Well cleaning apparatus

Aug. 22, 1961

2,997,104

J. G. BURCH

WELL CLEANING APPARATUS

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Aug. 22, 1961

2,997,104

J. G. BURCH

WELL CLEANING APPARATUS

Filed July 22, 1957

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Sheets-Sheet 2

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Julius G. Burch

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ATTORNEYS

United States Patent Office

2,997,104

Patented Aug. 22, 1961

2,997,104 WELL CLEANING APPARATUS

Julius Gordon Burch, 822 S. McGee, Borger, Tex.

Filed July 22,1957, Ser. No. 673,183 15 Claims. (Cl. 166—57)

This invention relates to new and useful improvements in well cleaning apparatuses and more particularly to apparatuses for heating and agitating wells.

Heretofore, many attempts have been made to clean paraffin, asphalt and similar deposits from wells by chemical reactions. Although sufficient heat has been generated to dissolve the waxy or gum-like deposits, the prior devices have not been commercially successful because of the difficulty of prolonging the reactions and maintaining said devices in sufficient proximity to said deposits. Usually, a metal chemically reactive to an alkali, such as sodium hydroxide, is employed but the quantity of metal or its surficial contact with the alkali has been insufficient to thoroughly clean a well. In addition to cleaning the open bore of the well or the perforations of its casing or screen, it is necessary to dissolve the deposits in the producing formation and/or behind said perforations. This thorough cleaning requires agitation as well as heat and must be performed by an apparatus capable of being readily positioned in and removed from a well.

It is one object of the invention to provide an improved apparatus for cleaning wells which is so constructed that an adequate quantity of metal chemically reactive to an alkali in the presence of water can be maintained in position for intimate and prolonged contact with the alkali to dissolve accumulated paraffin, asphalt and similar waxy or gum-like deposits.

A particular object of the invention is to provide an improved well cleaning apparatus, of the character described, wherein the chemically reactive metal has an amplified area and is supported for substantially continuous and unrestricted contact by an aqueous alkaline solution whereby the exothermic reaction is accelerated and is of sufficient volume and duration to thoroughly clean 40 the well.

An important object of the invention is to provide an improved well cleaning apparatus, of the character described, wherein the reactive metal is of such configuration and is so mounted that its surficial contact with the alkaline solution is amplified and the circulation of said solution is facilitated so that the exothermic reaction is enhanced.

Another object of the invention is to provide an improved well cleaning apparatus, of the character described, having means for directing the flow of the alkaline solution in intimate contact with the reactive metal and for discharging the products of reaction and solution laterally to cause agitation in the well.

A further object of the invention is to provide an improved well cleaning apparatus, of the character described, wherein the alkaline soltuion is recirculated through the apparatus due to its construction so as to prolong the duration of the exothermic reaction.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings, wherein examples of the invention are shown, and wherein:

FIG. 1 is a longitudinal, sectional view of a well casing having an apparatus, constructed in accordance with the invention suspended therein, _ FIG. 2 is an enlarged, broken, longitudinal, sectional view of the well cleaning apparatus,

FIG. 3 is a horizontal, cross-sectional view, taken on the line 3—3 of FIG. 2,

FIG. 4 is a horizontal, cross-sectional view, taken on the line 4—4 of FIG. 2,

FIG. 5 is a view, similar to FIG. 3, showing a modification,

FIG. 6 is an elevational view showing a modified apparatus suspended in an open well bore,

FIG. 7 is an enlarged view, partly in elevation and 10 partly in section, of another modification,

FIG. 8 is a view, partly in elevation and partly in section, of a modified apparatus mounted on the lower end of a mud anchor, and

FIG. 9 is an enlarged, horizontal, cross-sectional view, 15 taken on the line 9—9 of FIG. 8.

In the drawings, the numeral 10 designates the substantially cylindrical housing of a well cleaning apparatus embodying the principles of the invention and adapted to be suspended within a well casing 11 by a cable of 20 wire line 12. Usually, perforations 13 are formed in the casing 11 for establishing communication with the prox ducing formation which is not shown. The wire line 12 carries the usual swivel 14 at its lower end for connection with an internally screw-threaded box 15 at the upper 25 end of the housing 10. Preferably, a suitable rod 16 is interposed between the swivel 14 and box 15 for positioning a thermometer or other temperature-indicating or recording device in spaced relation to the housing. As shown by the numeral 17, the container or holder for 30 the temperature device is connected between the swivel and rod. In order to permit anchoring of the housing at the bottom of a well, an internally screw-threaded box 18 may be secured to the lower end of said housing.

