HEAVY CRUDE OIL AND TAR SAND

FffiLD OF THE INVENTION

The present invention relates generally to a process and system for treating tar sands to separate the entrapped crude oil from the tar sand. More particularly, the present invention relates to injecting exhaust gas from an internal combustion engine or natural gas into a mixture of crude oil and tar sand to free additional crude oil from the tar sand.

BACKGROUND OF THE INVENTION

Tar sand has long been known to contain large amounts of crude oil. However traditional methods to separate the crude oil from the tar sand involve the use of large amounts of thermal energy and/or the use of expensive chemical processes. Both of these types of treatments have be financially and environmentally prohibitive.

Historical prices for crude oil have not been able to justify the expense of these earlier processes. However with the recent increases in crude oil prices has come increased interest in producing crude oil from tar sand. Current market prices even make some of the previously uneconomical treatment methods financially feasible. However any savings in these processing costs are highly sought after. Regardless of the financial rewards of earlier processes the environmental costs remain.

What is needed, therefore, is a method to separate crude oil from tar sand in an economical and environmentally responsible manner. BRIEF SUMMARY OF THE INVENTION

The present invention achieves its objections by providing an economical and environmentally friendly process and system to separate crude from tar sands. A tar sand and crude oil are mixture is created using ground tar sands. The Tar sand and crude oil mixture is mixed under high pressure in a treatment vessel with either natural gas or exhaust gas from an internal combustion engine. The mixture is then moved through a entrainment vessel still under the high pressure. When the mixture is removed from the entrainment vessel excess gas is removed from the mixture. The crude oil is then separated from the sand typically through a cyclone separator. A portion of the crude oil may be used to mix with ground tar sand on the front end of the process.

Thus the present invention provides a method to release crude oil from tar sands using readily available substances, namely natural gas or exhaust gas from and internal combustion engine. This removes the financial and environmental costs associated previous methods that require the use of special chemicals and/or massive amounts of thermal energy

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described in further detail. Other features, aspects, and advantages of the present invention will become better understood with regard to the following detailed description, appended claims, and accompanying drawings (which are not to scale) where:

FIG. 1 is a flow diagram outlining an embodiment of the present invention;

FIG. 2 is a sectional view of the treatment vessel;

FIG. 3 is a cross sectional view of the treatment vessel; and

FIG 4 is a flow diagram outlining another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODHVIENT(S)

One embodiment of the present invention is shown in FIG. 1 which illustrates diagrammatically the preferred method and system 8 of this invention for using cooled exhaust gas from an internal combustion engine for treating tar sand to separate the crude oil from the sand. An internal combustion engine is diagrammatically illustrated by block 38. Engine 38, as is characteristic of internal combustion engines, employs fuel which is traditionally hydrocarbon fuel, such as gasoline, diesel, propane, butane and so forth. The combustion of the fuel mixed with air within the engine drives pistons which turn a crank shaft 40 to provide motive power to a drive pulley 42. Engine 38 produces exhaust gas through an exhaust 44. This invention is concerned with the use of gases 44 passing from engine exhaust to separate the crude oil and sand of the tar sand.

Exhaust gas from exhaust 44 passes through a chamber 46 wherein heated catalyst reacts with deleterious components of the combustion process to degrade these components so that they are more environmentally acceptable. Catalytic chambers, usually called catalytic converters, are commonly employed on automobiles and trucks. From catalyst chamber 46 the exhaust gas passes by way of conduit 48 to the input of a cooler 50 which, as illustrated and in the preferred embodiment, is an air cooler. That is, cooler 50 functions by exchanging the heat of exhaust gases passing through conduit 48 with ambient air to cool the exhaust gases that passes out of cooler 50 through a conduit 52. Cooler 50 typically requires forced movement of ambient air through it and this is achieved by a fan 54 which can be driven by a sprocket 56 rotatably coupled to drive pulley 52 by a flexible belt 58. This technique makes use of the motive power produced by engine 38, however, is not indispensable in practicing the invention as an auxiliary source of power could be employed to drive fan 54, such as an electric motor. The cooled exhaust gas flowing through conduit 52 enters a separator 60. Separator 60 is typically of the type commonly employed in the petroleum and chemical industry, that is a vessel in which any water, including water condensed from vapor contained within the cooled exhaust gas, can settle to the bottom. Water extracted from the exhaust gas is removed from separator 60 by a water outlet 62. Multiple passes of cooling and separating condensate may be employed.

Dried exhaust gas passes out of separator 60 through an outlet conduit 64 into the intake of gas compressor 66. Compressor 66 may be driven by any energy source, however, in a preferred arrangement it has a drive sprocket 68 connected by a belt 70 to drive pulley 42. In this way energy required to operate compressor 66, along with air cooler 50, is supplied from motive power available from internal combustion engine 38. However, as stated with reference to cooler 50, a separate source of energy may be employed to drive compressor 66.

