U.S. patent number 3,638,989 [Application Number 05/008,866] was granted by the patent office on 1972-02-01 for apparatus for recovering a drill stem.
This patent grant is currently assigned to Becker Drills Limited. Invention is credited to Alvin V. Sandquist.
United States Patent |
3,638,989 |
Sandquist |
February 1, 1972 |
APPARATUS FOR RECOVERING A DRILL STEM
Abstract
A tool is disclosed for recovering a drill pipe embedded in the
ground and detached from a drill string extending from the pipe to
a point above ground. The tool has an upper and a lower body
portion in axial alignment and a fluid chamber in the tool between
the body portions. Each body portion has longitudinal cavities
spaced radially about the axis of the body portions and communicate
with the fluid chamber. The cavities are at acute angles to the
axis of the tool the vertex of each angle being on the side of the
cavity nearest the fluid chamber and each cavity having an opening
at the end remote from the chamber which defines a groove along the
body portion. A wedging member is positioned in each cavity and is
slidable therein so that the shank of the wedging member projects
laterally and outwardly from the body portion when fluid is passed
into the cavities. The shank of each wedging member has a flat
toothed portion from gripping the inner wall of a drill pipe. The
tool is connected to the end of a drill rod and lowered down the
upper drill string until the upper body portion is positioned in
the upper drill string and the lower body portion is positioned in
the detached drill pipe. Fluid is passed down the drill rod and
into the longitudinal cavities whereby the wedging member is
projected and grips the inner wall of the upper drill string and
drill pipe. The drill rod upper drill string and drill pipe can
then be raised from the ground.
Inventors: |
Sandquist; Alvin V. (Calgary,
Alberta, CA) |
Assignee: |
Becker Drills Limited (Calgary,
Alberta, CA)
|
Family
ID: |
21734145 |
Appl.
No.: |
05/008,866 |
Filed: |
February 5, 1970 |
Current U.S.
Class: |
294/86.24;
166/212; 294/96; 166/98; 294/86.15 |
Current CPC
Class: |
E21B
31/20 (20130101); E21B 23/04 (20130101) |
Current International
Class: |
E21B
31/20 (20060101); E21B 31/00 (20060101); E21B
23/04 (20060101); E21B 23/00 (20060101); E21c
019/00 (); E21b 031/00 () |
Field of
Search: |
;294/86.24,86.15,86.27,86.31,86.33,96 ;166/98,212 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hornsby; Harvey C.
Assistant Examiner: Maffei; Merle F.
Claims
I claim:
1. In combination with a drill pipe having upper and lower detached
sections, a tool for recovering embedded drill pipe detached from
like drill pipe extending from the top of the embedded pipe to a
point above ground by lifting said embedded drill pipe from the
ground together with said like drill pipes, said tool
comprising:
a. an upper body portion and a lower body portion in axial
alignment;
b. a fluid chamber in said tool between said lower and said upper
body portions;
c. each of said upper and lower body portions having a plurality of
longitudinal cavities spaced radially about the axis of the upper
and lower body portions and communicating with the fluid
chamber;
d. said longitudinal cavities being at acute angles to the axis of
said tool, the vertex of each of said angles being on the side of
said longitudinal cavities nearest the fluid chamber, each of said
longitudinal cavities having an opening at the end remote from said
fluid chamber, said opening defining a longitudinal groove along
the respective body portion;
e. wedging members each having a crown of substantially uniform
cross section and a shank of bilaterally tapered cross section, one
of said bilateral sides having a substantially flat toothed surface
wherein said teeth are inclined in the direction of said crown;
f. one of said wedging members slidable in each of said
longitudinal cavities with the substantially flat toothed surface
facing outwardly whereby the crown of said wedging member is
positioned in said longitudinal cavity, the shank of said wedging
member projecting laterally and outwardly from said body portion
when the crown of said wedging member is slid away from said
longitudinal cavity;
g. a connector member secured to the upper end of said tool having
means connecting said tool to a drill rod for raising and lowering
said tool;
h. fluid passages in said connector member communicating with said
fluid chamber, the longitudinal cavities of said upper and lower
body portions communicating with said fluid chamber whereby
sufficient fluid from said drill rod may be delivered to said
longitudinal cavities to project the wedging members therefrom;
and
i. said wedging members extending simultaneously from said upper
body portion into gripping engagement with said upper detached pipe
section and from said lower body portion into gripping engagement
with said lower detached pipe section, said upper and lower
detached pipe sections extending respectively axially upward and
downward from said fluid chamber so that both said upper and lower
detached pipe sections are simultaneously axially moved upon axial
movement of said drill rod.
