US2320646A - Rod catcher - Google Patents

Description

June l, 1943- c. M. OLEARY 2,320,646

Y Y Ron CATGHER Filed Dec. 13, 1940 z'rsheets-sneet 1 www /0 K Ivg/ i A TTORNE Y June 1, 1,943. c, M.v oLEARY 2,320,646

Roig cATcHER Filed Dec. 1s, 1940 2 sheets-sheet 2 INV'ENTOR ZQS. @Zea/Iy,

TTORNE Y Patented June 1, 1943 UNITED STATES frisur oFFlce '7 Claims.

The present invention relates generally to rod catchers as used in the pump rod strings of deep Wells, such as oil wells, for gripping the internal surface of well tubing in case of rod breakage in order to prevent destructive fall of the rod portion below the break.

It is a well known fact that in deep wells the great length cf the necessary pump rod means great weight, which puts in the rod string a weight or normal stretch that is considerably augmented in use during each upward movement of the rod string, by the load raised thereby, this being a working stretch which is instantly relieved when, for any reason, the load is released.

The stretch of the rod string in the above manner and the variations thereof between up and down strokes, causes more or less rapid deterioration of the metallic structure thereof, so that rod breakage is in many instances of frequent occurrence, and many times requires vexatious delays and costly fishing operations to recover dropped rods. In other instances the dropped rods become buckled and cork-screwed to such an extent as to require complete replacing thereof rather than the mere substitution of one or two rod lengths.

All of the above facts and disadvantages are well known in the oil well industry and devices have been proposed, some controlled from thesurface, for catching the dropping rod lengths. Up to the present time they have not been used to anything approaching a general degree due to the fact that they have been much too complicated and too costly, and have presented operating disadvantages in various degrees. Many are susceptible to accidental operation preventing further operation of the pump rods until they have been pulled from the well and the rod catcher or catchers reset.

It is, in the light of the above, that the primary object of the present invention is to provide a rod catcher which will be simple in construction, economical to operate, and strong, durable and uniformly effective in use.

It is another object to provide a rod catcher which will be fully automatic, and in connection with which the parts thereof may be returned to n normal position, in any instance of accidental operation thereof, by the mere taking up of the load of the rods.

Since it is usual for the rods to break on the upstroke thereof, at a time when the rods are subjected to operating stretch over and above the normal weight stretch, it is another object to provide a rod catcher which, in case of breakage, will take advantage of the instantaneous retraction of stretch in the rod string, and shift to operative engagement with the Well tubing.

during this period of retraction.

v With the above in mind, one practical exemplication of the invention, land a modification thereof, will be described in detail in reference to the accompanying drawings,l which form a part of `this specification, and in which,

Figure 1 is a View in vertical, longitudinal section, showing the upper portion of the rod catcher of lthis invention in its normal position during rod operation within well tubing.

Figure 2 is a similar View showing the lower portion thereof, being a continuation of Figure 1.

Figures 3 and 4 are detail cross-sectional viewsl taken respectively on line 3--3 of Figure 1, and lined- 4 ofv Figure 2.

Figure 5 is a view similar to Figures 1 and 2, illustrating a modified form of the invention, and

Figures 6 and 7 are detail cross-sectional viewsv Referring now to Figures l to 4inclusive, there.

is shown a rod catcher coupled between rod lengths or sections I0 and Il, within well tubing',

I2, and consisting generally of upper and lower members I3 and I4. Of these members, therupper member lI3 is shown withan upper box I5 receiving the depending pin I5 of the rod length I0 above the catcher, and the lower member I4 is shown with a lower -depending pin I1 entering the upper box I8 of the rod length II below the catcher.

The above mentioned pins and boxes are to be understood as provided with the usual rod joint threads.