Compressor 66 increases the pressure of the dried exhaust gas to an elevated level. The pressure of gas appearing at the compressor outlet 72 is preferably at least 600 psi and further, is preferably in the range of about 600 psi to about 1800 psi. The compressed dried exhaust gas appearing at compressor outlet 72 is utilized in the system to separate the crude oil and sand of the tar sand. Accordingly, the compressed dried gas from compressor 66 is fed to gas injection pipe 18 communicating with treatment vessel 10.

The tar sand is prepared by grinding it to a uniform granular consistency in a hammer mill 100 or other type of grinder. The tar sand is then mixed with crude oil in a mixing tank 102. In the preferred embodiment this mixing is aided by an agitator 104. The crude oil and tar sand mixture is then introduced into a high pressure pump 78 which injects the mixture into the treatment vessel 10. The treatment vessel 10 has an inlet end 12 and an outlet end 14. At the inlet end 12 a flange 16 receives a gas injection pipe 18. In the cylindrical walls of vessel adjacent inlet end 12 is an oil inlet 20.

FIG. 2 shows an interior component of the treatment vessel 10. Gas injection pipe 18 is centrally positioned within vessel 10 and has affixed to its exterior surface a spiraled fin. In the illustrated arrangement there are twin spiral fins 20A and 20B although a single spiral fin would achieve the same results. Gas pipe 18 has spaced apart small diameter gas outlet openings 22, the openings being intermediate spiral fins 20A and 20B. The distal end of gas pipe 18 is closed although the closed end could have a small diameter gas outlet opening therein. An attachment flange 26 is secured to gas injection pipe 18 to mate with vessel flange 16 by which the injection with its spiral fin is maintained within the assembly. In the treatment process, crude oil and tar sand mixture is injected through oil inlet 20 at high pressure, such as a minimum of about 600 psi. Simultaneously gas is injected under the same or a greater pressure through gas pipe 18.

Gas is ejected through spaced small diameter openings 22 and thoroughly admixed with the crude oil and tar sand mixture as it flows through the vessel 10. The gas is absorbed by the crude oil and tar sand mixture. Sufficient gas is employed to release the crude oil trapped in the tar sand and attain the amount of reduction of viscosity that is required by the process. That is, if the crude oil and tar sand mixture injected through oil inlet 20 is only marginally too viscid for transportation a relatively smaller amount of gas needs to be injected to raise the gravity as required. However, if the crude oil and tar sand mixture is very viscid then larger amounts of gas are required.

The maximum amount of gas to be used is that which is needed to release the trapped crude and be absorbed within the crude oil. That is, the system is not predicated upon creating a dual phase mixture in which the crude oil is less viscid because of entrained bubbles of gas but the system is predicated upon mixing gas within the oil under conditions so that the gas is absorbed and the output of the mixture at vessel outlet 14 is essentially a single phase crude oil liquid with absorbed gas and the released sand.

The process must be conducted at high pressures. The pressure within vessel must be a minimum of at least about 600 psi and the pressure can increase up to about 1800 psi or higher. The pressure used in the method is that which is required to cause the absorption of sufficient gas to obtain the required viscosity reduction.

The crude oil and released sand mixture that flows out outlet end 14 of vessel 10 passes into a conduit 28 and then into an entrainment vessel 30 that has an increased cross- sectional area. The velocity of flow of the treated crude oil within the larger diameter entrainment vessel 30 is reduced, serving to increase the absorption of gas by the crude oil. A conduit 32 at outlet end of entrainment vessel 30 passes the treated crude oil and released sand mixture through a choke 34 to an outlet pipe 36. At this point the bonds between the crude oil and sand have been broken. However the sand still remains suspended in the crude oil. This mixture is then run through an oil and gas separator 84 where the excess exhaust gas 88 is removed in one stream 86 and the crude oil and tar sand mixture is sent out a second conduit 92.

The mixture of crude oil and sand is then introduced into a cyclone separator 106. The action of the cyclone 106 causes the sand to drop out at the bottom 108 of the cyclone separator 106 and the oil is removed from the upper outlet 1 10. The oil is then moved to one or more holding tanks 1 12. This is accomplished through either the remaining pressure of the oil, operation of a pump (not shown) or gravity. A portion of this separated crude oil may be used to mix with newly ground tar sand in the mixing tank 102 for continuing operation of the system 8.

The present invention provides improvements and additional uses of the inventions disclosed in U.S. Patent Nos. 6,491,053 and 6,644,334 which are incorporated herein by reference.

FIG. 4 diagrammatically illustrates a second embodiment of the invention in the method and system 8 of this invention for treating tar sand to separate the crude oil from the sand using natural gas.

Natural gas 6 is fed from a wellhead or other supply to a compressor 266. The natural gas 6 may be treated or untreated. Thus it may or may not be treated to remove natural gas liquids, light ends as well as, water, carbon dioxide, hydrogen sulfide and other impurities commonly found in raw natural gas.

