US2749091A - Safety back-off tool for removing pump rods in oil wells - Google Patents

Description

June 5 1956 c. WALL SAFETY BACK-OFF TOOL. FOR REMOVING BUMP RODS IN OIL WELLS 3 Sheets-Sheet 1 Filed Aug. 9, 1954 IN VENTOR June 5, 1956 c WALL 2,749 091 sAFETs? BACK-OFF TOOL FOR REMOVING PUMP RODS IN OIL WELLS Filed Aug. 9, 1954 3 Sheets-SheetZ ATTORNH June 5, 1956 c. WALL SAFETY BACK-OFF TOOL FOR REMOVING PUMP RODS IN OIL WELLS 5 Sheets-Sheet 3 Filed Aug. 9, 1954 WIII/AW INVENTOR ATTORNE respect to the view in Fig. 1;

SAFETY BACK-OFF TOOL FOR REMOVING PUMP RODS IN OIL WELLS Curtis Wall, Winnsboro, Tex.

Application August 9, 1954, Serial N 0. 448,567

4 Claims. (Cl. 255-35) My invention relates broadly to oil well installations and more particularly to a construction of tool for facilitating the stripping of oil wells.

One of the objects of my invention is to provide a construction of safety back-off tool for facilitating the stripping of oil wells while eliminating the danger of back-lash and tension on the rods, which generally occurs in stripping operations.

Another object of my invention is to provide a construction of safety back-off tool for stripping oil wells in which the power for operating the tool is secured from the conventional draw-works without the necessity of applying manual effort to the tool.

Still another object of my invention is to provide a construction of safety back-off tool for stripping oil wells which includes an actuating drum around which a cable is wound preparatory to an unwinding operation under power secured from the conventional draw-Works with means on the drum for positively separating the groups of turns of the cable where one group connects with the cathead on the draw-works for applying a rotative force to the drum and the other group of the turns leading to the tail line, the drum being associated with spaced arms engaging a hand wheel associated with the pump rod and operative to establish clamping connection with the pump rod for transmission thereto of a driving force applied to ing by reference to the accompanying drawings, in which:

Fig. 1 is an elevational view of the safety back-ofl? tool of my invention as applied to an oil well for stripping the rods therefrom;

Fig. 2 is an elevational view similar to the view shown in Fig. 1 but taken from a position revolved 90 with Fig. 3 is a horizontal sectional view taken substantially on line 3+3 of Fig. 2 and showing more particularly the manner in which a positive driving force is applied to the Fig. 4 is a transverse sectional view taken substantially on line 44 of Fig. 2 and illustrating particularly the manner in which the pump rod is clamped by a torqueapplying wheel for tensioning the pump rod with respect to the oil well casing in effecting the unscrewing thereof;

Fig. 5 is a fragmentary perspective view of the safety back-off tool of my' invention applied to the pump rod and oil well casing of an oil well installation;

Fig. 6 is an enlarged vertical sectional view of the safety back-off tool of my invention as applied to the upper end of a casing of an oil well, the view being taken substantially on line 66 of Fig. 7;

United States Patent,

2,749,69l Patented June 5, 1956 Fig. 7 is a fragmentary transverse sectional view taken substantially on line 77 of Fig. 6 and showing particularly the reversible dog provided on the tool of my invention; and

Fig. 8 is a horizontal sectional view on line 8-8 of Fig. 1, showing the arrangement of bracket for supporting the line guide with respect to the cable drum in the tool of my invention.

