US2632836A - Oil well heater - Google Patents

Description

March 24, 1953 c. s. ACKLEY 3 OIL WELL. HEATER Filed Nov. 8, 1949 2 SHEETS-SHEET 1 lull!!! INVENTOR. (Hp/u 5.9/5 140/ 5y March 24, 1953 v c. s. ACKLEY OIL WELL. HEATER 2 SHEETS,SHEET 2 10)! d/M 70 Pump 194 0 I INVENTOR. 62/4015: .5. 4a; 5;

Filed Nov. 8, 1949 SJRFHCE 9 3 W 14 mm p a 4: fi w W? M E w Patented Mar. 24, 1953 UNITED OIL WELL HEATER Charles S. Ackley, Brooklyn, N. Y., assignor to Thermactor Company, New York, N. Y., a corporation of Delaware Application November 8, 1949, Serial No. 126,089

Claims.

The invention here disclosed relates to the heat treatment of oil wells, gas wells or other subterranean reservoirs, particularly for promoting the removal and recovery of oils held in situ by congealation or congestion of the oil or of its component waxy, sludge or tarry portions.

It is known that with application of heat such viscous oils and deterrent components may be li uified and a non-producing or low production well be stimulated or restored to action or greater productivity.

The hot oiling method, as practiced in heavy gravity oil Wells, involving the introduction into the well of a relatively large quantity of surface heated oil, while helpful, is not satisfactory as the beneficial heating effect is of short duration and the repeated applications of heating oil and charging into the well is an expensive method of imparting heat to a subterranean body of congealed oil necessary to reduce to a fluid state suitable for pumping.

Hot air, steam and various forms of electric heaters have been proposed, but these have been only partly successful. Particularly in the case of electric heaters, it has not been found possible to provide a heater which would stand up over the long, continuous periods of time required for effective heating.

One important reason for the failure of electric heaters has been the inability to carry the necessarily heavy current to theheater through the trying conditions present in the well. The water and oil and especially the hot oil, has a destructive and deteriorating effect on rubber and other insulation that has been used, rendering these heaters unreliable and uncertain and at best limited to such short usage as to be of no real advantage.

Furthermore, such heaters as proposed have been unsuited to present day well conditions and unable to withstand the hydrostatic pressure of such deep wells.

The purposes of the present invention generally are to overcome the objections and limitations noted and to provide an entirely practical and reliable heater which will withstand hard and continuous usage without failure of' electrical or other parts and which will conform to and enable practice of conventional and accepted procedures in oil well production.

' More specific objects and details of the invention are set forth or will appear in the course of the following specification.

. The drawings accompanying and forming part of the specification illustrate a present practical 2 embodiment of the invention. Structure, however, maybe modified and changed as regards the immediate illustration, all within the true intent and broad scope of the invention as hereinafter defined and claimed.

Fig. 1 in the drawings is a broken and part vertical sectional view' of one of the new heaters as coupled to the lower end of a flow line and lowered into operative position at the bottom of a well casing or perforated liner;

Fig. 2 is an enlarged cross sectional view of the heater taken on substantially the plane of line 2-2 of Fig. 1;

Fig. 3 is a cross sectional viewof the casing and flow tube, on substantially the plane of line 3-4; of Fig. 1, showing the heater in plan and the power cable attached to and forming part of the latter, in section;

Fig. 4 is a broken part sectional view showing in general theposition of the heater at the bottom of a well with a pump in the flow tubing above it and the clamps for holding the power cable to the tubing;

Fig. 5 is an enlarged broken sectional View illustrating details of the integral connection of the sheath of the cable with the heater and the sealing of the interior of the cable within the heater;

Fig. 6 is a horizontal sectional View across the flow tubing andcable, illustrating details of one of the cable clamps.

The body of the heater, as shown, is made up of inner and outer concentrically arranged tubular members 7 and 8 connected in such spaced relation by a top head 9 and a bottom head Ill.

The inner tubular member is dimensioned to suit the flow tube of the well and-screw threaded at its opposite ends as indicated at H to take the couplings employed in joining the sections of the flow tube together, thus enabling the heater to be connected in the flow line and to be locatedat the bottom or at any selected level in the well.

In Fig. 1 the heater is shown as connected at the bottom of the flowtube, above the perforated strainer section l2 at the bottom of the well casing I3, the latter shown cemented at M in the cap rock I5 overlying the oil producing sand The heating element illustrated is for a three phase system and istherefore shown, in Figs; 1 and 2, as made upof three sections ll, [8, lil, of

resistance wire laced back and forth longitudinally of the heater through openings 26 in the ceramic insulating rings 2! engaged over the inner tube 1, in the annular space between said inner tube and the outer tube 8.

