GB1562749A

GB1562749A - Spring adjustment system for drill string tool

Info

Publication number: GB1562749A
Application number: GB2462177A
Authority: GB
Original assignee: Dresser Industries Inc
Current assignee: Dresser Industries Inc
Priority date: 1976-08-02
Filing date: 1977-06-13
Publication date: 1980-03-12
Also published as: SU634687A3; IT1078940B; PL110471B1; ES460977A1; BR7705027A; PL199747A1; ES470826A1; FR2360741A1; DE2735174A1; SE7706690L; CA1062240A

Description

(54) SPRING ADJUSTMENT SYSTEM FOR DRILL STRING TOOL (71) We, DRESSER INDUSTRIES INC, a corporation organised and existing under the laws of the State of Delaware, United States of America, of the Dresser Building, Elm & Akard Streets, Dallas, Texas, United States of America do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement:- This invention relates to well tools suitable for use in drilling operations in connection with wells and mines. Torque transmitting well tools suitable for use in the drilling of oil and gas wells are known. Such tools include an elongate outer member having a longitudinal bore therethrough and an elongate inner member telescopically mounted in this bore. The outermost end of each member is provided with conventional connecting means so that the tool can be disposed in a string of drill rod or pipe with one member connected to the upper portion of the string above the tool and the other member connected to the lower portion of the string beneath the tool. Limiting means are provided to limit the axial movement of one member with respect to the other in either direction; the distance it is permitted to move is known as the "stroke" of the tool. The tool transmits torque and the two members are splined so that relative axial movement between them is permitted while relative rotation is prevented.

One such telescoping tool is commonly referred to as a "bumper sub" or "impact tool" because the limiting means is comprised of two sets of opposed shoulders one of which becomes engaged or "bumps" when the moving member reaches either end of its stroke. Bumper subs are often used to provide an upward and/or downward hammering action of relatively small magnitude or to allow a drill string to accommodate the rise and fall of a ship in off-shore drilling.

Another telescoping tool, often referred to as a shock or percussion tool is provided with resilient means which resist relative axial movement of the two members and provide a cushioning effect against shock.

During the drilling of an oil well by the rotary method, it has become common practice to provide a section of drill collars above the drill bit. The section of drill collars provides the desired weight on the bit during drilling. The drill pipe above the section of the drill collars is generally in tension. This allows a relatively constant weight to be applied to the bit during drilling. When the hole is being started from the surface, the section of drill collars cannot be used because the length of the drill string is insufficient. A much smaller weight is therefore applied to the bit during drilling near the surface.

The action of the bit during drilling transmits shock forces to the drill string. The shock forces can be quite damaging to elements of the drill string and to drilling equipment at the surface. Drill string shock absorbers are commonly placed in the drill string to absorb the shock forces. A drill string shock absorber generally includes telescopically related parts that are separated by a spring means. The prior art shock absorbers have worked effectively with the full drilling weight on the bit.

However, the prior art shock absorbers have not been effective during drilling near the surface because the weight on the bit is only a fraction of the weight on the bit at deeper depths. The spring means in the prior art shock absorbers has been too heavy to be effective during drilling near the surface.

In U.S. Patent 3,383,126 a drill string shock absorber is shown. The drill string shock absorber is adapted to be inserted into a rotary drill string to absorb vibrational and shock forces therein. The shock absorber includes telescopically related parts which are separated and isolated one from the other by a mass of compressible wire material.

According to one aspect of the present invention there is provided a torque transmitting well tool, comprising: first and second telescopically arranged members; spline means for transmitting torque between said first and second members; spring means between said first and second members, and adjustment means between said first and second members for adjusting said spring means.

In one embodiment of the invention a travelling nut system is located in the end of a spring sub of the torque transmitting well tool. The travelling nut has an integral gear wheel which is exposed to a threaded access opening in the spring sub. The positioning of the travelling nut is accomplished by removing a sealed, threaded plug from the access opening, installing a threaded bushing to protect the access hole threads during adjustment and engaging the gear tooth portion of the unt with a flat or roundend pry bar which allows for sufficient leverage to rotate the nut for proper positioning. A pre-calculated tabulation will reveal the number of gear teeth to engage in order to advance or retract the nut to the proper position. After achieving the proper adjustment, the threaded bushing is removed and the sealed, threaded plug is installed to close the access opening and engage the gear teeth in order to lock the travelling nut in place.

The invention will be better understood from the following description of a preferred embodiment thereof, given by way of example only, reference being had to the accompanying drawings, wherein: Figure 1 is a longitudinal view, partly in section and partly in elevation, of a preferred embodiment of a drill string tool constructed in accordance with the present invention, and Figure 2 is an enlarged view of a portion of the drill string tool shown in Figure 1.

