Note: Descriptions are shown in the official language in which they were submitted.
~45~
ICR 702
IMRE~OVEO USE OF FLOW IMPROVERS
This invention relates to the reduction of
frictional pressure loss encountered in the transfer of
liqulds by fluid flow through the use of a flow lmprovin~
or drag reducing substance. More specifically~ this invention
relates to an improved method of injecting such substances
into conduits transferring liquid~ in order to reduce turbulent
flow and to increase the effectiveness of ~he flow improver.
It is well known that whe~ a fluid is pumped or
otherwise caused to flow throuyh a conduit under pressure,
energy is expended as a result o friction, and a rictional
pressure los~ xesults Such frictional pressure losse~ are
particularly large under turbulent flow conditions/ for
example when the ve10c1ty of a liquid passing through a
conduit is such that turbulent flow results~ a large frictional
pressure loss is encountered. This problem of high rictional
pressure 109s or pressure drop in the Elow of liquids through
a conduit is commonly e~countered in industrial operati~ns
wherein hydrocarbon liquids are conveyed through pipelines
at high fluid velocities.
In order *o comperlsate for the frictional pressure
loss encountexed from the t~arbulent flow o such hydrocarbon
liquidsg considerable energy, generally in the orm of
pumping horsepower, must be expended. Thus, reduction of
the frictional pressure loss asad the 10w o such hydrocarbon
2S liquids brings about an ~dvantageous reduction of horsepower
requirements or alternatively an increased flow rate of a
hydrocarbon liquids under the same pumping conditions.
The art ls aware of ~hese problerns as is represented
by U.S0 Patent 3~692,676, which discloses a method of reducing
friction loss when fluids a pumped through pipelines by
adding a high molecular weight poly-alpha-olefin. This
patent taught th2t such polymers reduce friction in the
flowing liquid by reducing turbulence. A me~hod of measuring
performance of these polymers was defined as
~. .
.
~ ~2~ 9~
Drag reduction = ~pressure drop preSsure drop)
diesel polymer x 100
.
pressure drop diesel oil
U.S Patents 3,~48~266 and 3,75~,406 relate to
methods and compo~itions for reducing frictional pressure
loss in hydrocarbon flows. Reduction in pressure loss was
accomplished by adding a homopolymer SUC}I as a polyisobutyl~ne
having an intrinsic viscosity between 2 and 10 deciliters
per gram to allow a low total concentration of polymer to
hydrocarbon of about 2.5 pounds ~er 1~000 gallons, respectively.
U.S~ Patent 3,351~079 uses drag reducers comprising
ethylene~ propylene and butylene terpolymers having a molecular
weight up to about 1 million ana useful at concentrations
of from 0.01 to about 0.3 weight percent.
U.S. Patent 3,493,000 discloses high molecular
weight cis-polyisoprene, cls-polybutadiene and ethylene-
propylene copolymers used at concentrations of about 40 paxt~per million. U.S. 3,559,664 relates to the addition of
ethylen~ propylene ropolymers to hydrocarbon liquids at level~
of about 300 parts per million by weight.
These references, while not exhaustive of the art
in the area, genel^ally represent such art. ~hese references
all deal with total concentration of drag reducing ma~erial
in polymer and attri~u~e various levels of drag reduction
to such to~al concentration of polymersO
Drag reducing polymers currently in use are
reputed to be useful at low levels, yet often in practice
require hlyher levels in order to sufficiently reduce turbulent
flow to a desirable extent. In view of the cost of these
polym~rs, as well as the possible contamination effect if
used in a finished product pipeline, .it would be greatly
advantageous to provide a method whereby such polymers are
effective at lower concentrations, or in the alternative,
provide much higher levels of drag reduction at equivalent
concentrations in the flowing hydrocarhon fluid.
