FR2842886A1 - PROCESS FOR TRANSPORTING HEAVY OIL AND TREATMENT SITE - Google Patents

Abstract

The present invention relates to a method of transporting a heavy oil. This process comprises the following steps: a) an emulsion preparation step, where, at the starting point, an oil-in-water type emulsion is prepared by mixing the heavy oil with an aqueous solution containing a base; b) an emulsion transport step to the place of destination; c) an emulsion breaking step; andd) a separation step to obtain an oily phase and an aqueous phase; and it is characterized in that it further comprises, between step b) and step c), a step of destabilizing the The invention also relates to a site for treating a heavy oil, suitable for treating the transported oil. This site includes a unit for destabilizing an oil-in-water emulsion.

Description

PROCESS FOR TRANSPORTING HEAVY OIL AND

TREATMENT SITE

  The present invention relates to a method for transporting a heavy oil as well as a site for treating a heavy oil, capable of treating

the oil transported.

  In US Patent No. 4,923,483 is described the formation of a primary emulsion of the oil in water type from a heavy oil, the possible degassing of this primary emulsion, the adjustment of the difference in phase density of this emulsion, the breaking of the adjusted primary emulsion in a separator, the recovery of the separated heavy oil, the re-emulsification of the separated heavy oil by means of an emulsifier, its reconditioning to form a secondary oil in l water suitable for transport, the transport of this secondary emulsion, and finally the use of the secondary emulsion as fuel

or its refinement.

  This patent gives a certain number of indications on the primary emulsion. Concerning its preparation in particular, in Table IV and rows 34 to 39 of column 8 are described emulsions prepared from ammonia. The rupture of the primary emulsion is caused by adding a salt and / or a diluent to the emulsion as well as possibly a demulsifier when a surfactant has been used for the formation of

the primary emulsion.

  However, no indication is given in this patent on refining or further processing of

  the secondary emulsion other than its combustion.

  U.S. Patent No. 3,425,429 relates to a process for transporting a heavy oil in a pipeline, in which an aqueous solution of a nonionic surfactant is injected into the pipeline in order to create an oil emulsion in the water, we then move the heavy oil in the pipeline and once the emulsion has reached its destination, we separate the oil and water in a

  separator, at a temperature up to 820C.

  No details are given concerning the breaking of the emulsion. US Pat. No. 3,006,354 relates to a process for transporting heavy oil in a pipeline, in which an oil-in-water emulsion which is sufficiently unstable for it to rupture rapidly is prepared using ammonia. then the emulsion is transported in the pipeline, and once the emulsion has reached its destination, it is broken by heating at

  a temperature of up to 820C.

  This patent teaches, in particular by its Figure VIII, that it is advisable to use low ammonia contents (50 ppm), to obtain a satisfactory separation of the oily and aqueous phases. It follows that the emulsion prepared has too great instability and it is necessary to periodically add water so that

  its transport is done in good conditions.

  U.S. Patent No. 3,487,844 relates to a method of transporting a heavy oil, in which the heavy oil is contacted with water containing a base which may be an amine or hydroxide. ammonium, in the presence of an emulsifying agent, then stirred to form an oil-in-water emulsion which is then transported in the pipeline to the place of destination, where the emulsion is broken up and separated

heavy oil and water.

  This patent considers as better bases, sodium hydroxide and, in certain particular cases, hydroxides of alkaline earth metals. The exemplary embodiments of this patent use only sodium hydroxide. The emulsion produced is very stable. This is why it is proposed, with a view to breaking it inexpensively and effectively, to add a saline solution at temperatures which may be higher than 1350C. This technique therefore has the major drawback of introducing salt into the heavy oil, when the emulsion is broken. This salt is therefore added to the metal (sodium) introduced during the preparation of

the emulsion.

  This has the consequence of significantly increasing the amount of salt present in the heavy oil and which must in any case always be removed later, at the refinery, which increases the workload of the unit. desalting

  the refinery and therefore the overall cost of refining.

  In addition, the quantities of wastewater to be treated at the refinery are greater, which also increases the costs as well as the size of the

corresponding installations.