Referring now the the drawings and in particular Figure 1, a drill string tool is shown therein tha generally designated by the reference number 10. The tool 10 is adapted to be positioned between a drill bit (not shown) and the section of the drill string that connects the drill bit to the drilling equipment at the surface. The tool 10 maintains a spring force coupled into the drill string assembly in such a manner that shock loads resulting from the action of the bit are absorbed and prevented from being transmitted up the drill string. The tool 10 minimizes fatigue on the drill bit, the drill string, and the surface equipment.

The tool 10 includes an upper packer sub 11. The upper packer sub 11 is adapted to be connected to the portion of the drill string extending from the surface equipment. The threaded connection 24 allows the tool 10 to be easily connected to and disconnected from the drill pipe. The upper packer sub 11 is threaded into a spring sub 31 and the spring sub 31 is threaded into a spline sub 14. The spline sub 14 is threaded into a lower packer sub 20. A drive shaft mandrel 22 fits within the lower packer sub 20, the spline sub 14, the spring sub 31, and the upper packer sub 11. The drive shaft mandrel 22 includes a threaded connection 25 for connecting the drive shaft mandrel 22 to the bit. The drive shaft mandrel 22 has limited movement within the lower packer sub 20, the spline sub 14, the spring sub 31, and the upper packer sub 11. ~ Drilling fluid is transmitted through the tool 10 during drilling. Drilling fluid enters the passage 26 in the upper packer sub 11 from the section of drill string above the tool 10. The drilling fluid continues through a central passage in the wash pipe 12, through a central passage in the drive shaft mandrel 22, and is transmitted to the section of the drill string below the tool 10.

Upper packer seals 13 provide a dynamic fluid seal between the upper packer sub 11 and the wash pipe 12 and drive shaft mandrel 22. Lower packer seals 21 provide a dynamic fluid seal between the lower packer sub 20 and the drive shaft mandrel 22. The enclosed area between the upper packer seals 13 and the lower packer seals 21 is filled with a lubricating oil. A ball spline 15 on the drive shaft mandrel 22 is located between the upper packer seals 13 and the lower packer seals 21. The ball spline 15 includes a series of carrier balls 16 that reduce friction and facilitate relative longitudinal movement of the drive shaft mendrel 22 and the housing consisting of the upper packer sub 11, the spring sub 31, the spline sub 14, and the lower packer sub 20.

A ball spline 17 is positioned between the drive shaft mandrel 22 and the spline sub 14 to transmit torque from the housing consisting of the upper packer sub 11, the spring sub 31, the spline sub 14, and the lower packer sub 20. The ball spline 17 includes a series of carrier balls 18 that transmit torque between spline grooves 27 connected to the drive shaft mandrel 22 and spline grooves 19 connected to the spline sub 14.

A spring unit 30 is positioned between the upper packer sub 11 and the lower end of the spring sub 31. The spring unit 30 absorbs the shock loads resulting from the action of the bit. The spring unit 30 consists of disc or "Belleville" springs. The shock forces resulting from action of the bit may also be affected by a swabbing or damping action brought about by restricting the escape of the lubricant trapped between the springs 30. The geometry of the springs allows them to reduce in I. D. and expand in O. D. as loads are applied. Lubricant is trapped to some degree as the springs are collapsed.

lhe degree of damping action can also be influenced by the oil viscosity, clearance grooves, and spring geometry.

The previous methods of adjusting the spring settings, i.e. pre-load for shock absorbers and hammer-anvil gas settings for impact tools, involved tool disassembly and spring adjustment by the use of various width spacers. An embodiment of the present invention provides a more convenient and accurate method of adjusting the position and/or pre-load of a spring system used in shock absorbers or impact-type drilling tools. The need to adjust the impact tool operating load varies with the weight run on the drill bit. This load may require numerous tool settings as different formations are encountered. The ability toadjust the tool externally eliminates the need of tool disassembly.

Referring now to Figures 1 and 2, the system for adjusting the spring position and/or spring pre-load will be described.

The too 10 includes a traveling nut 29 located in the spring sub 31. The traveling nut 29 has an integral gear wheel 28 which is exposed to a threaded section 37 of the spring sub 31. The traveling nut 29 and integral gear wheel 28 engage a universal spacer 33 which in turn engages the spring system 30. It will be appreciated that rotation of the gear wheel 28 will cause axial travel of the universal spacer 33 and produce the desired positioning and/or preload of the spring system 30.

Rotation of the travelling nut 29 is accomplished by removing a sealed, threaded plug 32 from the access opening 34, installing a threaded bushing 35 to protect the access hole threads during adustment and engaging gear wheel 28 with a flat or round-end pry bar 36 which allows for sufficient leverage to rotate the nut 29 for proper positioning. The travelling nut 29 may be provided with a gear type head to facilitate rotation with the pry bar 36. A precalculated tabulation will reveal the amount of rotation of traveling nut 29 and gear wheel 28 in order to advance or retract the universal spacer 33 to the proper position.

