DE2210431A1 - CRUDE OIL MIXTURES - Google Patents

Description

SHELL INTERNATIONAL RESEARCH MiIATSGHAPPIJ Ή.Υ. The Hague / Netherlands

"Blends of Crude Oil"

Priority: March 5, 1971, Great Britain, No. 6132/71

The invention relates to crude oil mixtures with improved flow properties, especially at low temperatures.

Depending on the respective oil production fold, crude oils contain significant .- / axle quantities. This wax separates gradually evolves from the oil as it cools below a certain temperature. Through the cohesion of the spatial Structures excreted V / ach skr istalle will give the oil a certain Ausaali bestowed on solidification. At sufficiently low temperatures, the oil can even solidify completely. '.7, as will be explained below, has the presence of crystalline lized oxides in crude oil have a detrimental effect on the flow

209883/0980

properties and the manageability of the oil.

Crude oil is produced from a borehole, which is cut through strata with lower temperatures than those of the oil-containing form- < mation leads, the oil coming into contact with the cold wall of the bore can solidify, which causes the transport to Surface obstructed. If the pumping is temporarily interrupted, the oil can even solidify completely, which is the case with resumption of production leads to serious problems.

If the oil is stored in tanks that are not used; Öxner heating option or insulation are provided, cools down the oil that is in contact with the cold walls and bottom of the tank and may solidify as a result. this leads to difficulties in pumping the oil out of the tank; There can be considerable amounts of solidified oil remain in the tank, reducing the effective capacity of the tank.

This problem comes into play when transporting waxy crude oil unheated tankers, in which the walls of the chambers are partially are formed by the hull of the ship in direct contact with the cold army water, even larger ones Importance to. When the tanker is unloaded, large amounts of solidified oil are left behind and reduce the carrying capacity dos ship; in addition, the cargoes carried after the crude oil can become contaminated.

209883/0980

The poor flow properties of the oil at lower temperatures can also be caused either by pumping or by the prevailing pressure or differences in level, hinder the transport of the oil through pipelines.

When pumping waxy crude oils through a pipeline, high flow resistances can build up, resulting in a very high pumping force require. This can lead to high transportation costs, especially in the case of pipelines that run over long distances. If the resistance is very high, the existing delivery pressure of the pump or the permissible pressure determined by the thickness of the pipe can be used Pressure is no longer sufficient, so that the oil can no longer be pumped out.

The pumping stops while the crude oil is waxy is in the pipeline, cools the oil, which is often v / poorer than its surroundings. The deposited during cooling Wax can unhinderedly form three-dimensional structures that can extend over the entire cross-section of the pipeline and which require very high pump pressures to reduce them. If this pressure exceeds the available or permissible Delivery pressure, transport cannot be resumed.

i'jowoh! when a crude oil containing a week is pumped through a pipeline v / Jrd, as well as when it is in the pipeline, can be solidify the oil at dor kai ton Röhr en ν / and and a remaining Make deposit. This reduces the capacity of the Pi]) OJJnO un'J hai; the risk of contamination of the following

? HH P, 8 3 / Π 9 8 0

resulting in lots of crude oil to be pumped through the pipeline.

When refining crude oil, certain processes, such as the separation of water or sediment, e.g. by settling, centrifuging, Filtration or coalescence, a thin oil required. If because of the presence of crystallized If the oil is not sufficiently flowable, there is a possibility that these processes will not work at all or only to a limited extent can be carried out ..

Good flow properties of a crude oil are not only useful for transportation and storage, but also for many others Reasons desirable. In this regard, for example, sampling or the transmission of pressure signals through narrow lines and the proper functioning of the in refineries and along the pipelines for various purposes, e.g. Temperature and density measurements, attached automatic recorders.

From the above it can be seen that the flow properties of a crude oil both during production and storage, as well as during transport and refining of the oil play a major role. It is therefore extremely important to counteract the good flow properties of the oil To keep the influence of wax as small as possible.

In order to be able to predict the flow behavior of a crude oil under operating conditions, laboratory measurements are often used Property that is characteristic of the

Flow behavior of oil can be viewed, namely the pour point.

