CA2165865C - Process for deasphalting bitumen - Google Patents
Process for deasphalting bitumenInfo
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- CA2165865C CA2165865C CA002165865A CA2165865A CA2165865C CA 2165865 C CA2165865 C CA 2165865C CA 002165865 A CA002165865 A CA 002165865A CA 2165865 A CA2165865 A CA 2165865A CA 2165865 C CA2165865 C CA 2165865C
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- Prior art keywords
- bitumen
- asphaltene
- water emulsion
- water
- emulsion
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/02—General arrangement of separating plant, e.g. flow sheets specially adapted for oil-sand, oil-chalk, oil-shales, ozokerite, bitumen, or the like
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- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Geology (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Liquid Carbonaceous Fuels (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
Abstract
A process for upgrading heavy oil and bitumen includes deasphalting the bitumen by de-watering the bitumen/water emulsion to a water concentration of from about 0 to about 20% by volume. A surfactant is added to the de-watered bitumen/water emulsion to form a stable asphaltene-in-water emulsion as a separate phase from the deasphalted bitumen. The surfactant is preferably non-ionic and, more preferably, an ethoxylated alkyl phenol. In accordance with the present invention, the viscosity of the bitumen is significantly reduced and the quality of the bitumen is improved. The asphaltene is recovered in a useable form which can be used as a source of fuel at the production site and which additionally can be used to enhance the recovery of the bitumen from the rock formation.
Description
PROCESS FOR DEASPHALTING BITUMEN
FIELD OF THE INVENTION
The present invention relates to the f1eld of upgrading heavy oil or bitumen and, in particular, to a process for deasphalting heavy oil or bitumen.
BACKGROUND OF THE INVENTION
There are many subterranean tar sand formations throughout the world which contain high viscosity heavy oil and bitumen. The vast Athabasca tar sand field and the Cold Lake deposits in Alberta, Canada represent some of the most notable examples of such formations.
For the purposes of this application, all viscous hydrocarbons, including heavy crude oil and bitumen, will be referred to herein as bitumen.
A variety of methods have been proposed for recovering bitumen from these formations by increasing the mobility of the bitumen. Such methods include solvent injection and thermal steam injection processes. One known method for recovery of bitumen is the so-called Cyclic Steam Stimulation (CSS) process.
In the CSS process, steam is injected through a well into a bitumen-bearing formation.
Heat transferred to the formation lowers the viscosity of the bitumen, thereby improving the mobility thereof. Several cycles of steam injection and bitumen production are continued until bitumen production becomes too low to justify further steam injection.
Bitumen is recovered in the CSS process as a water-in-bitumen emulsion or as a mixture of a water-in-bitumen emulsion and free water which has a high viscosity due to a relatively high concentration, for example from about 15 to 40%, of asphaltene in bitumen.
Unlike conventional crude, viscous bitumen cannot be transported by pipeline. One method for transporting bitumen in a pipeline includes heating the bitumen prior to and during transport. However, this method is expensive and very impractical as heating equipment must be installed and the pipeline must be insulated.
Another method for transporting bitumen involves diluting the bitumen with a C5-Clo gas plant condensate diluent. For example, bitumen from the Cold Lake field is typically diluted with 27 to 30% (vol) C5-Clo gas plant condensates to sufficiently reduce the viscosity of the bitumen for transport to a refinery. However, the disadvantages of this method are the dependency on the availability of gas plant condensates, loss of the diluent during blending and recovering the full cost of the diluent from customers, i.e. refineries.
Partial upgrading has therefore been proposed to separate the heavier fraction of bitumen prior to transport. Known partial upgrading processes include separation of the heavier fraction by distillation or by using light hydrocarbon solvents. One such process involves dissolving bitumen in 2 to 10 times (v/v) of a C3-CI0 light hydrocarbon solvent to lower the viscosity by precipitating the solvent-insoluble asphaltene and subsequently removing the precipitate by liquid/solid separation.
French Patent Application Number 2,579,218 (Ballmgartner, P., September 26, 1986) relates to a process for deasphalting heavy hydrocarbon oils. The process consists of forming an oil-in-water emulsion and adding a sufficient quantity of a deasphalting solvent to separate the mixture into two phases, the upper phase consisting of a mixture of deasphalted oil and solvent and the lower phase consisting of a suspension of asphaltene in water. The water:oil ratio in the emulsion is in the range of from 25:75 to 40:60, preferably in the range of from 30:70 to 50:50. Optionally, the oil-in-water emulsion is prepared by mixing the heavy oil with water and with a surfactant, the proportion of surfactant sufficient to form an oil-in-water emulsion.
United States Patent Number 4,634,520 (Angelov, G. et al, January 6, 1987) describes a process for simultaneous de-emulsification and deasphalting of a heavy oil/water emulsion.
A heavy oil/water emulsion is mixed with from 2 to 5 times by weight of pentane or a mixture of pentane, butane and hexane, of which pentane is the major component.
Deasphalted oil, asphaltics and emulsion water are recovered separately in three different phases. The solvent-insoluble asphaltics coalesce around the dispersed emulsion water such that particles comprising water droplets stabilized by a sheath of asphaltics settle out of the emulsion. After some of the oil and solvent mixture is decanted, the particles are coalesced into large stable agglomerates by feeding the mixture to a hot water bath at a temperature of from 85 to 95C. The agglomerates are skimmed from the surface of the water.
International Publication Number WO 90/06350 (Muller, A., June 14, 1990) teaches a solvent-deasphalting process for a bitumen-in-water emulsion, which is performed in the presence of a surfactant selected to provide a three-phase mixture. The volume of solvent is from 2 to 5 times the volume of the bitumen-in-water emulsion. The upper phase contains the solvent and deasphalted bitumen, while the intermediate phase is aqueous and the lower phase contains the solvent-insoluble asphaltene. The intermediate phase contains the surfactant as well as any soluble mineral salts which were present in the bitumen-in-water emulsion. The asphaltene is in a semi-solid or solid form which is difficult to handle.
Bearing in mind that the partial upgrading is to be performed at the production site to facilitate transport to a refinery, the disadvantages of the processes for partial upgrading described above are that they increase production costs by involving a number of steps, costly equipment for heating or supplying water baths, relatively sophisticated liquid/solids separation techniques and equipment, and/or the addition of a significant amount, up to 10 times by volume, of a solvent.
Moreover, the asphaltene is in the form of a waste product when it is separated from bitumen using the above-described processes. As mentioned previously, asphaltene is typically recovered as a solid or a semi-solid which is difficult to handle. Also, in currently known processes wherein asphaltene is removed from the bitumen as an asphaltene-in-water emulsion, the water content is too high for the asphaltene-in-water emulsion to be useful as a fuel. For example, an asphaltene-in-water emulsion produced from a bitumen-in-water emulsion having a typical water content of 30% and an asphaltene yield of 20 to 30% (based 21 6586~
on bitumen) will have a water content of from 59 to 68% water, which is too high for use as a fuel. Another requirement for a fuel is a stable asphaltene-in-water emulsion.It will be appreciated by those skilled in the art that an integrated process for deasphalting bitumen and producing a useable asphaltene product would be very desirable.