I hava now discovered a method for reducing riction
loss in hydrocarbon fluids flowing ~hrough conduits comprising
adding to said hydrocarhon fluid an ultrahigh-molecular-weight
_3~ ~5~9~
polymer having an inherent viscosity o at lPast 11.0
deciliters per ~ram, said high molecular weight polymer
dissolved or suspend d in a hydrocarbon diluen-t, wherein the
polymer is present in the diluent at a concentration of
less than 10 pexcent by weight, based on the total weight
of the diluen~. and the ultrahigh-moleculctr-weight polymer, and
is placed into t~te flowing hydrocarbon 1uid such ~hat the
total polymer concentration in the flowing hydrocarbon fl-lid
ranges from about 0.01 to about 500 parts per million by
volume.
It is necessary in the present invention that the
ultrahigh-molecular-weight polymer have a inherent viscosity
of at least 11.0 deciliters per gram as measured in a low
polynuclear aromatic solvent ~LPA) at a temperature of from
about 77 ~o about 78F, at a shear rate o 300 reciprocal
seconds, and a~ a concentration of 0.10 g/100 ml.
Thus, in the process of the present invention the
drag re~ucing mixture wiil contain less than 10 weight
percent o an ultrahigh molecular-weight poly- ~ -olefin.
~0 These poly- ~ ~oleins can be homopolymers, copolymers,
or terpolymers prepared by con~acting ~ olsins contai.ning
from 2 to 30 carbon atoms with a polymerization catalyst.
The catalyst and method of preparing these polymers is not
critical other than the .inherent vicosities of the resulting
polymers must be greater than 11.0 deciliters per gram at a
shear rate o 300 sec 1, and that these materials be substantial.l~
soluble in the hydrocarbon liquid in o.rder to reduce turbulent
flow. It is preerred in the practice of the present invention
to have a polyltter content of ~rom about 2 to about 6 weight
percent at an inherent viscosity o~ from abou-t 12.0 to about
15.0 deciliters per grarn for maximum efectiveness.
The drag reducing polymer, once prepared, is placed
in a suitable caxrier substance. These materials are usually
inactive hydrocarbon solventsu ~epresenta~ive but non-
exhaustive examples of such materials are straight chainaliphatic compounds or branched hydrocarbons such as ethane,
:~%~4~997
propane, isobutane, bu~ane, pentane, hexalle, heptane, or
isooctane, octane. Also useful are alicyclic hydrocarbons
such as cyclohexane, methylcyclopentane, and tetralene.
Aroma~ic hydrocarbons can also be used as represented by
benz~ne, toluene, and xylene. Mixtures and analogues of
these compounds are also useful as represented by MOLEX
(~rademar~ of Universal Oil Products) raffinate, which is a
complex mixture of branched aliphatic, cyclic aliphatic,
aromatic and trace amounts of unbranched aliphatic hydrocar~ons.
Likewise useful are low polynuclear aromatic sol~ents~
Further, the hydrocarbon diluent can be an ~ olefin.
I-t should be noted in ~he context of the present
invention that when the ~ -olefin drag reducing pol~mer
contains significant amounts of lower olefins such as ethylene
and butene, a small ~ut significant amount of hydrocarbon~
insoluble material may be producedO This hydrocarbon-
insoluble material ~ill be apparent in the diluted ~ixture
prepared for injection into the 10wing hydrocarbon liquid,
but such materials will dis~olve in the much larger volumes
of the flowing hydrocarbon fluid. Therefore? in the context
of the present invention, these materia~s may be dissolved
or suspendad or a combination of these physical states when
injected in~o ~he pipeline. In either case, the term "suspended"
as used in this specifiration and claims will indicate that
the polymer can be totally or par~ially dissolved, with any
undissolved polymer suspended in ~he hydrocarbon medium.
In any e~ent, once in ~his s~ate, the material is
injected into a conduit containing flowing hydrocarbons.
In contxas~ to ma~erials which are produced a~ lower inherent
viscosities, or those having hi~h inherent viscosities which
are injected at concen~rations of 10% by weight or more, the
instant inven~ion shows a surprising increase in drag raduction
effectiveness.
The hydrocarbon liquids in which the additive o~ this
invention is eEfective include oleayinous or petroliferous
liquids as well as emulsions, suspensions, and dispersions
thereof. For example crude oil, refined petroleum product~
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such as kerosene, pale oil, diesel oll, fuel oil, asphalt,
etc., water-in-oil emulslons, surfactan~s and the like.