  It would therefore be advantageous to have a method for transporting a heavy oil, which makes it possible to transport this heavy oil under satisfactory conditions and then recover the starting oil without this increasing the workload of the unit. of the refinery and the quantities of water

waste produced.

  In addition, if the transport of the emulsion under good conditions involves obtaining an emulsion having good stability, this emulsion must also be capable of being easily broken at the place of destination. The object of the invention is therefore to propose a process making it possible to transport a heavy oil in the form of a stable oil-in-water emulsion, then to easily break this emulsion to recover the heavy oil, by introducing little, if any material which has a negative influence on the further processing of heavy oil. More specifically, this process comprises the following stages: a) a stage of emulsion preparation, o, at the place of departure, an emulsion of the oil in water type is prepared, by mixing the heavy oil with a solution aqueous containing a base b) an emulsion transport step to the place of destination; c) an emulsion breaking step; and d) a separation step to obtain an oily phase and an aqueous phase; and it is characterized in that it further comprises, between step b) and step c), a step

  destabilization of the emulsion transported.

  Thus, after the destabilization step, the nature of the emulsion has changed and it can then easily be

  break in the subsequent breaking step.

  This process also has the advantage of reducing the importance of washing, desalting and atmospheric distillation operations. Thus, compared to dilution techniques, the capacity of desalting and atmospheric distillation units is reduced by 20% for

  the same amount of treated heavy oil.

  According to a preferred embodiment of the invention, the method further comprises a step in which the

  base extracted and returned to the place of departure.

  This recycling of the base has the advantage of considerably reducing, or even eliminating, the need to continuously add fresh base at the production site and also makes it possible to reduce the

  emulsion preparation costs.

  The subject of the invention is also a site for treating a heavy oil which is capable of treating the oil transported according to the method of the invention, and, if necessary, then refining it according to conventional refining techniques. Such a site includes a destabilization unit

  an oil-in-water type emulsion.

  According to one embodiment of the invention, the unit

  destabilization includes a column.

  Other characteristics and advantages of the invention will now be described in detail in the description which follows and which is given with reference to the appended drawings in which - FIG. 1 schematically represents the steps of a method according to the prior art - Figure 2 schematically shows the steps of the method according to the invention; and - Figure 3 schematically shows a site of

  treatment of a heavy oil according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

  Method according to the invention The first step of the method according to the invention consists in carrying out the emulsion of the heavy oil in water on the starting site, that is to say,

  in most cases, the production site.

  Heavy oil can be very varied in nature.

  The invention applies in particular to so-called extra-heavy crudes, that is to say those whose viscosity is greater than 10,000 cP at 250C, the API degree (American Petroleum Institute) between 7 and 12, the TAN ( Total

  Acid Number) between 1 and 6 mg KOH / g of oil.

  In general, we start by mixing the water with the

  base to obtain the aqueous solution containing a base.

  As a base, a water-soluble base having a boiling point is generally used.

  lower than that of water, at atmospheric pressure.

  As examples of such a base, mention may be made of nitrogen compounds, in particular volatile amines such as ammonia, or alkylamines such as monomethylamine, monoethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine,

diisopropylamine, 2-amino butane.

  Preferably, ammonia or an amine having at most two carbon atoms in total or ammonia is used. The most preferred base of all the bases

  which have just been mentioned is ammonia.

  For practical reasons related to packaging, transport, storage and safety, ammonia is used in particular, that is to say ammonium hydroxide in aqueous solution, usually at a concentration of 20 to 30% by weight of ammonia. The aqueous solution containing the base is therefore preferably prepared by diluting such a mother ammonia solution until a 0.1% by weight aqueous ammonia solution is obtained intended to be mixed with

heavy oil.

  The mixing of the basic aqueous solution with the heavy oil, with a view to obtaining the emulsion, can be carried out in a mixer, for example of the collodal mill type. This emulsification can be carried out at the outlet of the well. It is then desirable to lower the viscosity of the heavy oil beforehand by heating it. In order to reduce the pressure losses during pumping, the emulsification can be carried out directly in the wells or in the drains, for example at the level of the suction of the pumps, or in the case of horizontal wells, over the entire length. drains from these wells. Wells can then be produced at high flow rates, using more powerful activation means, which is not possible with crude dilution techniques. In addition, formation water can be used to make the emulsion. This has the advantage of reducing the number of surface installations on the production site since there is no need to separate the crude from the formation water. In addition, this avoids, in some cases, heating of the heavy oil because it takes advantage of the fact that the heavy oil has a temperature

  high in the natural reservoir.