One particularly advantageous use for asphaltene is as a fuel. CSS is an energy-intensive process requiring three barrels of steam (water-equivalent) to produce one barrel of oil. The most preferred fuel for generating steam is natural gas although its availability and cost continue to be of concern. It would therefore be very advantageous to produce an asphaltene emulsion from a partial upgrading process for use as a fuel for steam generation.
Another use for an asphaltene product is for plugging the steam-swept zones of areservoir to produce bitumen from unswept zones during CSS, thereby increasing the sweep efficiency of the process.
Bitumen also contains heavy fractions which are rich in heavy metals, such as nickel and vanadium, and sulfur. It will be appreciated by those skilled in the art that a relatively simple partial upgrading process which increases the value of bitumen by removal of the heavy metals and sulfur would be very advantageous.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a process for upgrading bitumen, comprising the steps of: de-watering a bitumen/water emulsion to reduce the concentration of water therein to a concentration in the range of from about 0 to about 20% by volume; adding a solvent and an asphaltene-dispersing surfactant to the de-watered bitumen/water emulsion to form a stable asphaltene-in-water emulsion; settling the mixture into two phases, the upper phase comprising deasphalted bitumen and the lower phase comprising an asphaltene-in-water emulsion; and separating the two phases.
According to another aspect of the present invention, there is provided a process for upgrading bitumen, comprising the steps of: adding an inversion surfactant downhole to invert ~ I 65865 a water-in-bitumen emulsion to a bitumen-in-water emulsion; pumping the bitumen-in-water emulsion to the surface; de-watering the bitumen-in-water emulsion to reduce theconcentration of water therein to a concentration in the range of from about 0 to about 20%
by volume; adding a solvent to the de-watered bitumen-in-water emulsion; adding an asphaltene-dispersing surfactant to the bitumen-in-water emulsion to form a stable asphaltene-in-water emulsion; settling the mixture into two phases, the upper phase comprising deasphalted bitumen and the lower phase comprising an asphaltene-in-water emulsion; and separating the two phases.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A process for partially upgrading bitumen according to the present invention includes treating a bitumen/water emulsion, for example a wellhead emulsion, by at least partially de-watering the emulsion, adding a solvent and an asphaltene-dispersing surfactant to the de-watered emulsion, and settling the resultant mixture into a first layer cont~ining deasphalted bitumen (DAB) and solvent and a second layer cont~ining a stable asphaltene-in-water emulsion. The asphaltene particles are dispersed in a continuous water phase which is separated from the DAB and solvent. The bitumen is thus partially upgraded by deasphalting, de-watering and reducing the concentration of other impurities. Furthermore, the DAB has a significantly lower viscosity, facilitating transport to a refinery. As used herein, the term bitumen/water emulsion will be understood to include water-in-bitumen and bitumen-in-water emulsions and mixtures of water-in-bitumen emulsions and free water.
Thus, in accordance with the present invention, the bitumen is of a higher quality, and therefore of a higher value. Furthermore, the asphaltene is separated *om the bitumen as a stable asphaltene-in-water emulsion. The stable asphaltene-in-water emulsion produced by the present invention has a relatively low viscosity, especially as compared with known processes wherein the asphaltene is in the form of a solid or a semi-solid and is typically regarded as a ~ 1 6586~
waste material which is difficult to handle. The asphaltene-in-water emulsion can be used as an alternate fuel, as a CSS process enhancer and as road pavement and roofing material.
As discussed previously herein, bitumen is typically recovered from a well by a CSS
process in the form of a water-in-bitumen emulsion or as a mixture of a water-in-bitumen emulsion and free water. In one embodiment of the present invention, the bitumen/water emulsion is de-watered to a water content in the range of from about 0 to about 20% by volume, by a process known to those skilled in the art. Such processes include heat treatment, addition of a solvent, addition of a chemical demulsifier, electrostatic coalescence, membrane processes and combinations thereof.
By reducing the water content in the bitumen/water emulsion, the asphaltene-in-water emulsion is produced as a usable product. As mentioned previously herein, an asphaltene-in-water emulsion produced from a bitumen-in-water emulsion having a typical water content of 30% and an asphaltene yield of 20 to 30% (based on bitumen) will have a water content of from 59 to 68% water which is too high for use as a fuel. In accordance with the present invention, the water content of the asphaltene-in-water emulsion is reduced substantially to provide a product which is useful, for example as a fuel, instead of a waste product. The de-watering step has the further advantage that some of the impurities, such as sodium, calcium, magnesium and silica, are removed in the discarded water. The resultant asphaltene-in-water emulsion is therefore of a higher quality.
The solvent deasphalting step is performed by addition of a solvent and an asphaltene-dispersing surfactant to the bitumen/water emulsion. Suitable solvents are one or more C3-CI5 hydrocarbons or C5-Clo gas plant condensates. Preferably, the solvent is a C3-C10 hydrocarbon. Examples of suitable solvents are propane, butane, pentane, hexane, heptane and naphtha. As in conventional deasphalting, the yield of DAB increases while the quality of the DAB deteriorates with higher molecular weight solvents. A solvent is therefore selected such that it provides a good yield of DAB with acceptable quality.
Preferably, the bitumen/water emulsion, solvent and surfactant are mixed in a static in-line mixer. The in-line mixer is a tube or pipe having several alternating right- and left-2 1 65~b~
handed helices oriented so that each leading edge is at 90 to the trailing edge of the oneahead. The flow rate of fluids, the internal diameter of the tube or pipe and the number of elements are some of the parameters that can be varied to obtain good mixing and the required residence time to separate the asphaltenes.
The solvent is added to the bitumen/water emulsion, for example, in a ratio of from about l:1 to about 5:1 (v/v). Solvent deasphalting may be conducted at temperatures and pressures ranging from ambient temperatures and pressures to conditions typical of existing processing streams, for example to temperatures up to about 150C and pressures up to about 200 psi.
The asphaltene in the bitumen/water emulsion is not soluble in the solvent and if the de-watered bitumen/water emulsion was treated with solvent alone, the asphaltene would separate from the bitumen and the water as a third phase, as described in International Publication Number WO 90/06350 discussed previously herein. Moreover, the asphaltene would be in the undesirable form of a solid or a semi-solid. The addition of a suitable asphaltene-dispersing surfactant in accordance with the present invention results in a two-phase separation of bitumen/solvent and a stable asphaltene-in-water emulsion. Furthermore, the asphaltene-in-water emulsion has a relatively low viscosity.
The asphaltene-dispersing surfactant of the present invention is any non-ionic or ionic surfactant which is capable of forming a stable asphaltene-in-water emulsion. A stable asphaltene-in-water emulsion is defined herein as being an emulsion in which the asphaltene particles dispersed in the continuous water phase are small and do not readily settle out of the continuous phase over a period of time. Preferably, the asphaltene particles of the asphaltene-in-water emulsion are of an average particle size of about 10 ~m. A stable emulsion is also an emulsion which can be pumped without breaking.
