FIELD OF THE INVENTION

[0001] The invention relates to apparatus and methods for separating hydrocarbons such as bitumen from solid particles (or particulates), such as sand, soil, rock or sediment particulates. The invention may be used in a variety of oilfield, non-oilfield, industrial or environmental contexts. It will be appreciated that methods and apparatus for separating hydrocarbons from particulates may be used to separate particulates from hydrocarbons.

BACKGROUND

[0002] In oil extraction, it is common for the crude hydrocarbons to be mixed with solid particles such as sand, soils or rock. This is particularly the case in oil sands formations, which inherently comprise sands, clays and other minerals

[0003] Separating the oil from the solid particles may be further complicated in cases where the oil is made up of long-chain hydrocarbons (e.g. bitumen) which tend to be viscous and so adhere to any particulates within the oil-particulate mixture. Many hydrocarbon deposits that occur in near surface reservoirs have characteristically high molecular weight structures that make separating them from the inorganic reservoir material (e.g. rock particulates, minerals and sand) a difficult process. Indeed, the difficulties in separating heavy hydrocarbons from solid particles (e.g. in drill cuttings) mean that often hydrocarbons are not recovered from such oil-particulate waste mixtures.

[0004] For example, in the western Canadian sedimentary basin, currently the lowest cost solution for many operators is to stabilize their oil contaminated drill wastes with an absorbent material (i.e. wood chips) and transport it to a regulated waste management facility and limited or no hydrocarbon recapture is initiated or achieved.

[0005] Other methods of separating oil from solid particles include thermal desorption technology in which high amounts of mechanical energy is used to create friction forces to generate heat that is used to vaporize hydrocarbons off drill cuttings which vapors are subsequently condensed and reused or sold, and normally allows for the post treatment solids to be handled as “inert” non-dangerous waste and buried or land spread on/at site. [0006] However, this type of technology has not been successful when used to treat SAGD oil laden drill cuttings. In particular, it was found that the oils from SAGD operations were too viscous to effectively vaporize and if too high temperatures, long residence times in the treater and high energy were used, hydrogen sulfide (H2S) gas was formed which was dangerous for the operators. In addition, sand in SAGD drilling operations is abrasive and can damage devices which used mechanical shear heating elements.

[0007] More generally, the need for intensive energy addition may make the recovery of high molecular weight hydrocarbons more expensive than other known crude sources. Therefore, an energy efficient process is desirable. In addition, it would be advantageous that any by-product of the process would be sufficiently non-hazardous so that they could be disposed of safely with limited further processing.

Prior Art

[0008] Vermeulen et al. in CA 1 ,058,541 disclose a method and apparatus for separation of bitumen from tar sand involving an electric flotation cell formed of a container in which is placed a charge of unseparated tar sand to a first level and which is then filled with water to a second level and electrodes positioned in the cell in relation to the tar sand such that on application of a low voltage to the electrodes an electric current flows through the tar sand and water.

[0009] Jarvinen in CA 2,866,244 describes a method and apparatus for extracting oil or bitumen from the soil comprising oil or bitumen or from the solid soil materials comprising oil or bitumen, such as oil sand or from ice, wherein oil or bitumen is extracted by using hot liquid so that the soil or soil material is brought in touch with hot liquid. The heat of the hot liquid extracts oil or bitumen from the soil or from the solid soil materials. Hot oil or hot water is pumped down into the soil or solid soil particles are dropped into hot oil or hot water.

[0010] Steinnes in WO 2012/125,043 discloses a method and a device for cleaning drill cuttings comprising cuttings and oil-based drilling mud, wherein a significant proportion of the drilling mud is removed from the drill cuttings, and wherein the method comprises: disposing the drill cuttings in a receptacle; vibrating the receptacle until particle fluidization of the drill cuttings takes place; maintaining the drill cuttings in a particle-fluidized state during the subsequent treatment; adding a soap to the drill cuttings; allowing the soap to flow through the drill cuttings whilst the drill cuttings are particle-fluidized; draining liquid from the receptacle; and then emptying cleaned drill cuttings out of the receptacle.

[0011] Gene, A. and Bakirci, B. “Treatment of emulsified oils by electrocoagulation: pulsed voltage applications”, Water Science and Technology 71.8, 2015 (doi:

10.2166/wst.2015.092) describes the effect of pulsed voltage application on energy consumption during processing emulsified oils with electrocoagulation.

[0012] WO 2017/165,963 discloses an apparatus and method for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture. The apparatus comprises: a container for the mixture; a shockwave generator comprising two electrical terminals; and a pulsed power supply. The pulsed power supply is configured to apply a series of one or more voltage pulses to the terminals, such that, when each voltage pulse is applied to the terminals, a shockwave is applied to the mixture to promote separation of the components of the mixture.

SUMMARY

[0013] In accordance with the invention, there is provided a terminal assembly for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the terminal assembly comprising: a shockwave generator comprising an upper terminal and an opposed lower terminal, the upper and lower terminals forming a terminal pair; a well around a lower terminal having a barrier configured to trap granular material next to the lower terminal, wherein the lower terminal protrudes up from a bottom of the well.

[0014] The top of the lower terminal may be configured to be at the same height as, or above, the top of the barrier.

[0015] The base of the well may be formed from insulating material. [0016] The barrier may be configured to slope upwards and outwards from the bottom of the well.

[0017] The bottom of the well may slope upwards towards a bottom of the barrier.

[0018] The barrier may be an upright wall.

[0019] The barrier may be angled at an angle, Q, of at least 30° from horizontal. The barrier may be angled at an angle, Q, of at least 10° from horizontal.

[0020] The barrier may have a height of between 1-15 cm.

[0021] The top of the barrier may be below the bottom of the upper terminal.

[0022] The top of the barrier may extend around the bottom electrode such that the lateral distance to the electrode is less than 15 cm.

[0023] The terminal assembly may be connected together as a unit, wherein the unit can be inserted into or removed from a container. This may allow the inter-terminal spacing to be set accurately outside the container and maintained during insertion and removal.

[0024] At least one of the terminals may be mounted on a shock absorber. The shock absorber may be configured to allow one terminal to move away from the other along the inter-terminal axis. The terminal assembly may comprise one or more stops configured such that after the shock has passed, the shock absorber drives the terminal back to the stops. This may help ensure a consistent inter-terminal spacing over a series of successive shockwaves.

[0025] According to a further aspect, there is provided a method for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, method comprising: generating a shock using a shockwave generator comprising an upper terminal and an opposed lower terminal, the upper and lower terminals forming a terminal pair; trapping granular material (e.g. sand) in a well around a lower terminal, the well having a barrier configured to the trap granular material next to the lower terminal, wherein the lower terminal protrudes up from a bottom of the well. [0026] According to a further aspect, there is provided a method for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the method comprising: adding a granular dielectric substance to the hydrocarbon-particulate-aqueous mixture; applying a series of one or more voltage pulses between electrical terminals positioned within the hydrocarbon-particulate-aqueous mixture, such that, when a voltage pulse is applied to the terminals, a shockwave is generated in the hydrocarbon-particulate- aqueous mixture which promotes separation of components of the mixture.

[0027] The granular dielectric substance may be sand.

[0028] According to a further aspect, there is provided a method for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the method comprising: generating a shockwave within a hydrocarbon-particulate-aqueous mixture to promote separation of the components of the mixture; dividing the separated components based on size, shape and density by injecting a carrier fluid up through the separated mixture.

[0029] The separated hydrocarbon component may have a density greater than the density of the carrier fluid.

[0030] The carrier fluid may be water.

[0031] The separated hydrocarbon component may be in the form of droplets or spheroids suspended in the water, the droplets having a size of between 1-400 pm.

[0032] The upward velocity of the carrier fluid may be configured to allow the sand particulates to sink.

[0033] The upward velocity of the carrier fluid may be configured to impel clay particulates upwards.

[0034] The upward velocity of the carrier fluid may be configured to impel the hydrocarbon droplets or spheroids upwards. [0035] The carrier fluid may be water, and wherein the upward velocity of the carrier fluid may be between 2.95x10 ⁶ -4.0 m/s. The carrier fluid may be water, and wherein the upward velocity of the carrier fluid may be between 0.04-0.1 m/s. The carrier fluid may be water, and wherein the upward velocity of the carrier fluid may be between 0.001-1.0 m/s.

[0036] According to a further aspect, there is provided an apparatus for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the apparatus comprising: a container for containing the hydrocarbon-particulate-aqueous mixture; a shockwave generator comprising an electrical terminal pair located within the container; a pulsed power supply configured to apply one or more voltage pulses to the electrical terminal pair; the apparatus being configured such that, when a voltage pulse is applied to the electrical terminal pair, a shockwave is generated in the mixture to promote separation of the components of the mixture; an elutriation divider, the elutriation divider being configured to receive the separated mixture from the container and to divide the separated components based on size, shape and density by injecting a carrier fluid up through the separated mixture.