One of the heating lines, i9, is shown in Fig 2 as split at 22 for connection with a heat controlling thermostat 23 set in and projecting upwardly from the top head 9, Fig. 1.

A spacer ring 24 of insulating material is shown in Fig. 1 engaged over the return bends at the upper ends of the coils and bearing against a positioning or stop ring 25 attached to the inner tube. such as indicated at 26 for the end leads of the several coil sections. i l

Spacing rings 2? and 28 are shown engaged about the flow tube 1 below the heater unit, the

This spacing insulator has guide openings upper one of the first mentioned spacers, 27,.

engaging the lower return bends-of the heater lines, the lowermost of the spacers, 28, resting on the bottom head it and a helical spring 29 being interposed between these two sets of spacers to exert upward thrust holding the unit seated firmly against the fixed positioning ring 25.

The last described construction, while of value for holding the parts definitely located in the well, is of special value for holding the parts firmly but yieldingly against movement and breakage in shipment of the heater.

In the finished heater all electrical parts, including the cable which supplies electrical energy, are permanently hermetically sealed within the annular shell of the heater.

This is accomplished in the illustration by welding the upper head 9 to the inner flow tubing 1 at 38, by welding the outer sheathing 8 to the top head at 3| and by welding the bottom head It to the inner tubing at 32 and to the outer tube at 33.

Finally and of greatest importance, the sealing of the power supply cable to the heater is effected by employing a flexible, solid insulation, metal sheathed cable and by welding or brazing the metal sheathing of such cable to a metal adapter which is welded or brazed in the top head of the heater. v

In the illustration, the cable is shown as having a continuous, drawn copper or aluminum sheath,- ing 34 welded, brazed or soldered at 35 in the mouth of the tapered nipple or adapter 36, and the latter is shown welded, brazed or soldered at its base at 31 in the top head 9 of the heater.

This continuous metal sheathed cable is shown as containing insulation 38 such as magnesium oxide, holding the three conductors 39, 40, 4|, separated in insulated relation. The metal sheath is a thin, flexible shell and the wires and the solid insulating material are sufiiciently flexible in and of themselves and in their contained relation within the sheath to bend as much as need be for reeling and unreeling the cable in removing and replacing the heater in a well. Consequently the permanent, sealed connection of the cable to the heater is entirely feasible and practical.

To prevent adsorption or absorption effects through the cable, the end of the cable which is secured in the heater adapter, may be closed off with a suitable permanent sealing cement, this accomplished by first removing some of the magnesium oxide filling in the end of the sheath and then filling in the emptied space with the air and liquid-tight sealing cement and plug of silicon or the like such as indicated at 42, Fig. 1.

The thinned adapter nipple 35 is shown extending an appreciable distance alongside the flow tubing 1 so as to brace and hold the cable parallel with the tubing where it emerges from the head of the heater, and rings or clamps may be applied at diiferent points in the length of the flow tubing to hold the cable properly confined thereto.

The leads extending from the resistance lining to the cable and to the thermostat may be joined by compression bonds and suitably insulated as by the application of fish spine insulating beads thereon, as indicated at 43.

In practice, the top head may be sealed to the inner tubing and the adapter sealed to the top head and the cable sheath sealed to the adapter by providing grooves for rings of silver solder and then brazing all these parts together in a single heating operation. Similarly, the thermostat may be sealed in the top head by welding or silver soldering, as indicated at 44, Fig. 1.

Assemblage of the heater may be effected, after securing the top head on the inner tubing, by mounting the insulator rings, threading the heater wires therethrough, connecting the terminals as indicated, locating the spacers and spring over the tubin and then placing the outer tubing and welding it to the upper head and welding the bottom head to the inner and outer tubes.

Before finally sealing the structure the heater unit may be energized and during this time the annular heater chamber may be vented through an opening 45 in the bottom head. After this electrical test the heater chamber may be tested for tightness as by introducing nitrogen gas through opening 45 under pressure, for example, of at least 2500 p. s. i. If then free of leakage the gas may be withdrawn and a vacuum pump connected with the opening to evacuate gas and moisture, after which the opening may be closed with a plug it welded or brazed in sealed condition. In this way the whole electrical structure may be permanently hermetically sealed.

The disposition of the resistance wire in parallel lengths longitudinally of the heater casing provides for quick, easy assemblage and avoids creation of magnetic flux. This arrangement also allows for expansion and contraction of parts and locates the heating elements where they will do the most good, with the inside and outside runs of the resistance wire, Fig. 2, transmitting heat inwardly through the inner tube 7 and outwardly through the outer tube 8. With this arrangement, also, the heater may be made as long or as short as desired, simply by increasing length of parts and adding insulator rings, or by decreasing length of parts and reducing the number of insulator rings.

