[0001] This invention relates in general to wrenches and wrench assemblies and in particular
to a wrench assembly for use with a top drive well drilling apparatus.
[0002] In the drilling of oil and gas wells, hydraulically powered wrenches are used to
make and break connections between tubular members. The wrench assemblies generally
used in these applications have a pair of wrenches, one mounted directly above the
other. Each wrench grips a joint on either side of the connection, and torque is applied
to rotate the wrenches with respect to one another, to make up or break the connection.
One such wrench assembly is shown in US patent No. 4,348,920 (BOYADJIEFF), issued
September 14, 1982. One disadvantage inherent in the prior art has been that the wrenches
must be adjusted to accomodate tubular members of different diameters.
[0003] A top drive drilling system rotates a drill string from the top, rather than using
a rotary table, a kelly, and a kelly bushing. An electric drilling motor is suspended
from the drilling rig's conventional swivel and is attached to the top of the drill
string. The drilling motor may also be attached to a carriage, which is guided by
a pair of vertical tracks. The drilling motor is connected to the drill string by
a cylindrical stem, which extends downward from the motor. A top drive sub is the
bottom unit of the cylindrical stem, and is the unit to which the drill string is
threaded. A wrench assembly is also suspended from the drilling motor, in order to
make or break connections between the top drive sub and the drill string. In some
prior art top drive drilling systems, the wrench assembly rotates with the drill string
and is not removable therefrom. However, there are some top drive well drilling apparatus
in which the wrench assembly may be retracted away from the drill string.
[0004] The object of the invention is a wrench and wrench assembly which may be used, without
adjustment, on tubular members having a wide range of diameters.
[0005] According to the invention the wrench has a curved gate arm and a curved latch arm,
which are pivotally connected to the frame of the wrench. The gate arm has a plurality
of teeth on its outer surface, and the latch arm has a plurality of teeth on its inner
surface. When the gate arm and the latch arm have been closed against the tubular
member, the teeth on the gate arm will engage certain teeth on the latch arm, depending
upon the diameter of the tubular member being gripped.
[0006] According to the invention the wrench assembly comprises a lower wrench and an upper
wrench. The upper wrench of the wrench assembly has a semicircular plate having at
least one vertical splines. The spline, which may be beveled on the upper end, are
adapted to engage at least one spline on the top drive sub in a top drive drilling
system. When constructed with a wrench according to the invention, the wrench assembly
of the invention is capable of connecting and disconnecting connections between a
top drive sub and a tool joint on a drill string regardless of the diameter of the
tool joint.
[0007] The above, as well as additional objects, features, and advantages of the invention,
will become apparent in the following detailed description of a preferred embodiment
shown in the accompanying drawing, wherein:
Fig. 1 is a perspective view of a top drive drilling apparatus;
Fig. 2 is a perspective view of the (lower) wrench of the invention;
Fig. 3 is a top view, partially in section, showing how the gate arm and the latch
arm engage tubular members of different diameters; and
Fig. 4 is a perspective view of the wrench assembly of the invention.
[0008] Figure 1 illustrates a top drive well drilling apparatus. A conventional traveling
block 11 and a conventional hook 13 are suspended by cables 15 above the floor 17
of an oil well drilling rig. A top drive unit 19, which is a drilling motor of a conventional
type, is suspended from the hook 13. A carriage 21 guides the top drive unit 19 up
and down along a pair of vertical guide tracks 23. A tubular member, or stem 25, extends
downward from the top drive unit 19. The upper end of a drill string 27 is threaded
to a top drive sub 29, which is the lowest unit of the stem 25. The drill string 27
consists of a series of tubular members, called pipe sections, and has a rotary rock
bit attached at the lower end for drilling a well bore.
[0009] A wrench assembly 31 is used to make and break connections in the stem 25 and the
connection between the top drive sub 29 and the drill string 27. The wrench assembly
31 is mounted on the carriage 21, and is movable horizontally between a working position
along the stem 25, or the drill string 27, and a retracted position away from the
axis of the drill string 27. The wrench assembly 31 is also movable vertically along
the stem 25 and the drill string 27. When the wrench assembly 31 is used to make or
break the connection between the drill string 27 and the top drive sub 29, the lower
wrench 33 grips the tool joint 35 on the upper end of the drill string 27, and the
upper wrench 37 engages the top drive sub 29. The top drive sub 29 has a plurality
of splines 39 to facilitate the engagement between the wrench 37 and the sub 29.