As will be discussed in more detail below, if the asphaltene-in-water emulsion is to be used as an emulsion fuel, the surfactant should preferably not contain any sodium.
Accordingly, a non-ionic surfactant is preferred because it does not introduce any undesirable alkali metal ions to the emulsion or change the pH. The surfactant is selected to have the proper hydrophillic-lipophilic balance to create a stable asphaltene-in-water emulsion.
Suitable asphaltene-dispersing surfactants include ethoxylated alkyl phenols, ethoxylated dialkyl phenols, ethoxylated alcohols, block polymers of ethylene oxide and propylene oxide, propoxylated alkyl phenols and propoxylated dialkyl phenols. Preferably, the surfactant is an ethoxylated nonyl phenol with from about 4 to about 40 ethoxy groups per mole of nonyl phenol.
The asphaltene-dispersing surfactant is preferably used in a concentration in the range of from about 100 to about 50,000 ppm, more preferably from about 500 to about 10,000 ppm, based on the weight of bitumen/water emulsion. The asphaltene-dispersing surfactant may be added at ambient conditions or at elevated process stream temperatures, for example 150C, and pressures, for example 200 psi.
The asphaltene-dispersing surfactant may be introduced in the form of an aqueoussolution of the surfactant. In the case wherein the water is substantially completely removed from the emulsion, water is introduced by way of an aqueous solution of the asphaltene-dispersing surfactant and/or free water to achieve the desired water content in the asphaltene-in-water emulsion.
The mixture is then allowed to settle in a separation vessel. Due to the densitydifference, the DAB-solvent mixture separates at the top of the vessel and the asphaltene-in-water emulsion at the bottom. The asphaltene-dispersing surfactant creates a stable asphaltene-in-water emulsion.
In another embodiment of the present invention, the water-in-bitumen emulsion is first inverted downhole to a bitumen-in-water emulsion by injection of an inversion surfactant directly into the borehole. The bitumen-in-water emulsion is then de-watered at the surface in a manner known to those skilled in the art, for example, by fl~hing the water continuous phase, centrifugation, and membrane processes. In the embodiment wherein the bitumen/water emulsion is inverted downhole, the recovery of bitumen is increased because the viscosity is reduced.
A water-in-bitumen emulsion may be inverted by addition of an inversion surfactant before or after the de-watering step. It will however be appreciated by those skilled in the art that, as the water concentration in the de-watered bitumen/water emulsion approaches 0%, the emulsion may not be easily inverted.
Suitable inversion surfactants are ethoxylated alkyl phenols and ethoxylated dialkyl phenols. Preferably, the inversion surfactant is ethoxylated nonyl phenol. A particularly suitable ethoxylated nonyl phenol is an ethoxylated nonyl phenol with 10 to 20 ethoxy groups per mole of nonyl phenol. It is not necessary for the inversion surfactant to create a stable bitumen-in-water emulsion as the bitumen-in-water emulsion is merely an intermediate in the integrated process of the present invention. The inversion surfactant is preferably added in a concentration of from about 50 to about 50,000 ppm, more preferably in a concentration of from about 100 to about 10,000 ppm, based on the weight of bitumen/water emulsion.
The DAB-solvent mixture may then be subjected to a solvent recovery step whereinthe solvent is recovered by distillation. Preferably, the recovered solvent is recycled to the deasphalting step with make-up solvent. Optionally, enough solvent is left in the DAB during distillation to meet the pipeline viscosity specification.
Preferably, the asphaltene-in-water emulsion is further enhanced by sonication and/or by passing the asphaltene-in-water emulsion through a static in-line mixer to create smaller particles. This is especially desirable if the asphaltene-in-water emulsion is to be used as a fuel. The asphaltene particles in the asphaltene-in-water emulsion may be made finer by sonication, for example at 20 to 40 kHz. The use of sonication creates a more stable asphaltene-in-water emulsion.
The stable asphaltene-in-water emulsion produced in accordance with the present invention is in a form that may be used in various applications. For example, the asphaltene-in-water emulsion can be used to enhance the CSS process, as an alternate fuel or as road pavement and roofing materials.
One problem with the CSS process is that only the zone proximate the injection well is swept by the steam injected into the well, while further away from the injection well, bitumen 2 1 6~865 is still viscous in cold or unswept zones. The steam distribution problem is a result of steam leaking through pores in the steam-swept zone. A variety of efforts have been made to find fluids which can be economically injected to plug the pores in the steam-swept zone of the formation, where steam has displaced most of the viscous oil, so as to divert steam which is injected thereafter to the cold zones of the formation.
The asphaltene-in-water emulsion of the present invention may be injected downhole to block high permeability channels so that subsequent injection of steam forces asphaltene into the pores, thereby reducing the permeability of the rock formation and enhancing the distribution of steam into the formation, especially into previously cold zones.Another use for the asphaltene-in-water emulsion is as an alternate fuel. It will be appreciated by those skilled in the art that the creation of an emulsion fuel is difficult using solid asphaltene. Solid asphaltene must generally be heated to a high temperature and mixed at a high shear rate with water cont~ining a suitable surfactant. In accordance with the present invention, there is a fine dispersion of asphaltene in the water. The dispersion may be made even finer by sonication. If the asphaltene-in-water emulsion is to be used as an alternate fuel, the surfactant is preferably a non-ionic surfactant with no sodium ions. It will be appreciated by those skilled in the art that sodium ions would cause corrosion of the boiler tubes.
It will be appreciated by those skilled in the art that the present invention provides an integrated process for recovery and partially upgrading bitumen. In accordance with the present invention, the viscosity of the bitumen is significantly reduced and the quality of the bitumen is improved. The asphaltene is recovered in a useable form which can be used as a source of fuel at the production site and which additionally can be used to enhance the recovery of the bitumen from the rock formation. Furthermore, it is also possible to recycle the water recovered from the bitumen-in-water emulsion to the steam generation plant at the production site.
In accordance with the present invention, the viscosity of the bitumen is significantly reduced by deasphalting. Furthermore, as compared with conventional solvent deasphalting 2 1 6586~
processes, less solvent is required. For example, the requirement for solvent can be reduced to as low as about 1:1 (v/v) of solvent:emulsion. Accordingly, there is a significant savings in the cost of the solvent and the cost of recovery of solvent.
Described below are one example of a conventional solvent deasphalting process for comparative purposes and two examples of the process of the present invention. Examples of the present invention are for illustrative purposes only and are not intended to limit the scope of the invention defined by the claims below.
Comparative Example 1 Conventional Solvent Deasphalting Process A wellhead sample cont~ining a water-in-bitumen (30:70) emulsion was obtained from a CSS-stimulated well from the Cold Lake field in Alberta, Canada. The emulsion was deasphalted with pentane as a solvent using a pentane to emulsion ratio of 2:1 (v/v) at ambient conditions. The solvent was first mixed with 50 ml of emulsion using a glass rod.
