CA2904285A1

CA2904285A1 - System and method of reducing viscosity of hydrocarbons

Info

Publication number: CA2904285A1
Application number: CA2904285A
Authority: CA
Inventors: Pablo Marcial Contreras Carvallo; Peter Anthony Ferner
Original assignee: Cenovus Energy Inc
Current assignee: Cenovus Energy Inc
Priority date: 2014-09-16
Filing date: 2015-09-15
Publication date: 2016-03-16
Also published as: CA2864010A1

Abstract

Extracted hydrocarbons, such as bitumen extracted from oil sand deposits, may be mixed with an additive such as natural gas condensate or synthetic crude oil in order to meet transportation specifications for API gravity and viscosity. An amount of additive used may be reduced while still meeting the transportation specifications by subjecting the extracted hydrocarbons to an electric field which may break apart asphaltene agglomerations. The re-agglomeration of asphaltenes may be prevented or impeded by the presence of the additive.

Description

SYSTEM AND METHOD OF REDUCING VISCOSITY OF HYDROCARBONS
TECHNICAL FIELD
The current disclosure relates to reducing the viscosity of hydrocarbons for transport and in particular to reducing the viscosity of asphaltene-based hydrocarbons for transport via, for example, a pipeline.
BACKGROUND
Bitumen extracted from oil sands, such as those found in Alberta, Canada, and elsewhere, is a viscous mixture of saturated and aromatic hydrocarbons and other naturally occurring components including paraffins, naphthalenes, asphaltenes and small amounts of sulphur and nitrogen compounds. Extracted bitumen may be upgraded to synthetic crude which may be subsequently refined into petroleum products.
The extracted bitumen may require transportation to a geographically distant refinery or processing plant. Such transport may be done through a pipeline. However, transportation via pipeline requires that the hydrocarbons being transported meet specific requirements, such as the API (American Petroleum Institute) gravity and viscosity requirements.
Extracted hydrocarbons, such as bitumen, typically do not meet the transportation specifications and as such are processed prior to pipeline transportation.
The processing of the extracted hydrocarbons to meet the specific transportation specifications commonly involves mixing the extracted hydrocarbons with a diluent. The diluent may include natural gas condensate, refined naphtha or synthetic crude oil (SCO). The amount of diluent required depends upon the specific transportation specifications to be met, the characteristics of the extracted hydrocarbons and the characteristics of the diluent. For example, a smaller amount of a diluent having a higher API gravity would need to be added to the extracted hydrocarbons in comparison to a diluent having a lower API gravity.
Hydrocarbons such as Canadian bitumen may have an API gravity of, for example, 8 ¨ 10, and may require mixing with 20% to 50% diluent in order to meet the transportation specifications for transport. Regardless of the particular diluent used, the diluent either needs to be produced on site, which may require expensive processing equipment, or must be produced elsewhere and transported to site. There is a significant cost associated with using diluent to meet oil transportation specifications. A need therefore exists for providing a system and/or method that, in various embodiments, reduces viscosity of hydrocarbons.
SUMMMARY
In one embodiment, the invention provides for a method of reducing viscosity of hydrocarbons comprising:
i) breaking down agglomerations of the hydrocarbons by subjecting the hydrocarbons to an electric field, a magnetic field or ultrasonics to reduce the viscosity of the hydrocarbons; and ii) mixing the hydrocarbons with at least one additive to reduce the viscosity of the hydrocarbons, wherein step i) may be carried out before, after or concurrently with step ii).
In a further embodiment of the method or methods outlined above, breaking down agglomerations of the hydrocarbons comprises subjecting the hydrocarbons to an electric field.
In a further embodiment of the method or methods outlined above, the hydrocarbons are subjected to an electric field within a pipe or pipeline through which the hydrocarbons flow.
In a further embodiment of the method or methods outlined above, the hydrocarbons remain within the electric field for a period of time sufficient to at least partially break-up agglomerations of asphaltenes in the hydrocarbons.
In a further embodiment of the method or methods outlined above, the method further comprises adding the at least one additive to the hydrocarbons before applying the electric field, after applying the electric field or within the electric field.
In a further embodiment of the method or methods outlined above, the method further comprises detecting one or more characteristics of the mixture of the hydrocarbons and the at least one additive to determine if the mixture meets target specifications of a transport pipeline.

2 In a further embodiment of the method or methods outlined above, the target specifications comprise a minimum API gravity value, a maximum viscosity value, or both a minimum API
gravity value and a maximum viscosity value.
In a further embodiment of the method or methods outlined above, the method further comprises adjusting one or more of an amount of the at least one additive mixed with the hydrocarbons, an exposure time of the hydrocarbons within the electric field, and a strength of the electric field in order to adjust the characteristics of the mixture to meet the target specifications.
In a further embodiment of the method or methods outlined above, the method further comprises:
providing the mixture of the reduced viscosity hydrocarbons with at least one additive to a transportation pipeline or pipe; and periodically subjecting the mixture in the pipeline to a further electric field, magnetic field or ultrasonics.
In a further embodiment of the method or methods outlined above, the hydrocarbons comprise asphaltene based bitumen extracted from an oil sands deposit.
In a further embodiment of the method or methods outlined above, mixing the reduced viscosity hydrocarbons with the at least one additive impedes agglomeration of asphaltenes in the hydrocarbons.
In yet a further embodiment, the present invention provides for a system for reducing the viscosity of hydrocarbons comprising:
a pipe comprising:
a hydrocarbon inlet through which the hydrocarbons enter the pipe;
an additive inlet through which at least one additive for reducing the viscosity of the