[0010] Figure 2 shows the lower wrench 33 in the closed position. The lower wrench 33 has
a curved gate arm 41 and a curved latch arm 43, pivotally connected to a frame 45
at pivot points 47 and 49, respectively. The gate arm 41 and the latch arm 43 are
pivotable between the closed position, as shown in Fig. 2, and an open position wherein
the wrench can be applied to or removed from the tool joint 35. A fluid cylinder 51,
53 is connected to each arm 41, 43 to provide means for pivoting the arms between
the open and closed positions. The gate arm 41 has a plurality of latching teeth 55
on its outer surface, and the latch arm 43 has a plurality of latching teeth 57 on
its inner surface for locking engagement with the teeth 55 on the gate arm 41. A die
block 59, having tong dies 58, is mounted on the frame 45 opposite the gate arm 41
and latch arm 43. A clamping cylinder 61 moves the die block 59 reciprocally between
a retracted position away from the drill string 27 and an extended position against
the drill string 27. The clamping cylinder 61 and die block 59 are a means for forcing
the tool joint 35 against the gate arm 41.
[0011] Figure 3 illustrates how the wrench is capable of engaging tubular members of different
diameters, without having to be adjusted. The solid lines show tong dies 60 on the
gate arm 41 engaging a tubular member 62 of a larger diameter. The teeth 55 on the
gate arm 41 engage the teeth 57 on the latch arm 43, and the specific teeth 57 which
are engaged are near the outer end 63 of the latch arm 43. When the gate arm 41 engages
a tubular member 64 of a smaller diameter, as shown in shadow in Fig. 3, the teeth
55 on the gate arm 41 engage a different set of teeth 57 on the latch arm 43. In this
case, the engaged teeth 57 on the latch arm 43 are closer to the pivot point 49. For
tubular members of various diameters, the gate arm teeth 55 will engage different
latch arm teeth 57. Thus, the gate arm 41 is capable of engaging tubular members having
a wide range of diameters, without having to be adjusted.
[0012] Figure 4 shows the entire wrench assembly 31, which consists of the lower wrench
33 and an upper wrench 37. The upper wrench 37 does not completely encircle the top
drive sub 29 but rather has a semicircular plate 65. A plurality of vertical splines
67 are mounted on the interior surface of the semi-circular plate 65, for engaging
the splines 39 on the top drive sub 29. The splines 67 on the upper wrench 37 are
spaced apart so as to fit between the splines 39 on the top drive sub 29. The upper
end of each spline 67 is beveled to facilitate engagement with the splines 39 on the
top drive sub 29. A fluid cylinder 71 is attached to the lower wrench 33, and the
piston rod 73 is connected to the upper wrench 37. When the piston rod 73 is extended,
the upper wrench is rotated counterclockwise, relative to the lower wrench 33. The
fluid cylinder 71 and piston rod 73 are thus means for applying torque to the wrenches
33, 37 to rotate one of the wrenches with respect to the other wrench.
[0013] In operation, the wrench assembly 31 is first retracted away from the stem, and then
lowered to a position below the connection between the tool joint 35 and the top drive
sub 29. The wrench assembly 31 is then extended back to the center line of the drill
string 27. The wrench assembly 31 is raised to engage the splines 67 on the upper
wrench 37 and the splines 39 on the top drive sub 29. Interrotational capability is
provided to align the splines 39, 67, aided by the bevels 69 at the top of the wrench
splines 67. The splines 37 on the top drive sub 29 are beveled at the lower end.
[0014] When the upper wrench 37 is aligned with the top drive sub 29, the lower wrench 33
will be aligned with the tool joint 35 at the top of the drill string 27. The fluid
cylinder 51 is actuated to pivot the gate arm 41 to its closed position, in which
the inner surface of the gate arm 41 contacts the tool joint 35. Fluid cylinder 53
is then actuated to pivot the latch arm 43 to close onto the gate arm 41. The latching
teeth 57 on the latch arm 43 may or may not mesh with the teeth 55 on the gate arm
41 at this point. The clamping cylinder 61 is then actuated to extend the die block
59. The die block 59 pushes the tool joint 35 against the gate arm 41. The clamping
cylinder 61 exerts substantial pressure and overcomes the gate arm cylinder 51, causing
the gate arm 41 to be pushed back. The gate arm 41 will continue to be pushed back
until the teeth 55, 57 on the arms 41, 43 become interlocked. The pressure in the
clamping cylinder 61 is increased until the desired clamping pressure is achieved.