  The preparation of the emulsion on the production site also makes it easier to separate

  the associated gas only with dilution techniques.

  The amounts of heavy oil and basic aqueous solution are generally chosen so as to obtain an emulsion generally containing from 20 to 50% and preferably from 30 to 40% by weight of aqueous solution

  basic with respect to the total weight of the emulsion.

  The emulsion thus obtained generally has a viscosity of between 20 and 300 cP, preferably of the order of 30 cP, a value which is well below that of the heavy oil / diluent mixtures produced according to the techniques of the prior art. and who generally

a viscosity of 300 cP.

  The pH of the emulsion is generally between

  9 and 11, and is preferably less than 10.

  For certain types of heavy oils, it may be advantageous to add an organic acid to the heavy oil in order to facilitate the production of an emulsion. Reference may be made to British Patent No. GB 2,169,220 for

  get more information about this technique.

  The stability of the emulsion obtained is such that it is possible to transport this emulsion under good conditions to its place of destination, in general,

  the refining site where a refining unit is located.

  Transport is generally carried out by

  circulation inside pipelines.

  According to the invention, at the place of destination,

  the emulsion undergoes a destabilization operation.

  This destabilization of the emulsion generally consists in at least partially extracting the base of the emulsion, which causes a reorganization of the emulsion into two phases, one being rich in oil and

the other rich in water.

  The base extraction step can include a heat treatment of the emulsion. Thus, the emulsion is heated to a temperature generally between 70

and 1500C.

  Under such conditions, the base tends to

  evaporate, which facilitates its extraction.

  There is thus generally extracted at least 50%, preferably at least 70% and, more preferably

  again, the entire base contained in the emulsion.

  The extraction of the base can be carried out under

  other pressures than atmospheric pressure.

  It is generally implemented in a unit

  destabilization of the refining unit.

  Such a destabilization unit generally comprises an extraction column, which makes it possible to recover, at the bottom of the column, the destabilized emulsion and at the head of the column, the base as well as possibly

  traces of light hydrocarbons and water.

  According to an advantageous embodiment of the invention, provision is also made for stripping the column with a stripping gas which may be an inert gas, water vapor or a light hydrocarbon such

than methane.

  The destabilized emulsion from the destabilization unit can then easily break (by simple decantation or following heating) and be

separated in a conventional manner.

  At one of the separator outlets, an oily phase, that is to say rich in heavy oil, is recovered and at the other, an aqueous phase, that is to say rich in water. The invention provides the advantage that the oily phase has already undergone partial desalting, the initial salts of the heavy oil being found at least partly in the

  aqueous phase recovered at the outlet of the separator.

  To better understand the differences between the process according to the invention and the processes of the prior art (such as the process which is the subject of the aforementioned American patent No. 3,487,844), it is possible to compare the

Figures 1 and 2.

  It is thus clearly seen that, according to the invention, a destabilization step is provided between the step of

  transport b) and the breaking step c).

  According to one embodiment of the invention,

  the emulsion goes through a heater before breaking.

  According to another embodiment of the invention, before breaking, the destabilized emulsion is added with a diluent, for example at a rate of 10% by weight relative to the emulsion. This thinner is found

  then at the outlet of the separator in the oily phase.

  According to yet another embodiment of the invention, before breaking, the destabilized emulsion

  is added with a demulsifier.

  According to a preferred embodiment, the method according to the invention further comprises a step e) consisting in returning the base extracted from the emulsion to

the place of departure.

  This recycling of the base is advantageously done in the form of an aqueous solution, by dissolving the extracted base in water. The basic aqueous solution thus obtained can be brought back to the place of departure in trucks or via a pipeline. It can then be used for

preparation of the emulsion.

