Note: Descriptions are shown in the official language in which they were submitted.
3S9~44
In many oil wells, deposits of paraffin, wax,
asphaltic and bituminous organic solids and similar materials
accumulate in objectionable quantities on the face of the pro-
ducing formation, on the screen or liner, or in the pump, the
casing or the tubing of the well. Such deposits operate to
decrease materially the productivity of the wells in which they
occur. Similarly, deposits of the same character are found in
some oil flow lines and oil pipelines, where they effectively
reduce the capacity of the pipes, sometimes to the point
where little or no fluid can be passed through such conduits
in the normal manner of operation.
The purpose of removing such deposits is obvious.
In some areas, wells decline in productivity at a more or less
-- 1 -- ~
,`' ~
` ~L0597~4
rapid rate, because of deposition of such deposits on the
face o the producing formation. In some cases, the decline
is sufficiently rapid that the wells must be serviced in some
~anner or other at a frequency ranging from several days to
several weeks. In some instances, the deposition is so slow
that servicing at long intervals is sufficient to maintain
the well at a satisfactory level of productivity. The same
is txue of the various conduits through which the oil travels
from the well to the refinery; such as for example through
tank batteries, tanX farms~ pipes, etc.; and perlodic
servicing of such elements is also required. The capacity
of a conduit of circular cross-section is reduced greatly by
suCh deposits, usually well beyond the reduc~ion expected
from the ratio of effective cross-sectional areas of the
- conduit and the fouled conduit. Where organic deposits of
the present type occur on ormation walls, well productivity
~ay fall substantially to zeroJ especially in lo~-pressure
.
ieldsO Pipe capacities are frequently reduçed to a small
:
fraction of their capacities when clean. Ultimately such
pipes may be found completely clogg~d by such deposits. In
the case- of pipelines, for exampleJ the operator may find
himself burdened with the cost of a 6" or 8" line, yet
benefiting from a capacity equal to th~ o a 3" or 4" line.
Tank capacities are also reduced by such deposits.
The process which constitutes the present invention
consists in subjecting such clogging organic deposits of wax~
1~5~7~9L
~araff~n~ asp~altlc or bituminous s~lbstances and the like,
to the action of hot a~ueous solution of a chemical reagent
o the character described below) to the end that such
deposits are removed from the surfaces to whicll they were
originally adherent. B~ means of the process, t'ne productivit~
;of wells is restored as is the capacity ol flo~ linesg pipe-
lines J traps9 tanks, pumps, and other equipment, thr~gh
which such oil travels from formation to refinery.
;It will be o~vious that, if the first minute deposit
of such organic materials is subjected to hot aqueous
solution, and if such application is practised continuously
or periodically with sufficient frequency, the operation is
a preventive or inhibitive process rather than a corrective
process. In addition, it should be noted that our process
has a more real claim to acting as a preventive, in that
suxfaces effectively cleaned by its application tend to resist
x~newed deposition of such materials, and to xemain clean and
operative for Ionger periods than if the process had not been
appliea. m erefore, the present pro~ess is both a preventive
and a corrective oneO It may obviously be applied in eithex
sense, and achieve the same ultimate goal, the improvement of
efficiency of operation of wells and equipment. Thus, when
we have used the word "removing," it should be clearly undex-
stood to include the prevention of organic deposits of the
present kind.
Sometimes the deposit is located at some higher ox
l~wer level in the tubing. For exampleJ passage of the well
,
-3
~sg74~
fiuids past a point in the well which lies opposite a
water sand may produce a deposit at that point, beca~se
suc'n a ~7ater sand co~only represents a point of cooling.
In some instances~ it is possible to introduce the hot
solution into the tubing at the well head by unsc~ewing
; the stuffing box. (Usually the tubing does not stand
entirely full of fluid because of slight leakage past the
pump.~ ~ere the hot solution is introduced, it will settle
relatively slowly do~Jn through the oil in the tubing until
it reaches the deposit. After introducing ~he hot solution
in any desirable mannsr, it may be allowed to stand in the
tubing for any desired period of time before the well is
replaced on production. In some instances it may be advisable
to pump the well intermittently for very short periods of
time, so as to pick up the hot solution and lift it above
the deposit, letting it settle down past the deposit again
during t~e next idle period. However5 one of the advantageous
actors of our process is that it may not require shutting the
well d~wn if one so desires.
