velocity of the sand

particles with a pipe wall is a strong function of the fluid properties as well as the amounts of gas and

liquid phases that are present in the stagnation zone or stagnation length through which the particles

must travel in order to strike the pipe wall. A characteristic length, called the equivalent stagnation

length (Figure 3), is used to represent this distance. A simplified particle tracking is used in this region

to determine the so called characteristic impact velocity of the particles.

The equivalent stagnation lengths for an elbow as well as a tee geometry were obtained by

erosion testing, flow modeling and particle tracking results [10, 11]. Figure 4 shows the results which

could be used for estimating the equivalent stagnation length for an elbow and a tee geometries. This

figure shows how the equivalent stagnation length varies with the pipe diameter, D.

A simplified particle tracking model [11] was used to compute the characteristic impact velocity

of the particles. This model assumes that the particle is traveling through a one-dimensional flow field

that is assumed to have a linear velocity in the direction of the particle motion and uses a simplified drag

coefficient model. The initial particle velocity was assumed to be the same as the flowstream velocity.

However, in a two phase gas-liquid flow, sand is normally entrained in the liquid phase. Thus, it is

reasonable to assume that sand particles have the same velocity as the liquid velocity (this is not the

same as the liquid superficial velocity) in the two-phase flow mixture. Assuming this equivalent or

characteristic liquid (and sand) flowstream velocity is known before the sand particles reach the


5/24

stagnation zone, a simplified particle tracking model, identical to the one used previously [10], can be

used to determine the characteristic impact velocity of the particles.

The results for the characteristic impact velocity of the particles with the pipe wall as a function

of several production parameters are shown in Figure 5.

The impact velocity for two-phase flow

depends on: equivalent liquid flowstream velocity,

a characteristic length scale describing geometry

and size, L, density of the fluid in the stagnation zone, viscosity of the fluid in the stagnation zone,

density of the particle, and diameter of the particle.

As done previously for single-phase flow, these

parameters can be combined into three dimensionless groups related to one another as shown in Figure

5. The dimensionless groups are:

A particle Reynolds number, ReO,

based on the equivalent flowstream velocity and particle diameter:

where

V. =

Pm =

l-% =

dp =

Re _

Pm o

p

o-

I%n

equivalent flowstream velocity, m/s

density of fluid (mixture) in the stagnation layer, kg/m3

viscosity of fluid (mixture) in the stagnation layer, Pa-s (or N s/m2)

diameter of particle, m

The density and viscosity of the fluid in

gas and liquid at the flowing conditions,

(3)

the stagnation layer is computed based on the volume flow of

~m = QLPL + QGPG . SLPL + SG~G

QL + QG VSL + VsG

where

QL

= volume flow rate of liquid, m3/s

QG

= volume flow rate of gas, m3/s

SL

= superficial liquid velocity, m/s

SG

= superficial gas velocity, m/s

A dimensionless parameter @ which is proportional

by the particle to the mass of the impinging particle:

(4)

(5)

Pm

@=

dpPp

where

L = equivalent stagnation length, m

PP =

density of particle, kg/m3

to the ratio of the mass of the fluid being displaced

Figure 5 contains much useful information about how various

impact velocity of the particles, VL, and sand erosion rates.

(6)

parameters affect the characteristic

For example, it shows how the


6/24

characteristic impact velocity of the particles is affected by fluid and sand properties.

Once the

characteristic impact velocity of the particles is determined, it is used in Equation (2) to compute erosion

and penetration rates for a specific geometry such as an elbow.

Jordan [7] developed a simple equation that represents the curves that are shown in Figure 5 for

@/ReO 0.153, the particles do not have enough momentum to strike the pipe wall and the

characteristic particle impact velocity is zero. Figures 5 and 6 as well as Equation (7) are also valid for

single-phase flow. The mixture properties should be replaced by the appropriate property of the single-

phase fluid. Additionally, the equivalent flowstream velocity should be replaced by the bulk velocity of

the single phase.

Summary of the E/CRC Procedure

In this section, the present method is presented in a step-by-step summary which demonstrates

how the method could be used to compute the penetration rates for an elbow or a tee geometry.

SEJm.

The first step in the procedure is to estimate the equivalent stagnation length, L. The semi-empirical

equivalent stagnation length depends on pipe geometry and is presented as a function of pipe diameter in

Figure 4 for tees and elbows.

