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Description  |
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The present invention relates to the use of particular compound mixtures
for breaking petroleum emulsions.
A large portion of crude petroleum contains specific amounts of emulsified
water, or aqueous solutions of sodium chloride, or also of other salts,
mainly in the form of W/O emulsions. This water is separated, in practice,
by the addition of very minor amounts of demulsifying substances.
Demulsifying agents already have been proposed in the art in large
numbers. The reason for this is that the various mineral oils have a
different composition, and demulsifiers which are suitable for breaking
down emulsions of petroleum of one origin are frequently less suitable for
petroleum emulsions of a different type. The known demulsifiers act
therefore more or less markedly specifically upon individual petroleum
types.
As demulsifying agents, alkyl sulfates and alkyl aryl sulfonates as well as
petroleum sulfonates in the form of amine salts already have been
proposed. Furthermore, addition products of ethylene oxide to suitable
compounds with active hydrogen atoms, such as for example alkyl phenols,
castor oil, fatty acids, fatty alcohols, and aldehyde resins, have also
been mentioned. Corresponding statements are found, for example, in the
book "Oberflachenaktive Anlagerungsprodukte des Athylenoxids"
(Surface-Active Addition Products of Ethylene Oxide), by N. Schonfeld,
Wissenschaftliche Verlagsgesellschaft mbH (Scientific Publishing Company),
Stuttgart, 1959, page 295.
Despite the large number of demulsifiers available on the market, it is not
possible, however, to break all of the occurring petroleum/water emulsions
rapidly, safely, reproducibly, and with small quantities of addition
products.
The spectrum of the usable compounds has been expanded particularly due to
the introduction of specific organic silicone compounds for breaking
petroleum emulsions. Thus, specific mixed polyoxyalkylene-polysiloxane
block polymerizates already have been proposed as demulsifiers in German
Auslegeschrift No. 1,937,130. The widespread use of these very effective
products is diminished, however, by the relatively high price thereof.
It is the object of the present invention to provide demulsifiers,
particularly demulsifier mixtures, which are specific to petroleum types
to the smallest possible extent, which cause an effective breaking of the
petroleum emulsions when used in small quantities, and which have the
advantages of the mixed polyoxyalkylene-polysiloxane block polymerizates.
It has been found surprisingly that certain mixtures of a specific group of
mixed polyoxyalkylene-polysiloxane block polymerizates with silicon-free
demulsifiers effectively solve the problem. In addition thereto, it was
found that the mixtures used in accordance with the present invention are
very rapidly distributed in the petroleum to be demulsified. This
facilitates the mixing work and is probably also the cause that the
mixtures used according to the present invention lead in many cases to an
increase of the speed of the water separation, which represents a
significant commercial advantage.
During the further treatment of the petroleum, primarily in refineries,
there is frequently the formation of undesirable foam. The mixtures used
according to the present invention have the additional advantage that,
during the treating processes in the refineries, they act as defoamers, so
that the use of expensive silicon defoamers can be eliminated.
The action of the mixtures used according to the present invention as
demulsifiers indicates that the mixed polyoxyalkylene-polysiloxane block
polymerizate components in these mixtures primarily have the role of
bringing the demulsifying mixture rapidly to the interface of the W/O
emulsion, which is rendered possible by virtue of the extremely rapid
spreading capacity of the mixed polyoxyalkylene-polysiloxane block
polymerizates used according to the present invention.
In the present invention, mixtures are used of 0.2 to 30% by weight,
preferably 0.5 to 10% by weight, of mixed polyoxyalkylene-polysiloxane
block polymerizates whose polyoxyalkylene blocks have in each case a
molecular weight of 500 to 4000 and are composed of polyoxyethylene- and
polyoxypropylene blocks in a weight ratio of 40:60 to 100:0, and whose
polysiloxane blocks contain 3 to 50 silicon atoms per block; and 70 to
99.8% by weight, preferably 90 to 99.5% by weight, of conventional
silicon-free demulsifiers used for breaking petroleum emulsions.
In the mixed polyoxyalkylene-polysiloxane block polymerizates used
according to the present invention, those are preferred whose
polyoxyalkylene blocks have a molecular weight of 1000 to 3000.
If the polyoxyalkylene blocks are composed of ethylene oxide and propylene
oxide units, these preferably should be present in separate blocks and a
series connection of several ethylene oxide and propylene oxide blocks is
also possible.