The pour point is regarded as the criterion of the lowest temperature permissible during storage or transport or during a possible interruption in transport. There are known compounds which reduce their presence in a crude oil the pour point of this oil, for example, polymers having aliphatic hydrocarbon rare chains having at least 'obtained V \ carbon atoms, the olefinically unsaturated optionally substituted by Polymerisierimg compounds v / orden. Polyalkyl acrylates can be mentioned as examples of this type of polymer.

The pour point is determined according to a standard method, the oil being cooled at a rate of about 0.5 ° C / min (= 30 ° G / h). In practice, such as the pipeline transportation or decommissioning of the pipeline, one sometimes dealing with significantly lower rates of cooling, for example with cooling rates of 5 ° C / h or even less than 3 ⁰ C per day. It has been found that in this case the above-mentioned compounds generally do not have the desired beneficial effect on the solidification temperature of the crude oil, at which it can no longer be easily transported. Once the oil has solidified, for example in a pipeline, a very high pressure must be exerted in order to restart the oil flow, which pressure often cannot be made available by the pumps installed in the pipeline. In addition, the viscosity of the crude oil must

setting can quickly drop to an acceptable level, which is not is always the case. A type of compound has now been found which, when mixed with a waxy crude oil, causes the solidification temperature decreases not only at high, but also at low cooling rates.

Accordingly, a crude oil blend is provided that thereby is characterized in that it consists of a waxy crude oil and a polymer, the heterocyclic rings and aliphatic Contains side chains with at least 10 carbon atoms.

For the sake of brevity, the terms "long hydrocarbon chains" and "long hydrocarbon side chains" hereinafter to identify aliphatic hydrocarbon chains or aliphatic hydrocarbon side chains with at least 10 carbon atoms are used.

The polymers of the present invention can be any type of polymer, such as condensation polymers however, preference is given to using polymers obtained by copolymerizing olefinically unsaturated compounds are.

In the latter case, the polymer consists of one of carbon atoms constructed main chain, which carries heterocyclic rings and long hydrocarbon side chains. The in dar In the present specification, the term "heterocyclischor" is used Ring "denotes al Lo radical types with a, heterocyclic

20988 3/098 0.

Ring system.

According to the invention, pol. '/ Mere, in which the long hydrocarbon side chains are unbranched and saturated, i.e. polymers in which the long hydrocarbon side chains are through the formula CH ^ - (CHp) -Clip-, where n ^> 8, are represented can be used preferably. Polymers with long hydrocarbon side chains are preferred for practical use used, in which the number of carbon atoms 14 to 30, and in particular 16 to 26 is.

The polymers which can be used to lower the pour point according to the invention consist of one of carbon atoms main chain built up with long hydrocarbon side chains. Some or all of the carbon atoms present in a heterocyclic ring may be some of the Form the main chain, but in general the main chain carries the heterocyclic rings. The long hydrocarbon side chains and / or the heterocyclic rings can either be bound directly or indirectly to the main chain. in the in the former case there are no further atoms between the first carbon atom of the long hydrocarbon side chain and / or the heterocyclic ring system present in the heterocyclic ring and the carbon atom of the main chain that the side chain or the heterocyclic ring is attached. SJnd the long hydrocarbon side chain and / or the heterocyclic one Ring indirectly bound to the main chain, there are one or more atoms, such as carbon, oxygen,

? 09RR3 / n980

Sulfur, nitrogen or phosphorus atoms, between the first Carbon atom of the long hydrocarbon side chain and / or the heterocyclic ring system and the carbon atom the main chain to which the side chain and / or the heterocyclic ring are attached. Preferably polymers with long hydrocarbon side chains that have a or several oxygen and / or carbon atoms are indirectly bound to the main chain. Some examples of polymers, in which the aliphatic hydrocarbon side chains indirectly via one or more oxygen and / or Carbon atoms attached to the main chain are polymers with aliphatic hydrocarbon side chains attached to the main chain via a carboxyl group or via an oxygen atom are bound. The heterocyclic ring is preferably bonded directly to the main chain.

The production of such polymers can basically be carried out in two ways. First, you can use these polymers by copolymerization of olefinically unsaturated compounds are made, at least a portion of which are made from olefinic unsaturated compounds which, in addition to a polymerizable> C = rC (group, have a long hydrocarbon chain wear, and at least a part of compounds that are in addition to a polymerizable > C = C <group carry a heterocyclic ring system. A second way in which these polymers can be produced is the copolymerization of olefinically unsaturated compounds without a long Hydrocarbon chain and / or heterocyclic ring system

2O9RR3 / Π980

and a subsequent treatment of the polymer, through which the long carbon chain and / or the heterocyclic ring are introduced into the polymer.

