Note: Descriptions are shown in the official language in which they were submitted.
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Background of the Invention
The present lnventlon relates to the art of earth
boring, and more particularly to a torque transmltting well tool
with means for externally adJusting the spring means. The
present invention 1-s adapted for use in the drilling of oil wells,
gas wells including mining and all drilling operations and the
like and particularly to telescoping tools used in connection
therewith. Such tools generally include an elongated outer
member having a longitudinal bore therethrough and an elongated
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 Or 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 type of telescoping tool is commonly referred
to as a "bumper sub~ or ~limpact tool~ because the limlting
means is comprised of two sets of opposed shoulders one of whlch
becomes engaged or "bumps~ when the moving member reaches either
end of tis 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,offshore drilling.
Still another type of telescoping tool~ often referred
to as a shock or percussion tool is provided with resilient
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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 drilli.ng. 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.
There are other types of telescoping tools, e.g. some
which combine some of the features of the tools discussed above.
The previouS methods of adjusting the spring settings, i.e. pre-
3 load for shock absorbers and hammer-anvil gap settings for
impact tools, involved tool disassembly and i~pring adjustment by
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the use of various width spacers.
Descrl~tion of Prior Art
In U. S. Patent 3,383,126 to A. H. Salvatorl et al,
patented May 14, 1968, a drill string shock absorber is shown.
5 The drlll string shock absorber is adapted to be inserted into
a rotary drill string to absorb vibrational and shock forces
therein. The shock absorber includes telescoplcally related
parts whlch are separated and isolated one from the other by a
mass of compressible wire material.
In U. S. Patent No. 2,585,995 to C. C. ~rown,
patented February 19, 1952, a drilling joint is shown. The
drilling ~oint provides an improved means for controlling the
weight applied to the drill bit, localizes the neutral point
in the drill stem, and prolongs the life of the drill stem by
15 absorbing or damping out vibrations and other shocks imparted
to the drill stem during operations.
In U. S. Patent No. 2,991,635 to F. D. Warren,
patented July 11, 1961, a resilient drilling tool is shown.
The drilling tool comprises a pair of tubular housings or pipes 20 telescoped together and provided with cooperating splines to
transmit torque from one housing to the other. A plurality of
helical springs are anchored in the annulus between the two
telescoped housings to constantly urge the housings in opposite
directions and effectively dampen any vibration of the drill
25 string in which the tool is interposed.
; In U. S. Patent No. 3,871,193 to James Whitehurst
Young~ patented March 18, 1975, a shock absorbing torque
transmitting well tool is disclosed that includes an outer
member and an inner member telescopically arranged. A spline
3 means between said outer member and said inner member transmits
torque. A spring means is positioned between the outer member
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and the inner member. The spring means includes a multiplicity
of spring segments arranged in discrete spring units having
different spring rates. The spring means will accommodate a
wide range of loads or rapidly varying load situations. The
tool operates effectively in holes started from the surface with
very little weight on the bit and continues to operate effectively
as the weight on the bit is increased. ~-
In U~ S. Patent No. 3,884,051 to Clifford C. Bottoms,
- patented May 20, 1975, a tool is disclosed that comprises an
elongated outer member having a longitudinal bore therethrough
and an elongated inner member telescopically mounted therein.
i A plurality of rotating antifriction bearings are provided between
the two members to guide them in their telescopic movement. The
bearings have axes of rotation which are disposed normal to the
longitudinal axis of the inner member and which are fixed
, relative to one of the members. Limiting means are provided
-~ limiting the ax~al movement of the outer member relative to the
inner member in either direction.
In U. S. Patent No. 3,898,815 to James Whitehurst
Young, patented August 12, 1975, a reciprocating torque
, transmitting well tool is disclosed that lncludes an outer
.,
member and an inner member telescopically arranged. A spline
means between said outer member and said inner member transmits
torque. A spring means is positioned between the outer member
and the inner member. A first seal means provides a fluid
seal between said outer member and said inner member. A
second seal means spaced from said first seal means provides a
fluid seal between said outer member and said inner member. At
least one of said seal means can move axially between said
outer member and said inner member. The axial movement of the
seal means accomplishes at least two functions. The first
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function is ehat as the external pressure increases, the seal
means can move inwardly to compress any trapped air to the point
that a pressure balance i9 maintained at all times. The second
function is to accommodate variations in volume crested by the
drive mandrel as it moves axially within the tool housing.
Summary of the Invention
The present invention provides a more convenient and
accurate method of adjusting the position and/or pre-load of a
spring system used ln drill string shock ab~orbers or impact-
type drilling tools. The need to adjust the spring system varieswith operating conditions. The tool may require numerous spring
settings as different formations are encountered. The ability to -
adjust the tool spring system externally eliminates the need of
tool disassembly for this purpose. The torque tran~mitting well
tool of the present invention includes an outer member and an
inner member, said outer member and said inner member being
telescopically arranged. Spline means are provided between saia
.,
outer member and said inner member for transmitting torque. The
spring system is provided connecting 9aid outer member and said
inner member and ad;ustment means are provided between the
members for adjusting the spring system.