Note that the results in the figure are normalized with respect to a

reference stagnation length Lo which is the equivalent stagnation length for a 1 pipe diameter. The

values for Lo have been tabulated for several geometries in Table 1.

In order to estimate L, one obtains L/L. from Figure 4, and compute L using Lo value selected

from Table 1. Also shown in Table 1 are values of the penetration factor Fp used in Step 4 as

discussed below.

-

The next step is to compute two dimensionless parameters, namely, the particle Reynolds number Reo,

Eq. (3), based on the equivalent flowstream velocity VO and particle diameter, and the dimensionless

parameter, 0, given by Eq. (6). For single-phase (gas or liquid) flow, one can assume that the

equivalent flowstream velocity is the same as the average flow velocity in the pipeline. For two-phase

flow, an ad hoc equation is used to calculate the equivalent liquid flowstream velocity based on the

superficial gas and liquid velocities.

When the superficial gas velocity is much larger than the superficial liquid velocity

flow is annular), the liquid film thickness becomes a fraction of the particle size

entrain the sand particles. Thus, the particles may be entrained in the gas phase and

be used.

(V~G >> V~L and

and can no longer

VO= V~~ should


7/24

Swt3.

Use @ and Re in Figure 5 or 6 to find the ratio of the particle impact velocity VL to the equivalent

flowstream velocity VO.

Figure 6 presents the relationship between @ and impact velocity in log-log

form tomakeit easier toreadvaluesof VL/ VO between O.01 and O.1. Alternatively, Eq. (7) can be

used to compute the VL / Vo ratio.

-.

Then, compute the characteristic impact velocity by

v~ = (v~/vo) x V.

(8)

Select particle sharpness factor, Fs, from Table 2, the penetration factor FP, from Table 1, and the

material factor, FM , from Table 3.

In order to obtain the elbow radius factor, Fr1~, a general model that incorporates a flow model,

particle tracking model, and erosion ratio model was used. This general model that is described in detail

by Wang et al. [12] was developed at the E/CRC. The model was verified for standard and long radius

elbows by showing excellent agreement with several sets of experimental data for a variety of conditions

provided by Bourgoyne [5], Tone and Greenwood [9], Eyler [13], and Bikbiaev [14]. Many simulations

of the general model were performed and various parameters effecting elbow erosion were studied.

Based on the analysis of particle motion in elbows, the following equation based on curve fitting of the

particle tracking results was recommended as a first-order approximation for elbow radius factor in long

radius elbow:

{[

Fr/D=ex

0.1 ~4w~65 +o.015p:25+o. 12

1 1

:c~~d

d;.3

(9)

where F~iDis the elbow radius factor for long radius elbows, c~~dis the r/D of a standard elbow (assumed

to be 1.5). Eq. (9) accounts for the elbow radius curvature effect in different carrier fluids and sand

particle size. It should be noted that this equation was based on the condition that the particle density is

approximately 165 lb/ft3.

-

Compute penetration rate by using Equation (2).

VERIFICATION OF E/CRC MODEL

The ability to predict erosion in multiphase flow is a new addition to the E/CRC prediction

model. Previously, the E/CRC erosion prediction model was verified for use with single-phase

flow[2, 15]. The ability of the model to account for a variety of parameters (particle diameter, fluid

density and viscosity, flow velocity, and particle shape) was verified through comparisons with

experimental data[ 16]. Another verification of the entire erosion prediction procedure for single-phase

flow in elbows (both standard and long radius) is shown here through experimental data. The

experimental data of Weiner and Tone, Tone and Greenwood, and Bourgoye is used for comparison.

Table 4 provides the test conditions along with the experimental and predicted results. Figure 7 is a

graphical representation of the predicted results versus the experimental results. This figure shows that

the present method provides accurate results over a broad range of erosion rates.


8/24

Data provided by Salama [3] and Bourgoyne [5] is also used to verify the present erosion

prediction model for multiphase flow. Table 5 provides the test conditions and the fluid and material

types. Figure 8 shows a summary of the results presented in Table 5, and these results indicate excellent

agreement between the experimental and predicted results over a broad range of erosion rates for

multiphase flow.