  In addition, the aqueous phase originating from the separation of the emulsion can advantageously be treated, with a view to deoiling it and desalting in order to obtain a secondary aqueous solution. The latter is then preferably returned to the production site in

  view of its reuse to prepare the emulsion.

  Heavy oil treatment site according to the invention The heavy oil treatment site according to the invention is capable of treating the oil transported under

form of aqueous emulsion.

  This site may include a refining unit.

  An embodiment of such a site appears on the

single figure appended.

  In this figure, part A represents the place of departure, that is to say the heavy oil production site and part B, the beginning of the place of destination, that is to say the beginning from the oil treatment site

  heavy, which may include a refining site.

  The constitution of the heavy oil treatment site according to the invention will now be described in

link with its functioning.

  We can see on the figure that the heavy oil coming from a pump 1 of the production site A is brought to a temperature of 70-900C in a heater 2 before being introduced into a mixer 3 of the collodal mill type o it is mixed with a solution

  basic aqueous arriving via an inlet 4 of the mixer 3.

  The basic aqueous solution was itself previously prepared by mixing in a conventional mixer 3bis supplied with water via line 5 and at the base

by line 6.

  The heavy oil in water emulsion obtained in the mixer 3 is then introduced into a pipeline 7 which transports it to the treatment site for

heavy oil.

  The latter comprises according to the invention a unit of

destabilization of the emulsion.

  This emulsion destabilization unit can

  be a column 8 with trays or packed.

  The inlet of this column 8 is connected to the pipeline 7. The extraction column 8 is provided with heating means allowing it to operate at a temperature

can vary between 70 and 1500C.

  It can possibly be preceded by a heater (not shown in the figure) to heat

  the emulsion before its introduction into column 8.

  At the head of column 8, the base is recovered via outlet 9 as well as possibly light hydrocarbons

and water.

  At the bottom of the column, we recover by outlet 10

the destabilized emulsion.

  A stripping gas which can be an inert gas, water vapor or a light hydrocarbon such as methane, is optionally introduced by line 11 in the column to produce an improving stripping

the extraction of the base.

  The destabilized emulsion is then broken and separated in a known manner, that is to say in general by heating in a heater 12 to a temperature of 110-1400C, then, introduction into a breaker / separator 13 o firstly, by line 14, the dehydrated heavy oil and by line 15,

an aqueous solution.

  Optionally, one can introduce via line 16 into the destabilized emulsion coming from the extraction column 8, a conventional demulsifier, and / or via line 17, a diluent as in the techniques of the prior art. Line 14 leads the heavy oil, and, where appropriate, the diluent, to the conventional units of a refining unit generally included in the term

  "Upgrading" relating to the processing of extra heavy oils.

  An advantage of the process according to the invention is that the heavy oil contained in line 14 has substantially the same composition as the heavy oil extracted on the production site. It still contains a bit of base but it has the advantage of having been at least partially desalted. Indeed, the aqueous phase of the emulsion has recovered part of the salts initially contained in the heavy oil. These salts are then found in the aqueous solution collected by line 15 which also still contains a little base and, if necessary

if applicable, the demulsifier.

  According to a preferred embodiment of the invention, the extracted base collected by line 9 of the column

  extraction is returned to the production site.

  For this, one can dissolve all the gaseous effluents from the extraction column 8 collected by line 9 in water to give a basic aqueous solution. Line 9 can then be connected to a pipeline 18 returning to the production site so that the basic aqueous solution is redirected by pipeline 18 to the production site, where it can be introduced at the inlet 4 of the mixer 3 to serve again to prepare the emulsion. The possible presence of traces of hydrocarbons in the solution

  recycled basic water is not a problem.

  According to another preferred embodiment of the invention, the production site further comprises a treatment unit 16 in which the aqueous phase coming from the breaker / separator 13 and arriving via line 15 is de-oiled and desalted and the salts are eliminated. via line 17, in order to recover a secondary aqueous solution. Provision can then be made to connect the processing unit 16 to the pipeline 18, so that the secondary aqueous solution is brought back to the production site in

  view of its reuse to prepare the emulsion.

  Thus, the pipeline 18 can bring back both the extracted base, arriving via the outlet 9 of the extraction column 8, and the base contained in the secondary aqueous solution, coming from the treatment unit 16.