[0037] According to a further aspect, there is provided a terminal assembly for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the terminal assembly comprising: a shockwave generator comprising an electrical terminal pair; and wherein at least one of the terminals is mounted on a shock absorber.

[0038] At least one terminal may be surrounded by an insulating material, and wherein the terminal and the surrounding insulated material are rigidly mounted on the same shock absorber.

[0039] The shock absorber may comprise a resilient material. [0040] At least one of the terminals may be held in place opposite the other terminal by one or more arms, wherein the arm is shaped in order to disperse shockwaves generated by the shockwave generator.

[0041] The terminal pair may comprise an upper terminal and a lower terminal, and wherein the terminal assembly comprises a well around the lowerterminal having a barrier configured to trap granular material next to the lowerterminal, wherein the shock absorber is configured to allow the lowerterminal and well bottom to move up and down with respect to the well barrier and the upper terminal.

[0042] According to a further aspect, there is provided a method of administering a shock for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the method comprising: generating a shockwave using an electrical terminal pair; and absorbing the shock by at least one of the terminals by allowing the terminal to resiliently move in response to experiencing the shock.

[0043] According to a further aspect, there is provided a terminal assembly for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the terminal assembly comprising: a shockwave generator comprising an electrical terminal pair; wherein an upper terminal is held in place opposite a lower terminal by an arm, wherein the arm is shaped in order to disperse shockwaves generated by the shockwave generator.

[0044] In accordance with the invention, there is provided an apparatus for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the apparatus comprising: a container for containing the hydrocarbon-particulate-aqueous mixture; a shockwave generator comprising an electrical terminal pair located within the container; a pulsed power supply configured to apply one or more voltage pulses to the electrical terminal pair; the apparatus being configured such that, when a voltage pulse is applied to the electrical terminal pair, a shockwave is generated in the mixture to promote separation of the components of the mixture.

[0045] It will be appreciated that the pulsed power discharges between electrical terminal pairs of embodiments described herein is a complex electrical phenomenon involving high rate transients. For example, the electrical discharge may cause one or more of the following:

• Shock and Acoustic Waves;

• Direct and Indirect Chemical effects: For example, this may create highly reactive hydroxyls (such as O3, OH-, H2O2 etc.) and cause covalent bond breaking; hydrolysis reactions; changes in pH; synthesis or analysis reactions; reduction-oxidation reactions.

• Sonochemistry

• Volumetric displacement enabling a form of agitation

• Thermal Effects to bulk properties (e.g. heating may lower viscosity of heavy hydrocarbons);

• Ionization from Electric Fields; and

• Photochemistry (e.g. initiated by UV light).

[0046] One or more of these effects may combine to promote separation of the components in the hydrocarbon-particulate-aqueous mixture. That is, the energy contained in the electrical discharge between terminals may be distributed through one or more of the various mechanisms to the components of the hydrocarbon-particulate- aqueous mixture to effect separation.

[0047] It will be appreciated that how the energy from the electrical discharge is distributed may be dependent on the particular electrical characteristics of the components of the hydrocarbon-particulate-aqueous mixture (e.g. whether the components are conductors, insulators and/or dielectrics). The electrical discharge energy distribution may also be dependent on how the components of the hydrocarbon-particulate-aqueous mixture are spatially distributed. For example, small particulates may provide a large surface area for chemical reactions to occur.

[0048] The pulsed power supply may comprise a high-voltage power supply. [0049] The terminal pair may comprise an electrode pair having a positive and a negative electrode positioned within the container and separated by a gap, such that when a high- voltage pulse is applied to the mixture, a plasma arc is generated between the electrodes which applies a shockwave to the mixture. The hydrocarbon-particulate-aqueous mixture itself may transmit the plasma arc to generate the shockwave.

[0050] The container may be considered to comprise one or more walls for constraining the mixture such that at least a portion is positioned between a terminal pair.

[0051] The voltage between the terminals in the terminal pair may be at least 5kV. The voltage between the terminals in the terminal pair may be at least 10kV. The voltage between the terminals in the terminal pair may be at least 18kV. The voltage between the terminals in the terminal pair may be at least 35kV. The voltage between the terminals in the terminal pair may be at most 100kV. Lower voltages may reduce the rate of wear of one or more of the terminals. Lower voltages may reduce the need for electrical insulation and lower the power consumption. Higher voltage may produce stronger shock waves and/or facilitate different chemical reactions.

[0052] The voltage gradient between the terminals in the terminal pair may be between 39.4kV/cm and 7.1 kV/cm. The voltage gradient between the terminals in the terminal pair may be at least 7.1 kV/cm. The voltage gradient between the terminals in the terminal pair may be at most 50kV/cm (or at most 39.4kV/cm).

[0053] The shockwave generator may be configured to receive a bridgewire between the terminals in the electrical terminal pair, the bridgewire being configured to explode in response to a voltage pulse being applied to the terminal pair which applies a shockwave to the mixture.

[0054] The apparatus may comprise a bridgewire replacing mechanism, the bridge wire replacer configured to replace the bridgewire after each voltage pulse.

[0055] The shockwave generator may comprise an ionic bridge injector configured to inject a solution of ionic solution between the electrical terminal pair of the shockwave generator such that when a voltage pulse is applied to the mixture, a plasma arc is generated between the electrical terminal pair which applies a shockwave to the mixture. [0056] The ionic bridge injector may be configured to repeatedly inject a volume of ionic material to enable successive shockwaves to be generated by the shockwave generator.

[0057] The apparatus may comprise an agitator configured to mix and/or provide aggregate transport within the hydrocarbon-particulate-aqueous mixture.

[0058] The apparatus may comprise multiple terminal pairs.

[0059] Each voltage pulse may have an energy of at least 500J.

[0060] The apparatus may be configured to apply a series of shockwaves to the mixture.

[0061] The temporal separation between successive shockwaves may be at most 5 seconds. The apparatus may be configured to deliver shockwaves at a frequency of around 5 per second or much faster.

[0062] The rise time of the leading edge of the voltage pulse may be less than 3ps. The leading edge may be considered to be the time it takes for the pulse to ramp up to maximum voltage. The peak voltage rate of increase may be at least 2kV/ps.

[0063] The distance between terminals in a said terminal pair may be between ¼ inch (0.635 cm) and 1 inch (2.54 cm). The distance between terminals in a said terminal pair may be between 1 inch (2.54 cm) and 2 inch (5.1 cm).

[0064] One of the terminals in a said terminal pair may be a point terminal and the other terminal in the terminal pair may be a plate terminal.

[0065] One of the terminals in a said terminal pair may be configured to move to agitate and/or translate the hydrocarbon-particulate-aqueous mixture within the container.

[0066] The mixture may be introduced into the container via a gravity feeding system and/or a pressure filling system (e.g. comprising a pump).

[0067] One of the terminals in a said terminal pair may form part of an auger, the auger being configured to agitate and translate the hydrocarbon-particulate-aqueous mixture through the container from an inlet to an outlet. The auger may be formed from a continuous helical flighting (or flight). The auger flighting may be a ribbon flighting (e.g. for use in very thick viscous mixtures). The auger may be shaftless. The liquid flow in above the augers may be either counter current or concurrent with the solids transport flow in the augers. [0068] The auger may comprise a standard-pitch flight auger. Conveyor screws with pitch (e.g. distance for flighting to make 1 full turn) substantially equal to screw diameter are considered standard. They are suitable fora whole range of materials in most conventional applications.

[0069] The auger may comprise a short pitch auger. In this case, the flight pitch is reduced to a fraction (e.g. between ~2/3 diameter). This may be advantageous for inclined or vertical applications. Used in screw feeders. Shorter pitch reduces flushing of materials which fluidize.

[0070] The auger may comprise a half pitch auger. This auger is a particular variant of the short pitch auger where the pitch is reduced to 1/2 standard pitch. This may be useful for inclined applications, for screw feeders and for handling extremely fluid materials.

[0071] The auger may comprise a variable-pitch flight auger. Variable-pitch flights have variable, increasing or decreasing pitch and may be used in screw feeders, for example, to provide uniform withdrawal of fine, free flowing materials over the full length of the inlet opening.

[0072] The auger may comprise a double (or multiple) flight auger. Double (or multiple) flight augers may help provide smooth regular material flow and uniform movement of certain types or materials.

[0073] The auger may comprise a tapered flight auger. Tapered (or screw) flights increase or decrease in diameter along its length (e.g. from 2/3 to full diameter. These augers may be used in screw feeders to provide uniform withdrawal of lumpy materials. They may be more economical than variable pitch.

[0074] The auger may comprise a cut-flight auger. Cut-flights are notched at regular intervals at outer edge of these auger flightings. The notches may help mixing action and agitation of material in transit. These augers may be useful for moving materials which tend to pack.

[0075] The auger may comprise a cut & folded flight auger. These augers comprise folded flight segments configured to lift and spill the material. Partially retarded flow may help provide thorough mixing action. They may help heating, cooling or aerating light substances. [0076] The auger may comprise a ribbon flight auger. Ribbon augers may be advantageous for conveying sticky or viscous materials. That is, the open space between the flighting and the pipe or shaft may help eliminate collection and build-up of material.