The solvent-emulsion mixture was then shaken in an orbital shaker for 10 minutes at 300 rpm.
After mixin~, the asphaltenes were allowed to precipitate.
After 15 minutes of settling, the DAB and pentane layer was pipetted out from the top of the bottle. The asphaltene and water settled at the bottom of the bottle. The asphaltene was in a semi-solid form and entrained some of the water. Such a semi-solid asphaltene precipitate is difficult to handle and to emulsify.
The concentration of vanadium and nickel in the DAB was 98 and 40 ppm, respectively, as compared to 177 ppm vanadium and 80 ppm nickel in un-deasphalted bitumen. The viscosity of the DAB was 4000 cp at 23C compared to a bitumen viscosity of 110,000 cp at 23C.
Example 1 100 g (98 ml) of de-watered bitumen (0% water), 200 ml of pentane and 15.53 g of an aqueous surfactant solution cont~ining 3% ethoxylated nonyl phenol (11 ethoxy groups per mole of nonyl phenol) were mixed in an orbital shaker at 250 rpm for 10 minutes. The mixture was allowed to settle, forming two layers. The top layer was DAB diluted with pentane and the bottom layer was an asphaltene-in-water emulsion.
The two layers were separated and the pentane was recovered from the DAB. The asphaltene-in-water emulsion was sonicated at 20 kHz for 29 minutes to make a finer dispersion.
The DAB yield was 75% (by weight) based on the bitumen starting material and theasphaltene yield was 25% (by weight). The asphaltene-in-water emulsion contained 37%
water. The particle size of the sonicated emulsion was 10 ,um.
The concentration of vanadium, nickel, sodium and calcium in the DAB was 126, 52, 4 and 11 ppm, respectively, as compared to 190 ppm vanadium, 77 ppm nickel, 928 ppm sodium and 67 ppm calcium in un-deasphalted bitumen. The viscosity of the DAB was 2240 cp at 40C compared to a bitumen viscosity of 12,000 cp at 40C.
The Example generated two useful products. The viscosity of the partially upgraded DAB was reduced to approximately one-sixth of that of the bitumen starting material. The metal content of the DAB was approximately 50% lower than that of the bitumen starting material. The asphaltene-in-water emulsion had a water content sufficiently low to be used as a fuel to generate steam for the CSS process for recovery of bitumen. The asphaltene-in-water emulsion is also suitable for injection into the reservoir to improve the sweep efficiency of the CSS process.
Example 2 A water-in-bitumen emulsion (100 g) cont~ining 23.3% water from a steam-stimulated well at Cold Lake, Alberta was centrifuged to reduce the water content to 13.4%. The emulsion with reduced water was mixed with an ethoxylated nonyl phenol surfactant and a C5-C~o solvent at room temperature. The ratio of solvent to emulsion was 2.9:1 (v/v). The DAB yield of 94.3% was higher than that obtained in Example 1, in which a lighter solvent was used. However, the quality of the DAB was not as good, with concentrations of nickel and vanadium of 59 ppm and 148.5 ppm, respectively, as compared to the concentrations of 69 and 167 ppm in the original bitumen.
The viscosity of the DAB was 4257 cp at 25C and 1092 cp at 39.7C compared to abitumen viscosity of 33,530 cp at 25C and 5817 cp at 39.8C. Note that the asphaltene yield in this Example is only 5.7%. Thus, even though the water-in-bitumen emulsion feed contained only 13.4% water, the asphaltene-in-water emulsion contains 73% water, which is more than the desired content of 30% or less. To achieve a 30% water content in the asphaltene-in-water emulsion, the water content in the original water-in-bitumen emulsion should have been reduced to about 2.4%.
This Example illustrates the effect of a higher molecular weight solvent on the yield and quality of DAB. It also demonstrates the requirement for a low water content in the starting bitumen/water emulsion to achieve an asphaltene-in-water emulsion of the desired water content.
FIELD OF THE INVENTION
The present invention relates to the f1eld of upgrading heavy oil or bitumen and, in particular, to a process for deasphalting heavy oil or bitumen.
BACKGROUND OF THE INVENTION
There are many subterranean tar sand formations throughout the world which contain high viscosity heavy oil and bitumen. The vast Athabasca tar sand field and the Cold Lake deposits in Alberta, Canada represent some of the most notable examples of such formations.
For the purposes of this application, all viscous hydrocarbons, including heavy crude oil and bitumen, will be referred to herein as bitumen.
A variety of methods have been proposed for recovering bitumen from these formations by increasing the mobility of the bitumen. Such methods include solvent injection and thermal steam injection processes. One known method for recovery of bitumen is the so-called Cyclic Steam Stimulation (CSS) process.
In the CSS process, steam is injected through a well into a bitumen-bearing formation.
Heat transferred to the formation lowers the viscosity of the bitumen, thereby improving the mobility thereof. Several cycles of steam injection and bitumen production are continued until bitumen production becomes too low to justify further steam injection.
Bitumen is recovered in the CSS process as a water-in-bitumen emulsion or as a mixture of a water-in-bitumen emulsion and free water which has a high viscosity due to a relatively high concentration, for example from about 15 to 40%, of asphaltene in bitumen.
Unlike conventional crude, viscous bitumen cannot be transported by pipeline. One method for transporting bitumen in a pipeline includes heating the bitumen prior to and during transport. However, this method is expensive and very impractical as heating equipment must be installed and the pipeline must be insulated.
Another method for transporting bitumen involves diluting the bitumen with a C5-Clo gas plant condensate diluent. For example, bitumen from the Cold Lake field is typically diluted with 27 to 30% (vol) C5-Clo gas plant condensates to sufficiently reduce the viscosity of the bitumen for transport to a refinery. However, the disadvantages of this method are the dependency on the availability of gas plant condensates, loss of the diluent during blending and recovering the full cost of the diluent from customers, i.e. refineries.
Partial upgrading has therefore been proposed to separate the heavier fraction of bitumen prior to transport. Known partial upgrading processes include separation of the heavier fraction by distillation or by using light hydrocarbon solvents. One such process involves dissolving bitumen in 2 to 10 times (v/v) of a C3-CI0 light hydrocarbon solvent to lower the viscosity by precipitating the solvent-insoluble asphaltene and subsequently removing the precipitate by liquid/solid separation.
French Patent Application Number 2,579,218 (Ballmgartner, P., September 26, 1986) relates to a process for deasphalting heavy hydrocarbon oils. The process consists of forming an oil-in-water emulsion and adding a sufficient quantity of a deasphalting solvent to separate the mixture into two phases, the upper phase consisting of a mixture of deasphalted oil and solvent and the lower phase consisting of a suspension of asphaltene in water. The water:oil ratio in the emulsion is in the range of from 25:75 to 40:60, preferably in the range of from 30:70 to 50:50. Optionally, the oil-in-water emulsion is prepared by mixing the heavy oil with water and with a surfactant, the proportion of surfactant sufficient to form an oil-in-water emulsion.