j. a driving tip secured at the lower end of said tool.
2. In combination with a drill pipe having upper and lower detached
sections, a tool for recovering embedded drill pipe detached from
like drill pipe extending from the top of the embedded pipe to a
point above ground by lifting said embedded drill pipe from the
ground together with said like drill pipe, said tool
comprising:
a. an upper body portion and a lower body portion in axial
alignment;
b. a fluid chamber in each of said upper body portions and lower
body portions;
c. the upper body portion having a plurality of longitudinal
cavities spaced radially about its axis and communicating with the
fluid chamber in said upper body portion;
d. the lower body portion having a plurality of longitudinal
cavities spaced radially about its axis and communicating with the
fluid chamber in said lower body portion;
e. each of the longitudinal cavities of the upper body portion and
the lower body portion being at an acute angle to the axis of said
tool, the vertex of each of said angles being on the side of said
longitudinal cavity nearest the fluid chamber, each of said
longitudinal cavities having an opening at the end remote from the
fluid chambers, said opening defining a longitudinal groove along
the respective body portion;
f. wedging members each having a crown of substantially uniform
cross section and a shank of bilaterally tapered cross section, one
of said bilateral sides having a substantially flat toothed surface
wherein said teeth are inclined in the direction of said crown;
g. one of said wedging members slidable on each of said
longitudinal cavities with the substantially flat toothed surface
facing outwardly whereby the crown of said wedging member is
positioned in said longitudinal cavity, the shank of said wedging
member projecting laterally and outwardly from said body portion
when the crown of said wedging member is slid away from said
longitudinal cavity;
h. a connector member secured to and axially rotatable on the upper
end of said tool and comprising a plate of cross section
substantially equal to the cross section of said upper body portion
and means above said plate connecting said tool to a drill rod for
raising and lowering said tool, a plurality of grooves on said
plate alignable with the openings of the longitudinal cavities in
said upper body portion when said connector member is axially
rotated to permit passage therethrough of the shanks of the wedging
members in said upper body portion;
i. fluid passages in said connector member communicating with the
fluid chamber of each of said upper and said lower body portions,
the longitudinal cavities of each of said upper and said lower body
portions communicating with the fluid chamber of their respective
body portion whereby sufficient fluid from said drill rod may be
delivered to said longitudinal cavities to project the wedging
members therefrom;
j. said wedging members extending simultaneously from said upper
body portion into gripping engagement with said upper detached pipe
section and from said lower body portion into gripping engagement
with said lower detached pipe section, said upper and lower
detached pipe sections extending respectively axially upward and
downward from said fluid chamber so that both said upper and lower
detached pipe sections are simultaneously axially moved upon axial
movement of said drill rod; and
k. a tapered member at the lower end of said tool having a
plurality of grooves positioned around said member and which are
aligned with the openings of the longitudinal cavities in the lower
body portion to permit passage therethrough of the shanks of the
wedging members in said lower body portion.
3. A tool as claimed in claim 1 wherein said driving tip is tapered
and has grooves positioned around said tapered bit which are
aligned with the openings of the longitudinal cavities in the lower
body portion to permit passage therethrough of the shanks of the
wedging members in said lower body portion.