Another comparison of the present multiphase erosion prediction model is provided through

failure data obtained by Southwest Research Institute and Shell as reported by Jordan [7]. Since this is

field data and knowledge of the exact conditions is limited some assumptions had to be made in order to

apply the model. For this comparison, a sand size of 150 microns, pipe diameter of 2 inches, sand rate

of 0.06 ft3/day (10 lb/day), and a tolerable erosion rate of 5 mp y was selected. The density of the gas

and liquid at process conditions are 7.21 and 43.15 lb/ft3, respective y. The viscosity of the gas and

liquid are 0.0166 and 0.5369 cp, respectively. The fluid properties were suggested by Jordan [7]. The

material type selected for this comparison was AISI 1020. This information was used to predict the

threshold superficial gas velocity for a given superficial liquid velocity. Figure 9 shows the threshold

curve on the same plot as the failure data. The predicted threshold curve appears to capture the outline

of the shape that is created by the failure data. However, this is a first version of the erosion prediction

model for multiphase flow provided by E/CRC and plans are in place for further verification.

EFFECT OF PARAMETERS ON EROSION

The effect of several parameters such as flow velocity, pipe diameter, and sand size will be

shown for compressed methane and water for both single-phase and multiphase flow.

Single-Phase Flow

First, the effect of these parameters in single-phase flow is examined. The temperature of the

methane is 150 F and the pressure is 5000 psi; this corresponds to a density and viscosity of 8.28 lb/ft3

and 0.024 cp, respectively. The water also has a temperature of 150 W with a density of 61.7 lb/ft3 and a

viscosity of 0.432 cp. Unless varied to determine the effect of each parameter, the particle diameter is

150 microns and the diameter of the elbow is 4 inches with a standard radius of curvature (r/D = 1.5).

The flow velocity of the methane is 100 ft/s and the velocity of the water is 15 ft/s.

Figure 10 shows the effect of elbow diameter on the maximum penetration rate. For both the

compressed methane and water an increase in diameter decreases the severity of erosion. This occurs

since the impinging sand particles must pass through a larger stagnation region; therefore, there is more

time for the particles to decelerate. The effect of diameter is much greater for the water case. The

efficiency of transfer of momentum is larger for the water case, so the deceleration of the fluid in the

direction normal to the wall causes the particles to decelerate more efficiently.

Figure 11 examines the effect of sand size, and in both cases an increase in sand size results in

greater erosion. For the methane case, even the relatively small particles are able to pass through the

stagnation zone and impinge the elbow. However for the water case, the small particles travel with the

fluid and do not impinge the elbow wall. In water, the maximum penetration rate begins to decrease

rapidly with a decrease in particle size less than 150 microns (this is specific to the parameters elected

for this prediction).

The next parameter examined is flow velocity, which is shown on Figure 12. As expected, an

increase in flow velocity results in higher erosion rates. This figure displays similar behavior to Figure

11. The particles impinge resulting in erosion even at low velocities for the compressed methane, but

for the water case, the water is able to redirect the particles resulting in extremely low erosion for low

velocities. There is a sharp increase in penetration rate for the water case around 10 ftis; this appears to

be a threshold value for flow velocity for the water case.


9/24

For Figures 10 through 12, the effect of fluid properties has been investigated by showing the

behavior for both compressed methane and water.

Figure 13 examines the effect of fluid density for

compressed methane. These results are shown to display the effect of pressure on the penetration rate,

Table 6 shows the variation in the density and viscosity of methane with pressure using a temperature of

150~. Themaximum penetration rate decreases with anincrease intensity (increase in pressure). As

the methane becomes more dense it increases the efficiency of momentum transfer, and the particles

follow the flow more closely.

Multiphase Flow

Similar figures can also be created for erosion in multiphase flows in elbows. The values used

for these predictions are similar to those used for the single-phase cases. The primary difference is that

the compressed methane and water are now flowing together. The superficial liquid velocity for these

cases is set equal to 1 ft/s, and the superficial gas velocity is set equal to 25, 50, 100, and 150 ft/s.

Figure 14 examines the effect pipe diameter on erosion in the multiphase system. The behavior of this

family of curves is similar to the curve for compressed methane in Figure 10. In fact, the curve of

superficial gas velocity of 100 ftis of Figure 14 can be compared directly to the compressed methane

curve in Figure 10. The maximum penetration rates for the curve in Figure 14 are less than in Figure 10.