3 hydrocarbons enters the pipe; and a mixture outlet through which a mixture of the hydrocarbons and the at least one additive exit the pipe; and an electric field generator located between the hydrocarbon inlet and the mixture outlet for subjecting the hydrocarbons to an electric field to reduce the viscosity of the hydrocarbons; or a magnetic field generator located between the hydrocarbon inlet and the mixture outlet for subjecting the hydrocarbons to a magnetic field to reduce the viscosity of the hydrocarbons; or an ultrasonic generator located between the hydrocarbon inlet and the mixture outlet for subjecting the hydrocarbons to an ultrasonic wave to reduce the viscosity of the hydrocarbons.
In a further embodiment of the system or systems as outlined above, the system further comprises an electric field generator and the hydrocarbons remain within the electric field for a period of time sufficient to at least partially destabilize agglomerations of asphaltenes of the hydrocarbons.
In a further embodiment of the system or systems as outlined above, the additive inlet is located upstream of the electric field generator, downstream of the electric field generator or proximate the electric field generator.
In a further embodiment of the system or systems as outlined above, the system further comprises a monitoring and control device for detecting one or more characteristics of the mixed hydrocarbons and the at least one additive to determine if the mixture meets target specifications of a transport pipeline.
In a further embodiment of the system or systems as outlined above, the target specifications comprise a minimum API gravity value, a maximum viscosity value, or both a minimum API

4 gravity value and a maximum viscosity value.
In a further embodiment of the system or systems as outlined above, the monitoring and control device further adjusts one or more of an amount of the at least one additive mixed with the hydrocarbons, an exposure time of the hydrocarbons within the electric field, and a strength of the electric field in order to adjust the characteristics of the mixture to meet the target specifications.
In a further embodiment of the system or systems as outlined above, the hydrocarbons comprise asphaltene based bitumen extracted from an oil sands deposit.
In a further embodiment of the system or systems as outlined above, the system further comprises:
a lease automatic custody transfer (LACT) unit for monitoring and measuring the mixture of the reduced viscosity hydrocarbons with at least one additive provided to a transportation pipeline; and a plurality of additional electric field generators located along the transportation pipeline for periodically subjecting the mixture in the pipeline to a further electric field.
In yet another further embodiment, the present invention provides for a method of reducing asphaltene agglomeration in hydrocarbons comprising:
subjecting the hydrocarbons to an electric field to reduce the viscosity of the hydrocarbons; and mixing the reduced viscosity hydrocarbons with at least one additive to further reduce the viscosity of the hydrocarbons subjected to the electric field.
BRIEF DESCRIPTION OF THE FIGURES
Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

5 Figure 1 depicts diagrammatically a process for producing petroleum based products from oil sands;
Figure 2 depicts diagrammatically a process for mixing an additive with hydrocarbons;
Figure 3 depicts diagrammatically a process for reducing the viscosity of hydrocarbons;
Figure 4 depicts diagrammatically a process for reducing the viscosity of hydrocarbons;
Figure 5 depicts diagrammatically a process for reducing the viscosity of hydrocarbons;
Figure 6 depicts diagrammatically a process for reducing the viscosity of hydrocarbons;
Figure 7 depicts a possible embodiment for subjecting hydrocarbons and an additive to an electric field;
Figure 8 depicts a top view arrangement of the concentric plates of Figure 7;
Figure 9 depicts a plurality of treatment sections coupled together to reduce the viscosity of hydrocarbons;
Figure 10 depicts diagrammatically a process for transporting extracted hydrocarbons to a refinery;
Figure 11 depicts a method for reducing the viscosity of hydrocarbons;
Figure 12 depicts a further method for reducing the viscosity of hydrocarbons;
Figure 13 depicts a further method for reducing the viscosity of hydrocarbons;
Figure 14 illustrates an example of a relationship between asphaltene particle (cluster) size, asphaltene concentration, and viscosity; and Figure 15 is a photograph of a test cell and electrodes.
DETAILED DESCRIPTION
Described herein are methods, systems, apparatuses, techniques and embodiments suitable for reducing viscosity of produced hydrocarbons including bitumen. It will be appreciated that the methods, systems, apparatuses, techniques and embodiments described herein are for illustrative purposes intended for those skilled in the art and are not meant to be limiting in any way. All reference to dimensions, capacities, embodiments or examples throughout this disclosure, including the Figures, should be considered a reference to an illustrative and non-limiting embodiment or an illustrative and non-limiting example.