Examples

  The following examples are just for

  illustrate the invention without limiting its scope.

Example 1

  A Venezuelan crude oil of the Zuata type, having an API degree of 8 and a viscosity of 263 cP at 100 ° C. (40,000 cP at 250 ° C.) was heated to 800 ° C. and then added with an aqueous solution containing 1 g of ammonia. per liter, until an oil-in-water type emulsion containing 60% by weight of crude

and 40% by weight of water.

  The pH of the emulsion obtained is 9.7 and the average size of the oil drops is 22 microns. The emulsion has a Newtonian behavior and its viscosity is around cP.

  This emulsion was placed in a balloon.

  To destabilize the emulsion, the latter was kept stirring at a temperature

  from 80-900C and under nitrogen sweeping.

  The effluents passed through a condenser installed so that it only condenses the water vapor

entrained with ammonia.

  The condenser outlet was connected to traps

containing hydrochloric acid.

  After 2 hours of nitrogen sweeping, the amount of water condensed was determined by increasing the weight of the condenser. The quantity of ammonia entrained was determined by acid-base determination of the water contained in the condenser

and in the traps.

  Results The quantity of water vapor entrained with ammonia corresponds to 43% of the initial quantity of water in the emulsion and the quantity of ammonia entrained (extract) corresponds to 75% of the initial quantity

of ammonia in the emulsion.

  In the flask, the destabilized emulsion obtained corresponds to a mixture of two phases which settles easily. After separation of the two phases, 72% by weight of a very viscous oily phase are obtained containing 88% by weight of heavy Zuata oil and 12% of water; it is actually a water-in-oil emulsion; and - 28% by weight of an aqueous phase comprising by weight 40% of oil dispersed in 60% of water; it is a finer oil-in-water emulsion than the initial emulsion (the average size of the oil drops is now 8 microns); the pH of this emulsion is 8.1; this decrease in pH from the value of 9.7

  initial is due to the loss of ammonia.

  The calculation of the different mass balances (oil, water, ammonia) makes it possible to deduce that: - the oily phase contains 85% of the initial quantity of heavy oil; this therefore corresponds to an oil separation of 85%; the aqueous phase contains 15% of the initial quantity of heavy oil; - the balance as regards ammonia, even if one takes into account the ammonia contained in the aqueous phase is not 100%, but 80%.

Example 2

  We prepare an initial emulsion identical to that

from example 1.

  The same equipment is used as in Example 1, except that the condenser has been arranged differently, above the tank, so that the maximum amount of water

falls back into the ball.

  Results After 5 hours of nitrogen sweeping, thanks to the new arrangement of the condenser, the water loss is less than 1% and the amount of entrained ammonia (extract), calculated as in Example 1, corresponds to

  100% of the ammonia initially present in the emulsion.

  In the flask, the destabilized emulsion obtained also corresponds to a mixture of two phases which

decant easily.

  After separation of the two phases, 71% by weight of a very viscous oily phase are obtained containing 83% by weight of heavy Zuata oil and 17% of water; it is a water in oil emulsion; and - 29% by weight of an aqueous phase comprising by weight 10% of oil dispersed in 90% of water; it is an oil in water emulsion; the pH of this emulsion is 7.5; this decrease in pH from the initial 9.7 is

due to loss of ammonia.

  Calculation of the different mass balances (oil,

  water, ammonia) allows us to deduce that :.

  - the oily phase contains 95% of the initial quantity of heavy oil; this therefore corresponds to an oil separation of 95% - the aqueous phase contains 5% of the initial quantity of heavy oil. Conclusions drawn from examples 1 and 2 The emulsions of the oil in water type, containing from to 65% (by weight) of Zuata oil, obtained under laboratory conditions, are characterized by a particle diameter of approximately 20 microns and by a

viscosity of about 30 cP.

  The results show that it is possible to completely extract the ammonia from the emulsion without extracting at the

times water.

  In addition, the rupture of the emulsions gives two easily separable phases, one of which, oily, is very viscous. It is a water-in-oil emulsion which may contain a very high content (95% by weight) of

the initial oil.

