NO161726B - PROCEDURE AND DEVICE FOR AUTOMATIC AA INSULATE A HYDROCARBON FLUIDUM-FILLED STORAGE WITH HYDROCARBON FLUIDUM. - Google Patents

Abstract

There are disclosed methods and apparatus for increasing the fluidity of hydrocarbon fluids, by applying to those fluids electromagentic energy in the frequency range of from about 300 megahertz to about 300 gigahertz.

Description

The present invention relates to a method and device for automatically insulating a hydrocarbon fluid-filled storage container by using part of the hydrocarbon fluid to serve as an insulating layer in response to lower ambient temperatures.

The invention also relates to a device for automatically isolating a storage container when desired due to changes in ambient temperature by using a portion of the hydrocarbon fluid present within the container to provide the insulation.

The present invention represents an improvement over US patent Re. 31,241, (reissued May 17, 1983), which relates to a method and device for controlling the liquid state of hydrocarbon fluids using electromagnetic energy.

It is an object of the present invention to provide an improved method and device for heating hydrocarbon material with electromagnetic energy.

According to the invention, the method is characterized by

to generate electromagnetic energy in the frequency range from less than 300 megahertz to approx. 300 gigahertz,

propagating said energy through a waveguide and radio-transparent applicator with an energy deflector,

providing a wire mesh screen of metal concentric with the side walls, bottom and top of the container and separated therefrom by a distance equal to the desired thickness of the insulating layer, the openings in the screen being sized to allow the hydrocarbon fluid to flow from one side to the other of the shielding under higher ambient temperatures when the hydrocarbon fluid has a low viscosity while at the same time being smaller than the amplitude of the electric field, and

deflecting said energy into the hydrocarbon fluid to heat the fluid present within the perimeter of the shield while the shield reflects said energy to prevent heating of the layer of fluid between the shield and the sidewalls, thereby enabling said layer to remain solidified to providing an automatic insulating layer for the container under low ambient temperatures.

According to the method, an open channel can also be formed in the top layer of the hydrocarbon fluid to equalize the pressure on the opposite sides thereof and prevent an implosion due to the formation of a void under the top layer. Furthermore, it is possible to preset the movement of the deflector so that it is cycled up and down periodically in the radio-transparent applicator to emit electromagnetic energy throughout the hydrocarbon fluid.

The device according to the invention is characterized by: wire mesh shielding of metal which is concentrically arranged within the storage container and separated internally from the side walls, the top and the bottom of the storage container at a predetermined distance that corresponds to the desired thickness of the insulation layer,

means for maintaining the position of said shield within the storage container,

radio frequency generator means for generating electromagnetic energy in the frequency range of less than 300 megahertz to approx. 300 gigahertz,

waveguide means for transmitting the electromagnetic energy to the storage container,

radio-transparent applicator located within the storage container for receiving electromagnetic energy from said waveguide means,

deflector means located within said radiopaque applicator to deflect the electromagnetic energy

received by said radiolucent applicator In 1 said fluid,

As the holes 1 the shield is sized to allow hydrocarbon fluid to circulate between the shield and the side walls of the storage container and mix with the hydrocarbon fluid within the shield when the viscosity of the hydrocarbon fluid is low under higher ambient temperatures, and to prevent such circulation when the viscosity of the hydrocarbon fluid increases under low ambient temperatures, said hole in the shield increases under low ambient temperatures, and has a dimension smaller than the amplitude of the electric field, so that the shield will reflect the electromagnetic energy inward and prevent it from heating the layer of hydrocarbon fluid between the shield and the side walls of the storage container to allow the layer to solidify and form an insulating layer under low ambient temperatures.

Other purposes, scope and advantages of the present invention will be obvious from the detailed description considered in connection with the drawings that follow. Fig. 1 is a side elevational view, with parts broken away, of a device for providing clean, separated oil from hydrocarbon fluids stored in containers. Fig. 2 is an enlarged side vertical view of a

energy reflector in fig. 1.

Fig. 3 is an enlarged side vertical view of another

embodiment of the energy deflector.

Fig. 4 is an enlarged side vertical view of another

embodiment of the energy deflector.

Fig. 5 is an enlarged side vertical view of another embodiment of the energy deflector. Fig. 6 is an enlarged side vertical view of another

embodiment of the energy deflector.

Fig. 7 is a side elevational view, with parts broken away, of a storage container comprising metal shields to provide an insulating layer of hydrocarbon fluid.