Rounded or semi-spherical end fittings or caps 19 and 35 20, which have the boxes 15 and 18 extending axially therefrom, are provided at the upper and lower ends of the housing to facilitate assembly thereof as well as movement of the same through the well casing 11 or an open well bore (FIG. 6). The housing and its end caps are hollow and are formed of steel or other metal which is substantially inert to the action of an alkali, such as sodium hydroxide. As will be explained, the alkali is adapted to be introduced into the well in an aqueous solution for contacting a metal, such as aluminum, to 45 cause an exothermic reaction. A member 21 of such metal is positioned in the housing and the alkaline aqueous solution is admitted thereto· by a plurality of radial openings or ports 22 and 23 formed in the end caps 19 and 20 below and above the member (FIG. 2). Due 50 to the generation or liberation of heat and gases by the exothermic reaction, the flow is upward through the housing from the lower ports 22 toward the upper ports 23. In order to increase the jetting action of the liberated gases and products of reaction, the combined area of the 55 upper outlet ports is materially less than the combined area of the lower inlet ports and may be substantially onehalf the area, such as being one^Jhalf in number.

The member 21 is of such configuration and volume as to substantially fill the interior of the housing, while pro60 viding continuous, uninterrupted passages 24 which extend longitudinally of said housing between the inlet and outlet ports. As shown in FIGS. 2 and 3, the member is coiled concentrically upon itself about the longitudinal axis of the housing with the passages 24 being formed by 65 the spaces between its convolutions 25. If desired, the member may be in the form of open tubes or sleeves 26 as shown in FIG. 5; however, greater surficial area for contact with the alkaline aqueous solution is provided by the coiling of a sheet of metal upon itself. Although rela70 tively thin, the walls of the member are of sufficient thickness to provide adequate metal for prolonging the duration of the exothermic reaction and maintaining the de2,997,104 sired heat and agitation. In addition to amplifying the area of metal exposed to the solution, the plurality of passages have a combined area at least equal to the combined area of the inlet ports whereby there is no interference with the flow of said solution as well as gases and other reaction products through the housing to the outlet ports.

Due to the upward flow within the housing, the solution is forced downwardly externally of said housing so as to enter the inlet ports 22 and provide a continuous circulation. The jetting action of the restricted outlet ports 23 coacts with the generated heat to break down and melt paraffin, asphalt and similar deposits which adhere to the well casing 11 and its perforations 13 (FIG. 1) as well as to the wall of an open or uncased well bore 27 (FIG. 6). Due to the continuous generation of heat, the temperature of the surrounding portions of the producing formation is raised and the waxy or gum-like deposits are removed therefrom. Due to this heating of the formation, the same is more responsive to subsequent acid treatment. The agitation caused by the jetting of the gases and reaction products produces a cleansing or scrubbing action which coacts with the heat and which penetrates the formation behind the perforations.

As shown by the numerals 28 and 29 in FIG. 6, the housing 10 and the member 21 may be of continuous, onepiece construction between the end caps 19 and 20; however, the same are preferably made in sections 30 and 31, respectively. The housing sections 30 are in the form of cylindrical sleeves or pipes which are screw-threaded to the end caps and which are connected to one another by screw-threaded couplings 32, while the member sections 31 are of slightly less length. Any number of sections may be joined together to provide a housing of desired length. A solid, circular partition 33 extends across the medial portion of each coupling 32 so as to separate the ends thereof from each other and prevent direct communication therebetween. For supporting the member or its lowest section, a foraminous or reticulated, circular partition 34 is welded or otherwise secured in the upper portion of the lower end cap 20 above its inlet ports 22 (FIG. 4). Although not essential, the member or its upper section may be confined against upward displacement by a similar foraminous partition 35 secured in the lower portion of the upper end cap 19 below its outlet ports 23. Each coupling has similar foraminous partitions 36 and 37 at its upper and lower ends for supporting the member section thereabove and confining the member section therebelow. Inlet ports 38, similar to the ports 22, are formed in the upper portion of each coupling between the partitions 33 and 36 and outlet ports 39, similar to the ports 23, are provided in the lower portion of the coupling between the partitions 33 and 37. Preferably, the lower and upper ends of the member sections terminate above and below the inlet and outlet ports so that there is no interference with the flow into and out of the passages 24 through said ports.

