US2299978A - Casing protector - Google Patents

Description

Oct. 27, 1942. J L 2,299,978

CASING PROTECTOR Filed June 25, 1938 INVENTOR Jesae fid ATTO EY Patented 27, 1942 CASING PROTECTOR Jesse E. Hall, Bakersfield. Calif., aaaignor to Gustin-Bacon Manufacturing Company, Kansas City, Mo., a corporation of Missouri Application June 25. 1938, Serial No. 215,799

2 Claims.

My invention relatesto a casing protector and more particularly to a novel rubber protector for application to an oil well drilling string.

In a rotary method of drilling oil wells, the drilling string comprises a plurality of sections made up of lengths of drill pipe connected by couplings and tool joints. As the hole progresses in depth, casings are set and the drilling proceeds through a casing which has been cemented in place. When the drilling string is rotated, the tool joints will engage the casing with the result that couplings and joints in the string become worn and the well casing is frequently damaged, even to the extent of'being punctured.

After a casing has been set and cemented, damage to the casing may result in the loss of a well and always entails considerable expense and inconvenience.

In order to protect the casing and the couplings of a string of drill pipe, protector rings have been placed upon the drill pipe in proximity to the tool joints. These protector rings are usually formed of rubber or other buffer material and are of larger external diameter than the tool joints in order to. prevent metal to metal contact between the tool joint and the casing wall from taking place.

There are two general types of protectors in use, namely, the split type which is formed of sections adapted to be secured in place by various securing means and the elastic type. The split ring known to the prior art is in expanded condition, nicks or cuts along the upper or lower edges of the protector ring will frequently "run causing the protector ring to become split.

One object of my invention is to provide a novel protector ring formed with means for holding the protector ring in place during rotary drilling, the construction being such that any relative rotation between the protector ring and the drill pipe will cause a movement of the protector ring to its desired position immediately above the tool joint.

-Another object of my invention is to provide a novel protector ring in which the upper and lower edges are under less tension than the body of the protector ring so that these edges may act as buffers and will not become so readily v nicked, causing runs."

type has proven unsatisfactory in use, due to i tector rings stripped from their proper places and assembled upon a single section of drill pipe, permitting an extended length of drilling string to be without protection.

The elastic type of protector ring which is stretchedover the tool Joint and contracted upon the drill pipe has proven more satisfactory in use. Even with this type, during rotary drilling, protector rings will work away from their desired position adjacent the tool Joint, permitting Figure l is a sectional elevation of a protector ring embodying my invention.

Figure 2 is a plan view of the protector ring shown in Figure 1.

Figure 3 is a sectional view taken on the line 3-3 of Figure 1.

Figure 4 is a sectional view of the protector rilng shown in Figure 1, in position upon a drill P De.

Figure 5 is a sectional view taken on the line 5-5 of Figure 4.

Referring now to the drawing, the protector shown in Figure 1 comprises an annular ring molded of elastic rubber 'having'thick side walls I forming the main body portion of the protector ring which has the general form of an annular cylinder. The interior wall of the protector ring is formed with a left handed rubber thread 2. Since the rotation of the drilling string is right handed, the left handed thread 2 contacting the drill pipe will, upon relative rotation, tend to move downwardly. At a point below the top edge I of the protector ring, I form a step 4. At a point above the lower edge 5. of the protector ring, I form a step 8. The wall of the protector wear to take place, Since the type of protector ring 1 above the step 4 is tapered as is the wall 8 of the protector ring below the step ii. when the protector ring is expanded, slipped over the tool Joint, and permitted to contract around the drill pipe 9, the protector ring will assume the position shown in Figure 4. It will be noted that the rubber in the portion 1 and the rubber in the portion 8 due to the stepped and tapered construction, will not be stretched to as great a degree as the rubber in the main body portion I. If, upon raising or lowering of the drill pipe, the upper or lower edge of the protector ring strikes a protuberance, the danger of cutting the rubber and starting a "run is greatly minimized. As is known to those skilled in the art, rubber under tension, when out, tends to run." It will also be observed that the threads 2 present a non-skid surface, reducing the tendency for the rubber protector ring to slide axially of the drill pipe. The protector rings are normally placed immediately above the lower tool joints of a stand or section of drill pipe. The external diameter of the protector ring is greater than the external diameter of the tool joint sothat it acts as a fender or buiTer, preventing metal tometal contact between the tool joint and the casing wall. If the protector ring becomes displaced, it. does not exercise its protective action. As pointed out above, any relative rotation of the protector ring with respect to the drill pipe will cause it to move downwardly to its desired position. The same means causing this downward motion, namely the threads, also prevent axial movement of the rubber protector ring along the drill pipe.

It will be observed that I have accomplished the objects of my invention. I have proiided a novel protector ring formed with means preventing axial movement of the protector ring along the drill pipe, which means during drilling will tend tomaintain the protector ring in its desired position should relative rotation between the drill pipe and the protector ring occur. The construction is such that the upper and lower edges of the protector ring, when stretched in position upon the drill pipe, will be under lesser tension than the main body portion of the protector ring, thus minimizing the danger of cuts, nicks and ensuing runs."

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and sub-combinations. This is contemplated by and is within the scope of my claims. It is further obvious that various changes may be madein details within the scope of my claims without departing from the spirit of my invention. It is, therefore, to be understood that my invention is not to be limited to the specific details shown and described.

Having thus described my invention, I claim:

1. A well casing protector for application to a drill pipe operating within a well casing comprising an annular rubber ring adapted to be stretched and contracted upon the drill pipe in a desired position, said ring being formed with an internal thread terminating below the upper edge of said ring and above the lower edge of said ring, the internal unthreaded portions of said ring being of greater diameter than said threaded portion, the construction being such that, when said ring is expanded in position upon a drill pipe, said portions of greater internal diameter will be under less tension than the remaining portion of said ring and said threads will resist axial movement of said ring along said drill pipe and, upon relative rotation of said ring to said drill pipe, said ring will tend to be maintained in the desired position upon said drill pipe.

2. A well casing protector for application to a ring and the drill pipe.

JESSE E. HALL.

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