[0077] The auger may comprise one or more paddles. For example, adjustable paddles positioned between screw flights may be configured to oppose flow to provide gentle but thorough mixing action.

[0078] The auger can be operated in a negative angle (i.e. pushing solids downhill); a zero angle (horizontal) to a positive (uphill) angle up to 90° (vertical)

[0079] Flotation aids can be introduced at any low point along the length of the auger. Flotation aids may include: chemical flotation aids, entrained air or bubbles. Flotation may also be controlled by controlling the bulk fluid flow (e.g. elutriation).

[0080] The terminals may be located on or at the housing or container walls in any spatial array. For example, the terminals may or may not conform to a single linear line. The spatial separation between neighbouring electrodes may be different.

[0081] In multiple-terminal-pair embodiments, the energy deposition (e.g. pulsing strategy) for different terminal pairs may be different. For example, the pulse rate or energy distribution of different terminal pairs may be normally distributed, left or right biased or bi- modal or multi-modal to effect energy efficient separation of hydrocarbons in the mixture.

[0082] Opposed terminal pairs may be used anywhere outside the volume swept out by any auger flightings.

[0083] The apparatus may comprise a bulk separator comprising separate outlets for the particulate phase, the oil phase and the water phase.

[0084] The shock and/or acoustic waves may be applied to the mixture using a Lenoir- type thermodynamic cycle. In a Lenoir cycle, a material (e.g. a portion of the mixture or an ionic bridge) undergoes: substantially constant volume (isochoric) heat addition (in this case, the rapid heating by the plasma arc to form a gas filled channel or void which expands and creates a shockwave in the surrounding material); isentropic bubble expansion (which causes an acoustic wave in the surrounding material as the bubble volume increases to a maximum); and constant pressure (isobaric) heat rejection (where the bubble collapses also causing an acoustic wave in the surrounding material and the cycle can begin again). The drive velocity of the initial shock wave may be at least 1500 m/s. The drive velocity of the acoustic wave may be plus 10 m/s in bubble growth and minus 10m/s in bubble collapse.

[0085] The apparatus may comprise one or more augers for moving the mixture with respect one or more stationary terminals.

[0086] The apparatus may comprise one or more augers for moving the mixture and the container walls are configured to be shaped to correspond to at least part of the circumference of the one or more augers.

[0087] According to a further aspect, there is provided a method for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the method comprising: applying a series of one or more voltage pulses between electrical terminals positioned within the hydrocarbon-mineral-aqueous mixture, such that, when a said voltage pulse is applied to the terminals, a shockwave is generated in the hydrocarbon- particulate-aqueous mixture which promotes separation of the components of the mixture.

[0088] The method may comprise adding water to a mixture comprising hydrocarbons and particulates such that water makes up at least 25% of the resulting mixture by volume. The water content may be no more than 90% of the mixture by volume.

[0089] The series of pulses may be configured to limit the temperature of the sample to no more than 50°C. The series of pulses may be configured to limit the temperature of the sample to no more than 85°C

[0090] The solid particles may comprise soils or minerals. The solid particles may comprise rock fragments.

[0091] The hydrocarbons may comprise bitumen.

[0092] According to a further aspect there is provided An apparatus for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture, the apparatus comprising: a container for containing the hydrocarbon-particulate-aqueous mixture; a shockwave generator configured to generate one or more shockwaves within the mixture in the container; the apparatus being configured such that the generated shockwaves promote separation of the components of the mixture.

[0093] A point electrode may be considered to be an electrode configured to discharge or receive electricity at a tip or end. A rod electrode may be considered to be an electrode configured to discharge or receive electricity along a length. A plate electrode may be considered to be an electrode configured to discharge or receive electricity on a surface. It will be appreciated that designating an electrode as a point, rod, or surface electrode may depend on the orientation of the electrode with respect to other electrode in a system. For example, two elongate electrodes may be considered point electrodes if they are arranged end to end coaxially; or as rod electrodes if arranged substantially parallel to each other; or as one rod and one point electrode if the arranged transverse to each other in the same plane.

[0094] Sand may be considered to be a granular material composed of finely divided rock and mineral particles. Sand may be crystalline. Sand may consist of silica (silicon dioxide, or Si02) and/or calcium carbonate. Silica may be in the form of quartz. Calcium carbonate may be in the form of aragonite. Natural sand may include some impurities.

[0095] Sand particles may have a diameter of less than 10 mm and greater than 0.05mm. Sand may consist of particles with a diameter of between 0.074 and 4.75 millimeters. Sand may consist of particles with a diameter from 0.0625 mm to 2 mm. These diameter values may correspond to maximum dimensions of the particles.

[0096] Sand particles may be electrically insulating (resistivity of greater than 10 ¹⁰ Qm and/or less than 10 ²⁰ Qm). Sand particles may be formed from dielectric materials (e.g. with a dielectric field strength between 10-100 kV/mm at 1 MHz and 25°C).

[0097] The density of sand is 2.65 g/cm ³ . The density of Aragonite is 2.93 g/cm ³ .

[0098] The density of heavy hydrocarbons may be between 1 and 1 .1 g/cm ³ .

[0099] The density of light hydrocarbons may be between 0.9 and 1 g/cm ³ .

[0100] Clay may be considered to be sediment with particles smaller than silt, typically less than 0.00016 inch (0.004 mm). [0101] The apparatus may comprise a terminal assembly having a well for trapping granular material, and a container with a container bottom for containing the mixture, the container bottom being angled at an angle, a, less than a threshold angle, a _th r _esh , from horizontal, wherein the container bottom separates the wall of the well from the wall of the container a _th r _esh may be 30°, 45°, or 60°.

[0102] The one or more augers may be configured to move 0.5 m ³ /hr of 1 ,500-2,100 kg/m ³ slurry (hydrocarbon-particulate-aqueous mixture) at approximately 95% container loading. The material may have a retention time in the container of between 10 and 30 minutes (e.g. 20 min). It will be appreciated that, because the system is scalable, other design configurations (e.g. different diameter, length, auger helix angle etc.) are available depending on the desired outcomes.

[0103] The pitch of the auger flighting and diameter of the auger may or may not be constant across its length (e.g. from inlet to outlet). In addition, in a vertical or horizontal, batch or continuous modes, fluid flow may be introduced at the bottom that could aid in washing the sand and floating the oil/bitumen off the top. For example, the introduced water may form a fluidized bed that suspends the solids or an air sparger to introduce atmospheric air under pressure to form bubbles that aid in floatation.

[0104] The auger may operate at any angle between horizontal (zero degrees) and vertical (90 degrees from horizontal). When operating in a vertical mode, the gap between the auger flighting and the container wall may be smaller.

[0105] The auger and electrodes may, or may not, be separate components. The apparatus may comprise a propeller, an impeller, an angled or straight rod or paddle wheel which may or may not comprise one or more electrodes. The apparatus may comprise a plurality of angled paddles connected to a common shaft at various axial positions.

[0106] The container may comprise an outlet positioned towards the top of the container for removing separated light oil. The container may comprise an outlet at the bottom of the container for removing separated particles (and/or other denser-than-water materials) from the bottom of the container. The container may comprise an overflow weir configured to induce an upward current to generate elutriation. This upward current may be configured to allow heavier oil (greater than 1 .Og/cm ³ ) to be separated.

[0107] The lateral dimension of the well may be less than a quarter that of the container. [0108] The apparatus may be configured to administer 5-25 continuous successive shocks to the mixture. The apparatus may be configured to administer 25-400 continuous successive shocks to the mixture. The apparatus may be configured to provide between 2-15 pulses per kilogram of mixture. The apparatus may be configured to provide 2kJ of energy to the mixture per pulse. The apparatus may be configured to provide between 10- 50kJ per kilogram of mixture. It will be appreciated that the number and intensity of the pulses may depend on the materials being separated and on the pH of the water. For example, drilling waste may require 2-15 pulses per kilogram of mixture at a pH of 7-8. Ore may require 15-200 pulses per kilogram of mixture at a pH of 7-8. Other ore may require 50-400 pulses per kilogram of mixture at a pH of 12-13.

[0109] The machine may be configured to cycle or rotate between banks of electrodes firing (each bank comprising 1 or more electrodes). For example, one bank may be formed from every third electrode (1-4-7-10, numbered sequentially); a second bank may be formed from the next electrodes (2-5-8-11); and a third bank may be formed from the next electrodes (3-6-9-12). These banks may be fired in a repeating cycle.

[0110] The pulse repetition rate may be between 0.1 to 10 pulses per second per electrode. It will be appreciated that a pulse rate of 0.1 per second per electrode means that one electrode will administer a pulse every 10 seconds.

[0111] The energy per pulse per electrode may be between 1.5kJ/pulse and 3kJ/pulse (e.g. around 2kJ/pulse). Lower energy shocks may be less effective at separation, and larger energy shocks may be inefficient (i.e. separation may occur, but extra energy is expended).