In one embodiment of the invention a travelling nut
system is located in the end of the 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 asscomplished by
removing a sealed, threaded plug from the access opening, install-
ing a threaded bushing to protect the access hole threads during
adjustment and engaging the gear tooth portion of the nut with a
flat or round-end pry bar which allows for sufficent leverage to
rotate the nut for proper positioning. A pre-calculated tubula-
tion will reveal the number of gear teeth to engage in order to
advance or retract the nut to the proper position. After achieving
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the proper ad;ustment, the threaded bushing is removed and the
sealed, threaded plug is installed to close the access opening
and engage the gear teeth in orderto lock the travelling nut in
place.
. Thus the present invention may be also broadly defined
as providing a method of earth boring, comprising the ~teps of
- providing a torque transmitting well tool having an outer member,
an inner member with the outer member and the inner member being
telescopically arranged, an upper seal between the outer member
and the inner member, a lower seal between the outer member and
the inner member, a fluid between the upper seal and the lower
; seal, spline means between the outer member and the inner member
for transmitting torque, spring means connected with the outer
member and connected with the inner member with the spring means
including a multiplicity of disc spring units, a central passage
extending through the well tool, and connection means for connect-
ing the well tool to drill pipe; providing a threaded spring
adjustment mem4er connected to the disc spring units for axial movement in
the well tool upon rotation thereof; providing a removable plug
in the well tool to provide access to the threaded spring -
ad~ustement member and to seal the well tool from loss of the
fluid; removing the plug; rotating the threaded spring ad~ustment
member with an ad~ustment tool until the desired change of
poRition of the disc spring units has been accomplished; replac-
ing the plug; and connecting the well tool to drill pipe for
: . rotation and earth boring.
The above method may be carried out by a torque trans-
mitting well tool, comprising a torque transmitting well tool
body having an outer member; an inner member, the outer member and the
inner member being telescopically arranged; an upper seal
between the outer member and the inner member; a lower seal
between the outer member and the inner member; a fluid between
the upper seal and the lower seal; spline means between the
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outer me~ber and the inner member for transmltting torque; spring
means connected with the outer member and connected with the
inner member, the spring means including a multiplicity of disc
spring units; a central passage extending ~hrough the well tool;
connection means for connecting the well tool to drill pipe; a
threaded spring ad~ustment member connected to the disc spring
units for axial movement in the well tool body upon rotation
thereof; a passage through the well tool body adjacent the
threaded spring adjustment member; and a removable plug in the -
passage to provide access to the threaded spring adjustment
member and to seal the well tool from loss of the fluid.
The above and other objects and advantages of the
present invention will become apparent from a consideration of
the following detailed description of the invention when taken
in conjunction with the drawings.
Brief Description of the Drawin~s
Figure 1 is a longitudinal view, partly in section and
partly in elevation, of one embodiment of a drill string tool `-
constructed in accordance with the present invention.
Figure 2 is an enlarged view of a portion of the drill
string tool shown in Figure 1.
Detailed Description of the Invention
Referring now to the drawings and in particular Figure
1, a drill string tool is shown therein and 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 equip-
men~ 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 m~nimizes fatigue on the drill bit, the drill string,
and the surface equipment.
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The tool 10 lncludes 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
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threaded connection 24 allows the tool 10 to be easily connected
to and disconnected from the drlll pipe. The upper packer sub
11 is threaded into a sprlng 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 trans-
mitted 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 trans-
mitted 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 ls 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 mandrel 22 and the housing consisting
of the upper packer sub 11, the spring sub 31, the spline sub
3 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
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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 0. D. as loads are applied. Lubricant is
trapped to some degree as the springs are collapsed. The 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 gap settings
for impact tools, involved tool disassembly and spring ad~ust-
ment by the use of various Width spacers. The present invention
provides a more convenient and accurate method of ad~usting 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 to adjust
the tool of the present invention externally eliminates the
3 need of tool disassembly.
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Referring now to Flgures 1 and 2, the system for ad-
~usting the spring position and/or spring pre-load will be
described. The tool 10 includes a traveling nut 28 located in
the spring sub 31. The traveling nut 28 has an integral gear
5 wheel 29 which is exposed to a threaded section 37 of the spring
sub 31. The traveling nut 28 and integral gear wheel 29 engage
a universal spacer 33 which in turn engage the spring system 30.
It will be appreciated that rotation of the gear wheel 29 will
cause axial travel of the universal spacer 33 and produce the
deslred positioning and/or pre-load of the spring system 30.
Rotation of the traveling nut 28 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 adjustment and engaging the nut 28 with a flat or
15 round-end pry bar 36 which allows for sufficient leverage to
rotate the nut 28 for proper positioning. The traveling nut 28
~, may be provided with a gear type head to facilitate rotation
with the pry bar 3Ç. A pre-calculated tabulation will reveal
the amount of rotation of traveling nut 28 and gear wheel 29 in
- 20 order to advance or retract the universal spacer 33 to the
' proper position. After achieving the proper adjustment, the
~ threaded bushing 35 is removed and the sealed, threaded,plug 32
: is installed to close the access opening 34 and engage the nut
28 in order to lock it in place.
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