4. A tool as claimed in claim 1 wherein the connector member is
axially rotatable on the upper end of said tool and comprises a
plate on said upper body portion and means above said plate for
connecting said tool to a drill rod, a plurality of grooves on said
plate alignable with the openings of the longitudinal cavities in
said upper body portion when said connector member is axially
rotated to permit passage therethrough of the shanks of the wedging
members in said upper body portion.
Description
This invention relates to a tool for recovering drill pipe. More
particularly it relates to an apparatus for recovering a portion of
drill pipe which is embedded in the ground and broken or otherwise
detached from a drill pipe immediately above it and extending above
the ground.
The loss of a portion of a drill string in a hole involves
considerable cost. In drilling operations in certain types of earth
formations such as overburden, breaks in the drill stems result in
adding considerably to the expense of drill operations. Because of
this various attempts have been made in the past to recover such
drill stems. Apparatus for recovering drill stem are sometimes
known in the art as "fishing tools." Such fishing tools have met
with varying degrees of success.
The method used for recovering drill stem with a fishing tool of
the prior art required the removal of the portion of the drill
string above the break. The fishing tool was then secured to the
end of a drill string and lowered into the hole. The drill string
was lowered until the fishing tool was inserted into the inner
annulus of the broken drill stem. Once inside the fishing tool was
attached to the drill stem by means of slips on a tapered seat or
by threads on the tapered point of the fishing tool. However, when
the portion of the drill string above the break is removed from the
hole, the earth formations or overburden frequently fall into the
hole and closes the broken end of the drill stem. This not only
makes the drill stem difficult to locate but the slips or thread of
the fishing tool become dirty and cannot attach itself to grip the
drill stem properly. This problem is avoided by the applicant's
fishing tool by the nature of its construction and by reason of the
fact that the drill string above the break does not have to be
removed prior to lowering the applicant's apparatus.
It is therefore an object of this invention to provide an improved
tool for recovering a drill stem.
It is another object of this invention to provide a tool for
recovering the lower portion of a broken drill string from a drill
hole without first removing the portion of the drill string above
the break.
It is another object of this invention to provide a tool for
recovering the lower portion of a broken drill string which enables
the drill string both above and below the break to be raised
simultaneously.
These objects are obtained by a tool which comprises:
a. an upper body portion and a lower body portion in axial
alignment;
b. a fluid chamber in said tool between said lower and said upper
body portions;
c. each of said upper and lower body portions having a plurality of
longitudinal cavities spaced radially about the axis of the upper
and lower body portions and communicating with the fluid
chamber;
d. said longitudinal cavities being at acute angles to the axis of
said tool, the vertex of each of said angles being on the side of
said longitudinal cavities nearest the fluid chamber, each of said
longitudinal cavities having an opening at the end remote from said
fluid chamber, said opening defining a longitudinal groove along
the respective body portion;
e. wedging members each having a crown of substantially uniform
cross section and a shank of bilaterally tapered cross section, one
of said bilateral sides having a substantially flat toothed
surface;
f. a wedging member slidable in each of said longitudinal cavities
with the substantially flat toothed surface facing outwardly
whereby the crown of said wedging member is positioned in said
longitudinal cavity, the shank of said wedging member projecting
laterally and outwardly from said body portion when the crown of
said wedging member is slid away from said longitudinal cavity;
g. a connector member secured to the upper end of said tool having
means for connecting said tool to a drill rod;
h. fluid passages in said connector member, said upper body portion
and said lower body portion communicating with said fluid chamber
whereby fluid from said drill rod may be delivered to said fluid
chamber; and,
i. a driving tip secured at the lower end of said tool.