The compressor 66 increases the pressure of the natural gas 6 to an elevated level. The pressure of gas appearing at the compressor outlet 72 is preferably at least 600 psi and further, is preferably in the range of about 600 psi to about 1800 psi. The compressed natural gas appearing at compressor outlet 72 is utilized in the system to separate the crude oil and sand of the tar sand. Accordingly, the compressed dried gas from compressor 66 is fed to gas injection pipe 18 communicating with treatment vessel 10.

The tar sand is prepared by grinding it to a uniform granular consistency in a hammer mill 100 or other type of grinder. The tar sand is then mixed with crude oil in a mixing tank 102. In the preferred embodiment this mixing is aided by an agitator 104. The crude oil and tar sand mixture is then introduced into a high pressure pump 78 which injects the mixture into the treatment vessel 10.

{ The treatment vessel 10 has an inlet end 12 and an outlet end 14. At the inlet end 12 a flange 16 receives a gas injection pipe 18. In the cylindrical walls of vessel adjacent inlet end 12 is an oil inlet 20.

The same treatment vessel 10 explained above and used for the embodiment shown in Figure 1 is also used in this embodiment. An attachment flange 26 is secured to gas injection pipe 18 to mate with vessel flange 16 by which the injection with its spiral fin is maintained within the assembly. In the treatment process, crude oil and tar sand mixture is injected through oil inlet 20 at high pressure, between a minimum of about 600 psi and a maximum of about 1800 psi. Simultaneously gas is injected under the same or a greater pressure through gas pipe 18.

Gas is ejected through spaced small diameter openings 22 and thoroughly admixed with the crude oil and tar sand mixture as it flows through the vessel 10. The gas is absorbed by the crude oil and tar sand mixture. Sufficient gas is employed to release the crude oil trapped in the tar sand and attain the amount of reduction of viscosity that is required by the process. That is, if the crude oil and tar sand mixture injected through oil inlet 20 is only marginally too viscid for transportation a relatively smaller amount of gas needs to be injected to raise the gravity as required however, if the crude oil and tar sand mixture is very viscid then larger amounts of gas are required.

The maximum amount of gas to be used is that which is needed to release the trapped crude and be absorbed within the crude oil. That is, the system is not predicated upon creating a dual phase mixture in which the crude oil is less viscid because of entrained bubbles of gas but the system is predicated upon mixing gas within the oil under conditions so that the gas is absorbed and the output of the mixture at vessel outlet 14 is essentially a single phase crude oil liquid with absorbed gas and the released sand.

V The process must be conducted at high pressures. The pressure within vessel must be a minimum of at least about 600 psi and the pressure can increase up to about 1800 psi or higher. The pressure used in the method is that which is required to cause the absorption of sufficient gas to obtain the required viscosity reduction.

The crude oil and released sand mixture that flows out outlet end 14 of vessel 10 passes into a conduit 28 and then into an entrainment vessel 30 that has an increased cross- sectional area. The velocity of flow of the treated crude oil within the larger diameter entrainment vessel 30 is reduced, serving to increase the absorption of gas by the crude oil. A conduit 32 at outlet end of entrainment vessel 30 passes the treated crude oil and released sand mixture through a choke 34 to an outlet pipe 36. At this point the bonds between the crude oil and sand have been broken. However the sand still remains suspended in the crude oil. This mixture is then run through an oil and gas separator 84 where the excess natural gas 88 is removed in one stream 86 and the crude oil and tar sand mixture is sent out a second conduit 92.

The mixture of crude oil and sand is then introduced into a cyclone separator 106.

The action of the cyclone 106 causes the sand to drop out at the bottom 108 of the cyclone separator 106 and the oil is removed from the upper outlet 1 10. The oil is then moved to one or more holding tanks 1 12. This is accomplished through either the remaining pressure of the oil, operation of a pump (not shown) or gravity. A portion of this separated crude oil may be used to mix with newly ground tar sand in the mixing tank 102 for continuing operation of the system 8.

The compressor, 66, high pressure pump 78, hammer mill 100, agitator 104 and other components can be powered by various means commonly know in the art, including but not

{ limited to electric motors, internal combustion engines, hydraulic motors, pneumatic motors, and the like.

In addition to the method and system outlined above, it is anticipated that natural gas may be used in the methods and systems disclosed and claimed in US Patent Nos. 6,491,053 and 6,644,334 to thin or reduce the viscosity of heavy crude. In such an application the natural gas would be used to either supplement or replace the use of cooled, dried exhaust gas from the internal combustion engines.

The foregoing description details certain preferred embodiments of the present invention and describes the best mode contemplated. It will be appreciated, however, that changes may be made in the details of construction and the configuration of components without departing from the spirit and scope of the disclosure. Therefore, the description provided herein is to be considered exemplary, rather than limiting, and the true scope of the invention is that defined by the following claims and the full range of equivalency to which each element thereof is entitled.