[0112] The mixture may comprise hydrocarbons and particulates such that water makes up at least 25% of the resulting mixture by volume. The water content may be no more than 90% of the mixture by volume.

[0113] The series of pulses applied to the mixture may be configured to limit the temperature of the sample to no more than 50°C. The series of pulses may be configured to limit the temperature of the sample to no more than 85°C

[0114] The solid particles may comprise soils or minerals. The solid particles may comprise rock fragments and sand. [0115] An agitator may comprise one or more of: an auger and a paddle wheel. An agitator may comprise one or more surfaces configured to rotate about an elongate axis.

[0116] In the context of this disclosure, the term separation relates to converting the components from a bound mixture (e.g. where the components are stuck to each other) to an unbound mixture (e.g. where the components are not stuck to each other or are separate on at least a microscopic scale).

[0117] In contrast the term dividing relates to moving the components a significant distance apart on a macroscopic scale (e.g. phase disengagement). In some embodiments, the separation and dividing take place as the result of a single process. For example, if the mixture comprises a light oil and sand, shocking the mixture underwater causes separation of the oil and sand, and the division is effected when the sand sinks to the bottom and the oil floats to the top. In other embodiments, the separation and division require separate processes. For example, if the mixture comprises heavy hydrocarbon and sand, the shock wave may separate (or unstick) the heavy hydrocarbon from the sand but both components will remain at the bottom. Division may then be effected using an elutriation chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0118] Various objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the invention. Similar reference numerals indicate similar components.

Figure 1a is a cross-section view of an embodiment of a separator apparatus for separating hydrocarbons from solid particles.

Figure 1 b is a close-up of the lower terminal of the embodiment of figure 1 a. Figure 1c is a graph showing the current profile across the terminals during a shock pulse.

Figure 2a is a vertical cross-section view of a further embodiment of a separator apparatus for separating hydrocarbons from solid particles.

Figure 2b is a more-detailed vertical cross-section view of the container and augers of the embodiment of figure 2a. Figure 2c is a more-detailed vertical cross-section view of the terminal assembly of the embodiment of figure 2a.

Figure 2d is a horizontal cross-section view of the terminal assembly of the embodiment of figure 2a.

Figure 2e is a vertical cross-section view of the alternative terminal assembly. Figure 2f is a horizontal cross-section view of the terminal assembly of the embodiment of figure 2e.

Figure 3 is a graph of the Paschen type curves of four liquid mixtures.

Figure 4 is a schematic of the model used to analyse the presence of sand next to the lower electrode.

Figure 5 is a vertical cross-section view of a further embodiment of a separator apparatus for separating and dividing hydrocarbons from solid particles.

Figure 6 is a vertical longitudinal cross-section view of a further embodiment of a separator apparatus for separating hydrocarbons from solid particles.

Figure 7a is a vertical longitudinal cross-section view of a further embodiment of a separator apparatus for separating hydrocarbons from solid particles.

Figure 7b is a vertical transverse cross-section view of the embodiment of figure 7a.

DETAILED DESCRIPTION

Introduction

[0119] The invention relates to apparatus and methods for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture. With reference to the figures, these apparatus and methods for separating hydrocarbons from solid particles are described. The apparatus and methods may be particularly applicable for separating heavy and/or viscous hydrocarbons, such as bitumen, from rock or mineral particulates such as sand or carbonates. The subject technology seeks to effect separation of hydrocarbons from solid particles whilst mitigating the need of additives which may include chemicals potentially hazardous to the environment such as soap or ionic materials. The subject technology may also mitigate the need to supply external heat to the raw materials.

[0120] It will be appreciated that this technology may also work for separating lighter oils from particulates. For example, lighter oils may include diesel and/or mineral oil. [0121] The apparatus comprises: a container for the mixture; a shockwave generator comprising two electrical terminals; and a pulsed power supply. The pulsed power supply is configured to apply a series of one or more voltage pulses to the terminals, such that, when each voltage pulse is applied to the terminals, a shockwave is applied to the mixture to promote separation of the components of the mixture. Using shockwaves may mitigate the need to heat the mixture and/or add chemicals to facilitate separation of hydrocarbons from solid particles such as sand, mineral or carbonate particles. As will be described below, the apparatus may also include features for controlling the position and flow of materials in order to better control the shockwaves and/or control how the constituents are divided.

[0122] All terms used within this specification have definitions that are reasonably inferable from the drawings and description. In addition, the language used herein is to be interpreted to give as broad a meaning as is reasonable having consideration to the rationale of the subject invention as understood by one skilled in the art.

[0123] Various aspects of the invention will now be described with reference to the figures. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects of the invention. A number of possible alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the present disclosure.

[0124] Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the present disclosure. For example, it will be appreciated that all preferred features described herein may be applicable to all aspects of the present disclosure described herein.

[0125] This technology may be used in a fixed plant or in a mobile processing and treatment unit (e.g. truck-based or ship-based embodiments) to treat “oil contaminated” drilling waste of upstream oilfield operators. This technology may also be used in downstream and/or midstream applications. The present technology may be used to recover, for example, hydrocarbons from oil-based drill cuttings and/or hydrocarbons from reservoir cuttings (e.g. in SAGD markets), hydrocarbon deposits harvested from mining operations and/or to clean contaminated solids after an oil spill (e.g. sand from a contaminated beach) or hydrocarbons leaked into the ground from pipeline or tank.

Plasma Arc Embodiment

[0126] Figure 1 a shows an embodiment of a separator apparatus 100 for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture 103, the apparatus comprising: a container 101 (e.g. a crucible, tank, channel or pipe) for containing the hydrocarbon-particulate-aqueous mixture; a shockwave generator comprising a terminal pair 102 having a positive 102b and a negative 102a electrical terminal; and a pulsed power supply 104 configured to apply a voltage pulse between the positive and negative electrical terminals 102a,b, the apparatus being configured such that, when a voltage pulse is applied to the positive and negative electrical terminals, a shockwave is generated in the mixture to promote separation of the components of the mixture.

[0127] The pulsed power supply 104 is, in this case, a high-voltage power supply, and the terminal pair comprises an electrode pair 102 having a positive electrode 102b and a negative electrode 102a positioned within the container and separated by a gap, such that when a high-voltage pulse is applied to the mixture, a plasma arc is generated between the electrodes 102a,b within the hydrocarbon-particulate-aqueous mixture 103 which applies a shockwave to the mixture. In this case, the terminal ends are positioned within the container so that the gap (and the spark created within the gap) can be fully submerged within the hydrocarbon-particulate-aqueous mixture.

[0128] It will be appreciated that a pulsed power supply may comprise capacitors configured to store charge to deliver when the pulse is initiated.

[0129] The container may be as small as a few litres (e.g. 1 gallon or 4 litres) or may be significantly larger (e.g. up to 1000 litres or bigger). The container may be formed from steel (e.g. of thickness greater than ¼ inch or greater than ½ inch). It will be appreciated that the container should be configured to withstand the force of the shockwaves.

[0130] In this context, the negative electrode 102b is the cathode, because the negative electrode is the electrode from which a current leaves the polarized electrical device (i.e. from which electrons are supplied). Likewise, in this context, the positive electrode 102a is the anode, because the positive electrode is the electrode from which a conventional current enters the polarized electrical device (i.e. into which electrons are received). It will be appreciated that positive and negative in this context means the relative charge with respect to the other electrode in the electrode pair.

[0131] In this case, both electrodes are point electrodes. By using at least one point electrode, rather than a parallel rod or parallel plate electrode pair, the position of the plasma arc is reproducible. In other embodiments, where multiple plasma arcs are desired, or the position is less important, parallel rod or plate electrodes may be used.

[0132] In this case, there is provided a well 120 around a lower terminal having a barrier 121 configured to trap granular material next to the lower terminal, wherein the lower terminal protrudes up from a bottom of the well.

[0133] The barrier 121 in this case is an upright wall which encloses a flat bottom 122. In this case the barrier or wall may be angled at an angle, Q, of at least 30° from horizontal. This threshold angle means that the force along the slope on a particle sitting on the wall is at least half its effective weight within the fluid.

[0134] The barrier in this case has a height of 1.5 cm from the bottom of the well. It will be appreciated that other heights may also be used (e.g. greater than 1 cm up to 15 cm).

[0135] The top of the barrier 121 may extend around the bottom electrode such that the lateral (e.g. horizontal) distance to the electrode is less than 15 cm. In this case, the distance between the bottom electrode and the top of the well barrier is 7.5 cm.

[0136] It will be appreciated that the lateral dimension of the well may be significantly less than (e.g. less than a tenth or less than a hundredth) that of the container.

[0137] The well is configured to trap sand 123 (or other dielectric particulates) close to the lower electrode 102b. The inventors have discovered that sand has the effect of reducing the effective distance between the electrodes so as to facilitate generation of a spark across the terminal. In this way, the trapped sand can make the shock-wave generation more energy efficient.