6 It will be appreciated that reference to "hydrocarbon" or "hydrocarbons"
includes produced hydrocarbons including bitumen and can include pre-treatment with diluent or additives as may be observed in the production of the hydrocarbons. Such hydrocarbons may be extracted from a subterranean hydrocarbon reservoir or deposit, including oil sands.
Mixtures of hydrocarbons, such as bitumen, extracted from oil sands may be very viscous and have a low API gravity value. In order to transport the extracted hydrocarbons by, for example, a pipeline to a refinery where various petroleum products are generated via upgrading, the viscosity and API gravity are adjusted in order to meet transportation specifications. The transportation specifications may be met by mixing the extracted hydrocarbons with diluent. As described further herein, by applying an electric field to the extracted hydrocarbons, the amount of diluent required to meet the transportation specifications may be reduced.
Figure 1 depicts diagrammatically a process for producing petroleum based products from oil sands, such as those found in Alberta, Canada; Venezuela; or other regions that extract hydrocarbons from oil sands. As depicted in Figure 1, the overall process 100 includes the extraction and processing of hydrocarbons 102. The oil sands may be mined and carried to a processing location for extracting the hydrocarbons from the sand.
Alternatively, the extraction may be done in situ using various techniques, including steam-assisted gravity drainage (SAGD) and cyclic steam stimulation (CSS). Once the hydrocarbons are extracted they may be processed further, for example to remove sediment and water.
The extracted and processed hydrocarbons typically include asphaltenes, which may provide the extracted hydrocarbons with a high viscosity and low API gravity making the hydrocarbons unsuitable for transport by pipeline. The hydrocarbons may be mixed with one or more additives 106 in order to adjust the viscosity and API gravity in order to meet the transportation specifications. As described further herein, an amount of additive required to meet the transportation specifications may be reduced by subjecting the hydrocarbons to an electric field. Although not wishing to be bound by theory, it is believed that the electric field may break apart asphaltene agglomerations, and as such, less additive, for example diluent, is required to meet required transportation specifications. Further, it is possible that the additive, such as

7 diluent, may prevent or impede the asphaltenes from reforming agglomerations and as such the reduced viscosity may be maintained for an extended period of time or may even be a permanent reduction.
It will be appreciated that the term additive is used throughout this disclosure to encompass both diluent and, e.g., a dispersant. Further, the additive outlined herein is intended broadly and is intended to include diluent which is currently used to help meet transportation specs.
Because diluent is expensive, it is ideal to reduce the quantity needed.
Therefore, as outlined later, the combination of, for example, an electrostatic field and a non-diluent chemical additive is contemplated. In principle, a diluent may achieve the desired effect in the presence of the electrostatic field, but a significantly higher volume would be required (e.g., about 20,000 ppm aromatic solvent vs. just about 300 ppm asphaltene dispersant), which would increase the cost accordingly.
Once the extracted hydrocarbons have been processed and diluted so that the characteristics, for example the basic sediment and water (BS&W), API gravity and viscosity, meet the transportation specifications, the diluted hydrocarbons, often referred to as lidilbit" or "synbit"
depending upon the additive used, may be transported via a pipeline 108, or other means such as by rail or road. The diluted hydrocarbons may be transported by the pipeline 108 to one or more refineries where the diluted hydrocarbons can be processed and upgraded 110. The processing and upgrading produces one or more petroleum based products 112 including heavy oils, deasphalted oils, gasoline and lighter petroleum products.
Although the specific composition of the extracted hydrocarbons will vary depending upon the region and the specific deposit from which the hydrocarbons were extracted, the hydrocarbons generally comprise a mixture of saturated and aromatic hydrocarbons, asphaltenes, paraffins, naphthalenes, and small amounts of sulphur and nitrogen compounds as well as other trace compounds and metals. Asphaltenes are complex hydrocarbons and can include a variety of compounds with different structures. Generally, asphaltenes are insoluble in n-heptane, but are soluble in toluene and may be generally distinguished by a fused aromatic core with polar heteroatom functionality. The average molecular weights of asphaltenes may range from

8 approximately 800 to 3000 Da, although higher and lower weights are possible.
The extracted hydrocarbons may contain varying amounts of asphaltene. As an example, bitumen extracted from oil sands in Alberta may contain approximately 16%wt asphaltenes. The presence of asphaltenes can affect the viscosity of the hydrocarbons. A higher amount of asphaltenes present in the hydrocarbons may result in a higher viscosity.
The amount of additive, such as diluent, mixed with the hydrocarbons will depend on the target transportation specification required for transport, the initial characteristics of the hydrocarbons and the characteristics of the additive mixed with the hydrocarbons. For example, in order to be transported by a particular pipeline, the diluted hydrocarbons should have a BS&W of less than 0.5%vol, a viscosity of 380 cS or less, and an API
gravity of 19 or greater, which may be specified as a maximum density specification of 920 kg/m3. Bitumen extracted from oil sands in Alberta may contain approximately 15 to 20%wt asphaltenes and may be processed to remove water and sediment to meet the BS&W requirements, however, such treated bitumen may still have a much lower API gravity of, for example, 17 API and a higher viscosity of 8,250 cS compared to the required transportation specifications. A diluent used may have varying characteristics; however, the diluent should have a higher API gravity and a lower viscosity than the transportation specifications in order to meet the transportation specifications when mixed with the hydrocarbons. As an example, the diluent may comprise natural gas condensate with an API gravity of approximately 75 and a viscosity of 0.45 cS. It will be appreciated that the amount of diluent required to be mixed will depend upon the characteristics of the diluent used. However, generally between 20%vol and 50%vol is used in order to dilute the extracted hydrocarbons in order to meet transportation specifications.
Further, it will be appreciated that the measurements of the characteristics are given for a reference temperature, which may differ from the actual temperature of the hydrocarbons.
Further, the transportation specifications may change throughout the year.
Figure 2 depicts diagrammatically a process for mixing an additive with extracted hydrocarbons.
The process 200 involves extracted hydrocarbons 202, such as asphaltene based bitumen, entering a pipe 204. The extracted hydrocarbons 202 to be diluted may have already been