United States Patent Number 4,634,520 (Angelov, G. et al, January 6, 1987) describes a process for simultaneous de-emulsification and deasphalting of a heavy oil/water emulsion.
A heavy oil/water emulsion is mixed with from 2 to 5 times by weight of pentane or a mixture of pentane, butane and hexane, of which pentane is the major component.
Deasphalted oil, asphaltics and emulsion water are recovered separately in three different phases. The solvent-insoluble asphaltics coalesce around the dispersed emulsion water such that particles comprising water droplets stabilized by a sheath of asphaltics settle out of the emulsion. After some of the oil and solvent mixture is decanted, the particles are coalesced into large stable agglomerates by feeding the mixture to a hot water bath at a temperature of from 85 to 95C. The agglomerates are skimmed from the surface of the water.
International Publication Number WO 90/06350 (Muller, A., June 14, 1990) teaches a solvent-deasphalting process for a bitumen-in-water emulsion, which is performed in the presence of a surfactant selected to provide a three-phase mixture. The volume of solvent is from 2 to 5 times the volume of the bitumen-in-water emulsion. The upper phase contains the solvent and deasphalted bitumen, while the intermediate phase is aqueous and the lower phase contains the solvent-insoluble asphaltene. The intermediate phase contains the surfactant as well as any soluble mineral salts which were present in the bitumen-in-water emulsion. The asphaltene is in a semi-solid or solid form which is difficult to handle.
Bearing in mind that the partial upgrading is to be performed at the production site to facilitate transport to a refinery, the disadvantages of the processes for partial upgrading described above are that they increase production costs by involving a number of steps, costly equipment for heating or supplying water baths, relatively sophisticated liquid/solids separation techniques and equipment, and/or the addition of a significant amount, up to 10 times by volume, of a solvent.
Moreover, the asphaltene is in the form of a waste product when it is separated from bitumen using the above-described processes. As mentioned previously, asphaltene is typically recovered as a solid or a semi-solid which is difficult to handle. Also, in currently known processes wherein asphaltene is removed from the bitumen as an asphaltene-in-water emulsion, the water content is too high for the asphaltene-in-water emulsion to be useful as a fuel. For example, an asphaltene-in-water emulsion produced from a bitumen-in-water emulsion having a typical water content of 30% and an asphaltene yield of 20 to 30% (based 21 6586~
on bitumen) will have a water content of from 59 to 68% water, which is too high for use as a fuel. Another requirement for a fuel is a stable asphaltene-in-water emulsion.It will be appreciated by those skilled in the art that an integrated process for deasphalting bitumen and producing a useable asphaltene product would be very desirable.
One particularly advantageous use for asphaltene is as a fuel. CSS is an energy-intensive process requiring three barrels of steam (water-equivalent) to produce one barrel of oil. The most preferred fuel for generating steam is natural gas although its availability and cost continue to be of concern. It would therefore be very advantageous to produce an asphaltene emulsion from a partial upgrading process for use as a fuel for steam generation.
Another use for an asphaltene product is for plugging the steam-swept zones of areservoir to produce bitumen from unswept zones during CSS, thereby increasing the sweep efficiency of the process.
Bitumen also contains heavy fractions which are rich in heavy metals, such as nickel and vanadium, and sulfur. It will be appreciated by those skilled in the art that a relatively simple partial upgrading process which increases the value of bitumen by removal of the heavy metals and sulfur would be very advantageous.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a process for upgrading bitumen, comprising the steps of: de-watering a bitumen/water emulsion to reduce the concentration of water therein to a concentration in the range of from about 0 to about 20% by volume; adding a solvent and an asphaltene-dispersing surfactant to the de-watered bitumen/water emulsion to form a stable asphaltene-in-water emulsion; settling the mixture into two phases, the upper phase comprising deasphalted bitumen and the lower phase comprising an asphaltene-in-water emulsion; and separating the two phases.
According to another aspect of the present invention, there is provided a process for upgrading bitumen, comprising the steps of: adding an inversion surfactant downhole to invert ~ I 65865 a water-in-bitumen emulsion to a bitumen-in-water emulsion; pumping the bitumen-in-water emulsion to the surface; de-watering the bitumen-in-water emulsion to reduce theconcentration of water therein to a concentration in the range of from about 0 to about 20%
by volume; adding a solvent to the de-watered bitumen-in-water emulsion; adding an asphaltene-dispersing surfactant to the bitumen-in-water emulsion to form a stable asphaltene-in-water emulsion; settling the mixture into two phases, the upper phase comprising deasphalted bitumen and the lower phase comprising an asphaltene-in-water emulsion; and separating the two phases.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A process for partially upgrading bitumen according to the present invention includes treating a bitumen/water emulsion, for example a wellhead emulsion, by at least partially de-watering the emulsion, adding a solvent and an asphaltene-dispersing surfactant to the de-watered emulsion, and settling the resultant mixture into a first layer cont~ining deasphalted bitumen (DAB) and solvent and a second layer cont~ining a stable asphaltene-in-water emulsion. The asphaltene particles are dispersed in a continuous water phase which is separated from the DAB and solvent. The bitumen is thus partially upgraded by deasphalting, de-watering and reducing the concentration of other impurities. Furthermore, the DAB has a significantly lower viscosity, facilitating transport to a refinery. As used herein, the term bitumen/water emulsion will be understood to include water-in-bitumen and bitumen-in-water emulsions and mixtures of water-in-bitumen emulsions and free water.
Thus, in accordance with the present invention, the bitumen is of a higher quality, and therefore of a higher value. Furthermore, the asphaltene is separated *om the bitumen as a stable asphaltene-in-water emulsion. The stable asphaltene-in-water emulsion produced by the present invention has a relatively low viscosity, especially as compared with known processes wherein the asphaltene is in the form of a solid or a semi-solid and is typically regarded as a ~ 1 6586~
waste material which is difficult to handle. The asphaltene-in-water emulsion can be used as an alternate fuel, as a CSS process enhancer and as road pavement and roofing material.
As discussed previously herein, bitumen is typically recovered from a well by a CSS
process in the form of a water-in-bitumen emulsion or as a mixture of a water-in-bitumen emulsion and free water. In one embodiment of the present invention, the bitumen/water emulsion is de-watered to a water content in the range of from about 0 to about 20% by volume, by a process known to those skilled in the art. Such processes include heat treatment, addition of a solvent, addition of a chemical demulsifier, electrostatic coalescence, membrane processes and combinations thereof.
By reducing the water content in the bitumen/water emulsion, the asphaltene-in-water emulsion is produced as a usable product. As mentioned previously herein, an asphaltene-in-water emulsion produced from a bitumen-in-water emulsion having a typical water content of 30% and an asphaltene yield of 20 to 30% (based on bitumen) will have a water content of from 59 to 68% water which is too high for use as a fuel. In accordance with the present invention, the water content of the asphaltene-in-water emulsion is reduced substantially to provide a product which is useful, for example as a fuel, instead of a waste product. The de-watering step has the further advantage that some of the impurities, such as sodium, calcium, magnesium and silica, are removed in the discarded water. The resultant asphaltene-in-water emulsion is therefore of a higher quality.