[0138] In this case, the top of the terminal is configured to be above the top of the barrier. That is, a plane 129b which intersects the top of the lower terminal, and which is transverse to the axis 129a between the terminals, is above the top of the barrier. This means that when a shock is generated the interaction between the shock and the barrier is reduced. This can help reduce the damage on the barrier due to the shock waves.

[0139] In this case, the barrier is configured to slope outwards from the bottom of the well. That is, the angle Q with the horizontal plane is configured to be less than 90°. This means that any shock wave travelling outwards from the electrode which impinges on the barrier is reflected at least partially upwards. This may help prevent reflected shockwaves from directly impinging on the lower terminal and/or from ringing (e.g. repeatedly being reflected) within the well.

[0140] In this case, the base of the well is formed from insulating material 124. This prevents charge from passing between the terminal and the metallic container. The insulating material may be thermoplastic or a ceramic material.

[0141] It will be appreciated that other embodiments may have different well profiles. For example, the bottom of the well may comprise a surface which slopes upwards from the terminal towards the base of the barrier. Other embodiments the barrier may slope inwards from the top and downwards to intersect with the terminal at the bottom of the well.

[0142] It will be appreciated that, in some cases, the hydrocarbon-particulate-aqueous mixture may comprise sand. In other cases, a granular dielectric substance, such as sand, may be added to the hydrocarbon-particulate-aqueous mixture. The granular dielectric substance may be added until it makes up at least 5% of the mixture by volume (e.g. wherein the volume of the granular substance is the aggregate volume of the grains not including inter-grain volumes). As the components are separated by the shockwaves, the separated particulates will fall into, and be trapped by, the well.

[0143] The distance between the electrodes in this case is ½ inch (~1.3cm). It will be appreciated that, in other embodiments, the distance between the electrodes may be between about ¼ and 1 inch (~0.6cm-~2.5cm) or between ¼ and ¾ inch (~0.6cm-~1 9cm). [0144] As noted above, the cathode 102b in this case is grounded to earth 106. The other electrode is configured to provide a voltage between the electrodes of at between 5-15kV (higher voltages may be used, e.g. at least 25 kV). It will be appreciated that other voltages may be applied to the electrodes. E.g. the electrodes may have a voltage of the same magnitude (with respect to ground) but opposite polarities. Some embodiments may be configured to vary the voltage output of the high-power voltage supply.

[0145] In this embodiment, a 10kV voltage difference between the electrodes gives a voltage gradient between the two electrodes of 4kV/cm (10kV/ ½ inch). In other embodiments, the voltage gradient may be in the range between around 40kV/cm and 2kV/cm. It will be appreciated that embodiments with a higher voltage power supply may have larger inter-electrode spacing. It will be appreciated that some embodiments may allow the inter-electrode spacing to be adjusted (e.g. automatically depending on the composition of the hydrocarbon-particulate-aqueous mixture).

[0146] In this case, the high-voltage power supply 104, comprises a spark gap power switch 104b and a microcontroller 104a. Using a spark-gap power switch allows the pulse profile to have a rapidly increasing leading edge which helps facilitate formation of the plasma arc. The microcontroller 104 in this case is configured to produce a series of pulses (e.g. at 5 second intervals or much faster). It will be appreciated that the pulse train may be controlled using other circuits or processors (e.g. a microprocessor, an application- specific integrated circuit (ASIC), or a Multi-core processor). More rapid pulse trains may also be used. For example, the pulse frequency may be up to several pulses per second or faster.

[0147] The high-voltage power supply is configured to apply a series of high-voltage pulses to the sample (in this case 1 pulse is applied every 5 seconds). As shown in figure 1c, in this case, the leading edge of the current pulse is 13ps. It will be appreciated that other rise times may be used, for example, between around 1-20ps or faster. The leading edge of the current provided by the pulse may have a rate of 2-6kA/ps up to at least 10kA or higher (e.g. up to 30kA in this case). In this case, each pulse has an energy of at least 500J. The peak current may be greater than 10kA (or greater than 30kA and/or less than 200kA). It will be appreciated that larger apparatus and/or larger inter-electrode spacing may require more energetic pulses (e.g. greater than 1 k J up to 4kJ or greater). [0148] In this case, the container also comprises a first inlet 107 for introducing the oil- particulate-aqueous mixture into the container 101 . The container also comprises an outlet

108 positioned towards the top of the container for removing separated oil from the top of the container (e.g. through flotation or elutriation effects). It will be appreciated that other embodiments may also have an outlet for removing separated particles (and/or other denser-than-water materials) from the bottom of the container.

[0149] In this case, the container also comprises a second inlet 109 for introducing water into the container. In this case, the second inlet extends into the container and is positioned to provide a stream of water into the volume of the container where the plasma arc will be produced. In effect, this inlet acts as an agitator to the contents of the container by agitating the contents using fluid flow. It will be appreciated that other embodiments may comprise one or more physical agitators (e.g. stirring rod, auger, propeller, container rotator, stirrer or shaker). It will be appreciated that the agitator may be configured to agitate the contents of the container in the horizontal plane to help prevent mixing of strata in the container (e.g. to prevent mixing of layers of separated hydrocarbons and particulates).

[0150] It will be appreciated that one or more of the inlets and outlets may be connected with a pump to allow the contents of the container to be cycled to aid agitation, filling or discharging. For example, in one configuration and depending on the level of the contents, the contents of the container could be extracted from outlet 107 and reintroduced at inlet

109 to agitate the contents of the container. It will be appreciated that recycling of container contents may be directed to recycling non-separated components of the mixture.

[0151] In this case, the apparatus is configured to operate in a batch mode. That is, a hydrocarbon-particulate-aqueous mixture added to the container; separated using plasma arc induced shockwaves; and the separated products removed before further hydrocarbon-particulate-aqueous mixture is added. It will be appreciated that other embodiments may allow continuous operation where oil-particulate mixture may be continually added, and separated oil and particles removed.

Method

[0152] In order to separate the hydrocarbons from the solid particles using the above described apparatus, the hydrocarbon-particulate mixture is introduced into the container via first inlet 107. Water is added to the mixture comprising hydrocarbons and solid particles via second inlet 109. This results in a hydrocarbon-particulate-aqueous mixture. As noted above adding water from inlet 107 may agitate the oil-particulate mixture. It will be appreciated that, in some cases such as SAGD embodiments, water may already be present in the mixture, thereby limiting the additional water required for processing.

[0153] In this case, water is added so that water makes up at least 25% of the resulting mixture by volume but no more than 90% of the mixture by volume. A preferred range may be between 50% and 75%. This ensures enough water to generate a good shockwave and helps ensure that the shockwave interacts with hydrocarbon-particulate mixture. In this case, only water (e.g. pure water, fresh water, or natural water) is added to the mixture. Not using additives may mean that the water which is separated from the hydrocarbon- particulate mixture is cleaner, and so it may be easier to dispose of or recycle the water after use. Not using additives may make the method more cost effective.

[0154] An additive may be considered a chemical which is added to a bulk raw material to adjust the properties of the raw material. For example, additives may include surfactants and/or ionic materials or acids and bases. These additives may be potentially hazardous when by-products of the process are returned to the environment. That is, it is important for drilling operations that water by-products are clean as water processing is a significant technical and financial issue. It may also allow natural water sources to be used (e.g. rivers, lakes or seawater). It will be appreciated that in other embodiments, other chemicals (e.g. additives and/or solutes) may be added such as surfactants (e.g. soaps, such sodium stearate, to make the bitumen more hydrophilic) and/or salts or other ionic materials (e.g. to promote and/or control formation of the plasma arc).

[0155] A series of one or more high-voltage pulses is then applied to the hydrocarbon- mineral-aqueous mixture, such that, when a high-voltage pulse is applied to the mixture, a plasma arc 110 is generated between the electrodes 102a, b which applies a shockwave 111 to the mixture to cause separation of the components of the mixture. It will be appreciated that a shock wave travels faster than the speed of sound in the medium. A shockwave may also be considered to cause a step change in the density of the material before the shock front and the material behind the shock front. It will also be appreciated that a shock wave may be reflected and refracted as it interacts with different materials and material interfaces. For example, a shockwave may be partially reflected and partially transmitted by an interface between materials of different densities (e.g. between the water-hydrocarbon; hydrocarbon-particulate; and/or water-particulate interfaces). These properties may allow materials with different properties to be separated using a shock wave.

[0156] In addition to the shock wave, the plasma arc may form a bubble which expands with time. This expansion causes an acoustic wave to pass through the material. Like the shock wave, the sonic wave may also help to separate the hydrocarbons from the solid particles. It will be appreciated that the shock-wave, the acoustic wave, and/or movement of the bubbles may help agitate the mixture within the container.

[0157] Furthermore, a plasma arc may produce electromagnetic radiation in a range of frequencies (e.g. including one or more of IR, visible light and UV radiation). This radiation may help promote chemical reactions in the vessel (e.g. upgrading reactions and/or neutralizing potentially hazardous contaminants).