9 processed to remove water and sediment in order to meet BS&W requirements of the pipeline.
The extracted hydrocarbons 202 enter the pipe 204, which has a second inlet 206 through which an additive 208 can be added. The additive 208 is used to adjust the characteristics of the extracted hydrocarbons 202 in order to meet the transportation specifications.
The additive may be a diluent such as, for example, naphthalene, natural gas condensate or synthetic crude oil. Additionally or alternatively, the additive may comprise resins, asphaltene dispersants, or other compounds for reducing the viscosity of the extracted hydrocarbons. The extracted hydrocarbons 202 and additive 208 may be mixed together in the pipe 204. The mixing may be accomplished by diffusion and/or by the flow of the extracted hydrocarbons and additive through the pipe 204. Additionally or alternatively, the pipe may include mixing fins, grids or other structures 210 for increasing or facilitating the mixing of the extracted hydrocarbons and additive. Additionally or alternatively, the mixing may be accomplished by actively stirring or agitating the extracted hydrocarbons and additive, or through a pressure differential across a valve or device.
The mixture of the extracted hydrocarbons, and in particular bitumen, and additive may be referred to as various names depending upon the additive used. For example if a diluent such as natural gas condensate is used, the mixture may be referred to as dilbit.
If synthetic crude oil is used as the additive, the mixture may be referred to as synbit as outlined above. The mixture of the additive and extracted hydrocarbons is referred to further herein as sales oil 212, regardless of the additive used. The sales oil 212 is monitored by one or more sensors to determine if the characteristics, such as the density, water content, and viscosity are within the ranges required by the transportation specifications. If the characteristics of the sales oil are not within the required range, a monitoring and control component 214 controls an amount of additive added, for example by controlling a valve or pump 216, used for adding the additive.
The amount of additive may be increased or decreased to ensure the sales oil meets the transportation specifications while not using an excessive amount of additive.
The process for adjusting the characteristics of extracted hydrocarbons by mixing with an additive as described above with regard to Figure 2 provides a sales oil that meets the transportation specifications for transport. However, the sales oil may comprise 20%vol to 50%vol of additive. Due to the cost of the additive, it may be desirable to reduce the amount of the additive used in producing the sales oil. The amount of additive used may be reduced by monitoring and controlling the amount additive used so that the sales oil meets, but does not greatly exceed the transportation specifications. The amount of additive may be reduced by selecting a different additive or a combination of additives.
As described further below, the amount of additive used to meet the pipeline specification may be further reduced by reducing the asphaltene agglomeration of the bitumen.
Although not wishing to be bound by theory, one possible theory of the higher viscosity of hydrocarbons that include asphaltenes is that asphaltenes have a plate like molecular structure and the plate to plate agglomeration of the molecules causes the abnormally high viscosity as the particle size grows. Additives such as diluent, resins, or dispersants may inhibit the agglomeration process and compete for the bonding sites. The relationship between asphaltene particle (cluster) size, asphaltene concentration, viscosity, and impact of, for example, an electric field and an asphaltene dispersant additive, is illustrated in Figure 14. The attractive forces between the asphaltene molecules may be quite tenacious. Once the asphaltene molecules agglomerate they may be quite stable, and as such the additive may have difficulty cleaving the agglomerated structure. However, if the agglomerated structure can be broken apart, the additive may prevent or at least impede further agglomeration.
The application of an electric field to asphaltene based hydrocarbons causes a reduction in the viscosity of the hydrocarbons. The viscosity reduction caused by applying an electric field may be temporary and the viscosity of the hydrocarbons may rise without further application of the electric field. Applying an electric field to the hydrocarbons may break down the asphaltene agglomerations and as such may allow less additive to be used while still providing sales oil that meets transportation specifications. Although the following describes the use of an electric field to break down asphaltene agglomerations, it may be possible to break down asphaltene agglomerations of the extracted hydrocarbons using other techniques including applying a magnetic field or using ultrasonic pulses to break up the agglomerations.
Other techniques to break down asphaltene agglomerations of the extracted hydrocarbons may comprise, for example, sonication, mechanical mixing, cavitation, high shear forces, turbulent flow, electromagnetic radiation, or any other technique that induces sufficient breakdown of the asphaltene agglomerations.
Figure 3 depicts diagrammatically a process for reducing the viscosity of extracted hydrocarbons such as asphaltene based bitumen. The process 300 depicted in Figure 3 is similar to the process in Figure 2; however, an electric field is applied to the extracted hydrocarbons.
The extracted hydrocarbons 202 are received in the pipe 204 that has an inlet 206 through which an additive 208 can be added. The extracted hydrocarbons 202 and additive 208 pass through the pipe 204 and through a section 302 of the pipe that generates an electric field. The electric field is generated by applying a voltage to two or more separated plates 304, 306. As will be appreciated, the strength of the electric field is dependent upon the voltage 308 applied to the two plates and the separation between the plates. The electric field strength may be relatively high, for example 1000 V/mm, although the specific field strength may be higher or lower. The extracted hydrocarbons are subjected to the electric field for a period of time sufficient to at least partially break apart the asphaltene agglomerations.
The amount of time that the extracted hydrocarbons are subjected to the electric field may be controlled by the speed at which the hydrocarbons flow through the electric field and the length of the electric field. The amount of time that the extracted hydrocarbons are subjected to the electric field may vary depending upon one or more factors, including the strength of the electric field, an amount of asphaltenes present in the bitumen, an amount of agglomeration of the asphaltenes, as well as a desired reduction in the amount of additive used and the viscosity reduction desired. For example, subjecting the extracted hydrocarbons to a high strength electric field for a long period of time may result in substantial destabilization of the asphaltene agglomerations and may result in a substantial reduction in the amount of additive used to produce the sales oil that meets the transportation specifications. Subjecting the same extracted hydrocarbons to a lower strength electric field for a shorter period of time may result in less destabilization of the asphaltene agglomerations; however, may still provide a reduction in the amount of additive required to meet the transportation specifications.
It will be appreciated that even a small reduction in the amount of additive used may provide desirable cost savings due to the cost of the additive, the amount of additive used per barrel of sales oil produced and the number of barrels of sales oil produced.
In addition to controlling the pump or valve 216 for adding the additive, the monitoring and control functionality 314 may also control the strength of the electric field in order to produce the sales oil 312 with the desired characteristics. In addition to the strength of the electric field, the pattern of how the electric field is applied may also be controlled. For example, the electric field may be pulsed and the duration of the pulses may be varied.
After subjecting the extracted hydrocarbons to the electric field and mixing with the additive, the characteristics, such as the viscosity and API gravity, of the sales oil 312 may be the same as the characteristics of the sales oil 212; however, the amount of additive used to achieve the characteristics may be less than the amount of additive that would have been used to produce the sales oil having the same characteristics without applying the electric field. As described above, and without wishing to be bound by theory, it is believed that the application of the electric field breaks down asphaltene agglomeration, allowing a smaller amount of additive to achieve the same result in terms of the sales oil characteristics. Although described as being an electric field, it is contemplated that other techniques for breaking down agglomerations, such as applying a magnetic field or using ultrasonic pulses may be used as an alternative, or in addition, to the electric field.
Figure 4 depicts diagrammatically a further process for reducing the viscosity of extracted hydrocarbons. The process 400 is similar to the process 300 described above and as such, only the differences will be discussed. The extracted hydrocarbons, for example bitumen, 202 pass through the pipe section 302 where the electric field is produced. However, in contrast to the process 300, the process 400 generates the electric field between two pairs of electric plates 402, 404, 406, 408.

