US3438437A

US3438437A - Convector type heat exchanger

Info

Publication number: US3438437A
Application number: US568718A
Authority: US
Inventors: Carl Edward Christofferson
Original assignee: Individual
Current assignee: Individual
Priority date: 1966-07-11
Filing date: 1966-07-11
Publication date: 1969-04-15
Anticipated expiration: 1986-04-15

Description

April 1969 c. E. CHRISTOFFERSON 3,438,437

CONVECTOR TYPE HEAT EXCHANGEH Filed July 11, 1966 a a 7 9 L; iii W 2 W 5 m a $1 $1 a I W m. 64V F y W Z Z W, a

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Aka/A7 United States Patent ()1 ice 3,438,437 Patented Apr. 15, 1969 3,438,437 CONVECTOR TYPE HEAT EXCHANGER Carl Edward Christolferson, Los Angeles, Calif. (12637 Barlin, Downey, Calif. 90242) Filed July 11, 1966, Ser. No. 568,718 Int. Cl. E2lb 43/24 US. Cl. 166-57 13 Claims ABSTRACT OF THE DISCLOSURE A convector-type heat exchanger for oil wells or the like in which the heating chamber is provided with a number of extendable fins to increase the heat transfer surface. A relief valve and a check valve are provided to permit the condensate, but not the steam, to flow into the well.

This invention relates to a convector-type heat exchanger and more particularly to a novel heat exchanger of improved efliciency for use in oil wells, and the like.

Heating devices for heating the formation adjacent a Well bore and the crude products in the bore to improve the rate and quantity of the products produced have been proposed in the past. Various types of apparatus, including both electrical and steam heaters, have been constructed which are designed to be lowered into the oil well for heating the crude product therein. Such prior devices frequently have been relatively ineflicient in that sufficient heat has not been generated to achieve the desired results, particularly with respect to transmitting suflicient heat into the formation into which the well bore extends.

Accordingly, it is an object of this invention to provide an improved down-hole heater for use in oil wells and the like.

An additional object of this invention is to provide a convector-type heat exchanger for use in oil wells and the like which provides large heat transfer surfaces.

A further object of this invention is to provide a convector-type heat exchanger for use in oil wells and the like which includes extendable heat radiating or heat transfer surfaces.

These and other objects and features of this invention will become more apparent through a detailed consideration of the following description taken in conjunction with the accompanying drawing in which:

FIGURES 1A and 1B taken together from an elevational view, partially in section, of a convector-type heat exchanger constructed in accordance with the present invention;

FIGURE 2 is a cross-sectional view taken along a line 2-2 of FIGURE 1A;

FIGURE 3 is a partial perspective view of a portion of the apparatus shown in FIGURE 1A;

FIGURE 4 is a cross-sectional view taken along a line 4-4 of FIGURE 3; and

FIGURE 5 illustrates an alternative form of the invention.

This invention relates to the introduction of suflicient heat energy into an underground formation to facilitate removal of crude products therefrom at an increased rate and to allow maximum recovery of products from the formation. In many wells, a considerable portion of the available crude product is left in the ground because no economical method has been found by which its viscosity can be reduced sufliciently to enable it to flow properly, or because the formation in the vicinity of the well is blocked by congealed paraflins or the like. By use of the concepts of the present invention, suflicient heat is made available in the necessary areas to raise the temperature in the formation and the viscosity of the crude product thereby making possible increased production. Through the use of the concepts of the present invention it is possible to reactivate the otherwise lost or wasted products within formations adjacent existing wells and provide substantial savings through secondary recovery.

A partially successful recovery method currently in use is termed a water flood. Water is pumped into a formation, and water being heavier than the crude petroleum products penetrates below the products causing them to be floated to the production zone of the well. However, this method is only suitable where water is relatively cheap and available in large quantities.

In accordance with the teachings of the present invention, both controlled heating, and to a lesser extent, a water flood approach is provided. The convector-type exchanger of the present invention is lowered into a well, and includes a heating chamber which is supplied with steam from the surface above. The heating chamber has on its exterior surface one or more large heat radiating or heat transfer members. These members may take various forms, and a particularly suitable arrangement includes a plurality of extendable heat transfer members which are allowed to extend from the exterior of the heating chamher after the heat exchanger is lowered into the well. This construction allows the exterior dimensions of the heat exchanger to be relatively small as the exchanger is lowered into the well, but enables large heat transfer surfaces to be provided when it is desired to heat a formation.