Claims (23)

  1. A method of transporting a heavy oil comprising the following steps: a) a step of preparing an emulsion, where, on the place of departure, an emulsion of the oil in water type is prepared, by mixing the heavy oil with an aqueous solution containing a base; b) an emulsion transport stage to the place of destination; c) an emulsion breaking step; and d) a separation step to obtain an oily phase and an aqueous phase; characterized in that it further comprises, between step b) and step c), a destabilization step of the emulsion transported.   2. Method according to claim 1, characterized in that the step of destabilizing the emulsion transported comprises at least partial extraction of the base of the emulsion.   3. Method according to claim 2, characterized in that, in the step of destabilizing the transported emulsion, at least 50%, preferably at least 70% and, more preferably still, the entire base.   4. A method of transporting a heavy oil according to claim 2 or claim 3, characterized in that the extraction of the base comprises a treatment thermal emulsion.   5. Transport method according to claim 4, characterized in that during the heat treatment, the emulsion is brought to a temperature between and 1500C.   6. Method according to one of claims 1 to 5,   characterized in that the destabilization step is carried out in a column (8) so that the destabilized emulsion is recovered, at the bottom of the column and at the column head, the base as well as possibly   light hydrocarbons and possibly water.   7. Method according to claim 6, characterized in that one further carries out a stripping of the column (8).   8. Method according to one of claims 1 to 7,   characterized in that the emulsion contains 20 to 50% and preferably 30 to 40% by weight of basic aqueous solution relative to the total weight of the emulsion.   9. Method according to one of claims 1 to 8,   characterized in that the base is chosen from water-soluble bases having a boiling temperature   lower than that of water, at atmospheric pressure.   10. Method according to claim 9, characterized in that the base is chosen from the group consisting of ammonia and alkylamines, in particular monomethylamine, monoethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine,   diisopropylamine, 2-amino butane.   11. Method according to claim 10, characterized in that that the base is ammonia.   12. Method according to one of claims 1 to 11,   characterized in that the heavy oil is an extra-heavy crude having a viscosity greater than 10,000 cP at 250C, an API degree between 7 and 12, a TAN (Total Acid Number) of approximately between 1 and 6 mg KOH / g oil.   13. Method according to one of claims 1 to 12,   characterized in that the pH of the emulsion is understood   between 9 and 11 and is preferably less than 10.   14. Method according to one of claims 2 to 13,   further comprising a step e) consisting in returning   the base extracted at the place of departure.   15. Method according to claim 14, characterized in that, in step e), the extracted base is returned to the place of departure in the form of an aqueous solution basic.   16. Method according to one of claims 1 to 15,   characterized in that the aqueous phase originating from the separation is treated and then returned to the place of departure.   17. Transport site for a heavy oil, comprising - at a place of departure, means for preparing an emulsion of the oil in water type, by mixing the heavy oil with an aqueous solution containing a base; means of transporting said emulsion to a place of destination; - emulsion breaking means - separation means to obtain an oily phase and an aqueous phase; characterized in that it further comprises an emulsion destabilization unit arranged upstream of the breaking means.   18. Heavy oil treatment site according to claim 17, characterized in that the emulsion destabilization unit comprises a column (8) comprising an inlet (7) of emulsion to be destabilized, an outlet (9 ) gaseous effluents at the top of the column and an emulsion outlet (10) destabilized at the bottom of the column.   19. Heavy oil treatment site according to claim 18, characterized in that the column   extraction (8) is preceded by a heater.   20. Heavy oil treatment site according to claim 18 or claim 19, characterized in that the extraction column (8) comprises   in addition to an inlet (11) for stripping gas.   21. Heavy oil treatment site according to one   claims 18 to 20, characterized in that the   outlet (9) of the extraction column (8) is connected to a pipeline (18) returning to the place of departure. 22. Heavy oil treatment site according to one   of claims 17 to 21, characterized in that it   further comprises a separator (13) of destabilized emulsion and a treatment unit (16) of the aqueous phase separated from the emulsion, in order to obtain a secondary aqueous solution.   23. Heavy oil treatment site according to claim 22, characterized in that the outlet of secondary aqueous solution from the treatment unit (16) is connected to the pipeline (18) returning to the place of departure.