Where ~he hydrocar~on liquid is a hydraulic fracturlng fluid,
it may also contain solid particulate matter such as sand
as a propping agent~ a fluid loss control additive and other
materials commonly added to fracturing fluidso
In the preferred embodimen~ of ~he present invention
the drag reducing polymer is formed rom olefins containing
from 5 to 20 carbon atoms which optionally can contain from
about 0.01 to about 20% by weight of ethylene or propylene~
and up to 50% butene-l comonomer. Poly~ers so produced will
have an inherent viscosity of from about 11.5 to about 15.0
and will be placed in the flowing hydrocarbon fluid at a
concentration o~ from about 0.1 to about 3.5% by weight of
the diluent or suspending agent.
The invention is more concretely described with
reference to the ~xamples below wherein all parts and
percentages are hy weight unless otherwise specified. The
examples are provided to illustrate the present invention
and not t~ limit it.
Example 1
A catalyst slurry was prepared by mixing under an
inert atmosphere of dry argon, 0.104 grams of TiC13.A~ (Type
lo 1 catalyst frorn Stauffer Chemical Company), 0.36 milliliters
(ml) of dried and deoxygenated Molex raffinate ~obtained
from Conoco Chemicals; Molex is a trademark of Universal Oil
Products)O Thls mixture was stirred for approximately 2
minutes in a dry box. ~i-n-~utylether (60 microliters, dried
and degassed) was added. The mixture was then stirred
vlgorously for 15 minutes in a small vial equipped with a
microstir-bar. This mixture was then transferred to a gas-
tight syringe. The vial was washed with 10 milliliters of
iow polynuclear aromatic solvent (~A) and the wash material
added to the same syringe.
Example 2
The catalyst of example 1 was used in the
preparation of a drag reducin~ polymer.
~6~ 5~7
A mixture of 189 ml of dried and deoxygenated low
polynuclear aromatic solvent, 3.6 ml of diethylaluminum
chloride ~EAC, purchased from Texas Al~yls as a 10% solution
in heptane~ and 41 ml of dried and degassed decene-1 was
placed into a clean, dry l-~uar~ bottle under an atmosphere
of dry argon. Tha mixture was cooled ~o -7~C and agitated
in a sha];er bath at 500 revolutions per minute (rpm).
Tha catalyst mixture described in example 1 was
added to initiate the polymerization. The mixture became
thick. After 3 hours the bottle was removed from the
temperature bath. A thermometer was placed into the
center of the viscous material, recording a temperature of
6C. The pol~nerization was, therefore, semi-adiabatic due
to the insulation effect o the poly(decene-l~ mixture.
Approximately 1.7 ml of methanol was added to
deactivate the catalyst. The polymer mixture was stabilized
with aboutO.01 weight percent butylated hydroxy toluene
(BHT) as an antioxidantO The weight of polymer produced was
determined by pouring 84.9 grams o the deactivated polymsr
mix~ure in~o 400 ml of isopropyl alcohol with sufficient
mixing to precipitate a viscous material containing
poly~decene-l). The substance was washed with an additional
400 ml of isopropyl alcohol, filt~red and washed with 400 m~
of metha~ol -to remove catalyst residuP. The poly(decene-l)
was collec~ed by vacuum filtration and dried in a vacuum
oven overnigh~ t~ produce 4.2075 grams of polymerO The
polymer solution thus co~tained 4.95% poly(decene~
This polymer solution was used to determine the inherent
viscosity of dissolved polymer. The inherent viscosity
30 ~Fth~was determined in LPA solvent at 77.5 + 0.5F using a
Cannon-Ubbelohde four bulb shear dilution ~iscometer at a
shear rate of 300 reciprocal seconds.
