Casing expander
United States Patent 2499630

The invention relates to a casing reaming tool or expander to be used in pipe in situ in a well bore. In the rotary method of drilling wells, the drill bit is rotated by means of a drill stem and drilling mud circulated downwardly through the bit and upwardly through the well bore. Such mud...

Clark, Paul B.
Application Number:
Publication Date:
Filing Date:
Clark, Paul B.
Primary Class:
Other Classes:
29/523, 175/335, 175/346
International Classes:
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US Patent References:
2217592Well reamer1940-10-08
2029770Roller cutter reamer1936-02-04
1970061Swage for oil wells1934-08-14
1738860Hydraulic rotary underreamer1929-12-10
1594114Collapsed-casing roller1926-07-27
1569729Tool for straightening well casings1926-01-12
1545039Well-casing straightening tool1925-07-07

Foreign References:

The invention relates to a casing reaming tool or expander to be used in pipe in situ in a well bore.

In the rotary method of drilling wells, the drill bit is rotated by means of a drill stem and drilling mud circulated downwardly through the bit and upwardly through the well bore. Such mud is sufficiently heavy to prevent caving of the earth formation until the well is completed, whereupon a string of pipe is lowered into the well bore and firmly anchored into position. It is well known that the pressure of the earth formations, which are in pounds per square inch, can be expected to approximate 0.45 of the depth of the well in feet. Thus in a ten thousand foot well, a pressure of 4500 pounds per square inch can be expected. During the circulation of the drilling mud, it is not uncommon to loosen the portions of formation around the well bore and after the casing has been set in position, quite often the caving of the earth formation against the casing causes it to collapse or to be indented due to the external pressure. This is particularly true where the heavy drilling mud has been washed out of the casing and replaced with a liquid of lesser specific gravity. Many wells have been junked and abandoned due to the collapse of the casing, where such collapse restricted the passage through the casing to such an extent that it was either impossible to complete the well or to continue production.

The present invention directs itself to a means and method of expanding the casing to its original position after it has once been collapsed and while the casing stem remains in place in the well.

It is one of the objects of the invention to provide a tool which may be lowered into a well bore and by rotation and the application of a lowering force thereto operated to enlarge an area in a pipe.

Another object of the invention is to provide a method of reaming and expanding a collapsed casing in a well bore. A still further object of the invention is to provide a tool for expanded collapsed casing in the well bore where the tool has tapered rolling surface thereon which can be forced against the reduced area of the casing. Other and further objects of the invention will be readily apparent when the following description is considered in connection with the accompanying drawings, wherein: Fig. 1 Is a vertical sectional view taken on the line I-1 of Fig. 2, and illustrating the tool embodying the invention.

Fig. 2 is a section taken on the line 2-2 of Fig. 1.

Fig. 3 is a vertical sectional view of a portion of collapsed casing in the well with the tool in position ready to execute the expansion or reaming of the casing.

In Fig. 3 the well bore 2 has been drilled by the rotary method and the string of pipe 3 generally known as casing has been lowered into position.

The earth formation 4 has caved in or in some manner exerted an excessive pressure upon the outer periphery 5 of the casing 3. This pressure has curved the casing inwardly at 6 and 7 to create a reduced area 8 where the casing has been collapsed. In some instances, the collapsing action substantially exceeds that shown in Fig. 3 which is merely illustrative.

In order to restore the casing to its original contour and to eliminate the restriction in the size of the passage through the pipe, a tool 10 has been devised which includes the body II having a threaded box 12 at its upper end to receive a string of drill pipe 13 by which the tool is operated.

The body II of the tool has a passage 14 therethrough for the circulation of liquid if such circulation and washing action is desired.

As seen in Fig. 2 the body I has been formed with a plurality of recesses or pockets 16 which are segments of a cylinder and which are arranged in the periphery of the body. As seen in Fig. 1 each of these pockets 16 is arranged to receive a roller or expander 17. Each of these expanders is a frusto-conical member which may have a knurled surface 18 and which is arranged for rotation upon a spindle 19. The spindle 19 is arranged for insertion in a recess 20 formed in the outstanding shoulder portion 21 on the body, the body having been cut away at 22 to permit the drilling of the bore 20. This bore extends through the shoulder 21 and through the bottom surface 23 of the pockets 16 so as to form a bore 24 which receives the lower end of the shaft or spindle 19. A shoulder 25 formed by reducing the size of the body I and the threading thereof at 26 provides an area to receive the cap or nipple 27 which is threaded thereon and tapered at 28.

In order to hold the spindle 19 against rotation, the bore 24 has been extended at 30 into the upper portion of the threaded area 26 and through the shoulder 25. An eccentric extension $2 on the lower end of the spindle 19 fits into the portion 31 and will be locked against rotation by the nipple or cap 27. It seems ob- . vious that the reamer or roller 17 along with the thrust washer 35 can be slipped Into the pocket IS and the spindle 18 moved into the bore and through the roller to the position shown In Fig. 1. A retainer screw 38 can then be placed in position to insure that the spindle will not work itself out of position.

Fig. 2 shows three such assemblies carried by the body and particular attention is directed to the fact that the reaming knurled surface 18 Is tapered and additionally inclined due to the inclination of the spindle 19 so that the three rollers when taken together form a tapered lower surface which can be wedged into the reduced area 3 as seen in Fig. 3.

The pipe 13 will probably be a drill pipe which has a substantial weight and which is capable of applying a substantial rotative torque to the tool.

In operation the tool will be affixed to the lower end of the pipe 13 and lowered into the well bore until it reaches the collapsed portion. The pipe II will then be rotated and at least a portion of the weight of the drill pipe 13 applied thereto so as to gradually expand the collapsed area 8 forcing the earth formation 4 back with the casing so as to restore the casing to its original cylindrical configuration. Broadly the invention relates to a means and method of expanding collapsed casing in place in a well bore.

What is claimed is: A casing expander including a cylindrical body, a passage therethrough, a threaded box area on the top to connect a string of pipe thereto, a threaded pin on the lower end of said body, a pocket in the periphery of said body, a reduced area on the body above said pocket to provide a shoulder, a bore extending into the pocket from said shoulder and inclined inwardly and downwardly, a continuation of said bore in the bottom of said pocket and extending into an\ outer recess in the top of said pin, a shaft in said bores, a frusto-conical reaming roller on said shaft with the larger portion thereof at the top so that said roller presents an inclined surface to roll on a reduced area of a casing in a well bore so that as said body Is rotated and pressure applied thereto, the reduced area of the casing will be enlarged, said shaft having an eccentric portion on the lower end thereof lying within said recess, and a cap on said pin member covering said recess to retain such eccentric portion and to hold the shaft against rotation.


REFERENCES CITED The following references are of record in the file of this patent: UNITED STATES PATENTS Number 743,146 1,545,039 1,565,788 1,569,729 1,594,114 1,738,860 1,970,061 2,029,770 2,122,863 2,217,592 Name Date Carty --------------- Nov. 3, 1903 Deavers ----------- July 7, 1925 Carlson ---------- Dec. 15, 1925 Duda ----------- Jan. 12, 1926 Ptout ------------ July 27, 1926 Wigle ----------- Dec. 10, 1929 Stanfleld---------. Aug. 14, 1934 Grant ------------ Feb. 4, 1936 Howard ----------- July 5, 1938 Krick ------------ Oct. 8, 1940 FOREIGN PATENTS Number Country Date 483,652 France ------------ May 2, 1917