[0158] In addition, the plasma arc may ionize the water. This may help keep the particulates in the water phase and prevent the particulates rising to the top with the separated hydrocarbon.

[0159] The inorganic particulates (mineral clays, soil or sands) in the aqueous mixture may retain a charge when exposed to an electric field and when the EM is removed the particulates discharge amongst themselves creating secondary ionization and arc discharges that generate localized effects as described in 13.

[0160] The plasma arc 110 and the resulting shock wave 111 may heat the mixture. However, the apparatus may be configured such that the series of pulses are configured to limit the temperature of the sample to no more than 60°C (and/or the temperature rise to 40°C above an ambient temperature of 20°C). Limiting the amount of heating may reduce the need to cool the separated water before returning the water to the environment or the process. It will be appreciated that the apparatus may comprise a thermometer (e.g. a thermocouple) to measure the temperature of the sample. The thermometer may be connected to the controller for controlling the high-voltage pulsed power supply to control the pulse train based on the temperature of the sample.

[0161] When hydrocarbons have been separated from the solid particles, lighter hydrocarbons float to the top of the container as they are less dense than water when re heated and the chemical changes in the water phase promote hydrophobicity. In contrast, the solid particles (and possibly heavy hydrocarbons), which are denser than water, sink to the bottom of the container. This may facilitate continuous processing as the solid particles may be extracted from the bottom of the container and the hydrocarbons from the top as new hydrocarbon-particulate mixture is added to the container.

[0162] In some embodiments, the method comprises controlling the plasma arc to form bubbles of gas within the mixture. This allows a stable foam of hydrocarbons to be formed which floats to the top where they can be harvested (e.g. even if the density of the hydrocarbons themselves are greater than that of water).

[0163] It will be appreciated that this method may be used with other embodiments configured to generate a shockwave in the mixture by different mechanisms. As discussed below other shockwave generating mechanisms include generating shockwaves using a bridgewire and/or an ionic bridge.

Auger Embodiment

[0164] Figure 2a is a transverse cross-section of an embodiment of a separator apparatus 200 for separating hydrocarbons from solid particles in a hydrocarbon-particulate-aqueous mixture and which uses terminal pairs. Figure 2b is a transverse cross-section of the container. Figure 2c is a longitudinal cross-section of the terminal assembly which can be inserted into the container of figure 2b, without regard to the position of the flightings on the augers.

[0165] In this case, the apparatus comprises: a container 201 (in this case an elongate channel housing two augers) for containing the hydrocarbon-particulate-aqueous mixture; a shockwave generator comprising multiple terminal pairs 202:1 each having a positive and a negative electrical terminal; and a pulsed power supply (not shown) configured to apply a voltage pulse between the positive 202a: 1 and negative 202b: 1 electrical terminals, the apparatus being configured such that, when a voltage pulse is applied to the positive and negative electrical terminals, a shockwave is generated in the mixture to promote separation of the components of the mixture. [0166] In this case, the high-voltage power supply comprises a spark gap power switch and a microcontroller. Using a spark-gap power switch allows the pulse profile to have a rapidly increasing leading edge which helps facilitate formation of the plasma arc. The microcontroller in this case is configured to produce a series of pulses (e.g. at 5 second intervals or much faster). It will be appreciated that the pulse train may be controlled using other circuits or processors (e.g. a microprocessor, an application-specific integrated circuit (ASIC), or a Multi-core processor). More rapid pulse trains may also be used. For example, the pulse frequency may be up to several pulses per second or faster.

[0167] As shown in figure 2b, the container 201 , in this case, houses two augers 291 , 292. The multiple terminal pairs are arranged along the length of the container 201 between the augurs 292, 293.

[0168] The container 201 is configured to enclose the two auger flightings 291 , 292 only around a bottom portion of the flightings circumference (e.g. ~90° as shown in figure 2a. Embodiments with tapering container walls (e.g. ‘V’ shaped) may enclose less than 90° of the auger. Enclosing the bottom outside of the auger flighting helps ensure that the flighting can move substantially all the material within the container along the container’s longitudinal axis (perpendicular to the page in figures 2b and 2c).

[0169] In addition, in this case, the container walls extend upwards (e.g. vertically in this case although inclined walls are also possible) such that there is significant volume of liquid above the auger flightings. This additional “attic” or “overhead” volume of liquid may help prevent any floating separated oil/bitumen from being reintroduced into the mixture as the auger rotates. In this embodiment, the augers primary use is to transport rather than to agitate so low RPM is will be used. The apparatus is configured to transport the mixture from the inlet to the outlets such that the mixture experiences between 2-50 pulses per kilogram.

[0170] In this case, there is an interaction region 293 between the two auger flightings where the container bottom does not follow the auger flightings’ circumferences. This interaction region 293 extends between the bottom halves of the two auger flightings 291 , 292 and houses opposed terminal pairs 202a:1 , 202b:1 which are arranged longitudinally along the container axis. The opposed terminal pairs are arranged such that the mixture can pass directly between the positive and negative terminals. It will be appreciated that the interaction region between the augers is a region in which a shockwave is generated; however, the effects of the shockwave may extend beyond this region into the volumes swept by the auger flightings.

[0171] The augers in this case have opposite handedness and are configured to rotate in phase in opposite directions as shown by the curved arrows in figure 2a. This maintains symmetry through a rotation cycle about a mirror plane aligned with the longitudinal axis of the container. In particular, because the augers are configured to rotate such that the inner portions of the augers are moving upwards, the solid material at the bottom of the two augers are impelled towards the interaction region 293 between the two augers. This helps ensure that the shock waves generated within the interaction regions are more efficiently coupled with the solid sand-hydrocarbon components 298 of the mixture. It may also help to drive the dense sand towards the terminals in order to help control the generation of the plasma arc. The liquid components 299 of the mixture will flow more easily and so will form a more even level within the container. They may be operated out of phase so not mirror images.

[0172] Each auger, in this case, is 9" diameter (but other diameters may be used). Each auger may be configured to move 0.5 m ³ /hr or more of 1 ,500-2,100 kg/m ³ slurry (hydrocarbon-particulate-aqueous mixture) at approximately 95% container loading. The material may have a retention time in the container of between 10 and 30 minutes (e.g. 20 min). It will be appreciated that, because the system is scalable, other design configurations (e.g. different diameter, length, auger helix angle etc.) are available depending on the desired outcomes. The apparatus, in this case, is generally formed from steel (possibly stainless steel).

Terminal Assembly

[0173] Figure 2c shows the terminal assembly. It will be appreciated that this terminal assembly may be used in conjunction with other apparatus, such as the batch apparatus of figure 1 a.

[0174] In this case, the terminal assembly 240 comprises a shockwave generator comprising an electrical terminal pair. The terminals are opposed point terminals 202a, 202b. In this case, the upper terminal 202a is the negative electrode (in this case the ground electrode) and the lower terminal 202b is the anode (in this case a high voltage electrode). The terminal assembly is configured to form a unit which can be removed and inserted into the container jointly together. This allows the inter-terminal spacing (or spark gap) to be set before the unit is inserted into the container. In this case, the unit is configured to be connected to the container via threaded screws 230a, b.

[0175] When in use, the axis between the two terminals is aligned in a vertical direction. As with the system of figure 1a, the terminal assembly comprises a well 220 which surrounds the lower terminal. The well is configured to retain sand (or other granular dielectric material). The well 220 comprises an insulating base or bottom 222 and a retaining ring-shaped barrier 221. The lower terminal 202b is configured to protrude up from the bottom 222 of the well 220, such that the top of the lower terminal 202b is configured to be higher than or at the same height as the top of the barrier 221 .

[0176] In this case, the base of the well is formed from insulating material. However, unlike the embodiment of figure 1 a, the bottom of the well slopes downwards towards the barrier. This may help to reduce the effects of wear to the bottom of the well next to the electrode.

[0177] The barrier 221 in this case is an upright wall, with an angle, Q, of 90° from horizontal.

[0178] Because components of the terminal assembly are in close proximity to the shockwaves, there is a risk that these components may be damaged, and/or redirect the shockwaves unto other components.

[0179] The terminal assembly comprises a number of features to mitigate these damaging effects. Other embodiments may comprise one or more of these features.

[0180] Firstly at least one of the shockwave terminals is mounted on a shock absorber. In this case, the lower terminal is mounted on a shock absorber. In this case, the lower terminal 102b and the insulated bottom 222 of the well form a rigid unit which can move up and down with respect to the well barrier and the upper terminal. Between the bottom of the insulating bottom of the well and the bottom of the terminal assembly, there is provided a resilient material 241 (e.g. rubber, a spring and/or an enclosed chamber of gas). In this case, the resilient material comprises viscoelastic urethane polymer such as Sorbothane™. This allows the lower terminal 202b (and, in this case, the bottom of the well) to move up and down with respect to the upper terminal 202a to help absorb any forces emanating from the shockwave created between the opposed terminals. [0181] In other embodiments, the upper terminal may be mounted on a shock absorber. For example, the upper terminal may be mounted on arms which allow the upper terminal to move (e.g. along the inter-terminal axis).