The outer tubular member or shell of the heater, 8, may be fluted or finned to facilitate heat transfer and to create thermal circulation for preventing formation of coke in the annular space between the casing and the heater and for preventing formation of such coke on the exterior walls of the heater.

The heater being fully open and forming, in efiect, a continuous, full dimension portion of the flow tube, does not impede or impair circulation and permits full, effective pumping or pressure operations to be conducted as best suited for flowing the well.

The heater may be used alone or in conjunction with other heaters located at different levels, and it may be coupled in the flow tube with a pump either above or below it, the open passage through the heater providing for operation of aosa s se pump rods, just the same as any other portion of the flow tube.

The heater also may be combined with packers or other accessories located above or below the same on the flow tube.

The blank insulator or insulators above the heating wires protect the terminal connections at the top against over-heating and the blank insulators at the bottom serve in a like protective heat insulating character, resulting in a concentration or localizing of heat in the intermediate resistance terminal section of the heater and consequently a more rapid transmission of heat to the surrounding column or pool of liquid.

The thermostat 23 may be set to maintain a mean temperature which will be most effective in a given formation, and this heat may be maintained for as long as need be to accomplish any desired penetration of the adjacent structure.

The heater does not interfere with the pumping or production flow in any way and so may be kept on while pumping or other operations are in progress. Thus the heater is suited to various special uses as for carrying out certain novel methods, as disclosed in companion copending application for patent, Serial No. 133,384, filed December 16, 1949.

The continuous metal sheath, flexible, solid insulation cable bonded and sealed to the heater and with its insulation sealed off from the heater, is a permanent component part of the heater, capable of continuously withstanding the temperature, pressure and other conditions encountered in the well and not being subject to deterioration, places no limitations on the continuing, heavy use of the heater.

While primarily designed as a heater for oil Wells, it will be realized that the invention is adapted for many other special uses. Also, while a three phase form of heater is shown, it will be realized that single phase or other type heating may be employed.

In the general view, Fig. 4, the heater is shown connected by coupling M to the lower end of a string made up of lengths of tubing 48, this string including a pump 19 located an appropriate distance above the heater. This view also shows how the cable may be supported and held in closely parallel relation to the flow tubing by clamps made up of companion members 50 pivotally connected together at one side at 5!, Fig. 6, and adjustably secured together at the opposite side by clamp bolts 52. At this opposite side the members 50 are formed with companion jaw extensions 53 to grip and supportingly hold the cable when the clamp is seated on a coupling 41, as indicated in Fig. 4.

To allow the clamps freedom to settle and seat on the couplings, the jaw members 50 are finished with clearance, as shown at 54, to freely surround the tubing without actually gripping the same.

Fig. 5 shows in greater detail how the cable may be integrally united and sealed to the heater.

To facilitate the mechanical connection between the metal sheath of the cable and the adapter 36, that part of the cable sheath which enters this adapter and is braced or supported therein, may be tin plated, chromium plated, or the like and this plating may be extended a short distance above the heater to prevent corrosion or oxidation about or near this joint.

The plug 42 which is cemented and sealed in the end of the cable, has spaced passages for the wires, as shown in Fig. 5, in which the wires 6 are sealed, the plug thus serving further as a spacer for these wires where they issue from the end of the cable.

What is claimed is:

1. A heater for oil wells and the like as herein disclosed and comprising an elongated annular form of easing composed of an unobstructed, uniform diameter, inner tubular member continuously open through from one end to the other in the nature of a flow tube and having exposed ends screw threaded for engagement of flow tube couplings whereby the same may be connected at any point in a length of flow tubing without impeding flow or preventing use of pump rods or other equipment normally employed in flowing or pumping a well, an outer tubular member and top and bottom heads sealed to andrigidly connecting said inner and outer tubular members in hermetically sealed relationship and an electric heater disposed in the annular space between said inner and outer tubular members and comprising insulating supporting means and electrical heating elements carried by said insulating supporting means and disposed longitudinally of said flow tube simulating inner tubular member, said insulating supporting means consisting of ceramic rings slidably positioned over the inner tubular member and having registering openings disposed adjacent said inner and outer tubular members, respectively, and said heating elements consisting of lengths of heating wire threaded through said openings and thereby disposed in closely adjoining relation to said inner and outer tubular members to radiate heat inwardly to liquid flowing centrally up through the flow tube and outwardly into liquid surrounding the outer tubular member.