When the housing and member are formed in sections, as shown in FIG. 2, the inlet ports 38 of the couplings direct flow to the outlet ports 23 of the upper end cap or to the outlet ports 39 of the coupling thereabove. Of course, the outlet ports of the lowermost coupling coact with the inlet ports 22 of the lower end cap. As a result, there is a separate continuous circulation of alkaline aqueous solution for each housing section but the effect is substantially the same. The apparatus is adapted to be moved up and down in the well so as to cover the perforated portion of the casing or the producing formation of the well bore so as to clean the entire area which is clogged with the waxy or gummy deposits. In some wells, the liquid level is relatively low whereby the continuous, one-piece construction is not efficient. The sectional construction is advantageous in these instances because the sections can function independently of one another.

A modified construction is shown in FIG. 7 for use in wells having extremely low liquid levels, such as two to four feet. A housing section 40, having perforations 41 throughout the major portion of its area, is substituted for the lowermost housing section of the apparatus shown in FIG. 2. The housing section 40 is otherwise identical to the other housing sections and has the lower end cap 20 screw-threaded to its lower end with its upper end being screw-threaded to the lowermost coupling 32. A coiled member 42, similar to the member sections 31 and having similar convolutions 43 with passages 44 therebetween, is confined in the perforated housing section between the foraminous partitions 34 and 37 of the end cap and coupling. In order to increase the circulation, the convolutions 43 have radial openings or perforations 45 for substantial registration with the ports 41. By perforating the lowermost housing section as well as the member 42, the gases generated therein by the exothermic reaction aerate the liquids so that additional liquid is drawn into the well bore or casing from the formation and the liquid level is raised above one or more of the other housing sections. As a result, the reaction occurs in the other housing sections and raises the liquid level sufficiently so that the reaction will occur in all of the sections.

Although subject to variation, it has been found that 200 to 300 pounds of an alkali, such as sodium hydroxide, mixed with fresh or salt water at the surface is sufficient to thoroughly clean the average well. The solution should contain not less than 5% by weight of the alkali and is poured or dumped into the well. Usually, fifty to sixty pounds of aluminum or other suitable material is consumed by this quantity of solution and two to three hours is required to clean the average well. Ordinarily the heat generated by the exothermic reaction raises the temperature of the well liquids to between 150° and 200° Fahrenheit. Upon completion of the cleaning treatment, the solution and melted deposits are removed from the well by conventional pumping.

As shown in FIG. 8, the well cleaning apparatus may be more or less permanently mounted in the well bore 27 by being suspended from the lower end of a conventional mud anchor 46 which is carried by the lower end of a -well tubing 47. A gas anchor 48 depends from a well pump 49 suitably' mounted in the well tubing 47. The apparatus is modified and includes a hollow, cylindrical housing 58, similar to the perforated section 40 and having similar perforations 51, and is of extended length like the housing 28. A semi-spherical plug 52 closes the lower end of the housing 50 which has its upper end screw-threaded to the lower end of the mud anchor 46. A solid disk or circular partition 53 closes the upper end of the housing and prevents direct communication with the mud anchor. The metal for reacting with the alkaline aqueous solution is in the form of a plurality of elongated, solid rods or elements 54 which extend longitudinally of the housing and which are mounted therein in a suitable manner (not shown). As shown in FIG. 9, the rods 54 are preferably cylindrical and the spaces therebetween and therearound provide longitudinal passages 55 which are similar to the passages 24. Although the coiled member 21 or tubes 26 could be employed, the solid rods are preferred so that sufficient metal is available for several cleaning treatments without removing the apparatus from the well. Also, the rods could be substituted for the coils or tubes.

Of course, other metals reactive with caustic alkalis, such as magnesium, may be employed in place of the aluminum although aluminum is to be preferred by reason of cost as well as its characteristics of reaction. Also, other caustic alkalis such as potassium hydroxide may be utilized rather than sodium hydroxide, but again, cost makes the latter the preferred material of use. Considerable quantities of both heat and evolved gases and vapors are required to clean a well bore, to dissolve or destroy the barriers existent therein and insure the re2,997,104

S moval of obstructing fluids and materials from the well bore. The present invention, preferably employing aluminum and sodium hydroxide, has been found most effective in obtaining these desired results.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.