US2703621A - Oil well bottom hole flow increasing unit - Google Patents

Description

March 8, 1955 G. w. FORD OIL WELL BOTTOM HOLE FLow` INCREASING UNIT Filed May 4, 1955 IN V EN TOR.

GeoRef; w FORD United States Patent O OIL WELL BOTTOM HOLE FLOW INCREASING George W. Ford, Wichita, Kans.

Application May 4, 1953, Serial No. 352,827

2 Claims. (Cl. 166-60) This invention relates generally to apparatus for increasing the ow of underground oil into the bottom of an oil well by the application of heat to the oil bearing underground structure at desired levels, thus increasing the volume of oil which can be removed from the well by pumping or other means. The invention is especially advantageous when used in wells in which pitch, paraflin, tar and sludge have practically sealed the normally porous oil producing sand or other structure, thus preventing oil from flowing into the well.

An object of the invention is to provide an electrically heated unit which can be secured directly to the lower end of a string of tubing or to the lower end of the working barrel of a pump and let down into the well to a desired depth.

An additional object is to provide a unit of this type which may be used as a permanent but intermittent heater in a pumping well without interfering in any way with the pumping operation.

Another object is to provide a unit the operation and temperature of which can be controlled at the top of the well at ground level.

Still another object is to provide a heater unit which is so constructed that oil and other liquid in the well cannot directly contact and short circuit the electrical heating elements.

The invention, together with other objects attending its production, will be more clearly understood when the following description is read in connection with the accompanying drawings, in which:

Fig. l is a condensed schematic longitudinal vertical sectional view through an oil well showing a unit embodying my invention installed therein, the heater unit proper being secured to the lower end of the working barrel of a pump; and

Fig. 2 is a detailed view, partially in vertical section illustrating one type of relief valve used as a part of the unit.

Fig. 1 shows a casing 10 extending from ground level 11 to the bottom hole or shot hole 12. Casing 10 houses a string of production tubing 13, which carries a conventional plunger type pump 14 on its lower end.

My invention includes a conventional packer 15 which seals o the shot hole 12, thus limiting the rise of oil in the casing. A pressure relief valve 16, such as shown in Fig. 2, extends through the packer and prevents pressure in the bottom hole from exceeding a predetermined desired amount by permitting the escape of gas or air from the space above the oil in the hole.

Secured on the lower end of the working barrel of pump 14 by means of a coupling 17, is an elongated perforated heater casing 18. A sealed electrical immersion heating unit 19 is sealed in the lower end of casing 18, as by welding 20. This heating unit preferably is of the type having its electrical heating element sealed inside a nickel steel sheath 21. A pipe T22 is threaded on the lower end of casing 18, and the lower end of the T is sealed by a threaded plug 23.

The third opening of the T receives an elbow 24, which is connected to a copper pipe 25 which extends upward in the casing 10 through packer 15, as shown. The packer seals fluid tight around this pipe 25.

A two wire electrical conduit 26 extends downward through well head 27 into copper pipe 25, and on down into the interior of T22, where it is connected electrically to the two heater terminals 28 and 29. The packer ice 15, copper pipe 25, elbow 24, T22, plug 23, and welding seal 20- thus" combine t'o prevent any' possible contact of fluid in the' well with the ,electrical conduit 26. The conduit is supported by suitable clamps 36V around tubing' 13. The4 perforations in heater easing 18 permit oil and other liquid in the well to directly contact the internally heated sheath 21, so that over a period of time all liquid in the shot hole is heated to a desired temperature.

As a means of temperature control a conventional thermostatic circuit breaker 30 is mounted on production tubing 13 just above the well head. It includes a heat sensing element 31 which projects into the interior of the tubing, and senses the temperature of the liquid being pumped through the tubing from the shot hole 12. One wire of conduit 26 is connected to one terminal 32 of circuit breaker 30. The other Wire is connected to one lead of a source of electrical energy 33. The other lead from the source 33 is connected to the other circuit Y breaker terminal 34, through a suitable control switch 35.

Depending on the depth of the well and the underground structure through which well casing 10 extends, there will be a fairly constant temperature differential between the liquid in the shot hole and the liquid in Contact with sensing element 31. This can easily be determined by test on each individual well. If the oil temperature drop from the bottom to the top of the well is 10 F. during continuous pumping, and it is desired to maintain the temperature of the oil in the shot hole between 80 F, and 90 F., then the circuit breaker is set to close the electrical circuit when it senses a liquid temperature of approximately 69 F., and to open the gircuit when it senses a temperature of approximately From the above description, it will be seen that the invention provides a simple yet eicient means of increasing the flow of oil from the oil bearing formation into the shot hole at the bottom of an oil well, a means of settling out tar and other heavy fractions in the oil flowing into the well hole, a means for reducing parain accumulation in pumping wells, and thus a means for increasing oil production from a pumping oil well.

Having described the invention with suiiicient clarity to enable those familiar with this art to construct and use it, I claim:

l. In a cased pumping oil well which includes a string of production tubing extending through a well head downward through the well casing to a shot hole, and which tubing carries a plunger type pump on its lower end, an oil heating system for such wells comprising: a pressure sealing packer sealing oif the space between the tubing and casing at a point just above the upper end of the shot hole, the lower end of the pump working barrel extending downward through said packer; an elongated heater casing having its upper end secured to the intake end of said pump working barrel and its remaining portion extending downward into said shot hole, said heater casing having perforations in its wall; a one piece electrical immersion heating unit including means sealing the lower end of the heater casing and a liquid protected heating element extending upward into the perforated heater casing, the terminal ends of said heating element projecting through and below the heater casing sealing means; a liquid tight housing secured to the lower end of the heater casing and enclosing the terminal ends of said heater element against liquid contact; a pipe having its lower end in sealed communication with said housing and extending upward Athrough said packer and through the well head; a pair of electrical conductors extending through the well head downward through said pipe and connected to the respective terminal ends of said heater element within said housing, said conductors being connected to a source of electrical power at the upper end of the well; a heat sensing unit extending into said production tubing for sensing the temperature of oil pumped therethrough; and a thermostatically controlled circuit breaker in circuit with the heater element and heat sensing unit and responsive to the heat sensed by the latter to control the ilow of electrical power to the heating element.

2. The oil heating system described in claim l, and a pressure relief valve mounted in said packer in communication with the sealed off space in the well below the packer, and arranged to exhaust into the space in the well above the packer.

References Cited in the le of this patent 4 Powell Aug. 27, 1929 Strandell Aug. 25, 1931 Lewis June 27, 1933 Niles Jan. 9, 1940 Germain Apr. 10, 1951

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