Where the organic deposits in question occur in flow
lines, the hot solution may be introduced and allowed to "soak" -
the deposit. Thereafter, normal production may be resumed; and
the dislodged deposit flushed from the line by the flow of well
~luids. In other instances, gas pressure is put on the soaXea
line~ and the deposit flushed out in that manner. Sometimes,
introduction of hot aqueous solution is effected intermittently
1~5974~
a~d the deposit progressively removed. Or the hot solution
may be introduced in a continuous fashion, if desired.
In the case of pipelines, the diameter of the pipe
and the length of the line maXe it necessary to apply the
hot solution in the most economical fashion possible.
Soa~cing of the line, i.e., merely introducing the hot solu-
; ~ion into it and allowing the line to lie idle for a period
o~ tirne, is practicable~ Sometimes we prefer to prepare a
xelatively large volume of hot aqueous solution in a tank
at some convenient location at one end o the pipeline, and
- interrupt the pumping of oil only long enough to switch to the
solution tank and pump the volume of hot solution into the
line. Then the pumping of oil is resumed, and the liquid
~ylinder of hot solution is thereby moved across the face of
the deposit in the line, over the whole length of line. I~
desired, the dixection o pumping may be reversed when such
liquid cylinder of hot solution reaches the opposite end of
the line; and a second, or even a third pass or more may be
made, of the hot solution over the deposit in the line.
Where deposits have been allowed to accumulate over
a considerable period of timeg they may be of such proportions
that application of hok solution would produce sloughing of
su~ficien~ of the deposit to plug the conduit further d~n-
stream, by forming a bridge with undislodged deposit at that
point~ In such instances, we prefer to proceed more cautiousl~,
introducing successive small portions of hot solution and
1~597~4
cces5fuily dislodging portions oi the deposit which are
sufficiently small to pass freely through ~he limited
freeway in the conduit.
Merely introducing our hot solution into an area
containing a deposit, so that it contacts the deposit, is
sometimes sufficient to cause the removai of the latter.
So~etimes agitation of the hot solution at the face of the
deposit greatly accelerates removal of the latter. Any
suitable agitation means may be employed in such instances.
Application of our hot solution upstream in any
system, as, for example, into a well, results in an attack
on any such organic deposits further downstream. For
exampleJ wax or similar deposits, in traps and tanks, are
freed and usually flowed out of such vessels in subsequent
operation of the system. In the case of tan~s we have found
that waxy tank bottoms may be removed by introduciny the hot
solution into the tank containing such deposits and allowing
the whole to soa} for any desired-period of time. ~ne
depGsit is thereby made more lree and more readily removable.
Removal of deposits of organic matter ~rom oil pro~uction
equipment, such as traps and tanks and the like, is o~viously
contemplated by this process. -
Because t~ere are so many conditions under which such
organic deposits ~ay occurJ it is difficult to ~i~e a~y pre- I
~erred procedure for applying our process. The foregoing i;
descriptions have covered instances where such deposits t~ere
to be remo~ed irom the face of the formatlon, the well tuhing
'
~6-
~L~35974'~
or casing, flot~ lines, pipe]ines and tank batterie~. They
ma~ be ta]~en as preferred metbods of oporating the process
or the respoctive conditions outlined. All of them are
exemplary only. ~,1~ process may be varied as condi~ions
; may require. In all cases, the process consists broadly in
the application of the pro^ess to the organic deposits
~escribed ~bove.
In general3 the process is carried out by preparing
a solution of paraffin chemical, heating the solution to an
elevated temperature, an~ treating the system with the hot
solution of paraffin chemical.
The temperature of the solution should he sufficient
to enhance the effectiveness of the paraf~in chemical as
compared to the effectiveness of the same solution at ambient
temperature. In general, temperatures in excess of about
100 F. such as from abou~ 100 to steam temperature, for
example from about 120 to 212 ~, but preferably from about
150 to 200 F. are employed.
The concentration o~ the paraf~in cheMical will vaxy
widely depending on various factors, such as for example, the
~emperature of the solution, the severity of the paxafrin
p~oblem, the particular paraffin chemical employed, the
location of the paraffin problem, etc. In general a concen-
tration of at least about 0.1% by ~eight, suc'n as from about
0.5 to 10%, for example from about 0.75 to 5% but preferaoly
from about 1 to 3% in the hot aqueous solution.