When ethylene oxide and propylene oxide are added to water in a block,
polyoxyalkylene diols are produced. If a monovalent alcohol, such as for
example methanol, or other lower aliphatic alcohols, are used as the
starting alcohol, polyoxyalkylene monools are obtained. It is possible,
however, to use multivalent alcohols as starting alcohols, such as for
example glycerine or sorbitol, in which case one obtains polyoxyalkylene
glycols with three and/or six hydroxyl groups, respectively.
The polysiloxane blocks, which should have 3 to 50 silicon atoms per
siloxane block, are as a rule linear or branched methylpolysiloxanes, but
also suitable are those polysiloxanes which partially have, instead of
methyl groups, other lower alkyl groups or aryl groups.
The polyoxyalkylene blocks may be linked with the polysiloxane blocks
either via SiOC groups or via SiC groups with each other. The preparation
of such compounds with SiOC groups have been described, for example, in
German Pat. No. 1,012,602. The compounds may be prepared in a particularly
simple manner according to U.S. Pat. No. 3,115,512. Compounds with SiC
linkages are obtained, for example, when ethylene oxide and propylene
oxide are added to starting alcohols which are olefinically unsaturated,
and when these compounds are then reacted with polysiloxanes having SiH
groups. Such processes have been described, for example, in German
Auslegeschrift No. 1,220,615. In addition, there are a large number of
other processes for preparing such compounds.
The mixed polyoxyalkylene-polysiloxane block polymerizates employed
according to the present invention are liquid to wax-like solid substances
which may be dispersed or dissolved in water. They therefore may be added
to the petroleum emulsion to be broken either directly or in the form of
concentrated solutions or dispersions. Good results also are obtained,
however, when the demulsifiers are dissolved in organic solvents, such as,
for example, toluene or methanol, and then added to the emulsions.
Examples of mixed block polymerizates used according to the present
invention may be represented by the following formulae, wherein A
represents a polyoxyalkylene block and B a polysiloxane block:
##STR1##
(n=any desired integer, preferably 3 to 50). Polyoxyalkylene blocks with
OH and/or alkoxy residues at the end of the polymer chain are preferred
end groups.
This listing is not exhaustive but only exemplary. The polyoxyalkylene
block A may be represented by the formula:
##STR2##
In this formula, n may have a value of 2.0 to 2.6. The value of m is
determined by the requirement that the molecular weight of the
polyoxyalkylene block is to be between 500 to 4000, preferably 1000 to
3000. Z is the alkyl- or aryl residue of the starting alcohol onto which
ethylene oxide and propylene oxide have been added. The subscript r
corresponds therein to the valence of the alcohol having the function of
the starting alcohol. When for example, glycerine is employed as the
starting alcohol, Z has the following structure:
##STR3##
and r has a value of 3. If methanol is employed as the starting alcohol,
Z= CH.sub.3 and r= 1. A polyalkylene glycol obtained by the addition of
alkyleneoxide to H.sub.2 O leads to a block with Z= H; r is here again= 1.
In the structural diagram shown hereinabove, B signifies a polysiloxane
block. This polysiloxane block may have, for example, the following
structure:
##STR4##
In this formula, M is an alkyl residue, and c is 0 or 1.
The subscripts a and b are variable, but are delimited by the condition
that each polysiloxane block should contain at least 3, but not more than
50 silicon atoms.
A second example of the structure of the polysiloxane block B is
represented in the following formula
##STR5##
The substituents M and the index c have the above-identified meaning. The
subscripts d and e are variable, but the sum thereof must be between 1 to
48. It is evident therefrom that d or e may have a value of 0.
A further example of the structure of the polysiloxane block B is
represented by the following formula:
##STR6##
The symbols have the same meaning as in the previous formula but d must in
this formula have at least the value of 1.
The linkage of the blocks A and B also may be effected, instead of via
oxygen and/or a bivalent alkylene residue, through other bivalent
residues, such as for example
##STR7##
As a further linking group, the group
##STR8##
is another possibility, wherein R is a bivalent hydrocarbon residue which
may be substituted, if desired, for example the 2,4-toluylene residue. The
demulsifying effect of the mixed block polymerizates is not significantly
influenced by the group linking the blocks.