Figure 5 depicts diagrammatically a further process for reducing the viscosity of extracted hydrocarbons. The process 500 is similar to the process 400 described above and as such, only the differences will be discussed. In contrast to the process 400, which had a single section for subjecting the extracted hydrocarbons to the electric field, the process 500 has a plurality of sections 502, 510 at which the extracted hydrocarbons are subjected to an electric field. Each of the sections 502, 510 generate the electric field using a pair of plates 504, 506 and 512, 514, each connected to a respective voltage source 508, 516. Although depicted as using separate voltage sources 508, 516 it is contemplated that a single voltage source can be used to generate the electric fields in each section 502, 510.
Figure 6 depicts diagrammatically a further process for reducing the viscosity of extracted hydrocarbons. The process 600 is similar to the process 300 described above and as such, only the differences will be discussed. In the process 300, the additive 208 is added to the extracted hydrocarbons at an inlet 206 that is located upstream of the section 302 at which the extracted hydrocarbon is subjected to the electric field. In contrast, the process 600 adds the additive 208 to the extracted hydrocarbons at an inlet 602 that is located downstream from the section where the extracted hydrocarbon is subjected to the electric field.
Figure 7 depicts a treatment section for subjecting extracted hydrocarbons and an additive to an electric field. Although depicted as a pipe in Figure 7, a treatment section 700 may be provided by a pipe, conduit, tank or other structure through which the extracted hydrocarbons can pass. The electric field may be generated within a treatment section 700 that has a first end 702 through which the extracted hydrocarbons enter and a branch port 704 through which the additive 208 can enter. A further branch port 706 allows the sales oil 312 to exit the treatment section 700. The pipe of the treatment section has a sealed second end 708 through which electric connections for generating the electric field can enter the pipe of the treatment section 700. The electric field is generated by a rod 710 at the center of a number of concentric pipes 712, 714, 716 which form electrodes. The concentric pipes 712, 714, 716 may be made of a solid material or a grid. The concentric pipes 712, 714, 716 may have an opening 718 at the bottom of the pipes in order to allow the sales oil 312 to exit to the branch port 706.