-7-
597
;
~ wide variety of paraffin chemicals can be employed.
In general, these chemicals are surfactants ~hich are capable
of removing paraffin. Examples of surfactants ~hieh can be
foxmul~ted into paraffins chemical nay include t'ne following
typ~s.
I . Ani onic
tA) Carbo~ylic acids:
(1) Carboxyl joined directly to the hydro~hobic group
~subclassification on basis of the hydrophobic
~ I D group~, e.g. fatty acids, soaps, resin soaps, etc.
; ~2~ Carbo~yl joined t'nrough an intermediate lin~age.
(a) Amide group as intermediate link~
(b) Ester group as intermediate link.
(c) Sulfoamide group as intermediate link.
td~ Miscellaneous intermediate linXs, ether,
SO S
(B~ Sulfuric esters (sulfates):
(1) Sulfate ~oined directly to hydrophobic group.
(a~ Hydrophobic group contains no other polar
structures (sulfated alcohol and sulfated
olefin type).
- (b) Sulfuric esters with hydrophobic groups
containing okher polar structures (sulfated
oil type).
(2) Sulfate group joined through intermediate lin~sage.
(a) Ester li~age (Artic Syntex ~4 type).
(b) Amide linkage (Xynomine type).
,~,~ ,'`' ' .
1~35!~4~
(c~ Ether linkage (Triton 770 ~yp~).
(d) Miscellaneous lin~ages (e.g., o~yal~ylimida7-ole
sulfates).
(C) Alkane sulIonic acids:
(1) Sul~onic group directly linked
(a) Hydroohobic group bears other polar substituents
("highly sulfated oil" typ~. Chloro, hydro;~y,
acetoxy, and olefin sulfonic a~ids (Nytron~type~
~b~ Unsubstituted alkane sulfonic acids (MP 189 type;
¦C also cetan~ sulfo acid type).
tc~ Miscellaneous sul~onic acids of uncertain
structure, e.g., oxidation products o~ sulfurized
~le~ins, sulronated rosin~ etc.
(2) Sul~onic groups joined through intermediate linkage.
(a) Estex linkage.
tl) RC00- X- S03H (Igepon AP type).
(2) ROOC - X~ S03H (Aerosol and sulfoacetate
type).
(b~ Amide linkage.
RCON~ -X -S03H ~Igepon T type).
(2) ~NHOC- X -S03H (sulfosuccinamide type).
(c) Ether linkage (Triton 7aO type).
ta) Miscellaneous linkages and two or more linkages.
_9_
11D59~44
(D) ~lXyl aror,latic sulfonic acids:
(1) Hydropnobic group joined directly to sulfonated
aromatic nucleus (su~classes on basis of nature of
hydrophobic group. Alkyl phenols, terpene, and
rosin-aromatic condensates, alkyl aromatic XetonesJ
etc.).
t2) Hydrophobic group joined to sulfonated aromatic
nucleus through an intermediate linkage.
(a) Ester linkage (sulfo~hthalates, sulfobenzoates).
(b) Amide and imide lin~ages.
(1) R- CO~H - ArS03H type.
(2) Sulfob~nzamide type.
(c) Ether linkage (alkyl phenyl ether type).
(d) Heterocyclic lin~age (Ultravon type, etc.).
te) Miscellaneous and two or more links.
(E~ Miscellaneous anionic hydrophillic groups:
(1) Phosphages and phosphonic acids.
(2) Persulfates, thiosulfatesJ etc~
(3) Sulfonamides.
(4) - Sulfamic acids, etcO
II. Cationic
(A) Amine salts (primary, secondary, and tertiary amines)
tl) Amino group joined directly to hydrophobic group.
ta) Aliphatic and aromatic amino groups.
(b) Amino group is part of a heterocycle
_ I o--
l~S97~
(2) Amino group joined through an intermediate link.
(a) Es~er link.
tb) Amide linX.
(c) Ether link.
(d) Miscellaneous links.
(B) ~uaternary ammonium compounds:
(1~ Nitragen joined directly to hydrophilic group.
(2) ~itrogen joined through an intermed'ate link.
(a~ Ester link.
(b) Amide link.