Of course, polymers with different types of long hydrocarbon side chains (e.g. with a different Number of carbon atoms) and / or different heterocyclic rings can be used.

The molecular weight of the polymers which can be used to improve the flow properties of crude oil mixtures according to the invention can vary within wide limits. For practical use, polymers with an average molecular weight (number average M _n ) between 1000 and. 1,000,000 and in particular between 4,000 and 100,000.

Depending on the particular type of those present in the crude oil Paraffin waxes can preferably be added to this crude oil according to the invention Polymers mixed in, in which the long hydrocarbon side chains present in each molecule are respectively differ by a number of carbon atoms.

The heteroatoms in the heterocyclic rings are in particular sulfur, oxygen or phosphorus atoms. An example a compound suitable for incorporation into the polymer is üulfolen. - Preferably heterocyclic ring systems with a nitrogen atom, such as piperidine or pyrrolidone, and in particular aromatic heterocyclic ring systems, e.g. Chi.nolin, Irjochinolin and especially pyridine, are used. It

20 9 881/0980

can also use heterocyclic ring systems with two or more Höteroatomen are used.

The polymers are preferably earthed by radical copolymerization manufactured.

Examples of compounds with a pyridine ring and an olefinic double bond, which are good for the preparation of the invention Suitable polymers are 2-methyl-5-vinylpyridine and especially 4-vinylpyridine.

Examples of olefinically unsaturated compounds with long
Hydrocarbon chains which are suitable for the production of polymers according to the invention are vinyl esters and allyl esters of saturated monocarboxylic acids, such as, for example, vinyl and allyl esters of arachidic and behenic acid; Alkyl esters of unsaturated monocarboxylic acids, such as, for example, alkyl esters of methacrylic acid and, in particular, alkyl esters of acrylic acid; Alkylamides of unsaturated monocarboxylic acids such as n-eicosyl acrylamide and n-docosyl methacrylamide; Dialkyl esters of unsaturated dicarboxylic acids such as di-n-octadecyl maleate and di-n-docosyl fumarate; Dialkylamides of unsaturated dicarboxylic acids, such as, for example, di-n-eicosylmaleindiamide and di-n-docosylfumaric diamide; Imides of unsaturated dicarboxylic acids such as n-octadecylmalcimide and n-eicosylmaloimide; Alkyl vinyl ethers, such as, for example, n-docosyl vinyl ether and n-tetracosyl vinyl ether, and monoolefins, such as, for example, 1-octacoses and 1-docoses.

I / emi if desired, olefinically unsaturated compounds

2 0 9883/0980

are incorporated into the polymers without long hydrocarbon chains, e.g. vinyl esters of unsaturated monocarboxylic acids, such as e.g. vinyl acetate, alkyl esters of unsaturated mono- and dicarboxylic acids, such as methacrylate and diethyl maleate, alkyl vinyl ether, such as octyl vinyl ethers, and monoolefins, such as e.g. Athens and isobutene.

The ratio between the number of long hydrocarbon side chains present in the polymers of the invention to that The number of heterocyclic rings can vary within wide limits, e.g. between 1: 5 and 20: 1. Particularly suitable a ratio of between 1: 1 and 10: 1.

Copolymers of 4-vinylpyridine and are particularly suitable Alkyl esters of unsaturated carboxylic acids, e.g. alkyl esters of unsaturated Monocarboxylic acids such as methacrylates and especially alkyl acrylates.

The concentration in which the polymers are in waxy crude oils can be used within wide limits vary, depending on the type, structure and molecular weight of the polymer to be used, the type and the amount of the paraffin wax present in the crude oil and the intended one Improvement of the flow properties matters. In some cases an amount as low as 0.001 percent by weight, based on weight, is sufficient on the crude oil mixture in order to achieve the desired improvement in fluid properties. In most cases it is an amount of 2.0 percent by weight is completely sufficient. Preferably the crude oil is from 0.002 weight percent to

209883/0980

admixed to 0.2 percent by weight of the polymers.