The torquing cylinder 71 is then actuated to rotate the upper wrench 37 in relation
to the lower wrench 33, thus making or breaking the connection between the top drive
sub 29 and the tool joint 35 on the drill string 27.
[0015] To remove the wrench assembly 31 from the connection, the lower wrench 33 is first
released. To release the lower wrench 33, the clamping cylinder 61 retracts the die
block 59 from the tool joint 35. Fluid cylinder 53 then pivots the latch arm 43 to
the open position, and fluid cylinder 51 pivots the gate arm to the open position.
The wrench assembly 31 is then lowered to disengage the splines 39, 67 on the top
drive sub 29 and the top wrench 37. The wrench assembly 31 is retracted away from
the connection, raised, and returned to its storage position beneath the top drive
unit 19.
[0016] The wrench assembly of the invention has several advantages over the prior art. Because
of the various teeth 57 on the latch arm 43 which may be engaged by the gate arm teeth
55, the wrench assembly 31 may be used on a large variety of tubular members without
having to be adjusted. The spline connection between the upper wrench 37 and the top
drive sub 29 eliminates the need to repeatably grip the top drive sub with tong dies.
Repeated gripping with tong dies would damage the sub 29, which must then be replaced.
The wrench assembly 31 of the invention can be retracted away from the stem 25 and
the drill string 27. This capability allows the wrench assembly 31 to remain stationary
rather than to rotate with the drill string 27. The ability of the wrench assembly
31 to be raised to the storage position, shown in Fig. 1, allows the top drive drilling
apparatus to drill the drill string to a deeper depth before additional pipe sections
must be added to the drill string 27.
[0017] While the invention has been shown in only one of its forms, it should be apparent
to those skilled in the art that it is not so limited, but is susceptible to various
changes and modifications without departing from the spirit thereof. For example,
the wrench assembly may have an upper wrench of the same design as the lower wrench
33 described above.
1. A wrench for making and breaking connections between tubular members, characterized
by
(a) a frame (45);
(b) a gate arm (41), having latching teeth (55), the gate arm being pivotally secured
to the frame and pivotable between an open position and a closed position;
(c) a latch arm (43), having latching teeth (57) along the interior surface for engagement
with the latching teeth (55) on the gate arm (41), the latch arm (43) being pivotally
secured to the frame (45) and pivotable between an open position and a closed position;
(d) means (59,61) for forcing one of the tubular members against the gate arm (41);
(e) means (51) for pivoting the gate arm (41) between the open position and the closed
position; and
(f) means (53) for pivoting the latch arm (43) between the open position and the closed
position.
2. The wrench according to claim 1, characterized in that the gate arm is a curved
gate arm, the inner surface of the gate arm contacts one of the tubular members, and
a plurality of said latching teeth (55) is provided on the outer surface of the gate
arm, and that the latch arm (43) is a curved latch arm, the inner surface of the latch
arm contacts the outer surface of the gate arm, and a plurality of said latching teeth
(57) is provided for locking engagement with the latching teeth on the gate arm.
3. A wrench assembly for making and breaking connections between a tubular member
and a top drive sub having at least one spline, characterized by
(a) a lower wrench (33), for engaging the tubular member;
(b) an upper wrench (37), mounted above the lower wrench, and having a semicircular
plate (65);
(c) means (71) for applying torque to the wrenches to rotate one of the wrenches with
respect to the other wrench; and
(d) at least one spline (67), on the interior surface of the semicircular plate (65),
for engaging at least one spline on the top drive sub.
4. The wrench assembly according to claim 3, characterized in that the upper end (69)
of at least one spline (67) is beveled to facilitate engagement with the spline on
the top drive sub.
5. The wrench assembly according to claim 3 or 4, characterized in that the lower
wrench (33) is a wrench according to claim 1 or 2.