This demonstrates the effect of the presence of the liquid in the pipe.

As the superficial gas velocity

decreases, the effect of the liquid becomes more prominent and the penetration rates decrease,

Figure 15 explores the effect of sand size. Once again, the effect of sand size in the multiphase

flow is similar to the effect in single-phase flow.

As the sand size increases, the penetration rate also

increases.

The curve for a superficial gas velocity of 25 ft/s demonstrates that a threshold particle

diameter exists for this case at around 50 microns. This behavior was also seen for the water case in

Figure 11, except the threshold particle diameter was larger.

The effect of flow velocity in terms of the superficial gas velocity is shown in Figure 16. For

this figure, the superficial gas velocity was varied but the superficial liquid velocity was maintained at 1

ft/s, This figure shows that an increase in superficial gas velocity increases the maximum penetration

rate. This occurs for two reasons. Primarily, the higher velocity provides the particles with greater

initial momentum. Additionally at higher superficial velocities, the mixture properties for the flow

approach those of methane, which can not alter the trajectories of the particles as efficiently as water.

The effect of elbow diameter, sand size, and sand rate are also shown in Figures 17 through 19.

These figures show the threshold erosional velocity curve similar to that shown in Figure 9. In fact, the

fluid, particle, and material properties used to generate these figures are the same as for Figure 9. Figure

17 provides the theshold curve for elbow diameters of 1, 2,4, and 6 inches. Figures 10 and 14 showed a

decrease in erosion rate with increase in pipe diameter. Since the penetration rate decreases with

increase in diameter, the threshold superficial gas velocity increases with an increase in diameter for a

given liquid superficial velocity. Effectively, an increase in diameter shifts the threshold curve to the

right allowing operation at higher superficial gas velocities.

Figure 18 is similar to Figure 17 but demonstrates the effect of particle diameter. Threshold

curves are shown for particle diameters of 50, 150, and 300 microns.

Since smaller particles result in

less erosion, the threshold curves shift to the right for decreases in particle size. The effect of sand rate

is shown in Figure 19. Curves for sand rates of 1, 10, and 100 lb/day are shown. With less sand flowing

in the system, less erosion occurs. So for smaller sand rates, the threshold curve shifts to the right.

SUMMARY AND CONCLUSIONS

The effects of pipe diameter, sand size, flow velocity, and fluid properties on the severity of

erosion were examined for both single-phase and multiphase flows. The behavior or trend of the


10/24

amount of erosion as a function of these parameters was similar for both single-phase and multiphase

flows. In fact, the predictions made by splitting the multiphase flow into its single-phase components

should provide the bounds for the predictions made for the multiphase cases. This is true since at low

liquid rates the annular film becomes extremely thin and does not provide any resistance for impinging

particles. At the other extreme if the gas rate is small, the gas will have little effect on the particle

motion and the particles will behave in a similar manner to cases with only liquid present.

For this work, the erosion was only examined in elbows. It was shown that the erosion

prediction model must be able to capture the exchange of momentum between the fluid and the particles.

For elbows, much erosion occurs when the exchange of momentum between the fluid and the particles is

low. This is a result of the inability of the fluid to redirect the particles as they travel through the bend;

therefore, the particles travel in a relatively straight path and impinge the pipe wall. Any factor that

increases the efficiency of the exchange in momentum will decrease the erosion rate in elbows. This

includes decreasing the particle size or increasing the fluid density or viscosity. Another way to

decrease the erosion rate is to increase the time allowed for the transfer of momentum. This is

accomplished by increasing the diameter of the pipe or by using a long radius elbow. Finally, if the

initial momentum of the particles is less when entering the elbow, then there is less momentum that

needs to be overcome by the fluid. This explains why the flow velocity has such a tremendous effect on

the erosion rate.

ACKNOWLEDGEMENTS

The authors would like to thank the member companies of the Erosion/Corrosion Research

Center for their support and guidance.

1.

2.

3.

4.

5.

6.

7.

REFERENCES

API Recommended Practice for Design and Installation of Offshore Production Platfomn Piping

Systems, API RP 14E, American Petroleum Institute, Third Edition, Washington D.C.,

December 1981.

Shirazi, S.A., McLaury, B.S., Shadley, J.R., and Rybicki, E.F., Generalization of the API RP

14E Guideline for Erosive Services,

ournal of Petrolewn Technology

(Distinguished Author

Series), August 1995, pp. 693-698.