These objects are also obtained by a method which comprises:
a. lowering a hollow drill rod through the inner core of the drill
pipe, said rod having a tool secured to its lower end consisting of
an upper and a lower body portion in axial alignment, a fluid
chamber in said tool between said upper and said lower body
portions each of said body portions having a plurality of
longitudinal cavities spaced radially about the axis of the upper
and lower body portions and communicating with the fluid chamber,
said longitudinal cavities being at acute angles to the axis of
said tool, the vertex of each of said angles being on the side of
said longitudinal cavities nearest the fluid chamber, each of said
longitudinal cavities having an opening at the end remote from said
fluid chamber, said opening defining a longitudinal groove along
the respective body portion, wedging members each having a crown of
substantially uniform cross section and a shank of bilaterally
tapered cross section, one of said bilateral sides having a
substantially flat toothed surface, a wedging member slidable in
each of said longitudinal cavities with the substantially flat
toothed surface facing outwardly whereby the crown of said wedging
member is positioned in said longitudinal cavity, the shank of said
wedging member projecting laterally and outwardly from said body
portion when the crown of said wedging member is slid away from
said longitudinal cavity, a connector member secured to and axially
rotatable on the upper end of said tool comprising a flange of
cross section substantially equal to the cross section of said
upper body portion and means above said flange for connecting said
tool to the drill rod, a plurality of grooves on said flange
alignable with the openings of the longitudinal cavities in said
upper body portion when said connector member is axially rotated,
fluid passages in said connector member, said upper body portion
and said lower body portion communicating with said fluid chamber
whereby fluid from said drill rod may be delivered to said fluid
chamber, and a driving tip secured at the lower end of said
tool;
b. aligning the drill rod so that the upper body portion of said
tool is in the inner core of the drill pipe above the break and the
lower body portion is in the inner core of the drill pipe below the
break;
c. discharging fluid through said hollow drill rod and said fluid
passages thereby projecting the wedging members in the longitudinal
cavities of the lower body portion downwardly and outwardly from
said lower body portion and gripping the inner walls of the drill
pipe below the break by means of the toothed surfaces of said
wedging members;
d. rotating the drill rod and connector member of said tool so that
the grooves on the connector plate are aligned with the openings of
the longitudinal cavities in said upper body portion thereby
permitting the shank portion of the wedging members in said
longitudinal cavities to pass therethrough and project upwardly and
outwardly from said upper body portion and gripping the inner wall
of the drill pipe above the break by means of the toothed surfaces
of said wedging members;
e. disengaging the hollow drill rod from said tool and raising the
drill pipe above the break thereby raising the tool and the drill
pipe below the break which is held by said tool.
In the drawings:
FIG. 1 is a perspective view of the apparatus of the present
invention;
FIG. 2 is a perspective view of the upper portion of the apparatus
with two sectional breaks shown for simplicity of illustration and
a wedging member shown in exploded view;
FIG. 3 is a perspective view of another embodiment of a wedging
member suitable in the present apparatus;
FIG. 4 is a cross-sectional elevation of one embodiment of the
apparatus with one longitudinal cavity empty for purposes of
illustration;
FIG. 5 is a broken section showing wedging member 9d in gripping
position against an inner wall of a drill pipe;
FIG. 6 is an illustration showing the apparatus positioned between
broken sections of pipe, and
FIG. 7 is a cross-sectional elevation of another embodiment of the
present apparatus with a sectional break shown for simplicity of
illustration.
The tool shown generally at 1 in FIG. 1 comprises an upper body
portion 2 and a lower body portion 3 which are secured in axial
alignment either by threaded connections or by welding into a
single body unit. A connector member 4 is secured to and axially
rotatable on the upper end of upper body portion 2. A hollow drill
rod is shown in broken lines at 5 to illustrate that tool 1 can be
connected to such a drill rod by means of connector member 4 for
the purpose which will become apparent from the description given
below. A tapered member 6 is secured to the lower end of lower body
portion 3 by a threaded connection or by welding for guiding the
tool into the broken end of the drill pipe.
Upper body portion 2 has a plurality of longitudinal cavities 7
having openings which define longitudinal grooves 8 along upper
body portion 2 as can be seen with particular reference to FIG. 2.
A wedging member 9 is slidable in each of the longitudinal cavities
7 so that their substantially flat toothed surface 10 is facing
outwardly.