Since the heat transfer area is large, the total heat dissipated can be made quite large without raising the temperature of the heat exchanger to the point where the products contacting it will be caused to froth, thereby interfering with the pumping operation. As the heat from the steam is transferred to the well bore and adjacent formation the steam condenses. A relief valve is provided below the heating chamber and is followed by a check valve which allows condensate to flow into the well. The condensate with its remaining latent heat provides the added advantage of heating the crude product and washing the heavier impurities to the bottom of the well away from the production zone before the water is pumped to the surface along with the released products. The water and released products are removed from the well in a conventional manner by pumping, and separated at the surface in a conventional manner.

Turning now to the drawing, a convector-type heat exchanger according to the present invention is shown in FIGURES 1A and 1B and includes a heating chamber 10 relief valve 11 and check valve 12. A steam supply line or pipe (not shown) is coupled with the upper end 13 of the heating chamber 19. Both the steam line and heating chamber may be formed from copper pipe or tubing.

The heating chamber 10 includes a body 15 having a passageway 16 therein communicating with the steam supply line. A plurality of sets 17 through 19 of heat transfer members or flns 20 providing large heat transfer surfaces are mounted on the exterior of the body 15 of the heating chamber 10. In a preferred form of the invention, the members 20 are attached to the exterior of the body 15 by means of springs 21 as better seen in FIGURES 2 through 4. The fingers 22 and 23 of each spring as shown in FIGURE 4 are respectively secured to a member 20 and to the body 15 in any suitable manner, such as by soldering or welding. The springs 21 are tensioned to normally bias the members 20 to the position shown in FIG- URE 4 by phantom lines 25. The members 20 are folded downwardly substantially adjacent the body 15 and retained by a bead of a suitable adhesive 26 at the side or bottom of each member as respectively shown in FIG- URES 2 and 4.

After the heat exchanger is lowered into position in the well casing and steam is supplied to the heating chamber 10, the increased temperature in the chamber allows the members 20 to be released and flip up to the position shown in phantom lines 25 in FIGURE 4. Preferably, the adhesive 26 is a low melting point asphalt that will dissolve and mix with the crude product within the well, and will be pumped from the well bore with the crude product thereby leaving no foreign material in the well as a result of the adhesive used. The upper ends 28 of the members 20 may be contoured to fit against the exterior of the body 15 thereby improving the heat transfer efficiency between the body 15 and the members 20.

As the heating continues, it penetrates outward into the formation away from the well bore. Because of this penetration into the formation, the crude product is heated to a temperature at which it becomes sufficiently viscous to permit it to be released from sand or other impurities in the formation and allows a cleaner crude product to enter the production zone of the well enabling higher production at the surface. Released products which are heavier than the crude product will tend to settle out and will be Washed to the bottom of the well away from the production zone by the condensate which flows from the heat exchanger as will be discussed subsequently.

Folding or moving the members 20 to a cocked position as shown in FIGURES 1A, 2 and 3 substantially facilitates the insertion of the heat exchanger and steam supply line into the well casing. As is well known, typical wells have a minimum of space in the casing. The casing must be large enough to accommodate a pump line and the like and, consequently, there is little room left for additional objects within the well casing. Thus, the extendable members 20 provide large heat transfer areas while requiring a minimum of space during entry and removal of the heat exchanger. A heat exchanger constructed according to this invention also leaves more room within the casing at the producing or pumping zone for the crude product to accumulate because the dimensions of the heating chamber itself can be made smaller when the members 20 are provided.

In the event it is necessary or desirable to remove the heat exchanger, the members 20 will easily fold downwardly; and in the event of the removal of other equipment from the well casing, these members easily fold upwardly. This arrangement reduces the possibility of damage to the well casing, heat exchanger and other equipment within the Well. If the heat exchanger is removed, the members 20 may be returned to their folded position and recemented with a suitable adhesive, and the heat exchanger subsequently may be inserted into the same or another well.

It will be appreciated that the heat transfer members 20 may take any of various shapes, and may be arranged in many different fashions on the periphery of the body of the heat exchanger 10. Thus, the members may be essentially rectangular as shown and arranged in a circular fashion as described above, or for example, mounted in a spiral fashion on the body 15. It will be appreciated that the members 20 themselves may be made in other shapes, such as in the form of rods.