My invention is directed to the construction of an improved tool for use in stripping oil wells with a high degree of safety. In the operation of oil wells there are times when the oil pump in the well cannot be unseated and it is necessary to back the rods off in the hole. This is usually accomplished by use of a rod Wheel or pipe wrenches. This type of operation is very dangerous because the back-lash and tension on the rods causes the wheel to jump or whip when the rods are backed-off and a great number of accidents have resulted to the operating personnel. Such operations have required a relatively long period of shutdown of the oil well and has required the time of four to five men to keep the rod wheel turning until the rods are raised and unscrewed. The safety back-01f tool of my invention eliminates the danger to personnel with respect to the whipping or jumping of the rod wheel because it is unnecessary that any one remain in contact with the tool during the back-01f operation, and the motive power for driving the rod wheel is supplied from the conventional draw-works which performs substantially all of the work mechanically instead of the requirement for manual effort heretofore necessary. Two men can easily accomplish a stripping job with the tool equipment of my invention which heretofore required the services of four to five men; and the two men can complete the stripping job within less time than heretofore required by the services of four to five men.

The tool comprises a drum which is rotatably mounted on the upper end of an oil well casing and revolvable by a cable system operated from the conventional drawworks of the oil well machinery. The drum carries a pair of upright spaced arms which engage the radially extending spokes of the rod wheel which is clamped to a section of the rod for imparting positive movement to the rod system for successively unscrewing the sections of the rod as the rod is raised from the oil well. Special provision is made for eliminating the effects of back-lash by introducing a ratchet device between the rotatable drum and the oil Well casing, whereby the rod wheel operates unidirectionally and does not jump or back-lash and thus become a source of danger or accident to supervising personnel. The drum is provided with a special form of cable guide for separating the wrapped turns of the cable on that part of the drum to which the turning efiort is applied from the cathead as distinguished from that part of the drum where the cable leads to the tail line. The ratchet is reversible so that the unidirectional operation may be either clockwise or counter-clockwise. The tool is readily applied to or removed from the oil well casing when it is necessary to perform a stripping or assembly operation.

Referring to the drawings in more detail, reference character 1 designates the mandrel leading to the oil well casing, the mandrel being externally screw-threaded at its upper extremity, as represented at In, and having a vertically extending key slot 1b therein for receiving a key 4a which serves to secure spur gear 4 in non-rotative relation adjacent the top of the mandrel 1. The spur gear 4 rests against the bronze thrust bushing 5 which spaces spur gear 4 from the bronze bearing sleeve 6 around which the drum 7 revolves. Another bearing sleeve 8 is mounted on mandrel 1 and secured in position on the mandrel 1 by means of bronze thrust collar 9. The bearing sleeves 6 and 8 serve as mounting means for the revolvable drum 7. The revolvable drum 7 includes a top flange 16 and an outwardly projecting peripheral bottom edge portion 25. The exterior surface 711 of drum 7 serves to receive and support turns of cable 26 leading to the cathead of the conventional draw-works and extending to the tail line at 26' as represented in Figs. 2.5. The exterior surface 7a of drum 7 is mounted by means of annular spacing flange 7b on the inner portion of drum 7, whereby drum 7 may revolve about bronze bushing sleeves 6 and 8.

The lubricating fitting is provided at 11 secured in drum 7 and accessible through aperture 70 in the exterior surface 7a of drum 7 for distributing lubricant to the bearing sleeves 6 and 8, insuring rotative movement of drum 7 against minimum friction. The mandrel also supports the guide holder 10 which extends radially from the mandrel 1 to a position beyond the external surface of drum 7a and provides a mounting means for the guide adjusting shaft 17 through the aid of bushing 10a which is welded or otherwise secured to the holder 10 and which provides a mounting means for the set screw 21 which enables shaft 17 to be adjusted upwardly or downwardly and longitudinally of drum 7 and set in a selected position.

The shaft 17 carries the line guide 22 which is supported thereon by means of bolt 20 which passes through a slot 22a in line guide 22, permitting line guide 22 to be adjusted toward and away from the external surface 7a of drum 7 and serve as a means for separating the turns of cable 26 extending to the cathead of the draw-works from the turns of cable 26' leading to the tail line. The line guide 22 may be adjusted longitudinally of the surface 7a of the drum by loosening set screw 21 and changing the position of shaft 17 for sliding the guide line 22 to the desired position on external surface 7a of drum 7. The line guide 22 prevents the line from climbing the drum. The guide holder 10 carries eye-hook 23 which supports hook 24 to which a bacl;up chain may be attached to prevent the tool from unscrewing to the left.