Ether link.
(d) Miscellaneous links.
r~? O~her nitrogenous bases:
(1) Non-quaternary bases tclassified as guanidine,
thiuronium salts, etc.
~2~ Quaternary bases.
(D) ~on-nitrogenous bases:
(l? Phosphonium compounds.
(2) Sulfonium compounds, e~c. ,~
III. Non-ionic
(A) Ether linkage to solubilizing groups.
~B) Ester linkage.
(C) Amide linkage.
(D) Miscellaneous linkages.
~E) Multiple linkages.
~C~5974~
IV. ~mpholytic
(A) Amino and carboxy:
(1) Non-quaternary.
(2) Quaternary.
tB) ~mino and sulfuric ester:
tl) Non-quaternary.
(2) Quaternary.
IC) Amine and alkane sulfonic acid.
tD) Amine and aromatic sulfonic acid.
(E) Miscellaneous combinations of basic and acidic groups.
The preferred surfactants employed as paraffin
chemicals contain a non-ionic surfactant, preferably an
~xyalkylate,
In general/ the preferred compounds are oxyalkylated
sur~actants of the general ~ormula
æ toR)noH m
wherein z is the oxyalkylatable material, R is the radical
derived from the alkylene oxide which can be, for example,
ethylene, propylene~ butylene, epichlorohydrin and tlle like,
2 o n iS a number determined by the moles of alkylene oxide
reacfea, for example 1 to 2000 or more and m is a ~hole number
determined by the number of reactive oxyalkylatable groups.
Where only one group i~ oxyalkylatable as in the case of a
monofunctional phenol or alcohol R'OH, then m~ here Z is
water, or a glycol, m=2. ~ere Z ~s glyceroI, n=~, etc.
-12-
~0S97~
In certain cases, it is advantageous to react
alkylene oxides with the oxyalkylatable material in a
random fashion so as to form a random copolymer on the
oxyalkylene chain, i.e., the (OR)n ~ chain such as
AABAAABBABABBABBA. In addition, the alkylene oxides can
be reacted in an alternate fashion to form block
copolymers on the chain, for example
~ '; ' '
BBBAAABBBAAA~BBBB
.
or BBBBAAACCC~AAABBBB where A is the unit derived
from one alkylene oxide, fox example ethylene oxide, and
B is the unit derived from a second alky~ene oxide, for
example propylene oxide, and C is the unit derived from
a third alkylene oxide~ for example, butylene oxide, etc.
Ihusl these compounds include terpolymers or hig~er
cvpol~mers polymerized ra~domly or in a blockwise fashion
- ~ or many variations of sequential additions,
ThUSJ ~OR)n in the above formula can be written
AaBbCc or any variation thereof, wherein a, b and c
are O or a number provided that at least.one of them is
greater than O.
-13- -
~0597~4
RE~ES~I~TT?~TIVE EY~1PI.ES OF Z
No. ~
. O
1 ............ Il
RC -O -
2 ............ Rn ~ O -
- 3 ~........... R- O -
4 ............ R- S -
: 5 ... ,-~-
M
R~ C- N -
.
11
6 ... ~....... .....R- C -~
7 ~D~ H
R- ~ -
....... 0.,- ~
~; : 9 .......... . .....Phenol-aldehyde resins.
l0 ......... . ....- O - (Ex: Alkylene oxide. block polyMers)
R R
~ l o -~ x ~O _
- 11 .. I .
1l
0--9--S~ CH2--S--J etc.
.' . O
~597~
o
12 .........
R- S- CM2C - O -
13 ............ ~RP04H -
14 ............. ~.RPO~=
; 15 .............. P04- H
i
16 .. -.-Rn ~ S02N -
17 .. ~...... ~ ~ S02N=
O H
': 11 1 /
'~ ~ 'D ~ _ ~T -- ~ --
.
....... Polyol-derived (Ex: glycerol, glucose,
pentaaxithrytol).
20 ......... .Anhydrohexitan or anhydrohexide derived (Spans~
and Tween~ .
21 .. ~ Polycarboxylic derived.
