US2982354A - Paraffin removing device - Google Patents

Description

May 2, 1961 w. G. GREEN 'PARAFFINREMOVING DEVICE Filed April 26, 1957 FIG.

FIG. 3

INVENTOR.

W G. GREEN J. A. 6,126; p

AGENT United States Patent PARAFFIN REMGVENG DEVICE William G. Green, 1102 N. Mingo Road, Tulsa, Okla, assignor of one-eighth to Thomas D. Copeland, Jr.

Filed Apr. 26, 1957, Ser. No. 655,406

3 Claims. (Cl. 166-60) This invention relates generally to oil well servicing equipment and more particularly to an item which may be permanently installed at a well site to facilitate the production of petroleum products from a well bore.

The primary object of this invention is to provide a non-chemical device which will dissolve the objectionable parafiin deposits which accumulate in the tubing or casing of many petroleum producing wells.

Another object is to provide an entirely electrical device which will remove parafiin deposits.

A still further object is to provide a device for insertion into a well bore for eliminating parafiin deposits therefrom, which device employs as one of its main components a well casing or tubing which is already an integral part of the producing well and thus greatly minimize the cost of this device, and facilitate its shipment and handling.

An yet another object is to provide a permanently installed parafiin removing device which will automatically be energized to remove paraifin from a well bore at predetermined intervals. I

And another object of this invention is to provide a device of the type described which will automatically be energized to remove paraffin from a well bore when the need arises and independent of the time element.

These and other objects and advantages will be apparent from an examination of the following specification and drawing, in which:

Figure 1 is an outline view partly in schematic illustrating the problem involved and the basic operation of this invention to correct this problem.

Figure 2 is an enlarged cross sectional elevational view showing the device of this invention installed in one typical well using the special oil well casing head which has been modified to permit this installation.

Figure 3 is an enlarged cross sectional elevational view showing the installation of the lower section of the device shown in Figure 2.

Figure 4 is an outline view showing the use of this invention in combination with a well pump.

Figure 5 is a detail circuit drawing of a conventional circuit of a Wheatstone-bridge and a strain gage element suitable for installation in theparafiin removing device of Figure 4.

Referring now more particularly to the characters of reference in the drawing, it will be observed that the complete parafiin removing device of this invention is indicated generally at 2, and is shown in Figures 1 and 4 to be installed in a casing head 3 (and'32) of a petroleum well '4 having a bore hole casing 5 (and 3b) in which the cable 6 of a walking beam pump '7 is operating.

The device 2 in its basic form is necessarily comprised of three separately located components, the power input terminal 10 and the power return terminal 11 and the current bridge section 12 installed respectively at the surface (It) and 11) and down in the bore (12) of the well, and each section it) and 1-1 is in turn connected to the special power transformer 13 located at the well site and connected to any suitable available power source.

By way of illustration of manner and principle by which device 2 operates, let it be assumed that 700 feet of the tubing 2%) in the well of Figure 1 have paraflin deposits P which are desired to be removed. Assuming that under the existing conditions the power required to melt 700' or" this volume of parafiin in a period of 30 minutes is 13 kilowatts. It may be then calculated that the resistance of the combined lengths of 700 feet of tubing plus approximately 700 feet of casing is approximately .0025 (depending-on pipe size, etc.). From Ohms law we observe the relationship of the current required to provide the power of 13 kw. through a resistance of .0025 ohm to be:

W=E I and E=IR Substituting for E:

W=I R; 1 W/R Substituting for values:

Solving:

I= /5,2G0,000=230O amperes Further it is known that the voltage required to pass this amount of current through the resistance given is shown by the formula:

E=IR and substituting E=2300X.0025=5.7 volts From the above figures it is apparent that a special transformer 13 is necessary since conventional commercial power transformers to deliver the large amperage required are not made in this small voltage size.

This power input of 13 kilowatts or whatever amount is required may be delivered from transformer 13 direct to input section 1? through leads 25 and 26 by the manual closing of switch 27 which in turn trips a power relay 23. Current is then free to travel through the closed circuit including lead 25 to input terminal 18, tubing 29 down to bridge section 12, and then through section 12 and into casing 36* to return terminal 11 and thence through lead 26 back to transformer 13. That section of tubing 2% between input section It? and bridge section 12 is heated sufficiently by the passage of current therethrough to melt the paraffin P and cause it to go back into solution with hte oil in tubing 2% and consequently be pumped out through pump discharge 31.

It is essential to the proper operation of this device that good electrical contact be maintained where required and that no electrical contact be permitted at any other location in the well above bridge section 12. Referring to Figure 2 it will be observed that casing head 32 includes a main body 33 having a bore 34 through which tubing 26) passes, but from which bore the tubing is insulated by a non-conducting sleeve 35. A plug 36 threads into the top of. body 33 and includes a bore 37 which is also insulated from tubing 26 by sleeve 38 and disk 39 against which tubing collar 4 may rest. Another disk 41-is placed between plug '36 and the bottom 42 of recess 43. At the lower end of body 33, a threaded recess 44 receives the threaded upper end 45 of casing 30. Just below casing head 32, the heavy copper return terminal 11 is made integral with casing 38 by rivets 46 and lead 26 is attached thereto by large heavy duty terminal screws 47. Tubing collar 49 at the top of casing head 32 ineludes similarly attached terminal 19 to which lead 25 is attached by screw 43. it will be observed that within the area of easing head "32 there is no point of electrical -electrical contact with casing 30.

aasaasa 20 so that at no time can tubing 20 touch casing 30 above bridge section 12.