The wedging member 9 is shown particularly in the exploded view of
the tool in FIG. 2 consists of a crown portion 11 of substantially
uniform cross section and a shank portion 12 of bilaterally tapered
cross section. One of the bilateral sides has a substantially flat
toothed surface 10. By describing the shank as being bilaterally
tapered the applicant intends to show that the shank portion 12 is
tapered along two sides. One tapered side should be substantially
flat and have a toothed or notched surface. This is the surface
that faces outwardly when the wedging member is positioned in
longitudinal cavity 7. When the wedging member is projected in the
manner to be described below this substantially flat surface 10
must provide a suitable wedging surface to securely grip the
interior of a drill pipe. The other side of the tapered shank
should preferably be rounded or contoured in such a manner as to
match the contour of the longitudinal groove 8 so that the wedging
member 9 can only be slidably positioned in cavity 7 with the
substantially flat toothed surface 10 facing outwardly. While some
degree of tapering is permitted along the other two sides of the
shank it must be appreciated that tapering along these sides to any
extent reduces the surface area of surface 10 which is available
for gripping.
In the embodiment shown in FIGS. 1 and 2 the substantially flat
toothed surface 10 of the wedging members are aligned with the
outer circumference of body portions 2 and 3. This is desirable in
a tool in which the diameters of the body portions are only
slightly smaller than the inner diameter of the drill pipe. For
example, a tool having upper and lower body portion each having an
outer diameter of 3 inches can be positioned in a pipe having an
inner diameter of 31/4 inches and wedging members 9 need only be
projected slightly to provide the wedging and gripping action
necessary.
In the case where the inner diameter of the drill pipe is
considerably larger than the outer diameter of the tool, a wedging
member 9 as shown in FIG. 3 can be used. In this embodiment the
shank portion 12 protrudes laterally from the wedging member so
that when crown portion 11 is slidably positioned in longitudinal
cavity 7 the substantially flat toothed surface 10 will protrude
from the side of the tool. When the wedging member is projected in
the manner to be described below, the surface 10 will wedge or grip
the inner surface of the drill pipe. For example, wedging member 9
such as shown in FIG. 3 might be used in a tool wherein the outside
diameter of the upper and lower body portions is 3 inches and the
inner diameter of the pipe is 5 inches.
The crown portion 11 of the wedging members shown in FIGS. 2 and 3
have a sealing ring 13 for providing a substantially fluidtight
seal when crown portion 11 is positioned in longitudinal cavity
7.
In the embodiment of the connector member 4 shown in FIG. 2 said
member has a flange 14 axially positioned on the upper end of upper
body portion 2 and which is of a cross section substantially equal
to the cross section of body portion 2. Flange 14 has a number of
grooves 15 equal to the number of longitudinal grooves 8 in upper
body portion 2. These grooves are alignable with longitudinal
grooves 8 by axially rotating connector member 4 so that wedging
members 9 may project from the tool openings defined by
longitudinal grooves 8. In the preferred embodiment of the
applicant's tool, the wedging members 9 in upper body portion 2
cannot be projected from their position in longitudinal cavities 7
unless grooves 15 of plate 14 are aligned with longitudinal grooves
8. The reason for this will become apparent from the description
given below with particular reference to FIG. 6. A connector means
16 is mounted above flange 14 for connecting the tool to a drill
rod. In one particular embodiment of this invention the upper face
of upper body portion 2 which abuts flange 14 of connector member 4
has a circular groove (not shown) into which is inserted a pin (not
shown) which is flush with the top of the upper face. The flange 14
has one or more shear pins (not shown) in its lower end which are
so positioned that the drill rod 5 and connector member 4 can be
rotated to the extent that grooves 15 are aligned with longitudinal
grooves 8. When these grooves are aligned a shear pin on the flange
14 stops against the pin in the upper face and no further rotation
in that direction is permitted.
One embodiment of tool 1 can be seen in the cross section shown in
FIG. 4. Upper body portion 2 and lower body portion 3 are
threadedly connected in axial alignment. Longitudinal cavities 7a
and 7b are shown in upper body portion 2 and longitudinal cavities
7c and 7d are shown in lower body portion 3. Cavity 7a is shown
with the wedging member removed for purposes of illustration.
