US2688370A - Production shoe - Google Patents

Description

Sept. 7, 1954 D. M. BEST ETAL PRODUCTION SHOE Fi led May 28, 1952 IN VENTORS DAV/D M BEST ROBBINS M. CLAVPOOL ATTORNEY Patented Sept. 7, 1954 FFIGE PRODUCTION SHOE David M. Best, Houston, andRobbins M. Claypool, Bellaire, Tex.

Application May 28, 1952, Serial No. 290,482 I 2 Claims. 1

This invention relates to production shoes and particularly to a production shoe to be secured at the lower end of a production tubing.

In an oil drilling operation a production shoe embodying this invention is of special importance and isused when the well drilling operation reaches a stratum of oil bearing sand. It provides a form of drilling means for penetrating deeper into the oil bearing or pay sand and also a straining means to prevent solid matter from getting into the produtcion tubing whereby it would be carried to the surface of the well and would cause damage to the valves of the pump if a pumping operation is in effect or by fouling a pipe in a distributing system.

In addition to the foregoing it provides a means for cleaning and flushing out a well boring before actual oil production takes place.

It is an object of the invention to provide a production shoe designed for attachment to the lower end of a production tubing.

Another object of the invention is to provide a production shoe having an interiorly disposed strainer plug adapted to direct a stream of fluid to the bottom of a well boring to effect a cleanout operation.

Still another object of the invention is to provide a production shoe having a strainer plug with drillings arranged therein adapted to impart turbulent action to a fluid passing therethrough.

A further object or this invention is to provide acomposite production shoe that is made of two parts.

A still further and more specific object of the invention is to provide a composite production shoe that comprises an outer cylindrical casing and an inner dome-like strainer member, said strainer member having a number of downwardly directed holes drilled therein.

These and other objects will be apparent to those skilled in this particular art as set forth in the specification and defined in the appended claims when read in connection with the drawings in which Fig. 1 shows a vertical side view, partly in section, of a production shoe illustrative of the invention.

Fig. 2 shows a fragmentary sectional view in perspective of a portion of a modification of a strainer member having perforations extending vertically therethrough at the top and almost Upon a vertical axis in the side portions.

Fig. 3 shows a fragmentary section of another modification in perspective of the strainer 'memher showing perforations extending through said strainer member spirally arranged to impart turbulence to a fluid forced therethrough.

In the embodiment of the invention which is chosen for purposes of illustration, in Fig. 1 is shown a production shoe l comprising a casing it having a strainer member it disposed therein. This casing Ill is provided at its lower end with a series of serrated cutting members or teeth 52 which are adapted upon rotation to effect a drilling operation or to loosen material in the bottom of a well bore which is to be removed by means of a flushing operation. Disposed within this casing is an annular horizontalshcub "der it on which the strainer member i i is adapted to be seated. Periphera-lly arranged about said casing are one or more interiorly threaded holes adapted to receive set screws it for engaging a groove l6 located about the periphery of said strainer member for the purpose of connecting it fixedly with respect to said casing. The uppermost portion of said casing is provided with interiorly disposed screw threads for securing it to the lower portion of a production tubing.

The strainer member as here illustrated is substantially dome-shaped and is provided with a series of perforations 2i] and 20A. The perforations 2!], disposed at the upper portion of the strainer, may be straight, or otherwise stated, have their axes extending vertically and have a direction through the side wall of said tubing pointing towards the bottom thereof. The purpose and arrangement of these perforations is to direct all fluid towards the bottom of said strainer for flushing purposes. This arrangement of perforations is illustrated in Fig. 1 of the drawing.

In a modified form the side walls of the strainer may be provided with 'a plurality of spirally arranged perforations 28B extending therethrough and also directed towards the bottom of said casing, this arrangement being made for the purpose of imparting turbulence to any fluid forced therethrough for the purpose of flushing the interior of the well boring. The spirally ar ranged perforations'are illustrated inFig. 3.

This strainer is provided further with a conically flared base i l adapted to be seated on the shoulder [3 of the casing and the base is disposed below the groove i6 and cooperates with the groove and set screw arrangement to fixedly secure the strainer plug and casing to each other. The inner annular shoulder 13 which lies in a horizontal plane as shown prevents downward 3 movement of the strainer with respect to the casing. On the other hand the set screws l5 seated in the recess [6 prevent upward movement. The shoulder [3, if desired, could be placed above rather than below recess IS.

The production shoe, just described in some detail, functions in two ways. Before active production actually takes place, a suitable fluid, such as drilling fluid, may be forced under pressure down the production tubing where it will pass through the perforations and 20A and act as a cleansing agent to flush debris from within the well boring. The teeth on the bottom of the shoe function very eificiently as a cutting means. As

the shoe is rotated, the teeth out into the sand or other debris and cause a certain amount of agitation which helps to remove the undesirable material in the bottom of the bore. When actual oil production is taking place, either through natural pressure within the oil well or through a pumping operation, the perforations 2D and 20A will act as strainers to prevent solids from the interior of the well boring from being carried up the production tubing.