After achieving the proper adjustment, the threaded busing 35 is removed and the sealed, threaded plug 32 is installed to close the acess opening 34 and engage the nut 28 in order to lock it in place.

WHAT WE CLAIM IS: 1. A torque transmitting well tool, comprising: first and second telescopically arranged members; spline means for transmitting torque between said first and second members; spring means between said first and second members, and adjustment means between said first and second members for adjusting said spring means.

2. A well tool according to claim 1 wherein said adjustment means is operable to change the position and/or the pre-load of said spring means.

3. A well tool according to claim 2 wherein said adjustment means comprises travelling threaded means between said first and second members for axial travel relative to the direction of telescopic arrangement.

4. A well tool according to any preceding claim wherein said spring means comprises multiplicity of disc spring elements.

5. A well tool according to any preceding claim wherein said adjustment means is adjustable by means of a manually operable key means.

6. A well tool according to claim 5 wherein the key means comprises a pry bar insertable through an aperture in one of said members to engage said adjustment means.

7. A torque transmitting well tool, comprising: an outer member; and inner member, said outer member and said inner member being telescopically arranged; an upper seal between said outer member and said inner member; a lower seal between said outer member and said inner member; a fluid between said upper seal and said lower seal; spline means for transmitting torque between said outer member and said inner member; spring means connected with said outer member and connected with said inner member with said. spring means including a multiplicity of disc springs; a travelling spring adjustnient member connected to said spring means and located between said outer member and said inner member for axial travel in said well tool to adjust the position of said disc spring units, and means for moving said travelling spring adustment member axially in said well tool.

8. A method of adjusting the position of the disc spring units of a torque transmitting well tool having an outer member; an inner member, said outer member and said inner member being telescopically arranged; an upper seal between said outer member and said inner member; a lower seal between said outer member and said inner member; a fluid between said upper seal and said lower seal; spline meahs between said outer member and said inner member for transmitting torque; and spring means connected with said outer member and connected with said inner member with said spring means including a multiplicity of disc springs; comprising the steps of: providing a threaded spring adjustment member connected with said disc spring units for axial movement in said well tool upon relative rotation, providing a removable plug in said well tool to provide access to said threaded spring adjustment member

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. lhe degree of damping action can also be influenced by the oil viscosity, clearance grooves, and spring geometry. The previous methods of adjusting the spring settings, i.e. pre-load for shock absorbers and hammer-anvil gas settings for impact tools, involved tool disassembly and spring adjustment by the use of various width spacers. An embodiment of the present invention provides a more convenient and accurate method of adjusting the position and/or pre-load of a spring system used in shock absorbers or impact-type drilling tools. The need to adjust the impact tool operating load varies with the weight run on the drill bit. This load may require numerous tool settings as different formations are encountered. The ability toadjust the tool externally eliminates the need of tool disassembly. Referring now to Figures 1 and 2, the system for adjusting the spring position and/or spring pre-load will be described. The too 10 includes a traveling nut 29 located in the spring sub 31. The traveling nut 29 has an integral gear wheel 28 which is exposed to a threaded section 37 of the spring sub 31. The traveling nut 29 and integral gear wheel 28 engage a universal spacer 33 which in turn engages the spring system 30. It will be appreciated that rotation of the gear wheel 28 will cause axial travel of the universal spacer 33 and produce the desired positioning and/or preload of the spring system 30. Rotation of the travelling nut 29 is accomplished by removing a sealed, threaded plug 32 from the access opening 34, installing a threaded bushing 35 to protect the access hole threads during adustment and engaging gear wheel 28 with a flat or round-end pry bar 36 which allows for sufficient leverage to rotate the nut 29 for proper positioning. The travelling nut 29 may be provided with a gear type head to facilitate rotation with the pry bar 36. A precalculated tabulation will reveal the amount of rotation of traveling nut 29 and gear wheel 28 in order to advance or retract the universal spacer 33 to the proper position. After achieving the proper adjustment, the threaded busing 35 is removed and the sealed, threaded plug 32 is installed to close the acess opening 34 and engage the nut 28 in order to lock it in place. WHAT WE CLAIM IS:

1. A torque transmitting well tool, comprising: first and second telescopically arranged members; spline means for transmitting torque between said first and second members; spring means between said first and second members, and adjustment means between said first and second members for adjusting said spring means.

and to seal said well tool from loss of said fluid, removing said plug, rotating said threaded spring adjustment member with an adjustment tool until the desired change of position of said disc spring units has been accomplished, and replacing said plug.

9. A torque transmitting well tool, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

10. A method of adjusting a well tool, substantially as hereinbefore described with reference to the accompanying drawings.