The waxy crude oil to which the polymers of the invention are added, can consist of a waxy crude oil or a mixture of waxy crude oils. If desired, the polymers can also be mixed into mixtures that consist of one or more wax-containing crude oils and of one or several non-waxy crude oils.

The present polymers, in particular used as additives for facilitating the transport of waxy crude oils through Pipelines, by means of tankers or other means of transport, are also particularly suitable for use in the case of oil wells that produce wax-containing crude oil to access these V / alternatively to prevent the formation of wax deposits or in order to dissolve such V / axis deposits on the walls of the bore.

For the production of crude oil mixtures according to the invention can the polymers expediently the waxy crude oil as such or in the form of a concentrate, e.g. in a coal, hydrogen solvent, which is a single hydrocarbon, such as toluene, or a mixture of coals, e.g. a crude oil or a crude oil fraction can be added. Concentrations from 2 to 50 percent by weight of the polymer im Solvents are very suitable.

When a polymer according to the invention is a waxy crude oil promotional drilling must be added, it is special

209883/0980

It is advisable to inject the polymer (e.g. in a solution) into the waxy crude oil present in the bore, in particular in the lower part of the hole, e.g. with the help of a macaroni pipe. It is also possible to periodically pass the polymer down the annulus as a concentrate. is If the production of a well is temporarily interrupted, the polymer can be dissolved before the oil production is resumed Bore to be printed in the oil-containing formation.

If desired, in addition to the polymers present, other types of polymers which influence the flow properties can also be used for the waxy crude oil are added. As examples, polymers with aliphatic hydrocarbon chains with at least 14 carbon atoms, such as polyalkyl acrylates and "Copolymers of vinyl acetate and docosyl fumarate and Copolymers from Athens and olefinically unsaturated monomers with paraffinic side chains of not more than 10 carbon atoms (such as copolymers from Athens and vinyl acetate).

example 1

Two copolymers of alkyl acrylates and 4-vinyl pyridine were made. In the starting mixture for the preparation of polymer A, the alkyl acrylates consisted of a mixture of eicosyl and docosyl acrylates with an average length of the alkyl side chains of 21 carbon atoms. The polymerization was carried out by radical copolymerization with programmed addition of the ^z- l-vinylpyridine until 70 percent of the alkyl acrylates had polymerized. The relationship

209883/0980

nis of alkyl acrylates to ^ - vinylpyridine in copolymer A was 1: 0.3. The average molecular weight was 40,000.

Polymer B was prepared by polymerizing a mixture of 4-vinyl pyridine, eicosyl acrylate, and docosyl acrylate (alkyl side chain average length of alkyl acrylates 21.5 carbon atoms) until 10 percent by weight of the monomers Xn had been converted into the polymer. The ratio of alkyl acrylates to ^ -vinylpyridine in polymer B was 1: 0.3, the average molecular weight 40,000.

For comparison, a copolymer C of stearyl acrylate, eicosyl acrylate and docosyl acrylate (average side chain length 20 carbon atoms) with an average Molecular weight of 60,000 produced.

A North African waxy crude which had been stored for a few weeks at room temperature was heated to a certain temperature (rewarming temperature). The polymer was in the doping temperature, the admixed in two cases equal to the l / iedererhitzungstemperatur and lower in a case of 10 ⁰ C as the l / iedererhitzungsteiaperatur was in an amount of 400 ppm. The pour points were determined using two cooling rates. In the first series of tests, the cooling rate described in ASTM D 97-66 was used, namely a cooling rate of about 0.5 ° C / min (= 30 ° C / h). In the second series of tests, the cooling rate was reduced to 5 ° C / h and the last temperature at which the oil

20SRR1 / Π980

just showed flow (as in the ASTM D 97-66), taken as a pour point. Table A shows that the effect of polymers A and B on the pour point relatively faster cooling the effect of polymer C and that of a commercial pour point depressant D equal or was superior. With slow cooling (second series of experiments) that obtained with polymers A and B according to the invention was obtained Lowering of the pour point considerably greater than that of polymers C and D.

Table A.