Cavity 7a has an opening at its upper end which defines a
longitudinal groove 8a along the body portion 2. Groove 8b
similarly defines the opening of cavity 7b. A fluid chamber 17 is
located in upper body portion 2 and fluid passages 18a and 18b
place cavities 7a and 7b respectively in fluid communication with
chamber 17. It can be noted that longitudinal cavities 7a and 7b
are each at an acute angle to the axis of the tool so that the
vertex of each of these angles is one the side of the longitudinal
cavities nearest fluid chamber 17 so that a wedging member
projecting from cavities 7a and 7b would be projected upwardly and
outwardly.
Connector member 4 is positioned at the upper end of upper body
portion 2 and the connector grooves 15 in connector plate 14 are
shown aligned with longitudinal grooves 8a and 8b. A connector
means 16 is shown on connector plate 14 for securing the tool to a
hollow drill rod (not shown). A longitudinal fluid passage 19 in
connector means 4 is aligned with longitudinal fluid passage 20 in
upper body portion 2 whereby fluid such as compressed air may be
delivered from a hollow drill rod connector to connector means 16
into fluid chamber 17. Fluid passages 18a and 18b are in
communication with fluid chamber 17 whereby the fluid may be
directed through the longitudinal cavities 7a and 7b.
Longitudinal passage 21 below fluid chamber 18 is aligned with
longitudinal passage 22 in lower body portion 3 when the bodies are
axially threaded whereby fluid overflow from fluid chamber 17 is
directed into fluid chamber 23 of lower body portion 3. Fluid
passages 18c and 18d are in communication with fluid chamber 23
whereby fluid may be directed into longitudinal cavities 7c and
7d.
Wedging members 9 are positioned in each longitudinal cavity except
7a where the wedging member was removed to show the longitudinal
groove along the tool body. It can be noted that the flat toothed
surface 10 of the wedging member shanks are set in the longitudinal
grooves 8 and aligned with the circumference of the body portion of
the tool when the heat portions of the wedging members are
positioned all the way in cavities 7.
The section shown in FIG. 4 illustrates two longitudinal cavities
and this figure along with the other figures of drawings imply that
four such cavities are spaced radially around each of the upper and
lower body portions. While the preferred embodiments described in
this specification show four such cavities, three cavities radially
and equidistantly spaced apart in each of said body portions would
function well. While less than two such cavities in each body
portion would obviously not work, no significant gripping
improvement was noted in embodiments utilizing more than four
cavities radially aligned in each body portion. It can also be seen
that cavities 7c and 7d are at acute angles to the axis of the tool
in the manner described for cavities 7a and 7b with the vertex of
their respective angles being on the side of the cavities nearest
the fluid chamber 23.
The operation of the tool will now be described with reference to
FIGS. 4 and 6. When a break occurs in a drill pipe during drilling
operations, the break is usually made known to the drill operator
in a very short time due to the sudden drop in pressure of the
fluid delivered to the drill pipe or the sudden reduction in torque
load. Sometimes the noise occasioned by the break can be heard as
well.
When knowledge of a break occurs, drilling is stopped. The upper
section of the drill pipe shown as 101 in FIG. 6 and located in
earth formation 103 is disconnected from the driving means and held
by power tongs (not shown) or other gripping means on the drilling
apparatus. By "upper section of drill pipe" is meant that portion
above break 102. At the time of stoppage, the two sections of pipe
will be separated by a distance of a few inches depending on the
alertness and reflexes of the operator. A hollow drill rod 5 is
lowered down the center of the upper section of drill pipe with a
break locating device on its lower end. A break locating device
which is suitable for this purpose and is well known in the art
consists generally of a cylindrical device threadedly secured at
one end to the drill rod, the lower end of the device having hinged
fingers kept apart by a spring that forces the fingers against the
inner wall of the drill pipe. When the point of breakage is reached
the fingers that had been bearing against the inner wall of the
upper section of drill pipe are forced into the break area and
downward progress ceases when these fingers contact the top surface
of the lower section of broken drill stem.