The body 15 of the heating chamber 10 is threaded at to allow a housing 31 of the relief valve 11 to be secured thereto. A restrictor 32 is mounted within a bore 33 in the lower end of the body 15, and retained in position by an exteriorly threaded sleeve 34 having a bore 35 therethrough. An orifice 37 extends axially through the upper end of the restrictor 32 and terminates in a lower bore 38 of larger diameter. The orifice 37 and bore 38 communicate with a bore 39 in the lower end 40 of the body 15 which in turn communicates through an inclined passage or orifice 41 with the interior of the lower end 42 of the housing 31. A chamber 43 is defined by the lower end 42 of the housing 31 and a housing 44 of the check valve 12, and this chamber 43 forms a condensate trap. The orifice 37 in the restrictor 32 provides a restriction for the steam supplied to the heating chamber 10, and has a diameter selected to cause the desired pressure to be built up and to allow the water which has condensed to flow into the condensate trap 43. The passage 41 is formed at an angle with respect to the longitudinal axis of the body 15 to cause the hot condensate to impinge upon the wall of the condensate trap 43 thereby giving up additional heat to the body 44 bounding the trap while at the same time not presenting any appreciable restriction to the flow of condensate.

The body 44 of the check valve 12 is internally threaded at 48 to receive a threaded sleeve 49. The sleeve 49 has a bore 50 therethrough and provides a valve seat 51 for a ball 52. A pair of holes 53 and 54 are drilled into the lower end of the sleeve 50 to facilitate threading of the sleeve 49 into the lower end of the body 44, and a spring 57 is mounted in a bore 58 therein to bias the ball 52 toward the valve seat 51. The sleeve 49 may be appropriately positioned within the body 43 to select the desired force of the ball 52 against the seat 51. The sleeve 49 may be locked in positioned by a set screw 60, and the cap 56 is secured by set screws 61 and 62. The cap 56 includes four transverse rbores, only bores 64 through 66 being seen in FIGURE 1B, communicating with the bore 58 thereby providing condensate outlets to the well area. The arrangement of the relief valve 11 and check valve 12 prevents live steam from entering the well under pressure, and only allows the condensate to flow into the well area. The check valve 12 also prevents well fluid from entering the condensate trap 43.

In some instances, irreparable damage may be caused by known well heating devices not only to a particular well, but also to an entire formation. Pumping fluid or other substances into a formation under pressure can cause the formation to be altered thereby sealing a production strata and cutting off the flow of the crude product. In some producing zones, the oils and gases are imprisoned by a wax or heavy asphalt block which is commonly termed filter pack. Insufiicient heating can cause filter pack or wax sealing, thus diminishing or cutting off production. The filter pack condition prevents the flow of product causing the mistaken impression that the well is dry or that no crude product is in the formation. Through the use ofthe present invention, steam or fluid under pressure is not released directly into the producing zone. The condensate is released under gravity alone and helps float and wash clean the product without affecting the formation itself, i.e., only the product and not the formation is treated. In oil wells which contain sand or other impurities which interfere with the economical recovery of the crude product, it will be apparent that the concepts of the present inveniton may be employed to heat the crude product causing it to expand thereby freeing such impurities as sand from the crude product to allow the economical recovery of the crude product. The block or filter pack or other obstruction may be dissolved through the introduction of the hot condensate into the blocked zone, thus forcing the crude product to be released.

Furthermore, complete control over the heating zone may be obtained by utilizing thermal sensors along the heat exchanger in order to ensure that the proper or desired level of heat is provided to control the behavior of the crude product in the manner desired. In gas or oil well production, no two formations, wells, or specific gravity of the product to be recovered are identical. However, there is generally a suitable temperature or temperatures at which a product can be made to behave in the most favorable manner for its removal to the surface. The present invention enables such favorable conditions to be more readily obtained without harm to the formation.

In a typical installation in a formation where the product is a heavy gravity petroleum, it would be advantageous to raise the temperature of the product in the formation to its approximate fluid point temperature. For example, for an oil of ten gravity in a formation where the temperature is approximately 80 F., it would be desirable to inject sufficient heat to raise the temperature of the product to 330 F., its fluid point temperature. The temperature of the product in the well bore itself is preferably maintained at a slightly higher temperature, for example 332 F.-334 F. so that an out- Ward temperature gradient is established. This can be accomplished by the present invention by pumping steam at 150 p.s.i.g. at a temperature of 366 F. into the apparatus. The heat loss to the formation adjacent the steam line drops the tempearture at the heater to approximately 334 F., for a well 2000-2500 feet deep. The orifice diameter will of course depend on the depth of the well and the diameter of the steam line. In the illustration given, for a 1 inch steam line the orifice should be 0.1405 inch in diameter which is 1.8% of the area of the interior diameter of the heater.