Salama, M.M., An Alternative to API 14E Erosional Velocity Limits for Sand Laden Fluids,

presented at the 1998 Offshore Technology Conference, Houston, OTC 8898, 1998.

Salama, M.M. and Venkatesh, E.S.,

Evaluation of Erosional Velocity Limitations in Offshore

Gas Wells, 15th Annual OTC, Houston, Texas, May 2-5, OTC Number 4485, 1983.

Bourgoyne, A.T., Jr.,

Experimental Study of Erosion in Diverter Systems Due to Sand

Production, paper presented at the 1989 SPE/IADC Drilling Conference, New Orleans,

SPIYIADC 18716, 1989.

Svedeman, S.J. and Arnold, K.E., Criteria for Sizing Multiphase Flow Lines for

Erosive/Corrosive Service, paper presented at the 1993 SPE Conference, Houston, SPE 26569.

Jordan, K., Erosion in Multiphase Production of Oil& Gas, Corrosion 98, Paper No. 58,

NACE International Annual Conference, San Antonio, April 1998.


11/24

8.

9.

10.

11.

12.

13.

14.

15.

16.

Weiner, P.D. and Tone, G.C., Detection and Prevention of Sand Erosion of Production

Equipment, API OSAPER Project No. 2, American Petroleum Institute, Texas A&M Research

Foundation, March 1976.

Tone, G.C. and Greenwood, D.R., Design of Fittings to Reduce Wear Caused by Sand

Erosion, API OSAPER Project No. 6, American Petroleum Institute, Texas A&M Research

Foundation, May 1977.

Shirazi, S.A., Shadley, J.R., McLaury, B.S., and Rybicki, E.F., A Procedure to Predict Solid

Particle Erosion in Elbows and Tees, ASME PVP Vol. 259, Codes and Standards in a Global

Environment, 1993, pp. 159-167.

McLaury, B.S., A Model to Predict Solid Particle Erosion in Oilfield Geometries, M.S.

Thesis, The University of Tulsa, 1993.

Wang, J. and Shirazi, S.A., Shadley, J.R., and Rybicki, E.F.,

Application of Flow Modeling and

Particle Tracking to Predict Sand Erosion Rates in Elbows, in ASME FED Vol. 236, July 1996,

pp. 725-734.

Eyler, R.L., Design and Analysis of a Pneumatic Flow Loop, M.S. Thesis, West Virginia

University, 1987.

Bikbiaev, K.A., Krasnov, V.I., Maksimenko, M.I. Berezin, V.L., Zhilinskii, I.B., Main Factors

Affecting Gas Abrasive Wear of Elbows in Pneumatic Conveying Pipes, Chemical Petroleum

Engineering, Vol. 8, 1972, pp. 465-466.

McLaury, B.S., Wang, J., Shirazi, S.A, Shadley, J.R., and Rybicki, E.F., Solid Particle Erosion

in Long Radius Elbows and Straight Pipe, paper 38842 presented at 1997 SPE Annual

Technical Conference and Exhibition, San Antonio, October 5-8.

McLaury, B.S., Shirazi, S.A., Shadley, J.R., and Rybicki, E.F., Parameters Affecting Flow

Accelerated Erosion and Erosion-Corrosion, Corrosion 95, Paper No. 120, NACE International

Annual Conference, Orlando, April 1995.


12/24

TABLE 1

SHAPE AND PENETRATION FACTORS

Lo

FP (for steel)

SHAPE mm

Inch mm/kg

in/lb

90 Elbow

30

1.18 206

3.68

Tee 27 1.06 206 3.68

Sharp Corners, Angular

1.0

Semi-Rounded, Rounded Corners

0.53

Rounded. %herical Glass Beads

0.20

TABLE 3

MATERIAL PROPERTIES AND EROSION RATIO COEFFICIENTS

FOR NON-CARBON STEELS

Material

Type

Yield

Strength

Ksi

Tensile

Strength

Ksi

Hardness

Brinell

B

Material

Factor*

FMX106

0.833++

Material

Factor* *

FMX107

1.066

10

0.0

99.5

1018

l- -

1

77

105

93

190

180

1.267

1.089

1.622

1.394

1.009

4

35

37

111 217

0.788

85

91

183

160

0.918

0.877

1.175

1.123

*

For VL in rnls

** For VL in ft/s

++

For carbon steel materials, FM= 1.95 x 10-5/B-059for VL in m/s) where B is the Brinell

hardness factor


13/24

COMPARISON OF EXPERIMENTAL DATA WITH PREDICTIONS

FOR SINGLE-PHASE FLOW

Flow

Sand Elbow

Bend R

Measured

Pred.