Although the concentric pipes are depicted as being inserted from the second end 708 of the treatment section pipe, it is contemplated that the electrodes may be inserted from one of the branch openings and the sales oil can exit from the second end of the pipe.
However, having the electrodes enter from the second end 708 may facilitate the insertion and removal of the electrodes which may simplify replacement or maintenance of the electrodes.
Figure 8 depicts a top view arrangement of the concentric pipes of Figure 7. A
voltage source 802 generates the high voltage required to generate the electric field. The voltage source 802 is connected to each of the rod and concentric pipes 710, 712, 714, 716. Ground and voltage connections are alternatively made to the rod and concentric pipes so that an electric field is generated between each. Each of the concentric pipes may be separated from each other by a respective distance 804, 806, 808.
Figure 9 depicts a plurality of treatment sections coupled together to reduce the viscosity of extracted hydrocarbons. A plurality of treatment sections 902, 904, 906, each of which may be similar to the treatment section described above with regard to Figures 7 and 8, may be coupled together so that the outlet from a previous treatment section is connected to the inlet of the subsequent treatment section. Each of the treatment sections 902, 904, 906 can subject the extracted hydrocarbons 202 to a respective electric field and mix in additive 208. Each of treatment sections 902, 904 may be coupled to the subsequent treatment sections by a connection 908, 910 which may subject the mixture of extracted hydrocarbons and additive to further mixing in a mixing section. After passing through the plurality of treatment sections 902, 904, 906 and the connections 908, 910 the final sales oil 312 may be provided for transport, for example by pipeline, rail or road.
Figure 10 depicts diagrammatically a process for transporting extracted hydrocarbons to a refinery. As previously described, extracted hydrocarbons, such as bitumen, may be extracted from oil sands and processed to remove water and sediment 102. The processed extracted hydrocarbons may be mixed with an additive as well as subjected to an electric field 106 in order to meet transportation specifications. The resulting sales oil 1002 may be transferred to a pipeline 1006 by a lease automatic custody transfer (LACT) unit 1004. The LACT
unit 1004 may measure the quality and volume of the sales oil transferred to the pipeline 1006. The pipeline 1006 connects the extraction and processing of the hydrocarbons to the refinery 110 where the hydrocarbons can be further processed.
The use of an electric field with or without additives to temporarily or permanently reduce oil viscosity may be applied at one or more stages of the hydrocarbon extraction and transportation process. For example, extracted hydrocarbons may be subjected to an electric field with the addition of an additive upstream of, downstream of, or in combination with other upgrading or partial upgrading processes (e.g., catalytic hydrocarbon upgrading, total acid number (TAN) reduction, sulfur reduction, viscosity reduction, density reduction, improvement in API gravity, etc.) that improve the quality of the oil prior to pipeline, or other modes of, oil transportation.
As described above, subjecting extracted hydrocarbons to an electric field may decrease the viscosity of the extracted hydrocarbons by possibly breaking up asphaltene agglomerations.
Although the addition of an additive may impede the further agglomeration of asphaltenes, the length of time the sales oil travels in the pipeline may be long enough that further asphaltene agglomeration may occur despite the presence of the additive. This further asphaltene agglomeration may result in an increase in the viscosity possibly above limits of the pipeline. In order to maintain the viscosity of the sales oil at an acceptable level, the sales oil may be periodically subjected to electric fields. Electric field generating sections 1008, 1010, 1012, 1014 may be spaced along the pipeline 1006 to ensure that the viscosity of the sales oil does not increase above an acceptable level for the pipeline.
Figure 11 depicts a method for reducing the viscosity of extracted hydrocarbons. The extracted hydrocarbons may be asphaltene based bitumen and may be extracted from oil sands. After extraction from the oil sands, the extracted hydrocarbons may be processed in order to remove water and sediment so that the extracted hydrocarbons meet a BS&W value for transport. The extracted hydrocarbons are subjected to an electric field (1102). The electric field may break up asphaltene agglomerations and reduce the viscosity of the extracted hydrocarbons. At least one additive is mixed with the reduced viscosity extracted hydrocarbons in order to further reduce the viscosity of the hydrocarbons (1104). The amount of additive mixed with the reduced viscosity extracted hydrocarbons is sufficient to adjust the characteristics, such as the API
gravity and viscosity, of the hydrocarbons in order to meet the transportation specifications. By subjecting the extracted hydrocarbons to an electric field, an amount of additive that would have been required in order to meet the transportation specifications is decreased in comparison to an amount of additive that would have been required without subjecting the extracted hydrocarbons to the electric field.
Figure 12 depicts a further method for reducing the viscosity of extracted hydrocarbons. As described above, extracted hydrocarbons, such as bitumen, may be subjected to an electric field (1102) and mixed with an additive to further reduce the viscosity of the extracted hydrocarbons (1104). Characteristics of the resultant mixture such as the API
gravity and viscosity are detected (1202) and control parameters may be adjusted to further adjust the detected characteristics (1204). The control parameters may include a strength of the electric field, a duration of the electric field, a length of time the extracted hydrocarbons are subjected to the electric field and an amount of additive mixed with the extracted hydrocarbons. The mixture of extracted hydrocarbons and additive may be transferred for transport (1206), for example by pipeline, rail or road.