When the location of the break is established its distance from the
top of the drill hole can be measured by various means such as by
marking the top section of the hollow drill rod at a point which is
aligned with the top of the drill hole. The hollow drill rod is
then raised and the apparatus of the present invention is secured
on its lower end in place of the break locating device. The hollow
drill rod is again lowered into the upper section of drill pipe to
the point when the previously marked section would indicate that
the apparatus at the lower end of the rod was located at the break
102 with its upper body portion in the upper section 101 of drill
pipe and the lower body portion in its lower section 104 of drill
pipe. Since the recovery apparatus of this invention is generally
longer than the conventional break locating device, this difference
must of course be taken into account in judging the distance to the
break and locating the recovery apparatus at approximately midpoint
between the upper and lower sections of drill pipe.
It may be that the downward progress of the recovery apparatus is
impeded by material from earth formation 103 which caved into lower
section 104 of the drill pipe from the drill hole wall. For this
reason the apparatus is equipped with a driving tip 6 so that the
apparatus may be driven through the obstructing material until the
apparatus is correctly positioned between the upper and lower
sections of the drill pipe.
Fluid from drill rod 5 is passed through longitudinal passage 19 in
connector member 4 shown in FIG. 4 and then into fluid chamber 17
via longitudinal passage 20. Fluid is delivered into fluid passages
18 but wedging members are held in place by the edge of plate 14.
Additional fluid is delivered to fluid chamber 23 via longitudinal
fluid passages 21 and 22. Fluid from chamber 23 is delivered to
longitudinal cavities 7 in the lower body portion 3 via fluid
passages 18. Fluid pressure forces the wedging members in the lower
body portion to project downwardly and outwardly from longitudinal
grooves 8 in the lower body portion until the substantially flat
toothed surface 10 of these wedging members grip the interior wall
of the lower section of drill pipe.
When the wedging members of the lower body portion 3 are wedged in
place in lower pipe section 104, the drill rod 5 is rotated until
grooves 15 on connector plate 14 are aligned with the longitudinal
grooves 8 in upper body portion 2. As mentioned above, this
alignment may be effected when a shear pin in flange 14 abuts a pin
located on the upper face of the upper body portion 2. When these
grooves are aligned the fluid pressure in cavities 7 force wedging
members 9 to project upwardly and outwardly from longitudinal
grooves 8 in upper body portion 2 until the substantially flat
toothed surface 10 of these wedging members grip the interior wall
of the upper section of drill pipe 102. The sealing rings 13 on the
wedging members 9 insure a substantially fluidtight seal and
maintenance of fluid pressure.
When the wedging members of the upper and lower body portions are
firmly wedged in place the delivery of fluid through the hollow
drill rod can be stopped. The hollow drill rod is then rotated in
the direction for unscrewing the rod from the recovery tool. With
the wedging members in upper body portion protruding through
grooves 15 in connector flange 14 the connector member 4 is held
firmly in place and does not rotate with the drill rod. The hollow
drill rod is disconnected and removed from the drill pipe. The
recovery tool is firmly secured in the upper and lower sections of
the drill pipe thereby locking the two sections of drill pipe
together. The upper section of drill pipe is raised by conventional
pipe recovery means.
When the upper section 101 is raised, the recovery tool and the
lower section 104 of the drill pipe is raised simultaneously. The
lower section of drill pipe 104 is pulled up with the upper section
by means of the firm grip of the upper and lower section by the
wedging members. When the drill pipe is removed from the ground,
the tool is easily released from the drill pipe by knocking the
pipe in the direction towards the tool since the drill pipe is only
held by the wedging action of the wedging members.