FIGURE 5 illustrates an alternative embodiment of the invention including a heating chamber 69 in the form of a tube having an internal bore 70. The upper end 71 of the chamber 69 is attached to a steam supply line (not shown). A plurality of stationary heat transfer members 72 through 74 are secured to the exterior of the chamber 69 for radiating heat. A plurality of small orifices 76 and 77 are provided adjacent at least several of the

members

73 and 74 to drive well fluids away from the heating chamber 69 and heat transfer members aflixed thereto to create turbulence and movement of the fluid to enhance the heat transfer. The size of the orifices 76 and 77 and steam pressure within the heating chamber 69 are selected to prevent the well fluid from reaching the frothing point, the frothing point for the crude products being treated being readily available from conventional tables known to those skilled in the art. The lower end of the heating chamber 69 is coupled with a pressure relief valve 11 which in turn is connected to a ball-check vaIve 12 in the same manner described above.

The heat transfer members 72 through 74 may, for example, be one and one-half inch diameter copper Washers secured to a one-half inch internal diameter copper pipe forming the heating chamber 69, and the washers may be spaced apart one-half inch and have a typical thickness of around one thirty-second to one-sixteenth inch. The members may have similar dimensions, i.e., an external diameter =when extended of approximately one and one-half inch and have a similar spacing but which is suflicient to prevent an upper member from touching a lower member when they are folded. Likewise, orifices like orifices 76 and 77, may be provided through the heating chamber 10. The finned portion of the heating chamber 69, and the chamber 10, typically may be eight inches long, but this length can be varied depending upon the size of the formation to be treated.

The members 72 through 74 may be mounted in various configurations, such as circular as shown in FIG- URE 5, or they may be arranged spirally or longitudinally. Instead of being solid members, they may be in the form of spikes attached to and extending from the periphery of the heating chamber 69. In each instance, preferably a plurality of the orifices 76 and 77 are provided adjacent some of the members to provide the turbulence of the well fluids as described above.

The size of the steam supply line connected with either the heating chamber 10 or 69 may be anydesired size within practical limits, and essentially depends upon the heating requirements of the formation. Preferably, the internal bores 16 and 70 in the respective heating chambers 10 and 69 have a greater diameter than the internal diameter of the supply line in order to enable a faster heat transfer into the formation because of the immediate expansion of the steam into the heating chamber. Typically, the supply line has an inside diameter of one-half inch and the bores 16 and 70 in the heating chambers 10 and 69 have a diameter of approximately three-fourths inch. The heat exchanger, including the heat transfer members 20 and 72 through 74, may be made of copper. The supply line also may be made of copper tubing or copper plpe.

Apparatus constructed in accordance with the teachings of the present invention enables an even, controllable temperature to be obtained at the points desired within a formation and along the adjacent well casing. Thus, the product in the formation is heated because the casing itself is heated rather than just the fluid Within the casing thereby assuring that the product is sufliciently heated to remain heated during delivery thereof to the surface. This is particularly important in colder climates.

It will be appreciated that the heat exchanger may be used to treat gas and liquids as well as semiliquid material, such as hydrocarbons or other material. Extraction of natural gas in combination with crude petroleum can be benefited by heating the paraflin or other wax-like substance contained Within the formation. The wax, oil and asphalt are dissolved allowing gases to flow more freely. When used within crude oil wells, the oils can be heated to desirable temperatures for more complete removal, and by exercising control of the temperature of the heat exchanger by controlling the steam it is possible to maintain the fluid point temperature for each oil of different specific gravity. Live steam under pressure does not enter the well area to disturb the formation being treated or heated. Heating an oil or gas Well in this manner raises the temperature of the oil, thus releasing sand or other formation materials which then settle away by gravity from the oil or gas.

It will be apparent that the concepts of the present invention may be embodied in various forms, such as those described above, and others which will be apparent to those skilled in the art in light of the teachings herein. For example, the heating chamber may comprise a plurality of chambered units either arranged for steam flow serially therethrough or for parallel flow to a plurality of adjacent chambers having heat transfer members attached thereto.

Accordingly, the present embodiments of the invention are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims therefore are intended to be embraced therein.