Example 3
A calibrated Cannon-Ubbelohde Four-~ulb Shear
Dilu~ion Viscom~er is used ~o measure the flow time for both
solvent and polymer samples. Inherent viscosity values are
calcula~ed for each of the four bulbs. These calculated
_7~ S~7
values are plotted as a function oE shear rate, and the
resulting plot is used to obtain the irlherent viscosity at
~a shear ratP of 300 sec 1
Approximately 0.5 gm of the drag reducer material
(for example~ a solution contai~incJ 4.95 weight percent
poly~decene-l) in LPA solvent as obtained in Example 2) is
p7aced into a clean, dry Exlenmeyer flask equipped with a
ground glass stopper. LPA solvent is added to generate a
concentration of 0.10 gm polymer/100 ml. The stoppered flask
is placed on a ma~netic stirrer and stirred until dissolution
is completedO q~he stirrincJ speed is set to minimize shear
degradation of the pol~mer. Shear degradation will produce
an anomalously low inherent viscosity value.
LPA solvent ~lOml~ is placed into the viscometer,
and the viscometer is immersed into a water bath. The system
is allowed to equilibrate for at least 20 minutes.
The e~flux time for each ~ulb is determined
according to the proceduxa supplied with the viscometer.
The viscometer is cleaned and dried by 1ushin~ with
hexane, then with acetone. The efflux ~ime or the ~ample
solution i5 measured following the same procedure as used
for the LPA solvent~
The inherent visco~ity fQr reach bulb is calculated
using the following equationsO
RelatiVe Viscosity (~ rel) = tSoln./tsolven~
t here,
soln. = efflux time o the solution
tsolvent = eff 1UY~ time of the solvent.
Inherent Vis~ositY ~ nh~ a ln~rel/C r
30 C = concentration in gjdl
The shear rate for each bulb is calculated using the
relationship. shear Rate (~) ~ K/tSoln where,
K - shear rate constant.
~ p~ot of shear rate versus inherent visco~ity
is made. The inherent viscosity at a shear rat~ of 300 sec 1
is then determined~
.
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Examples 4 through 8
The instant inv2ntion was demonstrated in a pipeline.
A polymer solu~ion containing 10.8% poly(decene~1) with an
inherent viscosity of 11.8 dlfgm at a ~hear rate of 300 sec 1
was made using a procedure ~imilar ~o Examples 1 and 2.
5 Conditions and quantities were adjusted to yield 10~8%
polymer. Approximately 12 weight percent de~ene-l was charged
into th~ pol~meriza~ion vesselO The polymerization was
terminé~ with alcohol. The weight percent polym~r content
was de~ermined b~ the proc~dure set forth in Example 2.
The inherent viscosity of the dissolved polymer was
determined by the four bulb viscometer procedure as dascribed
in Example 3.
The 10.8% polymer solution was diluted with LPA to
yield a 5.95~ and a 0.94~ polymer solution. A Pfaudler
mixer was used to conduct the dilution. The agitator
was set at a low mixing speed to prevent shear deterioration
of the polymer.
The effectiveness of the drag-reducing materials
so produced was te~ted in the Kingfisher pipeline in Oklahoma.
~0 This crude oil pipeline runs from the Kingfisher pump station
near Hennessey, Olclahoma, to a ~ank storage area in Orlando,
Oklahoma. The inner diameter of the pipeline is 8.24 inches
and the total length of 28.3 miles. Drag reducer per~rmance
was evaluated in the first 7.4 mile section of the pipeline
from the Kingisher pump station. Dual-piston positive
clisplacemen~ pumps were used to maintain pipeline flow. The
drag reducers wexe injected direc~ly into the 8.~ inch line
downstream of the pump at Kingisher. The crude oil fl~w
rate during the tests was approximately 1,272 barrels per
hour (BPH), which corxesponds to a pipeline flow velocity of
5.3 ft/sec. As a control, a poly~decene-l) solution was
prepared containing 6.10% polymer having an inherent viscosity
o~ 9.5 dl~ at a shear rate of 300 sec 1
Test results are set forth in Table 1, where
examples 4 and 8 are control experiments, and ~xamples 5l 6
and 7 demonstrate the prasent invention.