Y / iederei-heating temperature, ⁰ C 50 50 40 doping ^{temperature, 0} C 50 40 4-0

Pour point ⁰ C

Cooling) waxy

,. ν crude oil 24 24 24 ge Schwin- )

age) "+ 400 ppm C 21 12 9

50 ° G / h,

) + 400 ppm D 21 24 15

) "+ 400 ppm A 12 12 12

) "+ 400 ppm B 12 12 12

Cooling) waxy

> -> O i-N /, oil Oil

speed) ^{Rohül 2V 24 2+}

digke it) "+ 400 TpM G 24 24 21

5 ° CA) "+ 400 ppm D 21 21 12

) "+400 TPM A 0 0 <-3

) "η- 400 TpM B 6 6 6

2098R3 / 0980

Example 2

In this example, the pumping of a crude oil through a pipeline was simulated. The flow of oil through the pipeline has been simulated by taking place under refrigeration to slow agitation (stirring) and the pumping operation by an occasional success end by forcing it through a nozzle. A standstill of the oil in the pipeline, as it would in the event of a fault

was simulated by cooling the standing crude oil in a queue.

A container was filled at about 3O ⁰ C with a crude oil and stirred ^r0 day slowly under cooling at a cooling rate of 3 ^Q CP. The contents of the container was then pressed at a temperature of ⁰ JO C, 15 ° C, 13.5 ° C and 12.5 ⁰ C. through a 2 cm long nozzle having a diameter of 0.5. After a temperature of 11.5 ^° C. was reached, a 16 m long snake with a diameter of 6 mm was filled with oil from the container. This snake, in which the oil in the stationary state was located, was then cooled at a rate of 3 ⁰ C per day up to a temperature of 9 ° C. then

became through the exertion of increasing pressure (a printing company

heightening of 1 K m 'per quarter of an hour) determined on the content of the queue, the pressure • n.edoringang.oetzung of ülflusses in the queue required to' After the crude oil in line.. "/ just ^one; - / o] .1 had begun, the

p
Pressure increased to 0 N / ra and the viscosity of the contents of the snake determined after 10 and 100 seconds.

209883/0980

ORIGINAL

The following crude oils were used in three consecutive trials: A North African waxy crude with an added copol, yaerori of alkyl acrylate (average Number of carbon atoms in the alkyl chain 19.5) and 4-vinylpyridine (ratio in the copolymer 2: 1; polymer E), and again the same oil with the added commercial pour point depressant D. Table B shows the results; it can be seen that the crude oil with the polymer E according to the invention moves considerably more easily can be set as the crude oil with additives G and D. Since aen today operated pipelines for transport over long The pumps used are unable to stretch one

To provide pressure of over 8 N / m, only a crude oil with the polymer E can be conveyed through these pipelines while putting one back into motion for some time at 9 ° C stagnant crude oil in the case of waxy crude oils with the additives. C and D extremely difficult, if not impossible is.

Table B.

Polymer __E CD

Concentration (pH) 200 400 400

Flow resistance at 9 ⁰ C (N / m ² ) * -1.5 7.5 ' > 20

Viscosity after 50 s <1 -

- after 100 s 850

N = - Newtons (1 N - 0.101972 Kp)

Example 3

A copolymer of alkyl acrylate (average number of carbon atoms in the alkyl chain 19) and 4-vinylpyridine (molar ratio of alkyl acrylate to 4-vinylpyridine 3> 3 ^: 1} molecular weight 60,000) was prepared (polymer F). The polymers C, E and F were dissolved in three types of waxy crude oils, and the solidification points were determined by cooling at a rate of 3 ° C per day. To simulate the occurring by a pump during the flow of the crude oil shear stress, the crude oil mixtures, after cooling to 21 ⁰ C and 18 ⁰ C were mm through a nozzle having a length of 17 and pressed a diameter of 1.2 mm. In a number of cases the flow through this nozzle was repeated at 15 ° C. Table C shows the results. It can be seen that the polymers E and F (polymers according to the invention) lead to crude oil mixtures which, after the shear stress, have a lower solidification point than crude oil mixtures with the polymer C not according to the invention.

2 0 9 fi 8 3/0 9 8 0

Table C.