The wedging action of wedging members 9 may be more clearly
understood with reference to FIG. 5 wherein the longitudinal cavity
7d of FIG. 4 is shown. In FIG. 5 the wedging member 9 is shown
projecting from the lower body portion 3 and gripping the inner
wall of the lower section 104 of the drill pipe. The arrow in fluid
passage 18d shows the direction of fluid from chamber 23 which
pushes wedging member 9 out of cavity 7d to the extent whereby the
substantially flat toothed surface 10 of shank portion 12 comes in
contact with the interior wall of the drill pipe. The fluid is
effectively sealed in by sealing ring 13 on head portion 11. In
FIG. 5 the wedging member projects downwardly and outwardly to the
extent generally used in normal operations of the tool, e.g., a
tool body of 3-inch diameter in a drill pipe of 31/4 inch inside
diameter.
It can be noted in FIG. 5 that the teeth on surface 10 are bevelled
to bit into the wall of the drill pipe when the tool is pulled
upward. For the sake of convenience the preferred embodiment of the
tool uses identical wedging members in all of the longitudinal
cavities. It can be appreciated that teeth bevelled in the manner
shown in FIG. 5 will also be suitable for the wedging members in
upper body portion 2 and will bit into the wall of a drill pipe
when the upper section of a broken drill pipe such as item 101
shown in FIG. 6 is lifted.
The wedging members are slidably positioned in the longitudinal
cavities 7 before the tool is lowered down a drill pipe. It can be
seen from the drawings that these wedging members, particularly
those in the lower body portion 3 can easily drop out of the tool
since they are freely slidable out of cavities 7. Of course the
wedging members in upper body portion 2 may be held in cavities 7
by gravity but in the preferred embodiment are also held in place
by flange 14 of connector member 4. When the tool is lowered down a
drill pipe a wedging member in the lower body portion 3 may drop
out to the extent that the toothed surface 10 contacts the wall of
the drill pipe. This does not restrict the movement of the tool
down the drill pipe however since the surface 10 easily slides over
the drill pipe wall. When the lower body portion 3 of the tool is
positioned in the lower section of the drill pipe as shown in 104
of FIG. 6 the teeth of the wedging members grip the walls of the
drill pipe as an upward force is exerted on the tool. Even though
the wedging members are otherwise free to slide out of cavities 7,
the angles of the longitudinal cavities with respect to the tool
body causes the wedging members to project laterally and outwardly
and the lifting force is exerted on the tool thereby increasing the
gripping force of the teeth against the drill pipe wall is
increased.
FIG. 7 shows another embodiment of the tool of the present
invention. In this embodiment the tool includes an upper body
portion 202 and a lower body portion 203 in axial alignment and
forming a tool body of unitary construction. A connector member 204
is secured to and axially rotatable on the upper end of upper body
portion 203 and is similar to connector member 4 shown in FIGS. 1
to 6. A driving tip 206 is secured at the lower end of lower body
portion 203 and is similar to driving tip 6 in the previous figures
of drawings. A wall section 205 secures the upper and lower body
portions and defines a fluid chamber 207 therebetween. Wall section
207 is shown in broken section since the tool may be more elongated
that is shown in the drawings.
Upper and lower body portions 202 and 203 contain longitudinal
cavities 208 spaced radially around their respective body portions
and positioned at acute angles to the axis of the tool. The vertex
of each angle is on the side of the longitudinal cavity nearest the
fluid chamber. As in the embodiment shown in FIGS. 1 to 5, each of
the longitudinal cavities have an opening defining a longitudinal
groove along their respective body portion. Wedging members are not
shown in FIG. 6 for simplicity of illustration but is must be
appreciated that the wedging members described previously are also
suitable in this embodiment.
Each of the longitudinal cavities has a fluid passage 209 whereby
the cavities are in fluid communication with fluid chamber 207.
Longitudinal passage 210 in upper body portion 202 is aligned with
passage 211 in connector means 204 whereby fluid from a hollow
drill rod (not shown) connected to connector means 204 may be
discharged into fluid chamber 207 and then into the longitudinal
cavities 208 via fluid passages 209. Wedging members in the
longitudinal cavities are projected from the cavities by fluid
pressure in the manner described in the previous embodiment.
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