WO2006061482A1

WO2006061482A1 - Method for treating viscous hydrocarbon by in situ inerting of asphaltenes

Info

Publication number: WO2006061482A1
Application number: PCT/FR2005/002943
Authority: WO
Inventors: Isabelle Henaut; Jean-François Argillier; François Henry
Original assignee: Institut Francais Du Petrole
Priority date: 2004-12-07
Filing date: 2005-11-24
Publication date: 2006-06-15
Also published as: FR2878937A1; FR2878937B1; CA2587634A1; US20110127196A1

Abstract

The invention concerns a method for treating viscous hydrocarbon containing asphaltenes, which consists in performing the following steps: precipitating at least part of the asphaltenes by adding into the hydrocarbon an appropriate solvent; adding into the hydrocarbon polymerization products adapted to encapsulate the precipitated asphaltenes to inert same.

Description

METHOD OF TREATING A HYDROCARBON

VISCOUS BY INTEGRATION IN SITU ASPHALTENES

The present invention relates to the field of production and

transport of viscous effluents, in particular so-called "heavy" crudes, for example

because of their asphaltenes content.

Methods of transporting viscous crudes which consist of

fluidizing the crude by heating, mixing with a fluidifying product, or

pre-transport treatment, for example aqueous emulsification.

However these techniques are expensive in energy, or implement

complex processes requiring significant infrastructures that penalize

exploitation of deposits.

In the present description, "slurry" is a suspension, or

a dispersion of solid particles in a liquid which can be

circulation, especially by pumping. This type of flow in "slurry" is already

commonly used during dredging operations of estuaries, rivers,

as well as in the mining industry. The interest is to carry a maximum of

solid cuttings with the least possible pumping energy. In regards to

the oil sector, "slurry" transport is used to enrich fuels with coal particles and thereby increase their calorific value. The solid content can reach 60% by mass all

keeping the flow properties acceptable.

The present invention is preferably applied to heavy crudes. It also applies to extra heavy crudes, bitumens, oil sands, or the like. It therefore consists in modifying the structural organization of the heavy crude which behaves like a viscous colloidal suspension, to obtain

a suspension of particles of lower viscosity. The particles concerned by this transformation are, in the context of a preferred embodiment of the present invention, asphaltenes. Asphaltenes are the molecules of more

high molecular weight contained in some petroleum crudes. They are characterized by their strong polarity and the presence of polycondensed aromatic rings. The recovery of these particles deployed in the crude is

largely responsible for the high viscosity of heavy crudes. This recovery can be suppressed by keeping the asphaltenes in the form of solid particles encapsulated in the crude. This configuration change

can be achieved by combining, in the crude, a precipitation and inerting of asphaltenes, then dispersing asphaltenes encapsulated in the base liquid, in particular under strong mechanical agitation. A procedure,

in no way limiting, has been developed and it has been verified that the change in morphology of the resulting crude in the form of suspension gives rise to

a decrease in viscosity.

Advantageously, according to the invention, the asphaltene particles in solid form are transported by the crude base liquid in which these asphaltenes are dispersed such that the liquid obtained is more fluid than the original crude. Thus, the pumped transport in the pipes is

facilitated up to the refining units. In these refining units, the "slurry" is either introduced as such into these treatment units, or after a phase of separation of suspended solid particles, asphaltenes, which can simplify downstream processes.

Thus, the present invention relates to a method of treating a viscous hydrocarbon containing asphaltenes, in which

the following steps: at least a portion of the asphaltenes are precipitated by the addition in the hydrocarbon of a suitable solvent,

polymers are added to the hydrocarbon which are suitable for encapsulating the precipitated asphaltenes so as to inert them.

Depending on the method, the asphaltenes can be precipitated with n-alkane. Polymerization products can be added to form a

membrane around asphaltene particles by interfacial polycondensation.

Di or triamine, or mixture thereof, and an acyl dichloride may be added to form an aromatic polyamide on the surface of the asphaltene particles to form a membrane.