In fig. 1 is a device 14 shown for use with a container, vessel, or storage tank 15 for oil with an open or closed top, or mud pit. Hydrocarbon fluid, such as oil, stored in the tank 15 often contains water, sulphur, solids and other unwanted constituents or contaminants, including bacterial and algal, as well as deposits and rust, all of which can be considered as basic sludge. Also, during storage, the contamination and oil viscosity will often increase to the point where the LACT (Lease Acquisition Custody Transfer) measurement is often too large to be acceptable for pipeline.

Advantageously, the device 14 not only heats the oil to reduce its viscosity and increase its buoyancy, but also separates water, sulfur and basic sludge from the oil in the tank 15, which results in clean oil. The gases that come out, including sulphur, can be collected via a collection line and holding tank (not shown) which is connected to the top of the tank.

The device 14 comprises a high frequency (RF) generator 16 having a magnetron 17 or klystron, or other similar device, such as a solid state oscillator as referred to in the aforementioned reissue patent, which is capable of generating radio waves in the frequency range from 300 megahertz to about. 300 gigahertz and generally use from 1KW to 2MW or more of continuous wave power. It should be understood that a plurality of magnetrons 17 or oscillators, or a klystron can be used to generate a plurality of heating frequencies which are far enough apart to prevent interference and which may have a greater absorption capacity towards certain fractions which it is desired to remove. The oscillator can be modified or another oscillator can be provided to generate a frequency outside this range for use with the previously mentioned frequencies according to the loss capability of the fractions to be removed. The magnetron 17 is mechanically connected to an applicator 18 which is transparent to radio waves in the aforementioned frequency range. The applicator 18 is in the form of an elongated tube with an open upper end 19 and a closed bottom 20. The applicator is preferably constructed of radio-transparent materials so that it is permeable to RF waves in the desired frequency range, but impermeable to liquids and gases. The applicator is attached to a tubular waveguide 21 which fits through a metal tank cover 22 which is bolted and grounded to the tank 15 using a plurality of nuts and bolts 24.

A metal transition member 26, comprising a flanged end 28, is bolted to one end of a 90" metal elbow 30 by means of bolts and nuts 32. The tubular end 33 of the transition member 26 is attached to the tubular waveguide 21 The other end of the 90° elbow 30 is bolted to one end of the rectangular metal waveguide section 36 by means of nuts and bolts 38.

The other end of the rectangular waveguide 36 is coupled to the WR x coaxial transition element 40 with nuts and bolts 42. Flexible coaxial element 44 is provided with flanged ends 46 and 48 which have internal gas barriers which allow the flexible coaxial element 44 to be charged with an inert gas refrigerant, such as Freon, to increase its power-carrying ability while preventing the flow of any gases coming from the hydrocarbon fluid back into the RF generator 16, which may be due to a crack or leak in the applicator 18. The flanged end 46 is connected to the WR x coaxial transition element 52 with bolts and nuts 54. The flanged end of the coaxial x WR transition element 52 is connected to the RF generator 16 via an extension 56.

A control device 58 controls the energization of the RF generator 16 and receives signals from a plurality of temperature sensors 60 A-E placed inside the tank 15. The control device 58 is connected to the sensors 60 A-E by means of wires or by means of fiber optic transmission lines 62. The sensors 60 A-E are arranged vertically at predetermined locations within the tank 15.

A generally conically shaped energy deflector 64 is disposed within the applicator 18 for upward and downward movement to control the emitting locations of the electromagnetic energy propagated through the applicator 18. This upward and downward movement is provided by a motor 66 which drives a pulley 68 which causes it to wind wind up or unwind cable 70 attached to energy deflector 64, thereby controlling the vertical emitting location of deflector 64 within tank 15. A separate frequency may be sent through waveguide 36 to activate motor 66. Preferably, energy deflector 64 is first placed near the bottom of applicator 14 and is gradually moved upwards.

By emitting the energy in this way, the magnetron 17 can be operated continuously at full power to operate at the greatest efficiency, the temperature of the various layers within the hydrocarbon fluid is effectively controlled, so that the production of oil is maximized, and the life of the magnetron 17 is extended .