The top plate 16 of the drum 7 serves as a support for the two upright arm attaching plates 18 which are segmentally shaped and attached to the top 16 of drum 7 by suitable screws 18a. Plates 18 support angularly disposed upright arms 19 which extend between the spokes 27 of the rod wheel 28 for exerting a rotative force on rod wheel 28 from the power delivered from the draw-works through cable 26 wrapped on the exterior surface 712 of drum 7. The rod wheel 28 is slotted at the periphery thereof as represented at 28a to enable the rod wheel to be slipped transversely over the sucker rod 29 which passes downwardly through the mandrel 1. The sucker rod 29 is suspended through universal joint 30 from hook 31 attached to hoist cable 32 leading to the winding drum of the draw-works.

The rod wheel 28 is provided with a central vise-like grip for the rod 29 consisting of jaws 33 and 34 where jaw 34 is pivoted at 34a in jaw 33 and extends radially through operating arm 35 in substantial alignment with any one of the spokes 27 of rod wheel 28 and adapted to be secured with respect to any selected spoke by a revolvable slotted band 36. Band 36 may be revolved about operating arm 35 to permit ingress or egress of any one of the spokes 27 as the jaws 33 and 34 are closed into gripping relation with the sides of the sucker rod 29.

The direction in which the rotative force from drum 7 is applied to the rod wheel 28 is controlled by the reversible ratchet shown more clearly in Figs. 6 and 7, The ratchet mechanism is contained within a housing 12 in which ratchet dog 13 is located, carried by angularly reversible shaft and ratchet knob 15, normally ejected by the pressure of coil spring 14. The head of ratchet dog 13 shown at 13a coacts with the teeth of spur gear 4. The head 13a is so shaped and located that drum 7 may revolve in one direction but is locked against rotation in the opposite direction. By selecting the position of ratchet dog 13 the direction of drum 7 is controlled.

The manner of associating the tool of my invention with an oil well is shown more particularly in Figs. 1 and 2 where the casing is represented at 37, terminating in the casing head 38, from which the tubing 39 extends and connects with the pumping T 40 from which flow line 41 extends with hand valve 42 interposed in the line from which the pipe 43 extends. The mandrel 1 fits into the pumping T 40 and terminates in a collar 44 against which the guide holder 10 fits and with respect to which the sleeve bearings 6 and 8 are mounted, enabling the drum 7 to revolve with respect to the mandrel. The tool is readily mounted with respect to and removed from the oil well installation.

The operation of the tool of my invention may be carried out in a number of ways. My tool is particularly effective for disconnecting the sucker rods at a subsurface point. Such sucker rods usually extend from 2500 to 8000 feet below the surface and the unscrewing of the rods at such depth is often a difficult and tedious operation. With the tool of my invention clamped to the upwardly extending sucker rod a rotative force can be applied to the sucker rod which is communicated to the sub-surface point where the disconnect can be effected. Whenthe disconnect is effected the sections of the sucker rod are raised from the casing section-by-section, and as the joint for each section is raised above the end of the mandrel 1, a wrench or clamp is applied to the section of the sucker rod immediately below the upper end of the mandrel for firmly anchoring the lower section of the sucker rod while the rotative force is positively applied to the upper section of the sucker rod through the rod wheel 28. As each section is raised, the lower section is clamped while the upper section is revolved under control of the cable 26-26 wrapped around rotatable drum 7. Generally the weight of the sucker rod below the joint to be unscrewed is sufficient to make it unnecessary to clamp the depending sections of the sucker rod against rotation and it is sutlicient to apply the rotative unscrewing torque to the section of the sucker rod immediately above the joint to be unscrewed.

In the reverse process the lower section of the sucker rod is clamped firmly in mandrel 1 while the adjacent upper section is lowered into position to be screwed into coupling relationship with the lower section of the rod.