2. A heater for oil wells and the like as herein disclosed and comprising an elongated annular form of casing composed of an unobstructed, uniform diameter, inner tubular member continuously open through from one end to the other in the nature of a flow tube and having exposed ends screw threaded for engagement of flow tube couplings whereby the same may be connected at any point in a length of fiow tubing without impeding flow or preventing use of Pump rods or other equipment normally employed in flowing or pumping a well, an outer tubular member and top and bottom heads sealed to and rigidly connecting said inner and outer tubular members in hermetically sealed relationship and an electric heater disposed in the annular space between said inner and outer tubular members and comprising insulatin supporting means and electrical heating elements carried by said insulating supporting means and disposed longitudinally of said flow tube simulating inner tubular member and a thermostat connected with said electric heater and mounted in projecting relation on the top head of the heater casing between the inner flow tube member and the outer tubular member in position to stand clear of surrounding well casing in which the heater may be used.

3. An electric heater for oil well comprising an annular heater casing having an open flow passage therethrough, an electric heating unit within said annular casing, a tubular cable adapter in the top of said annular casing, a cable having a flexible, continuous metal sheath entered within and brazed in said adapter, said cable having conductor wires insulated by a filling in the nature of magnesium oxide and a ceramic plug closing the end of the cable sheath within the heater, said plug having spacing passages for aesasse the cable conductors and said plug being sealed in place in the end of the cable sheath and the conductors being sealed in said passages.

4. A bottom hole heater as herein disclosed comprising an elongated annular heater casing composed of a length of flow tubing open and unobstructed from end to end and having the opposite ends exposed and screw threaded for engagement of flow tube couplings, an outer, shorter tubular member secured in sealed spaced relation about said open, inner flow tubing between the screw threaded opposit ends of the same and defining therewith a hermetically sealed annular chamber, an external stop ring on the flow tubing within and near one end of said annular chamber, rings of insulating material slidingly engaged over said flow tubing and positioned by said stop ring, said insulating rings having registering opening therethrough extending longitudinally of the heater casing, heater wire laced through said openings and thereby supported in longitudinally extending relation over the outside of the flow tubing but wholly enclosed within said hermetically sealed annular chamber and external electrical supply connections to said heater wire including a hermetically enclosed cable hermetically sealed to the top of said heater casing.

5. A bottom hole heater as herein disclosed comprising an elongated annular heater casing composed of a length of flow tubing open and unobstructed from end to end and having the opposite ends exposed and screw threaded for engagement of flow tube couplings, an outer, shorter tubular member secured in sealed spaced relation about said open, inner flow tubing between the screw threaded opposite ends of the same and defining therewith a hermetically sealed annular chamber, an external stop ring on the flow tubing within and near one end of said annular chamber, rings of insulating material slidingly engaged over said flow tubing and positioned by said stop ring, said insulating rings having registering openings therethrough extending longitudinally of the heater casing, heater wire laced through said openings and thereby supported in longitudinally extending relation 8 over the outside 01. the flow tubing but wholly enclosed Within said hermetically sealed annular chamber and external electrical supply connections to said heater wire including a hermetically enclosed cable hermetically sealed to the top of said heater casing, said stop ring being disposed near the upper end of the annular chamber, a coiled spring about the flow tubing in the lower end of the annular chamber for yielding supporting the insulating rings, said heater wire having return loops at the upper and lower ends where it is laced through the registering openings in the insulating rings, and abutment rings of insulating material overstanding said return loops of the heater wire and engaging the stop ring at the top and being supported by said supporting spring at the bottom.

CHARLES S. ACKLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 758,684 Peck et a1. May 3, 1904 965,287 Gardner July 26, 1910 1,174,444 Quain Mar. 7, 1916 1,176,739 Davis Mar. 28, 1916 1,426,407 Pennington Aug. 22, 1922 1,457,690 Brine June 5, 1923 1,504,208 Brine Aug. 12, 1924 1,576,102 Downes Mar. 9, 1926 1,681,523 Downey et al Aug. 21, 1928 1,957,984 Smith May 8, 1934 2,022,977 Quarles Dec. 3, 1935 2,047,000 Calvert July 7, 1936 2,076,669 Redfield et a1 Apr. 13, 1937 2,082,055 Higgins June 1, 1937 2,166,807 Ewald July 18, 1939 2,190,824 Cook Feb. 20, 1940 2,350,429 Troupe June 6, 1944 2,388,899 Bennett Nov. 13, 1945 2,484,063 Ackley Oct. 11, 1949 2,500,305 Ackley Mar. 14, 1950 2,548,360 Germain Apr. 10, 1951 2,587,391 Seaver Feb. 26, 1952

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