Alkyd resins suitable for crosslinking can be added to the surface of the

asphaltene particles.

A siccative may be added as a crosslinking promoting agent. The invention also relates to the application of the method for obtaining

a viscosity decrease of a viscous asphaltenic hydrocarbon.

The method can be applied to the transport of viscous asphaltenic hydrocarbon by pipe.

The present invention will be better understood and its advantages

will appear more clearly on reading the following examples of embodiments, in no way limiting, illustrated by the appended figures, among which:

FIG. 1 shows the results of an embodiment according to the invention,

FIG. 2 shows the behavior in time of the method according to the invention.

According to the invention, at least two modes of

polymerization to encapsulate asphaltenes contained in a viscous hydrocarbon to inert them.

The invention shows how the encapsulation of asphaltenes within a heavy crude can permanently reduce the viscosity of such oils.

The invention is not limited to these two modes of encapsulation.

The first embodiment of the invention is a polymerization which consists of an interfacial polycondensation. It's about making a synthesis

of polymer material at the solid-liquid interface between the asphaltenes and their environment. This method is based on the selection of two monomers

appropriate, one soluble in the liquid phase and the other having high affinities with asphaltenes. It is noted that the polymer obtained forms a membrane around the asphaltenes and must not be soluble in the liquid phase. The protocol of the preferred procedure implements the synthesis of aromatic polyamides obtained from the reaction between a di or

triamine and acyl dichloride. Due to its high polarity, di or triamine is preferentially located on the surface of asphaltenes. Acyl dichloride, on the other hand, is soluble in the surroundings of asphaltenes. The polyamide obtained is insoluble in the liquid phase and is formed at the

surface of asphaltene particles. It is part of the family of polyaramids whose aromatic structure is known to give them a

resistance to temperature, strong mechanical properties and good resistance to solvents and oxidizing agents [Odian: "Principles of Polymerization" 3rd ed., John Wiley & Sons, Inc., 1994.].

The operating procedure developed makes it possible to modify the organization

structural structure of heavy crude, by passing it to a suspension of encapsulated non-colloidal particles of high viscosity, and durably reduced. This protocol is realized in situ; it does not require prior deasphalting

crude with extraction, treatment and reincorporation of asphaltenes. The encapsulation method described merely requires the preliminary addition of a n-alkane in a controlled amount in order to precipitate the asphaltenes. The encapsulation reaction is then directly implemented on the precipitated asphaltenes without the need to filter them, then disperse. Once the polymer membrane is formed, the n-alkane is evaporated to be optionally recycled. In addition, some of the alkane may be left in place. Also, a light oil cut can be added to adjust the viscosity value.

Example of procedure

The selected n-alkane is added according to the selected amount of crude.

After mechanical stirring for 20 minutes during which the aphaltenes

precipitate, di or triamine is introduced, according to the proportion chosen by mass relative to the amount of asphaltenes. Tributylamine is also added. Its purpose is to neutralize the hydrochloric acid that

released during the reaction between an amino group and an acyl chloride function. The mixture is stirred for one hour during which the di or

triamine binds to precipitated asphaltene particles. The acyl dichloride is then introduced in the molar proportion chosen in relation to

to di or triamine. Encapsulation occurs then by the synthesis of the

polyamide between di or triamine and acyl dichloride on the surface of asphaltenes. The reaction is initiated by a light heating between 30 and 35 ⁰ C,

which is kept under reflux for one hour. The n-alkane is then evaporated. A suspension with a grainy appearance is obtained, the size of

particles reaching several hundred microns.