Figure 13 depicts a further method for reducing the viscosity of extracted hydrocarbons. As described above, extracted hydrocarbons, such as bitumen, may be subjected to an electric field (1102) and mixed with an additive to further reduce the viscosity (1104). Characteristics of the resultant mixture are detected (1202) and control parameters may be adjusted to further adjust the detected characteristics (1204) and the mixture transferred for transport (1206).
Depending on the length of the pipeline, the viscosity of the mixture of extracted hydrocarbons and additives may begin to rise. The mixture may be periodically subjected to an electric field (1302) to reduce the viscosity of the mixture in the pipeline to maintain the viscosity of the mixture within an acceptable range for the pipeline.
The above has described viscosity reduction for use in transport of hydrocarbons by pipeline.
Similar methods and systems may be used in order to reduce the viscosity of hydrocarbons transported in other ways, such as by rail. For example, the viscosity of hydrocarbons may be reduced as described above in order to facilitate the transport of the hydrocarbons to or from rail cars or road transportation thereby potentially allowing for a reduced need for diluents when transporting hydrocarbons by rail car or by road transport.
The application of electric fields to extracted hydrocarbons to reduce the viscosity of the hydrocarbons while potentially reducing an amount of diluent required to meet a sales oil specification was tested. To measure electrostatic conditions of the hydrocarbons and to apply an electric field to the sample, a BAUR insulating fluid test cell, model DPA
75C (ASTM D877), with two electrodes of 1.0" in diameter, was used, having a 450 ml cell volume and utilizing a magnetic mixer. A Haake 550 Rheometer and an Anton Paar SVM 3000 Viscometer were used to determine characteristics of the sample during the test. A photograph of the test cell and electrodes is shown in Figure 15.
A 60 Hz electrostatic field was applied to a 450 ml sample of diluent-bitumen blend extracted from a treater at a Foster Creek oil sands facility in Alberta, Canada. The diluent-bitumen blend was comprised of approximately 670 kg/m3 of diluent at a concentration of approximately 21.3%vol. The initial diluent-bitumen blend had a breakdown voltage of 13.7 kV. A 6 kV field at 60 Hz was applied (by ramping up to 6 kV at a rate of 1 kV/s) across a 5 mm gap, providing a 1.2 kV/mm electric field. The electric field was applied for 15 minutes. The diluent-bitumen blend was mixed continuously. Characteristics of the sample were periodically determined, the results of which are depicted in Table 1 below.
Table 1 ¨ Viscosity and Density of Sample Sample Time Temperature Dynamic Density (hot) (min) ( C) Viscosity (g/cm3)*
(mPa.$)*
Blank 0 30.7 431.23 0.9386 Treatment 0 31.0 403.75 0.9384 After Treatment 30 31.0 400.39 0.9384 90 31.0 403.76 0.9387 135 31.0 407.63 0.9388 1065 31.0 454.86 0.9398 *Anton Paar Viscometer As can be seen from Table 1, a significant reduction in viscosity was observed (from 431.23 mPa.s to 400.39 mPa.s by 30 min), and remained relatively consistent for at least 135 min. The results of the viscosity reduction due to the applied electric field illustrate that the application of an electrostatic field may provide a reduction, potentially a significant reduction, in the amount of diluent required when transporting bitumen, which in turn may result in a substantial cost reduction associated with hydrocarbon transportation.
The viscosity of 454.86 mPa.s observed at 1065 min post-treatment with the electrostatic field was higher than that of the blank sample (431.23 mPa.s at time zero). Without being limited to theory, it is believed that this may be due to an increase in density due to evaporation of a portion of light hydrocarbons during testing. Alternatively, the higher viscosity at 1065 min may indicate a change in asphaltene agglomeration, for example, as asphaltenes become more tightly packed, this may cause an increase in viscosity over time.
Using a modified version of the same 450 ml sample cell (reducing the volume using glass spacers to accommodate a smaller sample volume), a 60 Hz electrostatic field was applied to a 200 ml sample of diluent-bitumen blend extracted from a treater at a Foster Creek oil sands facility in Alberta, Canada. The diluent-bitumen blend was comprised of approximately 670 kg/m3 of diluent at a concentration of approximately 21.3%vol. The initial diluent-bitumen blend had a breakdown voltage of 10.7 kV. A 6 kV field at 60 Hz was applied (by ramping up to 6 kV at a rate of 1 kV/s) across a 5 mm gap, providing a 1.2 kV/mm electric field. The electric field was applied for 5-10 minutes. Before application of the electric field, a chemical asphaltene dispersant (product DX001, available from Dorf Ketal Chemicals) was added at a concentration of 300 ppm. The diluent-bitumen blend and the chemical asphaltene dispersant were mixed continuously. Characteristics of the sample were periodically determined, the results of which are depicted in Table 2 below. This testing was carried out at 25 C. It will be understood that a particular additive may function more or less effectively depending on the sample to which the electric field and additive are applied. A person of ordinary skill in the art will appreciate that the selection of additive may require optimization depending on, for example, the composition of extracted hydrocarbons or other parameters that are particular to a given hydrocarbon extraction operation.
Table 2 ¨ Viscosity of Sales Oil with Time After Treatment with Electrostatic Field and Asphaltene Dispersant Time Sample Dynamic Viscosity Sample Dynamic Viscosity (h) Viscosity Reduction Viscosity Reduction (mPa.$)* (%) (mPa.$)* (%) _ 0 Blank 1023 - Sales Oil + 1035 -(Sales Oil) Dispersant 0 Treatment 903 11.73 Treatment 807 22.03 with with Electrostatic Electrostatic Field Field _ 4 1001 2.16 805 22.22 After - - After 803 22.42 Treatment __________________________________ Treatment 21 - - 817 21.06 *Anton Paar Viscometer As can be seen from Table 2, the oil sample in the presence of an electrostatic field resulted in an initial viscosity reduction from 1023 mPa.s to 903 mPa.s (11.73%). By 4 hours, the viscosity