The upper member I3 has near its upper end a slip expander I9, preferably with downwardly tapering Vslip ways 20,'in which slips 2l are seated and guided. Below its expander I9, the upper member has a depending stem 22 whose lower portion telescopes within the upper barrel 23 of the lower member I4, through a collar 24 rigid with the upper end of the said barrel. The collar 24 is shown threaded within the upper end' of the barrel 23 in a manner to provide a downn spring is disposed in a coil around the stem and within the barrel, exerting` a pressure which tends Y to move the upper and lower members I3 and lengthwise relative to, and toward, each other.

By reason of the stem head and the barrel collar 24, relative lengthwise movements of the two members I3 and I4 are limited, although within such limits these two members are always freely movable in relation to each other, except in so far as the action of spring 26, and the rod weight and load, are concerned. For this reason the lower end of barrel 23 is preferably provided with wall openings 2'I to avoid any danger of entrapping fluid pressure in the barrel below stem head 25.

The slips 2I are mounted on the upper ends of Y upright, flexible, elastic rods or arms 28 which serve to yieldingly maintain said slips snugly against the bases of the slip ways 20. The rods or arms 23 upstand from a sleeve 29 loosely around the stem 22, which sleeve seats on the collar 24 and is preferably under control of a light coil spring 3i! around the stem above thesleeve 29, and between the same and the lower end of the expander I9.

Since the stem 22 of the upper member I3 slidably depends through the collar 24 of the lower member I4, these parts are preferably provided with companion grooves lengthwise thereof, for the reception of a key pin 3| which thus rotatively couples the two members I3 and I4 without interfering with their free relative lengthwise movements.

Figures 1 and 2 show the above described parts in the position they assume in use with the rodV against collar 24 under a pressure which avoids,

any danger of accidental or premature upward movement of the slips 2 I'.

^ Should the rod string break at any point above the rod catcher, the initial result is that the string, below the break, contracts as tension therein is relieved with the release of theV normal load. Coincident with this contraction, the spring 26expands, pulling the upper member I3 downwardly with respect tothe lower member I4. It will thus be obvious that, in lowering with the upper member I3, the expander I9 shifts the slips 2l radially, outwardly into contact with the inner surface of the tubing I2 and into gripping relation therewith which, by reason of the downwardly inclined teeth of i the slips, instantly tightens as the weight of the released lower or broken section of the rod string is assumed by the slips. Thus the rod string below the break is prevented from a possibly disastrous fall since, as above stated, the rods generally break during upward movement of the rod string.

By reason of the foregoing, the lower section of the rod string, in case of break thereof, will be held against fall and in position within the tubing making subsequent engagement thereof, byiishthus caught, is assumed from the surface andthe rods lifted, the slips 2I promptly retract as the upper member I3 is elevated. This is true at `any time the parts may, through accidental release of control of the rod string, move to set the slips, and it is therefore obvious that it is never necessary to pull the rod string after accidental setting of the slips of the rod catcher of this invention."

, '65 ing, an easy matter, l and permitting ofV ready withdrawal. As soon as the weight of the rods as Whenever the normal load of the rod string is properly assumed at the surface the parts of the present rod catcher will automatically return to their normal, inactive position as shown in Figures 1 and 2, so that normal reciprocation of the rod string may be resumed without pulling the same for the resetting of any parts, unless, of course, it is necessary to pull the string for the repair of the rods.

It is possible to do away with the controlling springs of the above described construction, by utilizing a series of rod catchers at spaced points in the length of the rod string, and such catchers may be constructed as shown in the modification, Figures 5, 6 and '7, wherein the arrangement of the parts previously described is preferably reversed to some extent.

In the modified construction the upper member I3a has a barrel 32 in which a head 33, at the upper end of the stem 34 of the lower member |48, is movable. The stem 34 has a lower threaded end which connects with a sub 35 and also with the sleeve 36 from which the slip supporting rods or arms 31 upstand. The slips 3B work in slip ways in an expander 39 which, in this instance, surrounds the stem 34 in spaced relation and is threaded at its upper end into the lower end of the barrel 32, and has channels 49 and openings 4I to prevent the entrapping of iluid pressure in the barrel.