The solvent deasphalting step is performed by addition of a solvent and an asphaltene-dispersing surfactant to the bitumen/water emulsion. Suitable solvents are one or more C3-CI5 hydrocarbons or C5-Clo gas plant condensates. Preferably, the solvent is a C3-C10 hydrocarbon. Examples of suitable solvents are propane, butane, pentane, hexane, heptane and naphtha. As in conventional deasphalting, the yield of DAB increases while the quality of the DAB deteriorates with higher molecular weight solvents. A solvent is therefore selected such that it provides a good yield of DAB with acceptable quality.
Preferably, the bitumen/water emulsion, solvent and surfactant are mixed in a static in-line mixer. The in-line mixer is a tube or pipe having several alternating right- and left-2 1 65~b~
handed helices oriented so that each leading edge is at 90 to the trailing edge of the oneahead. The flow rate of fluids, the internal diameter of the tube or pipe and the number of elements are some of the parameters that can be varied to obtain good mixing and the required residence time to separate the asphaltenes.
The solvent is added to the bitumen/water emulsion, for example, in a ratio of from about l:1 to about 5:1 (v/v). Solvent deasphalting may be conducted at temperatures and pressures ranging from ambient temperatures and pressures to conditions typical of existing processing streams, for example to temperatures up to about 150C and pressures up to about 200 psi.
The asphaltene in the bitumen/water emulsion is not soluble in the solvent and if the de-watered bitumen/water emulsion was treated with solvent alone, the asphaltene would separate from the bitumen and the water as a third phase, as described in International Publication Number WO 90/06350 discussed previously herein. Moreover, the asphaltene would be in the undesirable form of a solid or a semi-solid. The addition of a suitable asphaltene-dispersing surfactant in accordance with the present invention results in a two-phase separation of bitumen/solvent and a stable asphaltene-in-water emulsion. Furthermore, the asphaltene-in-water emulsion has a relatively low viscosity.
The asphaltene-dispersing surfactant of the present invention is any non-ionic or ionic surfactant which is capable of forming a stable asphaltene-in-water emulsion. A stable asphaltene-in-water emulsion is defined herein as being an emulsion in which the asphaltene particles dispersed in the continuous water phase are small and do not readily settle out of the continuous phase over a period of time. Preferably, the asphaltene particles of the asphaltene-in-water emulsion are of an average particle size of about 10 ~m. A stable emulsion is also an emulsion which can be pumped without breaking.
As will be discussed in more detail below, if the asphaltene-in-water emulsion is to be used as an emulsion fuel, the surfactant should preferably not contain any sodium.
Accordingly, a non-ionic surfactant is preferred because it does not introduce any undesirable alkali metal ions to the emulsion or change the pH. The surfactant is selected to have the proper hydrophillic-lipophilic balance to create a stable asphaltene-in-water emulsion.
Suitable asphaltene-dispersing surfactants include ethoxylated alkyl phenols, ethoxylated dialkyl phenols, ethoxylated alcohols, block polymers of ethylene oxide and propylene oxide, propoxylated alkyl phenols and propoxylated dialkyl phenols. Preferably, the surfactant is an ethoxylated nonyl phenol with from about 4 to about 40 ethoxy groups per mole of nonyl phenol.
The asphaltene-dispersing surfactant is preferably used in a concentration in the range of from about 100 to about 50,000 ppm, more preferably from about 500 to about 10,000 ppm, based on the weight of bitumen/water emulsion. The asphaltene-dispersing surfactant may be added at ambient conditions or at elevated process stream temperatures, for example 150C, and pressures, for example 200 psi.
The asphaltene-dispersing surfactant may be introduced in the form of an aqueoussolution of the surfactant. In the case wherein the water is substantially completely removed from the emulsion, water is introduced by way of an aqueous solution of the asphaltene-dispersing surfactant and/or free water to achieve the desired water content in the asphaltene-in-water emulsion.
The mixture is then allowed to settle in a separation vessel. Due to the densitydifference, the DAB-solvent mixture separates at the top of the vessel and the asphaltene-in-water emulsion at the bottom. The asphaltene-dispersing surfactant creates a stable asphaltene-in-water emulsion.
In another embodiment of the present invention, the water-in-bitumen emulsion is first inverted downhole to a bitumen-in-water emulsion by injection of an inversion surfactant directly into the borehole. The bitumen-in-water emulsion is then de-watered at the surface in a manner known to those skilled in the art, for example, by fl~hing the water continuous phase, centrifugation, and membrane processes. In the embodiment wherein the bitumen/water emulsion is inverted downhole, the recovery of bitumen is increased because the viscosity is reduced.
A water-in-bitumen emulsion may be inverted by addition of an inversion surfactant before or after the de-watering step. It will however be appreciated by those skilled in the art that, as the water concentration in the de-watered bitumen/water emulsion approaches 0%, the emulsion may not be easily inverted.
Suitable inversion surfactants are ethoxylated alkyl phenols and ethoxylated dialkyl phenols. Preferably, the inversion surfactant is ethoxylated nonyl phenol. A particularly suitable ethoxylated nonyl phenol is an ethoxylated nonyl phenol with 10 to 20 ethoxy groups per mole of nonyl phenol. It is not necessary for the inversion surfactant to create a stable bitumen-in-water emulsion as the bitumen-in-water emulsion is merely an intermediate in the integrated process of the present invention. The inversion surfactant is preferably added in a concentration of from about 50 to about 50,000 ppm, more preferably in a concentration of from about 100 to about 10,000 ppm, based on the weight of bitumen/water emulsion.
The DAB-solvent mixture may then be subjected to a solvent recovery step whereinthe solvent is recovered by distillation. Preferably, the recovered solvent is recycled to the deasphalting step with make-up solvent. Optionally, enough solvent is left in the DAB during distillation to meet the pipeline viscosity specification.
Preferably, the asphaltene-in-water emulsion is further enhanced by sonication and/or by passing the asphaltene-in-water emulsion through a static in-line mixer to create smaller particles. This is especially desirable if the asphaltene-in-water emulsion is to be used as a fuel. The asphaltene particles in the asphaltene-in-water emulsion may be made finer by sonication, for example at 20 to 40 kHz. The use of sonication creates a more stable asphaltene-in-water emulsion.
The stable asphaltene-in-water emulsion produced in accordance with the present invention is in a form that may be used in various applications. For example, the asphaltene-in-water emulsion can be used to enhance the CSS process, as an alternate fuel or as road pavement and roofing materials.
One problem with the CSS process is that only the zone proximate the injection well is swept by the steam injected into the well, while further away from the injection well, bitumen 2 1 6~865 is still viscous in cold or unswept zones. The steam distribution problem is a result of steam leaking through pores in the steam-swept zone. A variety of efforts have been made to find fluids which can be economically injected to plug the pores in the steam-swept zone of the formation, where steam has displaced most of the viscous oil, so as to divert steam which is injected thereafter to the cold zones of the formation.