Test 1: Influence of the amount of n-alkane added Three samples were prepared for the encapsulation of asphaltenes of a heavy crude containing 17% by weight. The monomers chosen for to give rise to the interfacial polycondensation reaction are melamine (eg provided by Sigma-Aldrich) and sebacoyl dichloride (supplied by VWR). The triamine is introduced at a level of 5% by mass of

asphaltenes. The amount of acyl dichloride is set at 1.7 moles per 1 mole of melamine. The n-alkane chosen to precipitate the asphaltene particles is pentane. Its amount is known to influence both the particle size and the precipitation yield. This parameter is varied between 10, 15 and 20 ml / g of crude. In each case, after polycondensation reaction

interfacial and evaporation of pentane, the samples are observed under optical microscopy and their viscosity is measured using a

imposed constraint. In this example, the size of the capsules changes with the amount of pentane, varying respectively for the samples prepared with 10, 15 and 20 ml / g crude respectively 300, 700 and 50 microns.

Figure 1 gives the viscosity V of the samples (in Pa · s) as a function of the amount of pentane added Q (in ml / g). The results show that

Encapsulated samples are less viscous than the original heavy crude and there is an optimum content of n-alkane to further reduce viscosity. This

optimum (here between 10 and 15 ml / g) is to be calibrated according to the nature of the heavy crude, that is to say of the state of solvation and the concentration of its asphaltenes.

Test 2: Influence of the amount of monomers on the decrease of

viscosity of the encapsulated samples In order to observe the influence of the amount of monomers on the quality of the encapsulated products, four samples were prepared starting from 2.5; 5;

10 and 20% by weight of melamine with respect to asphaltenes. The amount of sebacoyl dichloride is always set at 1.7 moles per mole of melamine introduced. The tests use pentane as n-alkane with

as content 15 ml / g of crude. In each case, after interfacial polycondensation reaction and evaporation of pentane, the samples are observed under optical microscopy and their viscosity is measured using a

constrained rheometer. The optical microscopy images allow to visualize the excess of polymer formed with the important concentrations in

monomer, the polymer whose presence in excess causes a high viscosity. Table 1 indicates that the viscosity increases with the amount of monomers. To observe the temperature behavior of these samples, the microscopic analyzes were resumed after their heating at 80 ⁰ C for 1 hour. The overall results show that to obtain a good compromise between

the level of the viscosity and the temperature resistance, the content of 5%

melamine is preferred.

Tab.l: Viscosity at 20 ° C of the samples encapsulated by interfacial polycondensation with different amounts of monomers.

Test 3: Resistance in time of the samples encapsulated by

interfacial polycondensation In order to check the durability of crudes containing asphaltenes encapsulated by interfacial polycondensation, the viscosity of a sample was measured at different time intervals. This is the sample prepared from 5% by weight of melamine, 1.7 moles / mole of sebacoyl dichloride, and the precipitation of asphaltenes being obtained with

pentane introduced at a level of 15 ml / g of crude. The rheological measurements are presented in FIG. 2 which gives the viscosity V (in Pa.s) as a function of

shear rate t (s ^"1 ), curve 1 relates to the crude, curve 2 after

encapsulation, curve 3 40 days after, and curve 4 after 66 days. The curves show the stability of the product over time.

The second mode proposed for encapsulating the asphaltenes of a crude is

to cause on their surface the crosslinking of alkyd resins. The alkyd resins are unsaturated polyesters (presence of double bonds) obtained from polyol and natural fatty acids. They are characterized by their vegetable oil content, called length in oil. The latter gives them a

drying power, that is to say an ability to polymerize in the presence of oxygen. This crosslinking process involves several physicochemical mechanisms

depending on whether the intervening double bonds are single or conjugated [Marshall et al., Polymer, 28, 1093, 1987.], [Solomon, "The chemistry of organic film formers" Wiley-Intersciences, New York, 1967].

It can appeal depending on the case to the addition of a siccatif whose role is to accelerate the crosslinking by promoting the supply of oxygen. These are the most often metal oxides. As for the first mode of polymerization by interfacial polycondensation described above, the

The procedure developed for this second method makes it possible to modify the structural organization of the heavy crude, making it pass to a suspension of

encapsulated particles of strongly reduced viscosity and durably reduced. This protocol is realized in situ; it does not require prior deasphalting crude with extraction, treatment and reincorporation of asphaltenes. The encapsulation method described merely requires the preliminary addition of a n-alkane in a controlled amount in order to precipitate the

asphaltenes. The alkyd resins will preferentially be placed on the surface of the asphaltenes. The crosslinking reaction then occurs directly on

precipitated asphaltenes. Once the membrane is formed, the n-alkane is evaporated to be optionally recycled. In addition, some of the alkane may be left in place. Also a light oil cut, or solvent, can be added to adjust the viscosity value.