While I have described my invention in one of its preferred embodiments, I realize that modifications may be made and I desire that it be understood that no limitations upon my invention are intended other than may be imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. A tool for unscrewing sections of a sectionalized sucker rod comprising a well structure, a rotary drum adapted to be supported in vertical position over the well structure concentrically around the vertically extending scctionalized sucker rod projecting from the well structure, a pair of arms projecting vertically from the upper end of said drum, a rod wheel having radially extending spokes, said rod wheel being clamped to a section of the sucker rod extending vertically above the well structure, said spokes being engageable by said arms whereby a rotary torque applied to said drum is imparted to said means and said spokes to the ole ripcd section of the sucker rod for imparting a turning torque thereto for unscrewing the successive sections of the sucker rod, and a guide holder mounted beneath said drum, said guide holder having a guide adjusting shaft. therein disposed in a position external to said drum and a line guide supported on said guide adjusting shaft and embracing the external surface of said drum whereby a cable wrapped over the external surface of said drum has the turns thereof separated into sections, one section of which extends to a force-applying means and the other section of which extends to a tail line.

2. A tool for unscrewing sections of a sectionalized sucker rod comprising a well structure, a rotary drum areaooi adapted to be supported in vertical position over the well structure concentrically around the vertically extending sectionalized sucker rod projecting from the well structure, a pair of arms projecting vertically from the upper end of said drum, a rod wheel having radially extending spokes, said rod wheel being clamped to a section of the sucker rod extending vertically above the well structure, said spokes being engageable by said arms whereby a rotary torque applied to said drum is imparted to said means and said spokes to the clamped section of the sucker rod for imparting a turning torque thereto for unscrewing the successive sections of the sucker rod, said drum including a horizontally extending top structure and an outwardly projecting bottom flange for confining the turns of an actuating cable thereon, and a line guide embracing a portion of the external surface of the drum for separating said surface into upper and lower portions, the said upper portion receiving the turns of a torqueapplying cable and the lower section of which receives the turns of the cable leading to a tail line.

3. A tool for unscrewing sections of a sectionalized sucker rod comprising a Well structure, a rotary drum adapted to be supported in vertical position over the well structure concentrically around the vertically extending sectionalized sucker rod projecting from the well structure, a pair of arms projecting vertically from the upper end of said drum, a rod wheel having radially extending spokes, said rod wheel being clamped to a section of the sucker rod extending vertically above the well structure, said spokes being engageable by said arms whereby a rotary torque applied to said drum is imparted to said means and said spokes to the clamped section of the sucker rod for imparting a turning torque thereto for unscrewing the successive sections of the sucker rod, and a line guide vertically adjustable longitudinally of said drum for separating the external surface of said drum into an upper and lower portion, said upper portion being adapted to receive the turns of a cable leading to a torqueapplying force and said lower portion being adapted to receive turns of a cable leading to the tail line.

4. A tool for unscrewing sections of a sectionalized sucker rod comprising a well structure, a rotary drum adapted to be supported in vertical position over the well structure concentrically around the vertically extending sectionalized sucker rod projecting from the well structure, a pair of arms projecting vertically from the upper end of said drum, a rod wheel having radially extending spokes, said rod wheel being clamped to a section of the sucker rod extending vertically above the well structure, said spokes being engageable by said arms whereby ajrotary torque applied to said drum is imparted to said means and said spokes to the clamped section of the sucker rod for imparting a turning torque thereto for unscrewing the successive sections of the sucker rod, and wherein said rotary drum has the external surface thereof embraced by a substantially semi-circular member constituting a line guide, and means for adjusting said member longitudinally of the drum for separating said drum into an upper and lower section, said upper section receiving the turns of a force-applying cable and said lower section receiving turns of a cable leading to a tail line.

References Cited in the file of this patent UNITED STATES PATENTS 466,653 Chamberlin Ian. 5, 1892 741,925 Oiler Oct. 20, 1903 1,300,995 Moody Apr. 15, 1919 1,787,185 Baird Dec. 30, 1930 2,217,238 Sisson Oct. 8, 1940

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