The key pin 42, in this instance, is disposed in cooperating grooves of the stem 34 and the upperA end 43 of expander 39 toprevent relative rotation of the upper member I3a and lower member' |44, thelatter of which telescopes within the former and thus reverses their arrangement as in Figures 1 to 4 inclusive.

With the modified rod catcher as shown and described above, the weight of the rods alone causes a series thereof in the rod string to act successively from the lowermost tothe uppermost throughout a broken rod section, and each has the advantage of return of its parts automatically to normal inactive position when the weight of -the rod string is assumed from the surface, without requiring pulling of the rod string for resetting of the catchers.

Having thus fully described the invention, what is claimed is:

l. A rod catcher comprising upper and lower relatively lengthwise movable members, the upper member including a downwardly tapering expander and a stem depending from said expander and having a lower head, the lower member havring a barrel within which the headed lower end of the stem projects, a collar at the upper end of the barrel opposing said head, an operating spring around the stem between said head and said coll lar, slips seated on the expander,A and a sleeve movable with the lower member and having upstanding spring arms on the upper ends of which the'said slips are mounted.

2. A rod catcher comprisingv upper and `vlower relatively lengthwise movable members, the upper member .including a downwardly tapering expander and a stem depending from said expander and having a lower head, the lower member including a barrel within which thelower portionA of the stem projects, having a collar at its upper tion of said members, slips seated on'the expander, and a support movable with the lower member having upstanding spring arms on the upper ends of which said slips are mounted.

3. A rod catcher having upper and lower coupling members respectively connected to upper and lower sections of a rod string operating within the bore of a well pipe, pipe gripping means associated with said members and normally held in retracted, inactive position, means for operating the pipe gripping means into holding engagement with the well pipe when the tension in the rod string falls below a predetermined value, and means for subsequently returning the pipe gripping means from holding engagement with the well pipe to normal retracted position when the tension in the rod string exceeds said predetermined value.

4. A rod catcher comprising upper and lower connecting bodies, an expander having an upper apertured sleeve depending from the upper body and provided with wall openings, a solid, axial stem connecting said upper and lower bodies for limited relative lengthwise movement between said bodies, and an expansible slip assembly slidably mounted upon said stem, said expander being spaced annularly from the stem and forming with said sleeve openings a iiuid by-pass between the stem and the expander communicating above and below the expander.

5. A rod catcher including upper and lower members having threaded means for respective connection to sections of a rod string above and below the catcher within the bore of a well pipe, said members having limited movement axially relative to each other and normally operating as a part of the rod string in its up and down movements, pipe gripping means associated with said members and normally held in retracted position when tension in the rod string exceeds a predetermined value, means for operating the pipe gripping means into holding engagement with the well pipe when the tension in the rod string falls below said predetermined value, and means for subsequently releasing the pipe gripping means from holding engagement with the well pipe and restoring the same to normal inactive position when the tension in the rod string again exceeds said predetermined value.

6. A rod catcher comprising upper and lower connecting bodies, a stem connecting said bodies for limited relative lengthwise movement between the bodies, a slip assembly movable with the lower body, and an expander depending from the upper body and upon which the slips are respectively expansible and contractible as the bodies move toward and away from one another, and means forming a fluid by-pass between the expander and the stem, communicating above and below the expander.

7. A rod catcher including upper and lower movably connected members having threaded means at their upper and lower ends, respectively for connection to sections of a rod string above and below the catcher within the bore of a well pipe, said members including means limiting axial movement thereof relative to each other, and normally operating as a part of the rod string in its up and down movements, one of said members consisting of a solid, elongated stem forming in use substantially an axially elongatable and contraotable part of the rod, pipe gripping means associated with said members and normally held thereby in retracted position when tension in the rod string exceeds a predetermined value, means for operating the pipe gripping means into holding engagement with the well pipe when the tension in the rod string falls below said predetermined value, and means for subsequently releasing the pipe gripping means from holding engagement with the well pipe and restoring the same to normal inactive or retracted position when the tension in the rod string again exceeds said predetermined value.

CHARLES M. OLEARY.

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