Examples of mixed polyoxyalkylene-polysiloxane block polymerizates
preferably used as those having the general formula
X(AB).sub.n AX
wherein
n= 1 to 100, preferably 5 to 20, and
A is a polyoxyalkylene block having the general formula
##STR9##
wherein f=0.5 to 3; g =6 to 12; h =8 to 13; g:h preferably 0.9:1.0;
preferably: f = 1.5; g =8 to 10; h=9.5 to 11.5, and
X=a monovalent hydrocarbon residue or, preferably, H.
B is a polysiloxane block having the formula
##STR10##
wherein: e= 1 to 48, preferably 2 to 5, 9 to 12, and 20 to 23.
Further mixed polyoxyalkylene-polysiloxane block polymerizates preferably
employed in the mixture of the invention are those having the general
formula
##STR11##
wherein: a= 0 to 20,
b= 0.1 to 10,
A= the polyoxyalkylene block,
R.sup.1 = a monovalent hydrocarbon residue, for example alkyl with 1 to 18
C atoms or phenyl,
preferably a= 3 to 6, b=3 to 10,
##STR12##
i=1 to 6; j =25 to 35, preferably 28.5, and k =5 to 9, preferably 7.5.
The subscripts n, m, r, a, b, c, d, e, f, g, h, i, j, and k used in the
formulae represented hereinabove are mean values inasmuch as the mixed
polyoxyalkylene-polysiloxane block polymerizates are polymer mixtures.
In addition, from among the polysiloxane blocks, those are preferred which
have been brought, prior to linkage with the polyoxyalkylene blocks, into
static balance with respect to their molecular weight distribution and the
distribution of the various siloxane units. This term of "bringing into
balance" is generally referred to as equilibrating.
The molecular weight of the mixed polyoxyalkylene-polysiloxane block
polymerizates employed in the mixture of the invention preferably should
be below 100,000.
From among the mixed polyoxyalkylene-polysiloxane block polymerizates whose
siloxane block is linked with the polyoxyalkylene block via an SiOC
connection, those compounds are used in which the linkage of the blocks is
through a
##STR13##
bridge.
Silicon-free demulsifiers used in the mixture of the invention are
predominantly compounds of one of the following groups:
I. Reaction products of alkylene oxides with alkylphenolaldehyde resins.
These are alkylphenol resins which are soluble in organic solvents and
whose free hydroxyl groups are reacted with ethylene oxide and/or
propylene oxide. The alkyl phenols required therefor are preferably
monoalkyl phenols with straight-chain or branched alkyl groups having 4 to
18 carbon atoms in the o- or p-position, and smaller quantities of
bis-alkylated phenols also may be present. For the conversion thereof into
resins, formaldehyde or substances which yield formaldehyde under the
conditions of the alkaline or acid condensation are used. Acetaldehyde and
higher aldehydes also may be used, however, at the same time. The quantity
of aldehyde employed during the condensation amounts to approximately 0.5
to 2.0 moles, preferably 0.9 to 1.1 moles, per mole of phenol. The
reaction takes place in known manner in the presence of acid or alkaline
catalysts with or without the addition of inert solvents. These alkyl
phenol-formaldehyde resins are oxyalkylated according to known processes,
and the quantity of the oxyalkylation agents employed depends, on the one
hand, upon the length of the alkyl groups contained in the starting phenol
resin, and on the other hand upon the properties of the crude oil to be
demulsified. Generally, about 2 to 20 moles of epoxide per one hydroxyl
equivalent are used.
Such demulsifiers have been described by way of example in U.S. Pat. Nos.
2,499,368; 2,499,370; 2,524,889; 2,560,333, and 2,574,543.
II. Block and mixed polymerizates of propylene oxide and ethylene oxide.
These are special products obtained when approximately 30 to 100% by
weight of ethylene oxide is added to propylene glycols with molecular
weights of 500 to 5000, preferably 1500 to 3000, while increasing the
final molecular weight. In this group of demulsifiers are furthermore
products which are obtained by the addition of ethylene oxide and
propylene oxide to compounds with 1 to 4 replaceable hydrogen atoms, such
as, for example, alkanols and polyalcohols, mono- and polyamines,
oxamines, and mono- and polycarboxylic acids. Compounds of this group are
described, for example, in French Pat. No. 1,069,615, and in German
Auslegeschrift No. 1,018,179.
III. Reaction products of the alkylene oxide polyadducts mentioned under
II. and/or the oxyalkylated phenol-formaldehyde resins mentioned under I.,
with dicarboxylic acids, such as succinic acid, glutaric acid, sebacic
acid, benzene dicarboxylic acids, and particularly adipic acid.