The motor 66 is connected to a power source (not shown) via the control device 58 by means of the line 72. The control device 58 activates the motor 66 to move the deflector 64 whereby the point of emission of the electromagnetic energy thereby changes in response to the temperatures sensed by the sensors 60 A-E. The frequency and application period of the electromagnetic energy is controlled by the control device 58 which can be preset or programmed for continuous or intermittent upward and downward operation to achieve homogeneous heating of the hydrocarbon fluid or localized heating to achieve the highest yield or best oil production at minimum energy cost.

The emitting location of the energy deflector 64 can be preset to provide predetermined controlled continuous or intermittent sweep of the electromagnetic energy through the hydrocarbon fluid using a conventional timing circuit and limit stop means for the motor 66.

Valves 74 A-D may be placed in the vertical wall of the tank 15 to withdraw oil after treatment with electromagnetic energy. After heating with electromagnetic energy, as shown in fig. 1, there is a bottom layer 76 which is mainly ground mud and water. Above the bottom layer 76 there is an intermediate layer 78 which is a mixture of mostly oil with some basic sludge and water. Finally, the overlay 78 is a top layer that represents the resulting oil that has been cleaned and is free of ground mud and water. An access hatch 73 is provided to remove the resulting base mud, which may include "drilling mud" solids. Any bacteria and algae present in the hydrocarbon fluid are disintegrated by the RF waves, with their remaining parts forming part of the bottom mud.

To further assist in circulating and cleaning the oil layer 80, a conventional heat conductor 75 such as a barrel heater may extend into the tank 15. The heater 75 circulates hot gases through conduit 77 to provide a low cost source of heat (BTU) for additional to heat the oil as soon as the water and bottom mud have been separated from the oil and the oil is sufficient in liquid form or as a fluid for the convection current to flow. These convection currents further help to reduce the viscosity of the oil and to remove fine deposits. A spark arrester 79 is provided in the tube 77 to eliminate any sparks in the gases that exit. The cleaned oil can be passed through a filter to remove any remaining fine sediment or sludge.

Pure oil can be easily and simply separated from ground sludge and water. This happens by heating the hydrocarbon fluid in the tank 15 with electromagnetic energy which causes the water molecules which are normally encapsulated in the oil to expand, whereby the encapsulated oil film is torn up. Heating can be done with radio frequency waves due to that water has a greater dielectric constant and greater loss agent than oil, which results in a higher loss capacity, whereby it is allowed to absorb significantly more energy than the oil in less time, which results in a rapid expansion of the volume of the water molecules within the oil film, whereby the oil film is affected to crack. The water molecules can then combine into a mass heavier than oil which sinks to the bottom of the tank carrying with it most of the sludge present in the oil. However, to further facilitate the removal of the bottom mud, particularly fine mud, seawater or salt water can be spread over the surface of the top layer of the oil 80 after the viscosity of the oil 80 has been reduced, by heating with electromagnetic energy according to the present invention. The heavier salt water will quickly sink by gravity through the layer 80 of oil towards the bottom of the tank 15, and carry the fine sludge with it.

Layers 76, 78 and 80 have arisen from treatment of hydrocarbon fluid containing oil, bottom mud and water stored in tank 15, by sweeping the fluid with electromagnetic energy 1 in accordance with the device in fig. 1 which has a power output of 50 KW under approx. 4 hours. However, it should be understood that the power output and the irradiation time may vary with the volume of the tank 15, the constituents or contaminants present in the hydrocarbon fluid, and the length of time during which the hydrocarbon fluid has been stored in the tank 15.

As hydrocarbons, sulphur, chlorides, water (fresh or salt water), and sludge and metals remain passive, reflecting or absorbing electromagnetic energy in various conditions, the irradiation of the hydrocarbon fluid with electromagnetic energy, according to the present invention, will separate the previously mentioned constituents from the original fluid in the generally reverse order of the constituents listed above. In addition, acids and condensable and non-condensable gases are also separated at various stages during the electromagnetic energy heating process. The optimum frequencies, loss tangents and boiling points for the various fractions present in the hydrocarbon material it is desired to recover can be obtained from Von Hippel, Tables of Dielectric Materials. (1954), published by John Wiley & sons, Inc., and Ashrae Handbook of fundamentals. (1981), published by The American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc.

Referring to fig. 2, the applicator 18 and the energy deflector 64 are shown enlarged relative to what is illustrated in fig. 1. The deflector 64 is suspended within the applicator by means of the dielectric cable 70 which is constructed of radlo transparent materials which are strong, heat resistant and have a very low dielectric constant and loss tangent. The height of the energy deflector 64 will determine the deflection angle of the electromagnetic energy.