22 .. ....-~IHC~2 ~n
C 2
amine
Examples of oxyalkyl2table materials derived fro~ the
above radicals are legion and theseg as well as other oxy-
alkylatable materials, are kno~n to the art. ~ good source of
such oxyalkylatable materialsg as wel~ as others, can be found
-15
:lOS9744
in "Surface ~ctive ~gents and Detergents," vols. 1 and 2,
by Schwartz et al~, Interscience Publishers (vol. 1, 1949,
vol. 2, 1958) J and the patents and references referred to
therein.
An e~ample of a formulation containing an o~yall~ylaLed
material is descrlbed in U.S.P. 3,4~1,870 which contains the
~: following composition claims.
1. A composition of matter for inhibiting the forming
of in and removing from oil wells and pipelines deposits of
paraffin and paraffin-like solids consisting essentially of:
~- . (1) an alkanol selected from the group consisting of
butanol, isobutanolJ sec-butanol~ amyl alcohol and isomers
thereof, hexyl alcohol and isomers thereof, and cyclohexyl
alcohol7 said alkanol being oxyethylat~dwith 1.5-3.5 moles of
ethylene oxide~
(2) an oxyethylated substituted phenolic compound
having the formula
(0 Et~nOM
~y ,
~: ~ R1_2
:
where n is an integex of 1-12, and R is a hydrocarbon group
having 2-12 carbons atoms, the weight ratioof (13 to (2?
being from 1:5 to 6:1,
(3) water in the amount of 0.5 to 20 times the weight
of the sum of (1) and (2), and
(43 an alcohol seleated from the group consisting o
-lG-
105974~
methanol, ethanolJ propanol, isopropanol, but and ethylene
glycolf said alcohol being present in an amount suf~icient to
be a pour point depressan~.
2. The composition OL claim 1 wherein (1) is an
oxyalkylaksd ~utanol.
3. ~ne composition of claim 1 wherein (1) is an
oxyal~lated butanol and (2) is an oxyethylated alkylphenol.
The composition of claim 1 wherein (1) is an oxy-
alkylated butanol and ~2) is an oxyethylated alkylp~enol
haviny 4-6 units of ethylene oxide~
5~ The composition of claim 1 wherein tl) is an oxy-
alkylated butanol and (2) is an oxyethylated alkylphenol
having 3-12 units of ethylen~ oxide.
6. The composition of claim 1 wherein (1) i5
n butyl - (OCH2CH2)20
and (2) is
sec-butyl ~ ~0CH2cH2)40H
~he weight rakio of (1~ to (2~ being 2.5:19 and (3) is present
in the amount or 1-1/7 times the weight of the sum of (1) and
(2), and (~) is msthanol in the amount of times the weight
o~ the sum of (1) and (2).
~ he following examples are presented for purposes of
illustration and not of limitation.
Compo~lnd A - Sulfated fatty alsohol ethoxylake
Trisodium phosphake
Isopropanol
-17-
I
~5~7~ ,
Compound B - Alkyl aryl sul~onate
Aromatic Hydrocarbon
Isopropanol
Compound C - Sulfated phenol ethoxylate
Trisodium ,~hosphate
Eutyl carbitol
Sul~ated fatty alcohol ethoxylate
Amine ethoxylate
Compound D - Ethox~lated phenol formaldehyde resin
; Aromatic H~drocarbon
Compound E - Oxyalkylated phenol-amine-~ormaldehyde
condensate
Ethoxylated phenol-formaldehyde resin
Aromatic solvent
~- ` Isopropanol
~ompound F - Oxyalkylated alkylphenol
- Butyl carbitol
Ethyl cellosolve
~ Exam~lè 1
; 20 A flowing well having a paraffin problem in the
~lowline was treated by injecting into the flowline at the well
, head, a mixture of 10 gallons of Compound A and 10 barrels ~f
lO0~F. water. The well was shut in for one hour then returned
tQ production. Parafin was removed as evidenced by a redu~-
t1on in flowline pressuxe.
, Example 2
~ flowing well having a paraffin problem in the tubing
and flowline was treated by injecting into the tubing, a mixture
of 10 gallons Compound B and 10 barrels of 200F. waker. m e
well was immediately returned to production. To check for
paraffin removal, a wireline cutter was run down the tubing and
encountered no paraffin.
. . .
-1~3- ' . . . .
~L1059744
Example 3
A gas lift well having a paraffin pro~lem in the
tubing was treated by injecting into the tubing, a mixture
~f l0 gallons Compound C and 10 barrels of 50F. water.