The asphaltene-in-water emulsion of the present invention may be injected downhole to block high permeability channels so that subsequent injection of steam forces asphaltene into the pores, thereby reducing the permeability of the rock formation and enhancing the distribution of steam into the formation, especially into previously cold zones.Another use for the asphaltene-in-water emulsion is as an alternate fuel. It will be appreciated by those skilled in the art that the creation of an emulsion fuel is difficult using solid asphaltene. Solid asphaltene must generally be heated to a high temperature and mixed at a high shear rate with water cont~ining a suitable surfactant. In accordance with the present invention, there is a fine dispersion of asphaltene in the water. The dispersion may be made even finer by sonication. If the asphaltene-in-water emulsion is to be used as an alternate fuel, the surfactant is preferably a non-ionic surfactant with no sodium ions. It will be appreciated by those skilled in the art that sodium ions would cause corrosion of the boiler tubes.
It will be appreciated by those skilled in the art that the present invention provides an integrated process for recovery and partially upgrading bitumen. In accordance with the present invention, the viscosity of the bitumen is significantly reduced and the quality of the bitumen is improved. The asphaltene is recovered in a useable form which can be used as a source of fuel at the production site and which additionally can be used to enhance the recovery of the bitumen from the rock formation. Furthermore, it is also possible to recycle the water recovered from the bitumen-in-water emulsion to the steam generation plant at the production site.
In accordance with the present invention, the viscosity of the bitumen is significantly reduced by deasphalting. Furthermore, as compared with conventional solvent deasphalting 2 1 6586~
processes, less solvent is required. For example, the requirement for solvent can be reduced to as low as about 1:1 (v/v) of solvent:emulsion. Accordingly, there is a significant savings in the cost of the solvent and the cost of recovery of solvent.
Described below are one example of a conventional solvent deasphalting process for comparative purposes and two examples of the process of the present invention. Examples of the present invention are for illustrative purposes only and are not intended to limit the scope of the invention defined by the claims below.
Comparative Example 1 Conventional Solvent Deasphalting Process A wellhead sample cont~ining a water-in-bitumen (30:70) emulsion was obtained from a CSS-stimulated well from the Cold Lake field in Alberta, Canada. The emulsion was deasphalted with pentane as a solvent using a pentane to emulsion ratio of 2:1 (v/v) at ambient conditions. The solvent was first mixed with 50 ml of emulsion using a glass rod.
The solvent-emulsion mixture was then shaken in an orbital shaker for 10 minutes at 300 rpm.
After mixin~, the asphaltenes were allowed to precipitate.
After 15 minutes of settling, the DAB and pentane layer was pipetted out from the top of the bottle. The asphaltene and water settled at the bottom of the bottle. The asphaltene was in a semi-solid form and entrained some of the water. Such a semi-solid asphaltene precipitate is difficult to handle and to emulsify.
The concentration of vanadium and nickel in the DAB was 98 and 40 ppm, respectively, as compared to 177 ppm vanadium and 80 ppm nickel in un-deasphalted bitumen. The viscosity of the DAB was 4000 cp at 23C compared to a bitumen viscosity of 110,000 cp at 23C.
Example 1 100 g (98 ml) of de-watered bitumen (0% water), 200 ml of pentane and 15.53 g of an aqueous surfactant solution cont~ining 3% ethoxylated nonyl phenol (11 ethoxy groups per mole of nonyl phenol) were mixed in an orbital shaker at 250 rpm for 10 minutes. The mixture was allowed to settle, forming two layers. The top layer was DAB diluted with pentane and the bottom layer was an asphaltene-in-water emulsion.
The two layers were separated and the pentane was recovered from the DAB. The asphaltene-in-water emulsion was sonicated at 20 kHz for 29 minutes to make a finer dispersion.
The DAB yield was 75% (by weight) based on the bitumen starting material and theasphaltene yield was 25% (by weight). The asphaltene-in-water emulsion contained 37%
water. The particle size of the sonicated emulsion was 10 ,um.
The concentration of vanadium, nickel, sodium and calcium in the DAB was 126, 52, 4 and 11 ppm, respectively, as compared to 190 ppm vanadium, 77 ppm nickel, 928 ppm sodium and 67 ppm calcium in un-deasphalted bitumen. The viscosity of the DAB was 2240 cp at 40C compared to a bitumen viscosity of 12,000 cp at 40C.
The Example generated two useful products. The viscosity of the partially upgraded DAB was reduced to approximately one-sixth of that of the bitumen starting material. The metal content of the DAB was approximately 50% lower than that of the bitumen starting material. The asphaltene-in-water emulsion had a water content sufficiently low to be used as a fuel to generate steam for the CSS process for recovery of bitumen. The asphaltene-in-water emulsion is also suitable for injection into the reservoir to improve the sweep efficiency of the CSS process.
Example 2 A water-in-bitumen emulsion (100 g) cont~ining 23.3% water from a steam-stimulated well at Cold Lake, Alberta was centrifuged to reduce the water content to 13.4%. The emulsion with reduced water was mixed with an ethoxylated nonyl phenol surfactant and a C5-C~o solvent at room temperature. The ratio of solvent to emulsion was 2.9:1 (v/v). The DAB yield of 94.3% was higher than that obtained in Example 1, in which a lighter solvent was used. However, the quality of the DAB was not as good, with concentrations of nickel and vanadium of 59 ppm and 148.5 ppm, respectively, as compared to the concentrations of 69 and 167 ppm in the original bitumen.
The viscosity of the DAB was 4257 cp at 25C and 1092 cp at 39.7C compared to abitumen viscosity of 33,530 cp at 25C and 5817 cp at 39.8C. Note that the asphaltene yield in this Example is only 5.7%. Thus, even though the water-in-bitumen emulsion feed contained only 13.4% water, the asphaltene-in-water emulsion contains 73% water, which is more than the desired content of 30% or less. To achieve a 30% water content in the asphaltene-in-water emulsion, the water content in the original water-in-bitumen emulsion should have been reduced to about 2.4%.
This Example illustrates the effect of a higher molecular weight solvent on the yield and quality of DAB. It also demonstrates the requirement for a low water content in the starting bitumen/water emulsion to achieve an asphaltene-in-water emulsion of the desired water content.
Claims (23)
1. A process for upgrading bitumen, comprising the steps of: de-watering a bitumen/water emulsion to reduce the concentration of water therein to a concentration in the range of from about 0 to about 20% by volume; adding a solvent and an asphaltene-dispersing surfactant to the de-watered bitumen/water emulsion to form a stable asphaltene-in-water emulsion; settling the mixture into two phases, the upper phase comprising deasphalted bitumen and the lower phase comprising an asphaltene-in-water emulsion; and separating the two phases.
2. A process for upgrading bitumen according to claim 1, wherein the bitumen/water emulsion is a water-in-bitumen emulsion.
3. A process for upgrading bitumen according to claim 2, wherein the water-in-bitumen emulsion is inverted to a bitumen-in-water emulsion prior to de-watering.