The bridge section 12 may be made up of any of several commercial casing-tubing packers or hangers which maintain a good large area metal to metal contact between both the tubing and the casing, one such unit might be a combined Baker Oil Tools Anchor Tubing Seal Assembly, Product No. 443-E2 and Baker Oil Tools Retainer Production Packer, Product No. 415-D; a second such unit might be an Equipment Engineers Inc. Double E Tension Tubing Anchor. adapt these commercial tools for their function as bridge section 12 is to increase the size of certain electrical contact area parts and remove any obstruction to current flow such as coating materials, surface finishes, and the like. The basic parts in bridge section 12 include a casing packer section 50, toothed slips 51 pivoted by link 51a and pins 51b to packer section 50 and including upwardly inclined tapered flanges 52 and a slip guide collar 53 having corresponding tapered grooves 54 which are adapted to ride under flanges 52 and force slips 51 outward under pressure until the latter grabs casing 30 in tight secure contact. Since slips 51 are in electrical contact with the inner wall of casing 30, and tapered flanges 52 of slips 51 are in binding engagement with grooves 54 of guide collar 53, and'the latter is directly attached to the tubing .20, there is provided a continuous large area electrical contact between the casing and tubing which contact is identified for purposes of this application as bridge section 12.

Although the manual operation of switch 27 will prowhich would be unduly expensive, and second, a person observing the well from the surface would not always be able to detect if parafiin has accumulated down in the well bore, and even if he were able to detect its presence, his detection would occur after large deposits has col-' lccted, and not at the early stages of the paraffin formation when it would be easy to remove, and with a minimum period of delay in correcting the condition, which while it continues reduces the pumping efiiciency output.

'By installing an electrical time switch 55 in place of manual switch 27, and using a time delay relay 56 in place of relay 28, an operational cycle may be maintained wherein at predetermined intervals relay 56 will energize the heating circuit of device 2 for a pre-set period and then automatically shut off for a similar interval.

In a third embodiment, the time switch 55 is replaced by an electrical strain gage 57 which is mounted directly on pump plunger rod 58 so that when the strain increases beyond a certain limit, as would definitely happen when paraffin deposits accumulate, an electrical'signal is sent through circuit 60 to time delay relay 56 and the heating a cycle is carried out as previously described.

The circuit drawing of Figure 5 is a well known manner of utilizing a strain gage to produce an output current for indication purposes or for doing work (in this case actuating the time delay relay 56).

This basic circuit is a Wheatstone-bridge wherein'the strain gage element 57 A necessary modification to 4 to Figures 2-3 on page23 of The Strain Gage Primer by C. C. Perry and H. R. Lissner, published in 1955 by McGraW-Hill Book Co., Inc. The usual method of attachment of astrain gage element (57) to a unit such as plunger 58 is by special cements such as described on pages 37-40 of the mentioned book, and an installation of a strain gage in a manner corresponding to the applicants installation is showne in Figures 3-4 of page 40.

What is claimed is: V

1. An-electrical heating parafiin removing circuit for a well having a casing and a tubing and having a pump with a plunger installed therein, comprising: an electrical power source of a substantial current, and an electric terminal on said casing, a second electric terminal on said tubing, means to electrically complete the circuit between said tubing and casing down in the well bore, and a switch circuit adapted to complete the circuit from the power source at a point above the well bore, said switch circuit comprising: an electrical strain gage installed on the pump plunger, said electrical strain gage being responsive to the application of a strain of greater than a predetermined value to said plunger for producing an electrical indication, means including a time delay relay electrically connected to said strain gage and responsive to said electrical indication for energizing said heating circuit for a predetermined interval when the strain on said plunger exceeds said predetermined Value.

2. In a pumping unit installed on a production oil well having a casing and a tubing and an electrical conducting means between said casing and tubing, a reciprocating ,pump plunger extending into the tubing and adapted to lift oil therefrom, a strain gage on said plunger responsive to a certain strain on said plunger due to the presence of paraflin in the tubing for producing an electrical indication of said strain, an electrical heating circuit including said casing and tubing, a high current electric power source, and means connected to said strain gage responsive to said electrical indication for neergizing said heating circuit by connecting said power source to said circuit to pass said high current through said circuit to melt the paraffin.

3. In an oil well having a casing, a tubing within said casing, a pump plunger within said tubing, and detecting means for detecting a change in the strain on the pump plunger due to restriction to flow through said Well when parafiin deposits reduce the Well bore, automatic heating apparatus for maintaining a deposit-free well comprising: a source of high amperage electrical current, movable bridging means for establishing a high current carrying capacity contact between said tubing and said casing at a point in said well bore lower than the areas from which deposits are to be removed, controllable circuit-completing means for connecting said source of electrical current in V series with said casing and said tubing when said circuit completing means is activated thereby to supply heating current of large magnitude to said tubing and casing when'said controllable circuit means is activated, and means including said detecting means efiective when the strain on said plunger exceeds a predetermined value for activating said controllable circuit-completing means for apredetermined interval. t

' References Cited in the file of this patent V UNITED STATES PATENTS 1,169,261 Hull Ian. 25, 1916 1,764,213 Knox June 17, 1930 2,244,256 Loamann Q June 3, 1941 2,597,261 Rhoads May 20, 1952 2,667,626 Blancher J an. 26,1954

1 2,728,396 Carpenter Dec. 27, 1955 2,741,915 Renken et al. Apr. 17, 1956 2,757,738 Ritchey Aug. 7, 1956 2 2 8

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