Note Velocity Size Diameter Erosion

Erosion

(m/s) (microns)

(mm) Diameter

mrnlkg

mmikg

1 9.15 300 52.5 1.5 2.14E-03

2.66E-02

1

12.2

300

52.5 1.5 3.81E-03

4.38E-02

1 15.25

300

52.5 1.5 7.52E-03

6.45E-03

1 18.3 300 52.5 1.5 9.16E-03

8.85E-O?

1

21.35

300

52.5 1.5 1.22E-02

1.16E-02

1

24.4

300 52.5 1.5 1.62E-02

1.46E-02

1 27.45

300

52.5 1.5 1.80E-02

1.79E-02

1 30.5 300

52.5 1.5 2.04E-02

2.14E-02

2

21.35

300

52.5 1.5 4.44E-03

1.16E-02

2 30.5 300 52.5 1.5 1.56E-02 2.14E-02

3

11.49

350

52.5 3 1.18E-06

2.12E-06

4 116

350

52.5 2.125 1.64E-01

1.72E-01

4 141 350 52.5

2.875 1.75E-01

2.18E-01

4

107 350 52.5

2.875 1.21E-01

1.35E-01

4

141

350

52.5 2.875 1.74E-01

2.18E-01

4

107 350 52.5

2.875 1.36E-01

1.35E-01

4

111

350

52.5 3.25 1.12E-01

1.37E-01

4

141

350

52.5 3.25 2.07E-01

2.07E-01

4 141 350 52.5 3.25 1.91E-01 2.07E-01

4

148

350

52.5 3.25 2.09E-01

2.25E-01

4 111 350 52.5

4.5 5.26E-02

1.15E-01

Notes:

1) Data from Weiner and Tolle8, Fluid is air at standard conditions, Material is assumed to be

carbon steel with a Brinell hardness of 109.

2) Data from Weiner and Tolle8, Fluid is air at standard conditions, Material is assumed to be

carbon steel with a Brinell hardness of 109, High sand rate

3) Data from Bourgoyne5,

Fluid is drilling mud, Material is assumed to be carbon steel with a

Brinell hardness of 140.

4) Data from Bourgoyne5, Fluid is air at standard conditions, Material is assumed to be carbon steel

with a Brinell hardness of 140.


14/24

TABLE 5

COMPARISON OF EXPERIMENTAL DATA WITH PREDICTIONS

FOR MULTIPHASE FLOW

Superficial

Superficial

Sand Elbow

Bend R

Measured

Pred.

Note

Gas Vel.

Liquid Vel.

Size Diameter Erosion

Erosion

(In/s) (m/s)

(microns) (mm)