IIIa. Products obtained by cross-linking of the alkylene oxide polyadducts
mentioned under II. with each other and/or with the oxyalkyllated
alkylphenol-formaldehyde resins mentioned under I. Cross-linking agents in
this case are compounds with 2 or 3 reactive groups which are suitable to
react with the hydroxyl groups of the components to be cross-linked. Such
cross-linking agents are, for example, diisocyanates, such as
hexamethylene-diisocyanate, toluylene-2,4- and toluylene-2,6-diisocyanate,
1,4- and 1,5-naphthalene-diisocyanate, diphenylmethane-diisocyanate,
4,4-dicyclo-hexylmethane-diisocyanate, as well as phosphorus oxychloride
and phosphorus trichloride. The quantity of the cross-linking agents used
amounts, in bivalent cross-linking agents, to about 1/5 to 1/2 mole and,
in trivalent cross-linking agents, to about 1/10 to 1/3 mole per hydroxyl
equivalent of the products to be cross-linked.
IV. Physical mixtures of products of the groups I to III enumerated
hereinabove.
In the following comparative examples, the effect of the demulsifier
mixtures employed according to the present invention is illustrated.
EXAMPLE 1
Used in this test was a water-in-petroleum emulsion from a German field
which is particularly difficult to demulsify. Employed as a comparison and
simultaneously for mixing with specific mixed polyoxyalkylene-polysiloxane
block polymerizates were two silicon-free demulsifiers which were
relatively well suited for the demulsification of this water-in-petroleum
emulsion. The silicon-free demulsifiers are designated A and B.
Demulsifier A is a cross-linked product of a polypropylene glycol-ethylene
oxide polyadduct and a nonylphenol-formaldehyde resin reacted with
ethylene oxide with the use of toluylene-diisocyanate as a cross-linking
agent. The preparation of this product is described in Example 1 of German
Pat. No. 1,642,825.
Demulsifier B is a mixture of one part by weight of a
nonlyphenyl-formaldehyde resin to which were added 3 to 4 moles of
ethylene oxide per phenolic hydroxyl group, and one part by weight of a
polyalkylene oxy adduct with a polypropylene glycol nucleus and a
molecular weight of 2000, to which ethylene oxide up to a content of 38%
by weight in the final product was added and subsequently cross-linked
with 0.4 mole of phosphorus oxychloride.
The petroleum sample was reacted at 50.degree. C. with 15 ppm each of
active material (demulsifiers and/or demulsifier mixtures). The addition
of the demulsifiers took place therein from a 1% solution in a 1:1 mixture
of toluene and methanol. After the addition, shaking was effected 200
times. The speed of the water separation is shown in the following table
1.
Table 1
______________________________________
H.sub.2 O separation,
in %, after
Product 10' 30' 60' 120' 180'
______________________________________
15 ppm demulsifier A
55 64 70 72 73
15 ppm demulsifier B
49 62 68 69 72
12 ppm demulsifier A +
3 ppm mixed polyoxyalkylene-
polysiloxane block (+)
polymerizate C 69 81 86 92 95
12 ppm demulsifier B +
3 ppm mixed polyoxyalkylene-
polysiloxane block (+)
polymerizate C 63 75 90 90 95
______________________________________
(+) The mixed polyoxyalkylene-polysiloxane block
polymerizate C was a product having the formula:
##STR14##
##STR15##
wherein
##STR16##
and the block distribution was such that 2 moles
of propylene oxide had been added on at the end position;
the remaining propylene oxide was statistically distributed in the
polyoxyalkylene block.
The sole use of 3 ppm of the mixed polyoxyalkylene-polysiloxane block
polymerizate C produced almost no measurable water separation, which was,
however, not surprising in view of the small amount, particularly for
laboratory tests.
EXAMPLE 2
A water-in-petroleum emulsion, also originating from a German field, which
was even more difficult to demulsify was chosen in this example in order
to show the superior effect of the mixtures used according to the present
invention. Employed here were again in each case a total of 15 ppm of
demulsifier active material. The results obtained are compiled in Table 2,
below.