Example of procedure

The selected n-alkane is added according to the selected amount of crude. After mechanical stirring for 15 minutes during which the asphaltenes precipitate, the alkyd resins, the optional siccative and a dispersant are introduced. Mechanical stirring is maintained under heating at 35 ° C.

during two hours. The n-alkane is finally evaporated. A suspension with a smooth appearance is obtained. Test 4; Influence of the quantity of alkyd resins on the decrease

of viscosity

In order to observe the influence of the quantity of alkyd resins on the quality of the encapsulated products, three samples were prepared from 4, 6 and 8% by weight of Synolac 6883 (supplied by the company DSM) with respect to the asphaltenes. . The proportion of siccatives (Combi QS of Nuodex) is

fixed at 4% by weight relative to the resin and the amount of dispersant (Montane 80 from Seppic) is 1% by weight of the added alkane. The tests use pentane as n-alkane with a content of 10 ml / g of crude. In each case, after crosslinking reaction and

evaporation, the viscosity of the samples is measured using an imposed stress rheometer. The results in Table 2 show that the lowest level of viscosity is obtained for 6% of resins.

Tab.2: Viscosity at 20 ° C of the samples encapsulated by crosslinked alkyd resins.

Test 5: Temperature resistance of crosslinked samples

In order to check the temperature resistance of the crosslinked products, the

viscosity of a sample was measured after heating at 50 and 80 ^° C. for 1 hour. This is the sample prepared from 6% by weight Synolac 6883 alkyd resins (cf test 4). The rheological measurements are presented in Table 3 and show a good stability of the product. Despite the important heat treatment, in particular at 80 ^° C., the viscosity of the crude oil is not

not reached.

Tab.3: Temperature resistance of the samples encapsulated by crosslinking of alkyd resins, viscosity measured at 20 ^° C.

Trial 6: Influence of the drying agent.

In order to observe the influence of the addition of the desiccant, a sample was

prepared from 6% Synolac resins without introducing siccatives. Its viscosity was measured after elaboration and after heating at 50 and 80 ^° C. for 1 hour. The results show that the non-drying sample has the same viscosity as the equivalent sample with siccative (50 Pa.s). In

However, the non-drying sample is much less resistant to

important heat treatment such as that at 80 ^° C. (see Table 4).

Tab.4: Temperature resistance of the samples encapsulated by crosslinking of alkyd resins, influence of the drying agent, viscosity measured at 20 ^° C.

Claims

1) A method of treating a viscous hydrocarbon containing asphaltenes, wherein the following steps are carried out:

at least a portion of the asphaltenes are precipitated by the addition in the hydrocarbon of a suitable solvent,

2) Method according to claim 1, wherein the asphaltenes are precipitated with n-alkane.

3) Method according to one of claims 1 or 2, wherein one adds polymerization products to form a membrane around the

asphaltene particles by interfacial polycondensation.

4) The method of claim 3, wherein di or triamine, or mixture thereof, and an acyl dichloride are added to form an aromatic polyamide on the surface of the asphaltene particles.

5) Method according to one of claims 1 or 2, wherein one adds

alkyd resins adapted to crosslink on the surfaces of the particles

asphaltenes. 6) Method according to claim 5, wherein a drying agent is added

as an agent promoting crosslinking.

7) Application of the method according to one of the preceding claims to obtain a viscosity reduction of a viscous hydrocarbon

asphaltene.

8) Application of the method according to claim 7, for the transport

of a viscous asphaltenic hydrocarbon by pipe.