.~
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Table 1
Weight Inherent Polymer Percent
Percen~ Viscosity 1 In~ected into Dra~
Example Polymer (dl/4 ~ n ~ ~eductic~
4 10.8 ~1.9 4.0 33
5.95 11.9 3.1 36
6 0.9~ ~1.9 3~2 39
7 0.9~ 11.9 0.8~ 1~
8 ~.10 9~5 3.1 20
Control example 4 shows that injection of a 10.8 wt~
11.9 inherent viscosity material into the pipeline at
approximately 4.0 ppm level o polymer content resulted
in 33~ drag reduction in the 7.4-mile section of pipeline.
An 11.9 inherent viscosity material containing 5.95 wt~ polymer
and 0. ~4 wt% polymer resulted in much hetter drag reduction
perormance. Lesæ polymer was required ~o yield grea~er
drag reduction. Surprisingly, the 0.94 wt% material
~exsample 6 j was more effecti~e than the 5.95 wt~ material
(example 5).
Examples 9 through 11
A tes~ was carried out in the ~rent pipeline
system in the North Sea connecting Conoco's Murchison
Platform and Shéll ' s Dunlin-~ platform. This connecting
lS pipeling ~egment is 14.7$~inches in diameter ~ID) and 11~74
miles in length and carries crude oil production from ~he
Murchison plat~orm. The Murchison crude pxoperties are-
API Gravity 3a . 5
Vlsco~ity, Cs 11.3 - 12.4 at 32F
5.4 - 5.8 at /0F
3.5 - 3.7 at 100F
In the5e test~l three materials were employed.
Comparative example 9 used a 10.8 wt~ poly(decene-l) solution
with an inherent viscosity of 11.9 dl/~n at a shear rate of
300 sec . ~xample 10 used a 10.~ wt~ material diluted to
approxima~ely 3.0 wt3 polymer content in LPA solven~.
~gain, thc dilution was conduc~ed in a Pfaudler mixer under
conditions which prevented shear degradation of the polymer.
-~o~
The inherent ~iscosity o:E the polymer was 11.9 dl/ym at a
~hear rate o 300 sec 1 Example 11 used a drag reducer
which contained approximately 10.5 w~% poly(decene-l~ wi~h
an inherent vi~cosity of 9. 5 dl/gm at ~ shear rate of 300
5 sec 1,
Compaxative example 11 was al50 conducted using A
dra~ reducer with an inherent viscosity o 90S at a polymer
content of 10 5% prior to in~ecting i~to the pipeline. Test
results are presented in Table 2
Table 2
Weigh~ Inherent Polymer Pexcent Calculated
Percent VisoDsity Injected into Drag Flow
9 10.8 1109 10 19 12
10 3.0 llo~ :~0 50 ~
111~.5 9.5 22 17 11
1~' The test results clearly show th~t performa~ce
of the 11 o ~ inhieXE3ilt Vi5C05i ty materizl is greatly enhanced
by dilution prior to injection into the pipeline. When
comparing Example 9 wi~h Example 10, a flow increase of abou~
~6% was ob~ained usinc3 the diluted material (10~, compared
to only a 12~ incxea3e in flow using the concentr~ed dra~
reducer (9). Comparative examples 9 and 11 showed only 12%
and 11% flow in~rease~ respectively. There was a great deal
o~ difference in inherent viscosities.
While theoretical in nature/ and I do not wish to
2~ be bound thereby, it is believed ~hat the higher weight con-
cen~ration polymer sol~ltions require lvnyer tim2s to go into
solution Wi th the ~rude oil. The higher inherent vi~cosity
ma~erial, however, provides for bet~er dray reduction if the
material is dissslved in the crude oil. This hypothesis is
supported by t'he data as eviclenced by comparing example 5
~ith example 8.
Wl:ile certain embodiments and deta.tls have ~een
shown for the purpl~se c~f illus~ratiny this inverltivn, it
t`7ill 3:e appar~nt to those ~killed in this ~rt ~hat various
ch~nges ancl modification~ may ~e masle herein without d~par~ing
5 from the Spi:rlt or ~cope of the lnv~ntion,
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