Tv ρ des via cn rh a 1 - ■
tigoη of crude oil Cord African 30th 21 21 Nigerian 21 lord african 21 30th 21 Dispensing
temperature ⁰ C 18th 18th 22nd 18th -3 21 18th Shear stress
chung at ⁰ C 15th - 21st 15th -6 18th 15th 18th - -9 6th 9 < <-12 0 polymer
none 18th 12th 6 < 6 - <-12 0 6th E. 0 18th -12 <-12 9 0 12th P. 3 : -12 <-12 12th C. 9 '_ΊΡ Q

o fj i> ß 3 / η s a n

Claims (16)

Claims 1. Crude oil mixture, characterized in that? it consists of a crude oil containing v / ax and a polymer ", which contains heterocyclic rings and aliphatic side chains of at least 10 carbon atoms. 2. crude oil mixture according to claim 1, characterized in that the polymer used has been obtained by copolymerization of olefinically unsaturated compounds. 3. crude oil mixture according to claim 1 and 2, characterized in that the aliphatic hydrocarbon side chains with at least 10 carbon atoms in the polymers used are unbranched and saturated. 4. crude oil mixture according to claim 1 to 3> characterized in that the polymers used have aliphatic hydrocarbon side chains with 14 to 30 carbon atoms. 5. crude oil mixture according to claim 4, characterized in that the polymers used contain aliphatic hydrocarbon side chains with 16 to 26 carbon atoms. 6. crude oil mixture according to claim 1 to 5 »characterized in that that the polymer used consists of a main chain made up of carbon atoms, and that this Main chain the aliphatic hydrocarbon side chains 209883 / Π98Π 7210431 with at least 10 carbon atoms and carries the heterocyclic rings. 7. crude oil mixture according to claim 6, characterized in that the aliphatic hydrocarbon side chains in the polymers used indirectly bound to the main chain via one or more oxygen and / or carbon atoms are. 8. crude oil mixture according to claim 6 or 7, characterized in that the heterocyclic polymer used Ring is bound directly to the main chain. 9. crude oil mixture according to claim 1 to 8, characterized in that that the average molecular weight of the polymer is in the range from 1,000 up to 1,000,000 and especially from '4-000 to 100,000. 10. crude oil mixture according to claim 1 to 9, characterized- / that in the polymers used, the length of the chain in each mole k ü 1 vo rh an de ne η al ipr> at is cfc en Kohl e ir. Is. s ε 9 ν »st ο ί 'f · side chains with at least 10 carbon atoms differing by a few carbon atoms« 11. crude oil mix according to claim 1 to 10, characterized that the polymers used in ilen are heterocyclic Rings contain an otickstoffatosn. 12. Crude oil mixture according to claim H _5, characterized. · ΊΌ ..> 2 Π 9 8 R3 f "0 i) 8 0 the heterocyclic ring present in the polymers used is a pyridine ring. 13. Crude oil mixture according to Claims 1 to 12, characterized in that the polymer is obtained by radical copolymerization has been. 14. Crude oil mixture according to claim 1 "to 13, characterized in that ¹ V vinylpyridine has been used to prepare the copolymer. 15 crude oil mixture according to claim 1 to 14, characterized in that that an alkyl ester of acrylic acid was used to prepare the copolymer. 16. A crude oil mixture according to claim 1 to 15, characterized in that the ratio between the number of aliphatic hydrocarbon chains with at least 10 carbon atoms to the number of ¹ heterocyclic rings present in the polymers is from 1: 5 to 20: 1, preferably 1: 1 up to 10: 1 ;. 17 · Crude oil base according to claim 1 bin 16, characterized in that the polymer e: in copolymers :? from '! —Vinylpyridine and Alkylur'.ryü ".ter ..:: ^r ' t. 'U). Rohö; ic; oi: xj .--. Ch liV.'Si /.r^spruch 1 to I7, thereby gokonrizcichno t "that d-ic; Concentration of the, Polyraoren of 0.00 ', Gc ^; - ^r ichtspro-ZOiI; b: i "to 0.2 (ϊ; w light percent be tr''45t. ? Tj 9fiB.1 / 0980 " ²⁵ ~ 771 0431 19 · Process for the production of a crude oil mixture according to claim 1 to 18, characterized in that one is a polymer with heterocyclic rings and aliphatic hydrocarbon scvitenketten with at least 10 carbon atoms or a concentrate of this polymer in a carbon solvent in a crude oil that contains a v / ax Injected bore. ? η 9 R R λ / ίϊ 9 8 O BAOORtGtNAL