US1776997A - Oil-well heater - Google Patents

Description

P. V. DOWNEY OIL WELL HEATER Sept. 30, 1930.

Filed sept. 10, 1928 @ttor mq Patented Sept. 30, 1930 PTBICK V. DOWNEY, OF DENVER, COLORADO OIL-WELL HEATER Application med September 10, 1928. Serial No. 305,098.

This invention relates to improvements in apparatus for heating oil wells and has reference, more particularly, to an improvement of the apparatus shown and described in United States application for patent Serial Number 178,679, filed March 26, 1927.

.In many places where there are oil wells, natural gas is often times available and it is therefore quite customary to employ this gas for raising the oil from the wells instead of using pumps.

It is well known that when gas is permitted to expand from high pressure to a lower pressure, that it becomes very cold and therefore when high pressure natural gas is used for the operati-on of gas lifts, the low temperature of the gas as it enters and becomes l mixed with the oil has a tendency to congeal the paraiiin and to facilitate its solidification on the walls of the well'to such an extent that the well very ofteny becomes sealed to such a -degree that it becomes unproductive. In wells of this type where such gas lifts are employed, itis evident that there is a great necessity for the introduction of heat into the well. In the copending application which has been identified above, an apparatus has been described which employs a plurality of heating elements located within a closed pipe for the purpose of heating the oil at the bottom of a deep well. In the apparatus described in the above identified applica-l tion, air or gas is circulated about the heating elements but this air or gas is not permitted to escape into the well, and serves merely to 'distribute the heat and to prevent the formation of points ofv excessively high temperature.

In this invention the heating elements are located in a pipe whose lower end is closed by means of a spring pressed check valve so that the gas may escape from the lower end of the pipe after having passed the heater. The gas, therefore, enters the oil in a heated condition and tends to prevent the solidication of the paraffin and if sufficient heat is applied, may raise the temperature of the well to such an extent that paraffin which is already solidified will melt.

In order to more clearly describe this invention and the manner in which it functions, reference will now be had to the accompanying drawing, in which the sin le f1 e shows a vertical section through an o1l we l to which this invention has been applied. Numeral 1 represents the surface of the ground and 2 the ordinary well casing with which the interior of the well is lined. In practice deep wells are lined with casings of different diameters, but for the sake of simplicity the entire casing in the well illustrated has been shown ofthe samediameter. Secured to the upper end of the casing is a cover 3, which is provided with a central o ning 4 through which the pipe 5 extends. collar is secured to pipe 5 and is held in place thereon by means of a set screw 7. This collar forms a support for the pipe which is suspended from the top of cover 3. The up er end of pipe 5 is closed by means of a cap 8 t at is provided with a central opening containing an insulating bushing 9. Cover 8 is also provided with an opening 10 for the reception of pipe 11 that conveys high pressure gas from the storage reservoir 12 to the interior of tube 5. The valve 13 in pipe 11 controls the flow of gas. The lower end of pipe 5 is provided with a coupling 14 to which the short section of pipe 15 is secured. Pipe 15 has secured to its inside a cylindrical plug 16 3 having an opening 17. `The lower end of opening 17 hasconical sides 18 and serves as a seat for the ball 19. A spring 20 holds this ball in place against the seat and has its lower end supported by a ring 21 which is threaded u to the lower end of pipe 15. A plurality of bars 22 extend transversely of the upper end of pipe 15 and serve as supports for the heating elements. The heating elements comprise a plurality of spools 23 of refractory insulating material such as porcelain. Each spool contains a number of turns of high resistance wire 24. This wire must be very refractory so that it will withstand high temperatures without fusing, and must also be made of such material that it will not readily oxidize when it is hot. These spools are supported on a rod 25 whose upper end is provided withan eyelet 26. The lower end of rod 25 terminates in a cylindrical flange 27 that is adapted to rest on the transverse bars 22. The sleeve 28 of metal separates the lower end of the lowermost spool from member 27 and similar sleeves separate the several heating elements from each other. In the embodiment shown three heating elements have been indicated, but in actual practice a larger number is used. One end of each coil is connected to the adjacent sleeve 28 by means of a connector 29, so that these coils are grounded to the pipe 5 and also to the casing 2, which, therefore, form the return path for the current. Current for the heating coils is obtained from any suitable source and as illustrative of such a Source a direct current generator G has been provided. One terminal of this generator has been connected to the casing 2 by means of conductor 30, while the other terminal is connected through a switch 31 with the electrical cable 32. This cable is of large current carrying capacity and extends through the eyelet 26 to which it is connected by means of a loop of insulating material 33. A conductor 34 extends from the cable 32 downwardly along the heating elements and one end of each coil is electricallyA connected with this conductor in the manner shown. Conductor 34 is preferably insulated with asbestos so that it will withstand high temperatures. When switch 31 is closed, current will flow from the generator through the cable 32 and be distributed to the different heating elements by means of the conductor 34 and will return by way of pipe 5 and casing 2 in the manner shown. In actual operation the oil extends a considerable distance upwardly and the oil level has been indicated by means of a line 35. During operation current is passed through the heating elements in the manner indicated and gas from the reservoir 12 is caused to fiow into pipe 5 and passes downwardly past the heating elements and outwardly through the check valve at the bottom of pipe 5. This gas mixes with the oil and causes the latter to rise to the top of the casing and to flow through the pipe 36 to the storage reservoir which. however, has not been shown. By properly adjusting` the intensity of the current, and the rate of flow of the gas. the latter can be heated to any temperature desired on passing the heaters so that when it enters the oil it will be warm and will. therefore, prevent the solidification of the paraffin.