~ne well was ret~rn~d to production. A wireline cutter
run down ~he tubing found para~fin t~en production
decreases again indicated a paraffin buildup. (Cold Treatment~
is well was then treated by injecting into the
tubing a mixture of lO gallons Compound C and 10 barrels
o~ 200~F. water. A wire line cutter run down the tubing
encountered no paraffin. (Hot Treatment)
Exam~le 4
A pumping well having a paraffin problem in the
flowline was treated by injecting into the flowline at the
well'head, a mixture of 20 gallons ~ornpound D and 20 barr~ls
of 150F. water. Flow line pressure decrease and produc~ion
increase indicated good paraffin removal.
Example 5
A gas lift w~ll produced 68 BOD through a 10,000 ft.
20 flowline. A mixture of 10 gallons CL~m~ound E and l0 barrels ~,
180F, water was pumped through the flowline. ~JO days later
the same treatment was repeated. Production increased to
10~ ~OD.
Exam~le 6
,
A gas lift well having paraffin buildup problems in
-19- !
59~7~4
both ~he tubing and flowline was treated by in~ecting a
mi~ture o 10 gallons Compound F and 10 barrels 165~F.
water into the flowline and then an equal chemical/hot
water mixture into the tu~ing. The well returned ~o pro-
~uction and showed a 250 psi drop in 1O~line pressure.
Example 7
A flowline thought to be restricted by paraffin
~uildup was opened at a point about 2500 ft. from the well
headO mere was less than 1/2 inch opening in the 2 inch
lin~. m e flowline was treated by pumping into it at the
well head~ a mixture o~ 20 gallons Compound C and 20 barrels
200F. water. Ihe ne~t dayJ the line was opened at the same
,inspsction point and no paraffin was found.
, Exam~le 8
A well wi~h a history of paraffin buildup was treated
with a mixture of 10 gallons Compound C'and 10 barrels 165F.
water and the well op~ned to the pit. A full 2 inch s~ream
o ~lushy paraffin flowed out for 15 minutes.
~ he ~lowline o~ a well was completely plugged off
with paraf~in. ,Attempts to pump 300F~ oil through the line
were unsuccessful. One ~xum of Compound E pumped into line
and allowed to soak under pressure for 24 hours with no
change. Three barrels fluid drained rom flowline at well
~20-
~059744
head and replaced witl~ three barrels of a 5% solution of
Compound E in 200~F. water. Gradual reduction of p.ressure
showed some action. Further chemical/hot water mi~ture
pumped into tlle line. Within a couple of hours~ a trickle
of fluid started coming out the end of the line. ~Jithin
24 hours, the line was clean~
As is quite evident, other s~rfactants which are
use~ul as paraffin chemicals are known or will be developed
which are useful in our invention. It is~ therefore, not
only impossible to aktempt a comprehensive catalogue of
such compositions, but to attempt to describe the invention
in its broader aspects in terms of speci.fic chemical names
of its components used would be too voluminous and unneces- :
sary since one skilled in the art could by following the
: descriptioD of ~he invention herein select a useful surfactant
useul as a paraffin chemical. m is invention lies in the .
use of suitable surfactants in hot aqueous systems in
removing paraffin type deposits and their individual compo-
sitions axe important only in the sense that their properties
can a~fect this function. To precisely define each specific
u~eful surfactant in light of the present disclosure would
merely call for chemical Xnowledge within the skill of the .
art in a manner analogous to a mechanical engineer who
prescribes in the construction of a machine the proper
materials and the proper dimensions thereof. ~rom the
~L059~74~ ` -`
descxiption in this specification and with the kn~ledge
of a chemist, one will know or deduce with confidence the
applicability or speci~ic suxfactants suitable for ~his
invention by applying them in the process set forth herein.
In anaIogy to the case of a machine, wherein the use of
certain materials of construction or dimensions of parts
wou~d lead to no practical useful result, various materials
will be rejected as inapplicable where o~hers would be
operative. We can obviously assume ~ha~ no one will wish
~o use a useless surfactant nor will be misled because it
is possible to misapply the teachings of the present
disclosure to do so. Thus, any surfactant in a hot aqueous
sys~em ~hat can perform the function staked herein can be
employed.
, ' .
' " .
il
-22- j