Referring to fig. 3, is an alternative embodiment of the deflector 64 1 fig. 1 shown at reference numeral 82. The deflector 82 has a larger deflection angle (less included angle) than the deflector 64 to cause the deflected waves to propagate from the applicator 18 in a somewhat downward direction below a horizontal plane through the deflector 82. This embodiment sets the radio frequency capable of penetrating feed zones can be placed below the end of a wellbore, when the method and device are used for in situ heating in a geological substrate.

The energy deflector 82 is suspended by means of a fiber optic cable 84 which provides temperature readings. In this regard, the individual fiber optic strands 83 in the cable 84 may be oriented to detect conditions at the various locations in a container or borehole. The information sent to the remote ends of the fiber optic wires 83 can be converted into digital signals converted for recording and/or control of power output level and placement of the deflector 82. For example, it may be desirable to provide a vertical sweep pattern for the RF energy as a reaction on temperature gradients sensed by the fiber optic wires 83. The frequency for use with the fiber optic wires 83 is chosen to be sufficiently different from the frequency of the RF generator 16 to prevent interference or cancellation.

Referring to Fig. 4, the radio-transparent applicator 18 is soldered to the waveguide 21 at 88 for downhole applications where the high temperatures encountered would be destructive to a glass fiber applicator.

Disposed within the applicator 18 is another embodiment of an energy deflector designated 88 which is constructed of pyroceram or other dielectric material with a helically wound band of reflective material 90, such as stainless steel. Instead of providing the previously mentioned metal band 90, a spiral portion of alumina or silicon nitride energy reflector 88 can be sintered and metallized to provide the desired reflective band.

Other means may be used to raise or lower the deflector to accomplish the sweep function, including hydraulic, vacuum, air pressure, and refrigerant expansion-lift systems. Moreover, the waveguide coupling from the RF generator 16 can also be used to send control signals from the control device to the motor or other mechanism to raise or lower the RF deflector. The frequency of such control signals must be selected to be sufficiently different from the frequency or frequencies selected for the electromagnetic energy heating the hydrocarbon fluid to prevent interference or cancellation.

Referring to fig. 5, another form of energy deflector is shown at 91, essentially a right triangle in cross-section with a concave surface 93 for focusing all of the deflected electromagnetic energy in a particular direction to heat a predetermined volume in a container or in a particular feed zone or coal-lele in subsurface applications.

Referring to fig. 6, includes another form of energy deflector shown at 94 interconnected segments 95A-95D which provide an angle of deflection of the electromagnetic energy when the deflector impinges on the applicator 18 and a different angle of deflection of the electromagnetic energy when the cable 70 is pulled upward whereby the segments 95A-95D is caused to withdraw. Other means may be used to change the deflection angle of the deflector 94, such as a remotely controlled motor.

Getting rid of drilling fluids known as "drilling mud" has become a serious problem for the oil industry. The device shown in fig. 1, modified to include any of the energy deflectors shown in FIG. 2-6, can be used to reconstitute drilling mud for renewed use by applying radio frequency waves to remove excess fluids and leave behind a mud of bentonite, barite salts etc.

Referring to Fig. 7, there is shown a device 350 for use in a container containing hydrocarbon fluid to effectively use a portion of the hydrocarbon fluid to provide an automatic insulating layer for the container by providing a specific thickness of immobile oil in contact with and adjacent to the internal tank walls when the ambient temperature or temperature conditions are low. The R-value for the insulation and the U-factor will vary according to the k-factor of the oil.

The tank 352 comprises a perforated screen of metal or wire mesh 354 arranged concentrically with and separated from the side walls 356 of the tank. The screen 354 is held from the side wall 356 by means of distance brackets 358. Likewise, perforated metal screens 355 and 357 are placed at a predetermined distance from the bottom surface 359 and the top surface 366. Spacer brackets 361 and 363 are respectively arranged on the metal shield 355 and the bottom surface 359, and the metal shield 357 and the top surface 366.

Under higher ambient temperatures, the oil can expand and contract without restriction and flow through the perforations 360, 365 and 367 so that it is available for use. However, when the ambient temperatures are low and the tank walls 356, 359 and 366 become cold, the viscosity of the oil will increase so that the oil will not be able to flow through the perforations 360, 365 and 367 and will tend to solidify inwards against the screens 354, 355 and 357, whereby a thick insulation layer is formed which is no longer able to transfer external heat to the tank's Interior 352 by convection.