[0182] In this case, the upper terminal is held in place opposite the lower terminal by two arms 243a, b. The side of each arm which is towards the inter-terminal gap is curved/beveled (e.g. outwards or convexly) in orderto disperse shockwaves generated by the shockwave generator. An example of this is shown in the horizontal cross-section of figure 2d. Each example has beveled arms 243a, b with surfaces angled away from the central terminal 202a. It will be appreciated that other cross-sections may also provide the same advantages. For example, an electrode arms may have a triangular cross- section with one of the triangle vertices pointing towards the electrodes.

[0183] Other embodiments may be configured to use one arm or more than two arms. The electrode arms can be at any angle up to 90°. It will be appreciated that, during use, the sharp blade formed by the two angled surfaces may be blunted over time to form a more curved surface.

[0184] Figure 2e shows the terminal assembly. It will be appreciated that this terminal assembly may be used in conjunction with other apparatus, such as the batch apparatus of figure 1a.

[0185] In this case, the terminal assembly 240’ comprises a shockwave generator comprising an electrical terminal pair. The terminals are opposed point terminals 202a’, 202b’. In this case, the upper terminal 202a’ is the negative electrode (in this case the ground electrode) and the lower terminal 202b’ is the anode (in this case the high voltage electrode). The terminal assembly is configured to form a unit which can be removed and inserted into the container jointly together. This allows the inter-terminal spacing (or spark gap) to be set before the unit is inserted into the container. In this case, the unit is configured to be connected to the container via threaded screws 230a’, b’.

[0186] When in use, the axis between the two terminals is aligned in a vertical direction. As with the system of figure 1 a, the terminal assembly comprises a well 220’ which surrounds the lower terminal. The well is configured to retain sand (or other granular dielectric material). The well 220’ comprises an insulating base or bottom 222’ and a retaining ring-shaped barrier 22T. The lower terminal 202b’ is configured to protrude up from the bottom 222’ of the well 220’, such that the top of the lower terminal 202b is configured to be higher than or at the same height as the top of the barrier 221 ’.

[0187] In this case, the upper terminal is held in place opposite the lower terminal by two arms 243a’, b’. In this case, the arms comprise two vertical pillars and a cross-section. This allows the arms to be further away from the shockwaves which may help mitigate damage. The side of each arm which is towards the inter-terminal gap is curved/beveled (e.g. outwards or convexly) in order to disperse shockwaves generated by the shockwave generator.

Sand Modelling

[0188] Both of the above embodiments use a well to trap sand around the lower terminal. The inventors have discovered that trapping sand next to the terminals can help generate an efficient plasma arc in the media at any electrode gap.

[0189] Experimental results are shown in Figure 3 and Table 1. The experimental results show how the media breakdown voltage of various compositions fordifferent inter-terminal distance, D. Figure 3 shows Paschen type curves for the breakdown voltage for four mixtures with compositions by % volume as provided below:

• Potable: 100% city potable water

• Production Waste: 50% potable water, 25% clay minerals, 25% bitumen

• Conductive: 100% city potable water with 1% NaCI

• Drill cuttings: 50% potable water, 10% clay minerals, 10% bitumen, 30% quartzitic sand.

[0190] Table 1 : Breakdown voltages of various mixtures.

[0191] The drill cuttings sample, which includes sand, exhibits a markedly higher breakdown voltage across the measured gap distances. That is, more of the energy of the pulse is transmitted to the material and shockwave. That is, the sand acts as an accelerator to initiate the media breakdown so less energy is lost in breaking down the media to create the plasma arc.

[0192] To help explain this phenomenon, the presence of sand was modelled during a discharge. Sand particles are assumed static during the discharge dynamics. Given the time scale of the discharge dynamics, it was assumed that sand particles do not move during the evolution of the discharge allowing sand particles to be included into the mesh.

[0193] The geometry consists of a 20x20mm square 461 that includes a simplified anode electrode tip 402a. At the bottom of the mesh, there is provided a planar ground electrode 402b. In this model, we used a 1 cm gap for convenience.

[0194] In this case, a 2D model was used as a starting point. Figure 4 describes the geometry including the mesh and boundary conditions of the computational model.

[0195] The electrostatic model is obtained by solving the Laplace equation to obtain the electric potential and electric field assuming that sand particles are treated as part of the mesh. As shown in figure 4, sand particles (shown in black) are arranged towards the bottom of the mesh to simulate that the sand will tend to sink towards the bottom. For this report, we have used two different models to treat the sand particle surfaces. In the first model, we assumed that sand particles are insulated and act as insulated surfaces. In the second model, we give each sand surface a small constant potential. A more refined surface charge model will be implemented as a next step since the sand particles are typically coated with a water and oil layer that may be charged.

[0196] The electrode potential is set to 10kV while sand diameters are sampled from a bimodal distribution N(25um, 5um). The bottom surface is kept at zero potential and the top and right surfaces are solved for using far-field boundary conditions. Whenever sand particles are considered to be charged, we used a simplified approach that assigns each sand particles a surface potential of -50 mV, representative of the zeta potential typically found under these conditions. As stated earlier, a more realistic model of surface charge will be considered in the future. A mesh was used with around 600k cells.

[0197] The simulations indicated that the overall effect of sand in the media is to insulate the region next to ground from the electric field created by the electrode potential. This has the effect of bringing up the ground potential above the bottom level. The overall effect is that the electrode sees an apparent smaller gap and a higher breakdown voltage occurs.

[0198] This model thus predicts a higher breakdown voltage for a determined electrode gap when sand is in the media.

[0199] However, other effects contributing to the dynamics of the process were not simulated and may have an effect. In particular, the effect of ions in the solution may also contribute to changing the electric potential in addition to the sand particles.

Elutriation

[0200] In the context of this technology, the apparatus is configured to separate a hydrocarbon-particulate-aqueous mixture into constituent components. In some scenarios, the hydrocarbon component will have a density less than that of water, and the particulate component will have a density greater than that of water. In such scenarios, the hydrocarbon component will float to the top, and the particulates will sink to the bottom. Providing outlets at the top and bottom of the container can therefore provide simple and effective method of harvesting the separated components.

[0201] In other scenarios, the hydrocarbon component may comprise materials which have a density greater than that of water. For example, the hydrocarbon component may comprise extra heavy oil having an API gravity below 10.0° (i.e., greater than 1000 kg/m ³ ). The inventors have found that the shock waves are still effective in separating the hydrocarbons from the particulates (i.e. so that the two components are no longer bound together).

[0202] However, in these cases, when the hydrocarbon is separated from the particulates, the heavy hydrocarbon and the particulates both sink towards the bottom of the water. There, they remain separate with the particulates remaining separate from globules or spheroids of heavy hydrocarbon. [0203] To separate the heavy hydrocarbon spheroids from the particulates, the heavy hydrocarbons are, in this case, divided from the particulates using elutriation. Elutriation is a process for separating particles based on their size, shape and density, using a stream of gas or liquid flowing in a direction usually opposite to the direction of sedimentation. In this case, the hydrocarbon spheroidaly shaped droplets have a size of between 1 -400 pm.

[0204] Elutriation, in this case, involves dividing the separated components based on size, shape and density by injecting a carrier fluid up through the separated mixture. The carrier fluid, in this case, is water.

[0205] The velocity of the water is typically between 2.95x10 ^_6 -4.0 m/s. The water velocity is governed by the largest diameter hydrocarbon particle to allow the sand to be separated from the treated mixture.

[0206] Figure 5 shows an embodiment 500 of an apparatus for separating a hydrocarbon- particulate-aqueous mixture into constituent components. In this case, the apparatus comprises two interconnected vessels: a separation container 501 ; and an elutriation dividing chamber 543.

[0207] The separation container and arrangement of terminal pairs is similar to that of figure 2a. In this case, the apparatus comprises: a separation container 501 (in this case an elongate channel housing two augers) for containing the hydrocarbon-particulate-aqueous mixture; a shockwave generator comprising multiple terminal pairs 540a-g each having a positive and a negative electrical terminal; and a pulsed power supply (not shown) configured to apply a voltage pulse between the positive and negative electrical terminals, the apparatus being configured such that, when a voltage pulse is applied to the positive and negative electrical terminals, a shockwave is generated in the mixture to promote separation of the components of the mixture.

[0208] The container also receives the hydrocarbon-particulate-aqueous mixture from an inlet 509. The mixture comprises solid components which will sink to the bottom and liquid components 599 which will flow to fill the bottom of the container. The container 501 , in this case, houses two augers 591 which are configured to move the separated components from the inlet 509 to the outlets 542, 508. A first outlet 508 is located towards the top of the container 501 for removing components which float to the top of the container (e.g. light hydrocarbons). A second outlet 542 is configured is configured to direct denser separated components (e.g. particulates and heavy hydrocarbons) into the elutriation chamber.

[0209] It will be appreciated that an elutriation chamber may be used in conjunction with other embodiments of separating apparatus (e.g. the batch apparatus of figure 1a).