Attention is called to the fact that the gas passes downwardly about the heaters so as to cool the latter and will therefore prevent the formation of excessive temperatures that will burn the heating elements. Since the gas passes downwardly, it carries the heat absorbed by it into the oil and therefore the eiciency of this apparatus for the purpose of heating the oil is very great.

Attention is called to the fact that although gas has been designated as the fluid used, it is to be understood that air can also be employed for this purpose. It has been explained above Athat the reason for employing natural gas is that it is sometimes available in large quantities and at high pressure and can therefore be utilized for this purpose with a minimum expense. Besides the cheapness and availability of the natural gas, it is also possible to collect the gas after it has served its function and to store it in suitable gasometers so that there need be no loss of gas due to this operation.

Having described my invention what is claimed as new is:

l. An apparatus for heating the interior of an oil well comprising, in combination, a pipe extending from the top of the well to a point near its bottom, the upper cnd of the pipe being closed and connected with a source of gas under pressure, an electric heater element located within the pipe and spaced from the inside wall thereof, means for connecting the heater with a source of electric current, and a check valve located in the lower end of the pipe, whereby gas may ow from the inside of the pipe and into the well.

2. An apparatus for heating the interior of an oil well comprising, in combination, a pipe extending from the top of the well to a point near its bottom, the upper end of the pipe being closed, the lower end of said pipe having a check valve which permits fluid to flow outwardly from the interior of the pipe, a plurality of electric heaters located within the pipe, means for conducting current to said heaters, a source of gas under pressure, and means for conducting said gas to the interior of the pipe, said gas being under sufficient pressure to pass outwardly through the check valve at the bottom of the pipe.

3. An apparatus for heating the interior ofy an oil well comprising, in combination, a pipe extending from the top of the well to a point near the bottom thereof, the upper end of the pipe being closed, the lower end of the pipe having an opening of restricted area, through which gas may flow from the interior of the pipe into the well, means for obstructing the flow of liquid from the well into the pipe, an electric heater element located within the pipe, means for making electrical connection between the heater and a source of electrical energy, a source of gas under pressure, and means for conducting the gas to the interior of the pipe, said gas being under sutlicient pressure to pass outwardly through the opening at the lower end of the pipe.

In testimony whereof I affix my signature.

PATRICK V. DOWNEY.

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