Diameter mg

mm/kg

1 30 1 150 49 5 5.52E-04 7.22E-04

1 30 0.5 150

49 5 2.46E-03 1.27E-03

1 20

5.8 150

49 1.5 5. 19E-05 1.35E-04

1 20

3.1 150

49

1.5 6.93E-05 1.58E-04

1 15

5 150

49 5 6.38E-05 3.39E-05

1

15

1

150 49 5 1.47E-04 9.63E-05

1 10

5 150 49

5 1.35E-05 1.42E-05

1 10

0.7 150 49

5 7.OIE-05 4. 13E-05

1 8

0.2 150 49 1.5 1.23E-04 1.49E-04

1 3.5 4

150 49 5 4.60E-06 1.32E-06

2 9 6.2 250 26.5 5 1.80E-04 2.52E-04

2 14.4 1.5

250 26.5 5 2.30E-04 4.99E-04

2

14.6

1.5 250

26.5 5 4.20E-04 5. 13E-04

2 34 2.1

250 26,5 5 2.83E-03 2.76E-03

2 35 1

250 26.5 5 6.56E-03 4.44E-03

2 34.3 0.5 250

26.5 5 7.20E-03 5.87E-03

2 37 0.7 250 26.5 5 8.03E-03 5.98E-03

2 38.5 0.5 250 26.5 5 8.03E-03 7.52E-03

2

44

1.5 250 26.5 5 1.05E-02 6.00E-03

2 51 0.6 250 26.5 5 1.34E-02 1.27E-02

2 52

0.7 250 26.5 5 1.33E-02 1.25E-02

3

86 0.53

350 52.5

2.625 1.27E-01 9.57E-02

3

92

0.53 350 52.5

2.625 1.21E-01 1.08E-01

3 89 0.12 350 52.5

2.625 1.08E-01 1.06E-01

3

84 0.53 350

52.5

2.625 9.34E-02 9.19E-02

3

72 0.53 350 52.5 3,25 5.37E-02 6.46E-02

3

84 0.12 350 52.5 3.25 7.51E-02 8.46E-02

3

92 0.12 350

52.5

3.25 9.94E-02 9.87E-02

3

107

0.53 350 52.5

3.25 1.05E-01 1.28E-01

Notes:

1)

2)

3)

Data from Salama3, Fluid is air and water at 2 bar, Material is carbon steel with a Brinell hardness

of 160.

Data from Salama3, Fluid is nitrogen and water at 7 bar, Material is Duplex stainless steel.

Data from Bourgoyne5, Fluid is air and water at standard conditions, Material is assumed to be

carbon steel with a Brinell hardness of 140.


15/24

TABLE 6

EFFECT OF PRESSURE ON DENSITY

AND VISCOSITY

Pressure

I Density I Viscosity

(psi) (lblft) (Cp)

14.7 0.036

0.0124

50

\ 0.122 i 0.0124

100 0.245

0.0124

250 0.613 0.0126

500 1.25 0.0129

700

1.77 0.0134

1000

2.58 0.0139

2500

6.81 0.0191

5000 12.0 0.0239

7000

14.7 0.0318

10000 17.5

0.0350

Figure 1. Sample Particle Trajectories in Air.


16/24

Figure 2. Sample Particle Trajectories in Water.

Stagnation

Zone

Tee

Stagnation

Zone

Elbow

\

/

Equivalent Stagnation Length

*---

k

Particle initial

Position

n

Linear Fluid Velocity

E

Figure 3. Concept of Equivalent Stagnation Length.


17/24

3,5

3.0

2.5

2.0

1.5

1,0

0.5

0,0

Tee --------------- - -----------

- L

-/- -- -. . . . .

~ = 1- 1.27 Tan-1(1,01 D-189)+D0129 ----

~-- - ----

Lo=l,18jn

-- - - - - - - - --- -

... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

---

Tee Elbow Curve Fit Tee Curve Fit Elbow

Figure 4.

23456789

10

11 12

Inner Diameter (inches)

Stagnation Length versus PipeDiameter forElbow.

0

09

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.0

Km

I I

1E-2

lE-1

lE+O

lE+l

[H

Pm

@=

dP pP

1E+2 IE+3

Figure 5. Effect of Different Factors on Particle Impact Velocity.


18/24

1.00

0.10

0.01

i- . li

eO= 1

lE-2 lE-1

lE+O lE+l 1E+2

1E+3

[H

Pm

m=

dP pP

Figure 6. Effect of Different Factors on Particle Impact

Velocity (log-log scale).

lE+O

lE-1

lE-2

lE-3

IE-4

1E-5

Perfect Agreement

IE-6 ~ ~

, , 1,, (,

n

lE-6

IE-5 1E-4 IE-3 lE-2 lE-1 lE+O

Measured Eroion Rate (mm/kg)

Figure 7. Comparison of Experimental Data with Predictions for Single-Phase Flow.


19/24

lE+O

IE-I

IE-2

IE-3

IE-4

IE-5

lE-6

Perfect Agreement

. .0 . . . . . . . . . . . . . . . . .

a=

.................

8

~l,,lrl

/

I

D

lE-6 IE-5 IE-4

lE-3 lE-2 IE-I lE+O

Measured Eroion Rate (mm/kg)

Figure 8. Comparison of Experimental Data with Predictions for Mulitphase Flow.

1E+2 ~ - -- -------- ~~~--- -- -

Threshold Erosional

lE+l

Documents

99034 How Operating and Environmental Conditions Affect Erosion (51300-99034-Sg) (1)