[0210] The elutriation chamber 543 in this case comprises a separation chamber inlet 542 for receiving separated heavy oil droplets and particulates (e.g. such as sand). The separation chamber inlet 542 is positioned towards the top of the elutriation chamber 543. In this case, there is a wall separating the separation chamber from the elutriation chamber to help mitigate the turbulence from the separation chamber reaching the elutriation chamber.

[0211] Below the separation chamber inlet 542, and within the elutriation chamber 543, there is provided a carrier fluid source 546. in this case, the carrier fluid is water. The carrier fluid source 546 is configured to inject water into the elutriation chamber 543 such that above the carrier fluid source there is an upward flow of carrier fluid towards an upper overflow outlet 544 positioned at the top of the elutriation chamber. In addition, there is a lower underflow 545 outlet positioned at the bottom of the elutriation chamber. The fluid source 546 comprises a series of nozzles to inject the carrier fluid in such a way as to minimize turbulence. Multiple nozzles allow the injection to be distributed along a line or across an area. It will be appreciated that the carrier fluid source does not span across the total area of the elutriation chamber to allow the particulates to sink below the carrier fluid source. The carrier fluid source may have sloped surfaces so as not to trap the sinking particulates.

[0212] The separation container inlet is configured to inject separated heavy oil droplets and particulates into the upward flow of carrier fluid above the carrier fluid source. Those particles having a terminal velocity less than that of the velocity of the fluid will report to the overflow 544, while those particles having a greater terminal velocity than the fluid velocity will sink to the underflow 545. The particulates are directed to the underflow 545 using a series of sloped surfaces. A particles terminal velocity is based on size, shape and density.

[0213] In the context of this disclosure, the carrier fluid velocity can be adjusted to separate sand particles (which are relatively large diameter and dense) from droplets of hydrocarbon (which are of relatively small diameter and weight). The hydrocarbons (shown as black circles) are directed towards the overflow outlet while the sand particles (shown as white squares) sink to the underflow. Smaller particles of dense material (e.g. clays) may be directed upwards. The flow velocity of the carrier fluid may be adjusted in order to control the separation of the small dense particles from the larger droplets of hydrocarbon. It will be appreciated that, depending on the context, in some cases it will be desired that more clay particles are kept with the hydrocarbon but in others it will be desired that more clay particles are kept with the sand particles.

[0214] It will be appreciated that to cause spheroidal hydrocarbon droplets to move upwards, the flow velocity of the carrier fluid must exceed the terminal velocity of the particle. The terminal velocity for a certain particle size, v, is given by Stoke’s Law v = (2/9)(pp - p _f ).g.R ² /p where p _p is the density of the particle and p _f is the density of the fluid. R is the radius of the particle and g is the acceleration due to gravity.

[0215] Table 2: Representative Terminal Velocities of Sand and Hydrocarbon Particles

[0216] The rearranged Stoke’s Law equation was used to find the terminal velocity of the hydrocarbon and the sand particles. These velocities could be used to find a velocity for the water stream so that the hydrocarbon particles would float, and the sand would sink. As shown in Table 2, it was found that at large hydrocarbon and small sand particle sizes, the hydrocarbon spheroids would sink, and the sand would float. Therefore, to utilize the significant difference in density between the sand and the hydrocarbons, the spheroids of hydrocarbon must be reasonably close in size to that of the sand particulates. The shock regime (size, frequency and number of shocks) may be configured to generate spheroids of hydrocarbon of the same size as (or smaller than) the particulates of sand.

[0217] The carrier fluid velocity may be in the range between 0.001 - 0.888 m/s for one sample, and 0.037 - 3.478 m/s for another sample.

[0218] This range may also change due to the turbulence in the system, but not significantly. As we approach sample 50 plasma pulses/kg it can be noted that the size of the largest spheroidal hydrocarbon particle exceeds the smallest sand particle. Therefore, when using the vertical velocity separator, at a certain number of pulses, the sand removed from the system will yield some hydrocarbons.

[0219] However, if there is an overlap in size between the hydrocarbon and sand particles and it can be expected that some small sand particles will also float to the top of the separator. Adjusting the size of the sand particulates (if adding sand), the size of the hydrocarbon spheroids and/or the carrier fluid velocity will allow the separation process to be tailored (e.g. depending on whether clean sand is desired or pure hydrocarbon).

Paddles

[0220] Figure 6 shows an embodiment 600 of an apparatus for separating a hydrocarbon- particulate-aqueous mixture into constituent components. In this case, the apparatus comprises a separation container 601 . It will be appreciated that the separation container shown in figure 6 could be used in conjunction with an elutriation dividing chamber.

[0221] The separation container and arrangement of terminal pairs is similar to that of figure 5. In this case, the apparatus comprises: a separation container 601 (in this case an elongate channel housing two augers) for containing the hydrocarbon-particulate-aqueous mixture; a shockwave generator comprising multiple terminal pairs 640a-e each having a positive and a negative electrical terminal; and a pulsed power supply (not shown) configured to apply a voltage pulse between the positive and negative electrical terminals, the apparatus being configured such that, when a voltage pulse is applied to the positive and negative electrical terminals, a shockwave is generated in the mixture to promote separation of the components of the mixture.

[0222] The container also receives the hydrocarbon-particulate-aqueous mixture from an inlet 609. The mixture comprises solid components which will sink to the bottom and liquid components 699 which will flow to fill the bottom of the container. The container 601 , in this case, houses two augers 691. which are configured to move the separated components to the outlets 642, 608. A first outlet 608 is located towards the top of the container 601 for removing components which float to the top of the container (e.g. light hydrocarbons). A second outlet 642 is configured is configured to direct denser separated components (e.g. particulates and heavy hydrocarbons) into the elutriation chamber or for further processing and separation. The second outlet 642 is directly at the end of the augers so that momentum induced by the augers carries the solids out through the second outlet.

[0223] In this embodiment, the auger is mounted between paddles 685a, b on a common axis. The paddles are each a planar section which lies in the same plane as the auger axis and are configured to sweep a portion of the sides of the separation container 601. These paddles are configured to ensure that the solid material does not stick to the container surfaces. Because the paddles are in the same plane as the auger axis, they do no impart motion along the auger axis. The paddles in this case are have the same radius from the auger axis as the augers.

Paddle Wheel

[0224] Figures 7a and 7b shows an embodiment 700 of an apparatus for separating a hydrocarbon-particulate-aqueous mixture into constituent components. In this case, the apparatus comprises a separation container 701 . It will be appreciated that the separation container shown in figure 7 could be used in conjunction with an elutriation dividing chamber.

[0225] The separation container and arrangement of terminal pairs is similar to that of figures 5 and 6. In this case, the apparatus comprises: a separation container 701 (in this case an elongate channel housing two paddle wheels) for containing the hydrocarbon-particulate-aqueous mixture; a shockwave generator comprising multiple terminal pairs 740a-e each having a positive and a negative electrical terminal; and a pulsed power supply (not shown) configured to apply a voltage pulse between the positive and negative electrical terminals, the apparatus being configured such that, when a voltage pulse is applied to the positive and negative electrical terminals, a shockwave is generated in the mixture to promote separation of the components of the mixture.

[0226] The container also receives the hydrocarbon-particulate-aqueous mixture from an inlet 709. The mixture comprises solid components which will sink to the bottom and liquid components 799 which will flow to fill the bottom of the container. The container 701 , in this case, houses two paddle wheels 786a, b rather than augers which are configured to move the separated components to the outlets 742, 708. A first outlet 708 is located towards the top of the container 701 for removing components which float to the top of the container (e.g. light hydrocarbons). A second outlet 742 is configured is configured to direct denser separated components (e.g. particulates and heavy hydrocarbons) into the elutriation chamber or for further processing and separation. The second outlet 742 is directly at the end of the augers so that momentum induced by the augers carries the solids out through the second outlet.

[0227] In this embodiment, the paddle wheels 786a, b comprise multiple paddles mounted on a respective paddle wheel axis. In this case, the paddles comprise elongate surfaces configured to be held apart from the rotation axis with multiple arms. This allows the fluids to flow around the paddles between the paddle and the rotation axis.

[0228] In this embodiment, the paddle wheel axis along a direction between the inlet and an outlet. Because, the paddles are aligned with the paddle axis, the paddle wheel is not configured to impart motion of the mixture from the inlet to the outlet; it is primarily used to move and agitate the mixture as it is undergoing separation.

[0229] In this embodiment, the container 701 comprises a sloped bottom which is configured to help the mixture move from the inlet 709 towards the outlets 708, 742 along the paddle wheel axis. In other embodiments, fluid flow circulating from the inlet to the outlets may be enough on its own to move the separating mixture. [0230] The paddle wheels may allow the size of the interaction region to be reduced by overlapping the paddle wheels as shown in figure 7b.

[0231] Although the present disclosure describes preferred embodiments and preferred uses thereof, it will be appreciated that the present disclosure may encompass various modifications and changes that the skilled person can envisage.