10 had increased to 1001 mPa.s, indicating that under the conditions of the experiment the reduction in viscosity was impermanent. In contrast, in the presence of both an asphaltene dispersant and an electrostatic field, the viscosity of the oil initially decreased from 1035 mPa.s to 807 mPa.s (22.03%) and the viscosity remained relatively consistent at subsequent sampling times of 4 h (805 mPa.$), 15 h ( 803 mPa.$), and 21 h (817 mPa.$). The results of the 15 experiments shown in Table 2 indicate that a more permanent viscosity reduction can be achieved in the presence of both an asphaltene dispersant and an electrostatic field.
Various embodiments of methods, apparatuses and systems have been described for reducing the viscosity of hydrocarbons, for example, bitumen. The above-described embodiments are intended to be examples and alterations and modifications may be effected thereto, by those of ordinary skill in the art, without departing from the scope of the teachings.

Claims

WHAT IS CLAIMED IS:

1. A method of reducing viscosity of hydrocarbons comprising:
i) breaking down agglomerations of the hydrocarbons by subjecting the hydrocarbons to an electric field, a magnetic field or ultrasonics to reduce the viscosity of the hydrocarbons; and ii) mixing the hydrocarbons with at least one additive to reduce the viscosity of the hydrocarbons, wherein step i) may be carried out before, after or concurrently with step ii).

2. The method of claim 1, wherein breaking down agglomerations of the hydrocarbons comprises subjecting the hydrocarbons to an electric field.

3. The method of claim 2, wherein the hydrocarbons are subjected to an electric field within a pipe or pipeline through which the hydrocarbons flow.

4. The method of claim 2 or 3, wherein the hydrocarbons remain within the electric field for a period of time sufficient to at least partially break-up agglomerations of asphaltenes in the hydrocarbons.

5. The method of any one of claims 3 to 4, further comprising adding the at least one additive to the hydrocarbons before applying the electric field, after applying the electric field or within the electric field.

6. The method of any one of claims Ito 5, further comprising detecting one or more characteristics of the mixture of the hydrocarbons and the at least one additive to determine if the mixture meets target specifications of a transport pipeline.

7. The method of claim 6, wherein the target specifications comprise a minimum API gravity value, a maximum viscosity value, or both a minimum API gravity value and a maximum viscosity value.

8. The method of claim 6 or 7, further comprising adjusting one or more of an amount of the at least one additive mixed with the hydrocarbons, an exposure time of the hydrocarbons within the electric field, and a strength of the electric field in order to adjust the characteristics of the mixture to meet the target specifications.

9. The method of any one of claims 1 to 8, further comprising:
providing the mixture of the reduced viscosity hydrocarbons with at least one additive to a transportation pipeline or pipe; and periodically subjecting the mixture in the pipeline to a further electric field, magnetic field or ultrasonics.

10. The method of any one of claims 1 to 9, wherein the hydrocarbons comprise asphaltene based bitumen extracted from an oil sands deposit.

11. The method of any one of claims 1 to 10, wherein mixing the reduced viscosity hydrocarbons with the at least one additive impedes agglomeration of asphaltenes in the hydrocarbons.

12. A system for reducing the viscosity of hydrocarbons comprising:
a pipe comprising:
a hydrocarbon inlet through which the hydrocarbons enter the pipe;
an additive inlet through which at least one additive for reducing the viscosity of the hydrocarbons enters the pipe; and a mixture outlet through which a mixture of the hydrocarbons and the at least one additive exit the pipe; and an electric field generator located between the hydrocarbon inlet and the mixture outlet for subjecting the hydrocarbons to an electric field to reduce the viscosity of the hydrocarbons; or a magnetic field generator located between the hydrocarbon inlet and the mixture outlet for subjecting the hydrocarbons to a magnetic field to reduce the viscosity of the hydrocarbons; or an ultrasonic generator located between the hydrocarbon inlet and the mixture outlet for subjecting the hydrocarbons to an ultrasonic wave to reduce the viscosity of the hydrocarbons.

13. The system of claim 12, wherein the system comprises an electric field generator and the hydrocarbons remain within the electric field for a period of time sufficient to at least partially destabilize agglomerations of asphaltenes of the hydrocarbons.

14. The system of claim 12 or 13, wherein the additive inlet is located upstream of the electric field generator, downstream of the electric field generator or proximate the electric field generator.

15. The system of any one of claims 12 to14, further comprising a monitoring and control device for detecting one or more characteristics of the mixed hydrocarbons and the at least one additive to determine if the mixture meets target specifications of a transport pipeline.

16. The system of claim 15, wherein the target specifications comprise a minimum API gravity value, a maximum viscosity value, or both a minimum API gravity value and a maximum viscosity value.

17. The system of claim 15 or 16, wherein the monitoring and control device further adjusts one or more of an amount of the at least one additive mixed with the hydrocarbons, an exposure time of the hydrocarbons within the electric field, and a strength of the electric field in order to adjust the characteristics of the mixture to meet the target specifications.

18. The system of any one of claims 12 to 17, wherein the hydrocarbons comprise asphaltene based bitumen extracted from an oil sands deposit.

19. The system of any one of claims 12 to 18, further comprising:
a lease automatic custody transfer (LACT) unit for monitoring and measuring the mixture of the reduced viscosity hydrocarbons with at least one additive provided to a transportation pipeline; and a plurality of additional electric field generators located along the transportation pipeline for periodically subjecting the mixture in the pipeline to a further electric field.

20. A method of reducing asphaltene agglomeration in hydrocarbons comprising:
subjecting the hydrocarbons to an electric field to reduce the viscosity of the hydrocarbons; and mixing the reduced viscosity hydrocarbons with at least one additive to further reduce the viscosity of the hydrocarbons subjected to the electric field.