The device in fig. 1 can be used to maintain the buoyancy or easy flow of the oil in the tank 352 which is placed inside relative to the screens 354, 355 and 357. As shown in fig. 13, it is preferred to introduce RF waves from the top of the tank 352 into a radiolucent applicator 362 which is liquid tight at its bottom. This device ensures against oil leakage from the tank 352 should the applicator 362 be damaged or break. The RF waves propagated through the radio-transparent applicator 362 are deflected into the oil by the energy deflector 364, absorbed there and converted into thermal energy. The RF waves will not penetrate past the screens 354, 355 and 357 and will be reflected back into the oil by the screens 354, 355 and 357, if they have not already been absorbed.

The screen 357 above the top surface 366 of the tank 352 can be eliminated as the heated oil when cooled will form a solid layer near the top surface 366. However, a small passage must be provided through this upper solid layer for connection with the heated oil wind to provide a vapor flow path , for example, the pipe 372 sends heat from the anode cooling system for the magnetron 368 in the RF generator 370 to the tank 352. The pipe 372 extends a predetermined distance below the top surface 366 to penetrate any resulting solid oil layer by recirculating the deionized anode cooling solution through the pipe 372 which is submerged in the oil.

Claims (4)

1. A method of automatically insulating a hydrocarbon fluid-filled storage container by using a portion of the hydrocarbon fluid to serve as an insulating layer in response to lower ambient temperatures, characterized by the steps of: generating electromagnetic energy in the frequency range from less than 300 megahertz to about 300 gigahertz, propagating said energy through a waveguide and radio-transparent applicator (362) with an energy deflector (64, 82, 88, 91, 94), providing a metal wire mesh shield (354) concentric with the sidewalls (356) , bottom and top of the container and separated therefrom by a distance equal to the desired thickness of the insulating layer, Whereas the openings in the shield (354) are sized to allow the hydrocarbon fluid to flow from one side to the other of the shield (354) under higher ambient temperatures when the hydrocarbon fluid has a low viscosity while at the same time being less than the amplitude of the electric field, and deflecting said energy Into the hydrocarbon fluid to heat the fluid present within the perimeter of the shield (354) while the shield (354) reflects said energy to prevent heating of the layer of fluid between the shielding and the side walls, thereby enabling this layer 1 to remain solidified to provide providing an automatic insulating layer for the container (352) under low ambient temperatures. 2. Method as set forth in claim 1, characterized by also forming an open channel 1 in the top layer of the hydrocarbon fluid to equalize the pressure on the opposite sides thereof and prevent an implosion due to the formation of a void under the top layer. 3. Method as set forth in claim 1, characterized by also presetting the movement of the deflector so that it functions up and down periodically in the radio-transparent applicator (362) to emit electromagnetic energy everywhere in the hydrocarbon fluid. 4. Device for automatically isolating a hydrocarbon fluid-filled storage container (352) when desired due to changes in ambient temperature by using a portion of the hydrocarbon fluid present within the container to provide the insulation, characterized by: wire mesh shielding of metal (354) concentrically disposed within the storage container (352) and separated internally from the side walls/top and bottom of the storage container in a predetermined distance corresponding to the desired thickness of the insulating layer, means (358) for maintaining the position of said shield within the storage container (352), radio frequency generator means (370) for generating electromagnetic energy in the frequency range of less than 300 megahertz to about 300 gigahertz, waveguide means (36) for transmitting the electromagnetic energy to the storage container, radio-transparent applicator (362) located within the storage container (352) for receiving electromagnetic energy from said waveguide means (36), deflector member (364) located within said radio-transparent applicator (362 ) to deflect the electromagnetic energy received by said radio-transparent applicator (362) into said fluid, the holes in the shield (354) being sized to allow hydrocarbon fluid to circulate between the shield (354) and the side walls (356) of the storage container (352 ) and mixed with the hydrocarbon fluid within the shielding (354) when the viscosity of the hydrocarbon fluid is low under higher ambient temperatures, and to prevent such circulation when the viscosity of the hydrocarbon fluid increases under low ambient temperatures, said hole in the shielding (354) increases under low ambient temperatures, and has a dimension which is less than the amplitude of the electric field, so that the shield (354) will reflect the electromagnetic energy inward and prevent it from heating the layer of hydrocarbon fluid between the shield (354) and the storage vessel (352) side walls to allow the layer to solidify and form a insulating layer under low ambient temperatures.