Table 2
______________________________________
H.sub.2 O separation, in %,
Product after 180 minutes
______________________________________
demulsifier A 38
7.5 ppm demulsifier A +
7.5 ppm mixed polyoxyalkylene-
polysiloxane block
+)
block polymerizate D 46
7.5 ppm demulsifier A +
7.5 ppm mixed polyoxyalkylene-
polysiloxane block
+)
polymerizate E 52
7.5 ppm demulsifier A +
7.5 ppm mixed polyoxyalkylene-
polysiloxane block
+)
polymerizate F 63
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+) The polyoxyalkylene-polysiloxane block polymerizate D, E,
and F corresponded to the formula HA(BA).sub.10 H, wherein
##STR17##
##STR18##
##STR19##
and
e in the mixed polyoxyalkylene-polysiloxane block polymerizate D had a
value of 2, in the mixed polyoxyalkylene-polysiloxane block polymerizate E
a value of 12.74, and in the mixed polyoxyalkylene-polysiloxane block
polymerizate F a value of 22.5.
Here again, the sole use of in each case 7.5 ppm of the three different
mixed polyoxyalkylene-polysiloxane block polymerizates produced only a
moderate water separation.
EXAMPLE 3
On a wet oil from the area between the rivers Weser and Ems, Germany, with
a water content of 58%, the water separations were measured which were
obtained in each case with the use of 20 ppm of one of the
emulsion-splitting agents indicated below:
(a) Demulsifier G (nonyl phenol-formaldehyde resin which was reacted first
with 10 moles of propylene oxide per phenolic OH group, and thereafter
with 4 moles of ethylene oxide per phenolic OH group).
(b) A mixture of 97% by weight of demulsifier G and 3% by weight of the
mixed polyoxyalkylene-polysiloxane block polymerizate D.
(c) A mixture of 90% by weight of demulsifier G and 10% by weight of the
mixed polyoxyalkylene-polysiloxane block polymerizate D.
The separated water quantities, in % of the water originally contained in
the wet oil, are compiled in the following table:
Table
______________________________________
Water separations, in % of the water still
present, after
Splitting agent
10' 30' 60' 120' 180'
______________________________________
(a) 45 55 59 62 62
(b) 69 73 73 76 80
(c) 69 76 80 80 83
______________________________________
The foregoing results show the advantageous action of the mixed
polyoxyalkylene-polysiloxane block polymerizate by the quantity of water
separated.
EXAMPLE 4
In an oil field in the East Hannover, Germany, area, the procedure was
carried out, without a significant supply of heat, with the use of an
emulsion-splitting agent whose active substance contained 1 part by weight
of a block polymerizate with a nucleus of polypropylene oxide having a
molecular weight of 1800 and a proportion of 45% by weight of ethylene
oxide in the final product, and 2 parts by weight of demulsifier A. When
using 35 ppm of the emulsion-splitting agent, a good water separation was
obtained corresponding to mean salt values in the final product of 150
ppm. when the amount of emulsion-splitting agent was reduced to 20 ppm,
the residual salinity in the final product increased to 500 ppm.
When this test was repeated with the same emulsion-splitting agent to which
there had been added, however, 2.5% by weight of mixed
polyoxyalkylene-polysiloxane block polymerizate D, mean salt values of 100
ppm were obtained for added amounts of 20 to 40 ppm.
EXAMPLE 5
In an oil field between the rivers Weser and Elbe, Germany, the following
clarifying results were obtained, with the use of different
emulsion-splitting agents, for a wet oil with a 10% by weight water
content:
(a) Demulsifier H (a block polymerizate with a polypropylene glycol nucleus
having a molecular weight of 2000 and an ethylene oxide content of 38% by
weight in the final product).
(b) A mixture of 90% by weight of demulsifier H and 10% by weight of the
mixed polyoxyalkylene-polysiloxane block polymerizate D.
(c) Demulsifier A (see Example 1).
(d) A mixture of 90% by weight of demulsifier A and 10% by weight of the
mixed polyoxyalkylene-polysiloxane block polymerizate D.
The residual water and residual salt contents obtained after sedimentation
are compiled in the following table:
Table
______________________________________
Residual Water
Splitting Agent
(% by weight) Salt Content (ppm)
______________________________________
(a) 30 ppm 0.7-0.8 800-900
(b) 30 ppm 0.6-0.7 600-750
(c) 20 ppm 0.6-0.65 750-850
(d) 20 ppm 0.35-0.4 450-550
______________________________________
It will be obvious to those skilled in the art that many modifications may
be made within the scope of the present invention without departing from
the spirit thereof, and the invention includes all such modifications.
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Description |
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