What is claimed is:

1. A heat exchanger for use in oil wells, and the like, for heating products in an underground formation adjacent said well comprising:

heating means which may be lowered into a well and receive steam for radiating heat and heating products in an underground formation, said heating means including a body having a chamber therein for receiving steam and having heat transfer means coupled to the outer periphery of said body and movable relative thereto to provide a plurality of heat transfer surfaces extending from said body for radiating heat into an underground formation adjacent said well; and

means coupled with said body and communicating with said chamber therein for allowing hot water resulting from condensation of said steam to flow into said well while preventing substantially any well fluids from entering said last named means.

2. A heat exchanger as in claim 1 including a plurality of orifices through said body of said heating means substantially adjacent at least one of said fins for com-municating between the chamber in said body and the exterior of said body for allowing steam to flow through said orifices and cause turbulence in well fluid adjacent said one of said fins.

3. A heat exchanger as in claim 1 wherein said heat transfer means comprise a plurality of fins aflixed to and arranged around the outer periphery of said body in a ring-like fashion and in spaced groups.

4. A heat exchanger as in claim 3 wherein said fins are coupled to the periphery of said body by spring means tending to urge said fins to a substantially perpendicular position with respect to the periphery of said body, and said fins are retained substantially adjacent the periphery of said body during lowering of said heating means into said well.

5. A heat exchanger as in claim 4 wherein said fins are retained substantially adjacent the periphery of said body by a low melting point adhesive.

6. A heat exchanger for use in oil wells, and the like, for heating crude products in an underground forma tion adjacent said well comprising:

heating means which may be lowered into a well and receive steam for radiating heat and heating products in an underground formation, said heating means including a body having a chamber therein for receiving steam and having heat transfer means attached to the periphery thereof and movable relative thereto to provide a plurality of heat transfer surfaces extending from the periphery of said body; and

relief and check valve means coupled with said heating means and communicating with said chamber in said body and having a passageway therethrough and condensate trap therein for allowing hot water resulting from condensation of said steam to flow into said well, said relief and check valve means including restrictor means coupled with said body and adjacent an end of said chamber therein and having a restricted opening for substantially preventing any steam from passing into said condensate trap, and including means for allowing said hot water to flow from said condensate trap into said Well and for substantially preventing any well fluid from entering said condensate traps,

7. A heat exchanger as in claim 6 wherein said heat transfer means include a plurality of fins mounted substantially perpendicular to the periphery of the body of said heating means and spaced apart along the body thereof and extending therefrom.

8. A heat exchanger as in claim 6 wherein a plurality of orifices are provided through the body of said heating means substantially adjacent some of said heat transfer means for communicating between the chamber in said body and the exterior of said body.

9. The heat exchanger of claim 6 wherein said restrictor means communicates with said condensate trap through an inclined passage.

10. A heat exchanger as in claim 6 wherein a plurality of said heat transfer means are coupled to the periphery of said body by spring means and retained substantially adjacent the periphery of said body by an adhesive, said adhesive being capable of melting upon the application of heat thereto to thereby allow said members to move to an extended position substantially perpendicular to the periphery of said body.

11. A heat exchanger as in claim 10 wherein said heat transfer means are arranged in ring-like groups around the periphery of said body thereby forming a plurality of extended heat transfer surfaces when said adhesive melts.

12. A heat exchanger as in claim 10 wherein said adhesive is an asphalt material having a low melting point.

13. A heat exchanger for use in oil wells, and the like, for heating products in an underground formation adjacent said well comprising:

heating means which may be lowered into a well and received steam for radiating heat and heating products in an underground formation, said heating means including a body having a chamber therein for receiving steam and having heat transfer means coupled on the outer periphery of said body and providing a plurality of heat transfer surfaces extending from said body for radiating heat into an underground formation adjacent said well, said body having a plurality of orifices therethrough substantially adjacent at least one of said heat transfer means for communicating between said chamber in said body and the exterior of said body for allowing steam to flow through said orifices and cause turbulence in well fluid adjacent said one of said heat transfer means; and

means coupled with said body in communicating with said chamber therein for allowing hot water resulting from condensation of said steam to flow into said well while preventing substantially any well fluids from entering said last named means.

References Cited UNITED STATES PATENTS 1,639,008 8/1927 Shannon et a1 166-58 X 2,134,610 10/1938 Hogg 166-60 2,362,680 11/1944 Troupe 166-6O 2,675,081 4/1954 Nowak 16639 2,705,535 4/1955 Waterman 16640 2,828,821 4/1958 Waterman 166-57 DAVID H. BROWN, Primary Examiner.