This production shoe is made in two parts because, in the instance where it is being used to a large extent for drilling purposes, the outer casing is the member subjected to the greatest wear and would undoubtedly wear out first. However,

that would be subject to the greatest amount of wear due to the abrasive action of matter being in place, and perforations of the casing have been made adjacent to the producing zone, production tubing is run inside the casing to some predetermined point above the bottom of the cased hole. This production tubing string of pipe has a round bull plug screwed into the bottom 4 section, and the bottom section of this tubing has numerous perforations (approximately i diameter drilled holes) staggered along a length of from 2 to 6 feet or more. The oil flow first enters the cased hole from the producing zone through the perforations in the casing and then enters the production tubing string through the numerous perforations of the bottom section of tubing and thence on to the top of the well, the flow of oil being actuated by either the gas pressure present in the producing formation or by artificial means such as pumping or by gas lift equipment. Another method of completion em-v ploys the setting of a casing screen which is set adjacent to the producing formation thus eliminating the necessity of perforating the casing as referred to above, but in either case the use of the production tubing is the same.

When the production shoe of the present invention is to be used on the bottom of the tubing string, the pull plug and the perforations in the tubing section described above are eliminated. Oil flows up through the bottom of the production shoe through the strainer plug to the top of the ground (or is pumped).

Employing the conventional bull plug and perforated tubing, when it becomes necessary to wash the well to the bottom to remove sand or other debris which has either been brought into the well with the oil production or has not been cleaned out thoroughly after original drilling operations, the entire tubing string has to be pulled from the well. After this the bull plug and perforated tubing section is removed and a bit of some type installed, and then the tubing is run back into the hole and the debris is drilled, agitated, fluid circulated and removed. Next, after this cleaning process has been completed, the entire tubing string is once again withdrawn from the well; the bit is removed; and the perforated tubing section and bull plug once again installed and the tubing run back into the well again. Oil production is then resumed.

However, with the production shoe of the present invention installed on the bottom section of the tubing production string, when it becomes necessary to clean and remove sand and other debris from the Well bottom, the teeth on the bottom of the shoe serve the purpose of a bit, and actual drilling, milling, and agitation against the debris can begin immediately. Since there is no perforated tubing section in the string, all of the fluid circulation is directed to the bottom of the tubing string and the washing effect of the same is entirely directed out of the bottom. When all debris has been cut or milled up by the teeth on the shoe and has been circulated out of the hole, then the well may be immediately put back on production. It is to be noted that during these operations it was not necessary to remove the tubing string from the Well, but in the case of the conventional bull plug and perforated tubing section two round trips with the production tubing string in and out of the well were required.

Pulling the tubing string in and out of the well is a long and expensive operation requiring much equipment and labor. The well equipped with the present production shoe can be cleaned out and put back on production in a matter of a few hours, while it is quite possible that one or more days would be consumed when the conventional perforated tubing section and pull plug is employed. Also, wear and tear on tubing is eliminated when the present production shoe is employed.

It is important to note that in the present construction the force or velocity of the clean-out fluid is directed downwardly and concentrated at the location where it is most needed during drilling or clean-out operations. The Work to be performed in clean-out operations is immediately and directly below the bottom of the tubing, and inasmuch as fluid turbulence accomplishes much or more than mechanical agitation during cleanout operations, it is essential that the full force and volume of fluid be directed in its entirety to the very bottom of the tubing. This is believed to be the most important function of the herein described production shoe. In addition to the force of the fluid and turbulence created thereby the milling teeth will effectively remove any debris such as sand or heavy mud and shale from the bottom of the well bore. This could not be accomplished by conventional practice which requires a perforated section that is ordinarily installed in the tubing string at some distance from the bottom of the string.

If desired, a single strainer plug may have perforations extending along vertical axes, angularly and spirally.

It is to be understood that the perforations 20, 20A, and 203 may be drilled or otherwise formed in the strainer members. It is also possible to use slots as distinguished from holes of cylindrical cross-section and here again the slots may extend on a straight axis or may be curved as described in connection with the perforations.

The specific embodiment of the invention has been described in some details, but it is to be understood that changes and additions, substitutions and omissions may be made therein within the spirit of the invention defined by the appended claims.

We claim:

1. A production shoe designed for use in conjunction with production tubing, said shoe comprising an outer casing having a, strainer plug disposed within the interior thereof, a cutting means provided at the lower edge of said casing, a shoulder extending around the interior of said casing seating said strainer plug, a groove extending around the periphery of said strainer plug, securing means disposed around the periphery of said casing and extending therethrough and into said groove to secure said strainer plug in fixed relation with said outer casing.

2. A production shoe designed for use in conjunction with production tubing, said shoe comprising an outer casing having a strainer plug disposed within the interior thereof, cutting means provided at the lower edge of said casing, a shoulder extending around the interior of said casing seating said strainer plug, a plurality of perforations extending vertically through said strainer member and adapted to direct a stream of fiuid to the bottom thereof, and a second group of perforations extending through said plug, said second group of perforations being spirally arranged to impart turbulence to a fluid passing therethrough.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 560,399 Durbrow May 19, 1896 940,733 Sands Nov. 23, 1909 982,491 Heggem Jan. 24, 1911 1,804,819 Spencer et a1. May 12, 1931 1,869,352 Schneider et a1. July 26, 1932 2,192,945 Toney Mar. 12, 1940 2,491,796 Baume Dec. 20, 1949

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