4. A process for upgrading bitumen according to claim 2, wherein the water-in-bitumen emulsion is de-watered to reduce the concentration of water therein to a concentration in the range of from about 10 to about 20% by volume.
5. A process for upgrading bitumen according to claim 4, wherein the water-in-bitumen emulsion is inverted to a bitumen-in-water emulsion after de-watering.
6. A process for upgrading bitumen according to claim 1, wherein the asphaltene-dispersing surfactant is a non-ionic surfactant.
7. A process for upgrading bitumen according to claim 1, wherein the asphaltene-dispersing surfactant is selected from the group consisting of ethoxylated alkyl phenols, ethoxylated dialkyl phenols, ethoxylated alcohols, block polymers of ethylene oxide and propylene oxide, propoxylated alkyl phenols and propoxylated dialkyl phenols.
8. A process for upgrading bitumen according to claim 1, wherein the asphaltene-dispersing surfactant is an ethoxylated nonyl phenol.
9. A process for upgrading bitumen according to claim 8, wherein the ethoxylated nonyl phenol comprises from about 4 to about 40 ethoxy groups per mole of nonyl phenol.
10. A process for upgrading bitumen according to any one of claims 1 to 9, wherein the concentration of the asphaltene-dispersing surfactant is in the range of from about 100 to about 50,000 ppm, based on the weight of bitumen/water emulsion.
11. A process for upgrading bitumen according to any one of claims 1 to 9, wherein the concentration of the asphaltene-dispersing surfactant is in the range of from about 500 to about 10,000 ppm, based on the weight of bitumen/water emulsion.
12. A process for upgrading bitumen according to claim 1, wherein the ratio of the solvent to the bitumen/water emulsion is in the range of from about 1:1 to about 5:1 (v/v).
13. A process for upgrading bitumen according to claim 1, wherein the solvent is selected from the group consisting of C3-C15 hydrocarbons and C5-C10 gas plant condensates.
14. A process for upgrading bitumen, comprising the steps of: adding an inversion surfactant downhole to invert a water-in-bitumen emulsion to a bitumen-in-water emulsion;
pumping the bitumen-in-water emulsion to the surface; de-watering the bitumen-in-water emulsion to reduce the concentration of water therein to a concentration in the range of from about 0 to about 20% by volume; adding a solvent to the de-watered bitumen-in-water emulsion; adding an asphaltene-dispersing surfactant to the bitumen-in-water emulsion to form a stable asphaltene-in-water emulsion; settling the mixture into two phases, the upper phase comprising deasphalted bitumen and the lower phase comprising an asphaltene-in-water emulsion; and separating the two phases.
pumping the bitumen-in-water emulsion to the surface; de-watering the bitumen-in-water emulsion to reduce the concentration of water therein to a concentration in the range of from about 0 to about 20% by volume; adding a solvent to the de-watered bitumen-in-water emulsion; adding an asphaltene-dispersing surfactant to the bitumen-in-water emulsion to form a stable asphaltene-in-water emulsion; settling the mixture into two phases, the upper phase comprising deasphalted bitumen and the lower phase comprising an asphaltene-in-water emulsion; and separating the two phases.
15. A process for upgrading bitumen according to claim 14, wherein the asphaltene-dispersing surfactant is a non-ionic surfactant.
16. A process for upgrading bitumen according to claim 14, wherein the asphaltene-dispersing surfactant is selected from the group consisting of ethoxylated alkyl phenols, ethoxylated dialkyl phenols, ethoxylated alcohols, block polymers of ethylene oxide and propylene oxide, propoxylated alkyl phenols and propoxylated dialkyl phenols.
17. A process for upgrading bitumen according to claim 14, wherein the asphaltene-dispersing surfactant is an ethoxylated nonyl phenol.
18. A process for upgrading bitumen according to claim 17, wherein the ethoxylated nonyl phenol comprises from about 4 to about 40 ethoxy groups per mole of nonyl phenol.
19. A process for upgrading bitumen according to any one of claims 14 to 17, wherein the concentration of the asphaltene-dispersing surfactant is in the range of from about 100 to about 50,000 ppm, based on the weight of bitumen-in-water emulsion.
20. A process for upgrading bitumen according to any one of claims 14 to 17, wherein the concentration of the asphaltene-dispersing surfactant is in the range of from about 500 to about 10,000 ppm, based on the weight of bitumen-in-water emulsion.
21. A process for upgrading bitumen according to claim 14, wherein the inversionsurfactant is added in a concentration of from about 50 to about 50,000 ppm, based on the weight of bitumen-in-water emulsion.
22. A process for upgrading bitumen according to claim 14, wherein the ratio of the solvent to the bitumen-in-water emulsion is in the range of from about 1:1 to about 5:1 (v/v).
23. A process for upgrading bitumen according to claim 14, wherein the solvent is selected from the group consisting of C3-C15 hydrocarbons and C5-C10 gas plant condensates.
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|---|---|---|---|
| CA002165865A CA2165865C (en) | 1995-12-21 | 1995-12-21 | Process for deasphalting bitumen |
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| CA002165865A CA2165865C (en) | 1995-12-21 | 1995-12-21 | Process for deasphalting bitumen |
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| CA2165865C true CA2165865C (en) | 1998-06-02 |
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| CA2729457C (en) | 2011-01-27 | 2013-08-06 | Fort Hills Energy L.P. | Process for integration of paraffinic froth treatment hub and a bitumen ore mining and extraction facility |
| CA2906715C (en) | 2011-02-25 | 2016-07-26 | Fort Hills Energy L.P. | Process for treating high paraffin diluted bitumen |
| CA2733342C (en) | 2011-03-01 | 2016-08-02 | Fort Hills Energy L.P. | Process and unit for solvent recovery from solvent diluted tailings derived from bitumen froth treatment |
| CA2865126C (en) | 2011-03-04 | 2015-12-22 | Fort Hills Energy L.P. | Process for solvent addition to high viscosity bitumen froth |
| CA2735311C (en) | 2011-03-22 | 2013-09-24 | Fort Hills Energy L.P. | Process for direct steam injection heating of oil sands bitumen froth |
| CA2815785C (en) | 2011-04-15 | 2014-10-21 | Fort Hills Energy L.P. | Heat recovery for bitumen froth treatment plant integration with temperature circulation loop circuits |
| CA2848254C (en) | 2011-04-28 | 2020-08-25 | Fort Hills Energy L.P. | Recovery of solvent from diluted tailings by feeding a desegregated flow to nozzles |
| CA2857702C (en) | 2011-05-04 | 2015-07-07 | Fort Hills Energy L.P. | Process for operating a bitumen froth treatment operation in turndown mode |
| CA2832269C (en) | 2011-05-18 | 2017-10-17 | Fort Hills Energy L.P. | Temperature control of bitumen froth treatment process with trim heating of solvent streams |
| CA2963436C (en) | 2017-04-06 | 2022-09-20 | Iftikhar Huq | Partial upgrading of bitumen |
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