U.S. patent number 3,578,078 [Application Number 05/002,115] was granted by the patent office on 1971-05-11 for earth borehole tool.
This patent grant is currently assigned to General Oil Tools, Inc.. Invention is credited to Harold E. Shillander.
United States Patent |
3,578,078 |
Shillander |
May 11, 1971 |
EARTH BOREHOLE TOOL
Abstract
An oil well drill string or stem having a tubular mandrel fast
on its lower end and a drive sleeve assembly telescoped onto the
mandrel. A resilient packer fastened at its upper end to the
mandrel is slidable on the mandrel above the drive sleeve assembly,
and a retractor secured to the lower end of the packer with a
lost-motion connection is alternately latched to the mandrel when
the packer is extended, unlatched by the drive sleeve assembly as
the latter moves upwardly relative to the mandrel to compress the
packer longitudinally and thus expand it radially, and latched to
the drive sleeve assembly for positive longitudinal extension and
radial collapse of the packer as it is returned to the latched
condition. Circulation ports in the drive sleeve assembly are
opened only when the packer is expanded, and a driving spline
connection between the drive sleeve assembly and the mandrel has
squared spline elements for increased bearing strength.
Inventors: |
Shillander; Harold E.
(Albuquerque, NM) |
Assignee: |
General Oil Tools, Inc.
(Phoenix, AZ)
|
Family
ID: |
21699303 |
Appl.
No.: |
05/002,115 |
Filed: |
January 12, 1970 |
Current U.S.
Class: |
166/152; 166/196;
175/321 |
Current CPC
Class: |
E21B
33/128 (20130101); E21B 49/087 (20130101) |
Current International
Class: |
E21B
33/12 (20060101); E21B 33/128 (20060101); E21B
49/08 (20060101); E21B 49/00 (20060101); E21b
023/00 () |
Field of
Search: |
;166/152,187,196
;175/321 ;277/116.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leppink; James A.
Claims
I claim:
1. In an earth borehole drilling tool mountable on the lower end of
a drill string to be raised, lowered and rotated therewith, and
including an elongated hollow mandrel attachable to said lower end,
a packer telescoped over said mandrel and having an upper end
secured thereto, said packer being a sleeve of resiliently flexible
material that expands radially in response to longitudinal
contraction of the sleeve, a drive sleeve assembly telescoped over
said mandrel below said packer, and driving and indexing
connections between said mandrel and said drive sleeve assembly for
transmitting driving force to the drive sleeve assembly and
selectively indexing the latter about the mandrel, said drive
sleeve assembly being movable along said mandrel between packing
and drilling positions, the improvement comprising:
a retractor sleeve telescoped over said mandrel and connected to
the lower end of said packer, said retractor sleeve having a
plurality of resiliently flexible spring fingers projecting
downwardly along said mandrel inside the upper end portion of said
drive sleeve assembly, and having latching lugs on said fingers
pressed against the mandrel;
means forming a first detent in said mandrel latchingly receiving
said lugs when said packer is extended and said drive sleeve
assembly is in said drilling position;
an annular release element on the inside of said drive sleeve
assembly disposed below said first detent when said drive sleeve
assembly is in said drilling position, said release element being
movable into engagement with said lugs to shift the latter out of
said first detent as the drive sleeve assembly moves toward said
packing position, whereby the lower end of said packer is released
from said mandrel for longitudinal contraction and radial expansion
of the packer;
and means forming a second detent in said drive sleeve assembly
receiving said lugs as the latter are shifted out of said first
detent, and operable as said drive sleeve assembly moves back
toward said drilling position to positively slide said retractor
along said mandrel until said lugs reach and reenter said first
detent, thereby to collapse the packer radially prior to relatching
of the retractor to the mandrel.
2. In an earth borehole drilling tool mountable on the lower end of
a drill string to be raised, lowered and rotated therewith, and
including an elongated hollow mandrel attachable to said lower end,
a packer telescoped over said mandrel and having an upper end
longitudinally secured to the mandrel, said packer being radially
expandable in response to upward movement of its lower end along
the mandrel, a drive sleeve assembly telescoped over said mandrel
below said packer for longitudinal sliding movement along the
mandrel, and selectively operable means for shifting said mandrel
relative to said drive sleeve assembly between a drilling position
in which the assembly is lowered along said mandrel and said packer
is elongated and radially collapsed, and a packing position in
which the assembly is raised along the mandrel and said packer is
longitudinally contracted and radially expanded, the improvement
comprising:
a retractor secured to the lower end portion of said packer and
extending downwardly therefrom along said mandrel to said drive
sleeve assembly;
first means on said retractor and said mandrel latching the
retractor releasably to the mandrel when said packer is
longitudinally extended and radially collapsed;
second means for unlatching said retractor from said mandrel as
said drive sleeve assembly moves upwardly relative to the mandrel
toward said packing position thereby releasing the packer for
longitudinal contraction and radial expansion;
and third means for latching said retractor to said drive sleeve
assembly when the retractor is unlatched from said mandrel and the
assembly is moving back along the mandrel toward said drilling
position, whereby said packer is longitudinally extended and
radially collapsed with a positive action as the assembly returns
to said drilling position, said first means operating to relatch
said retractor to said mandrel when said packer again has been
elongated and radially collapsed.
3. The improvement defined in claim 2 in which said first means
include at least one latching lug on said retractor lying alongside
said mandrel, and a detent on the mandrel for receiving said lug
when said mandrel is in a preselected longitudinal position
relative to the retractor.
4. The improvement defined in claim 3 in which said retractor is a
sleeve telescoped over said mandrel and formed with a plurality of
resiliently flexible fingers on its lower end extending
longitudinally of the retractor, one of said lugs being carried on
the free end portion of each of said fingers and resiliently urged
toward said mandrel.
5. The improvement defined in claim 4 in which said detent is an
annular groove around said mandrel.
6. The improvement defined in claim 3 in which said second means,
for unlatching said retractor, includes a cam carried by said drive
sleeve assembly below said latching lug to engage the latter as the
assembly moves toward said packing position, and operable to shift
said lug away from said detent.
7. The improvement defined in claim 6 in which said drive sleeve
assembly includes a second detent aligned with said lug to receive
the latter as said cam shifts the lug out of the first-mentioned
detent, thereby forming said third means for latching the retractor
to the assembly during return movement.
8. The improvement defined in claim 2 in which the upper end of
said retractor is secured to said packer with a lost-motion
connection permitting limited longitudinal motion of the retractor
relative to the packer.
9. The improvement defined in claim 2 further including an upper
washover lock attached to the lower end of said packer, and a lower
washover lock attached to the upper end of said drive sleeve
assembly, said retractor being a sleeve telescoped onto said
mandrel between said locks with its upper end secured to said upper
lock and with its lower end portion extending into said lower
lock.
10. The improvement defined in claim 2 in which said selectively
operable means includes a spline connection between said mandrel
and said drive sleeve assembly having interfitting spline elements
formed with opposed end surfaces for transmitting downward force
from the mandrel to the assembly, said interfitting ends being
squared to lie in a plane substantially perpendicular to the
longitudinal axis of said tool.
11. The improvement defined in claim 2 in which said mandrel and
said drive sleeve assembly are formed with first and second ports
for communicating between the interior of the mandrel and the
exterior of said tool, said ports being brought into communication
during relative movement of the mandrel and the assembly to said
packing position and being out of communication in all other
relative positions of the ports, thereby to open the ports in the
assembly only while the assembly is in said packing position.
12. The improvement defined in claim 11 further including a
connecting chamber formed between said mandrel and said drive
sleeve assembly to establish communication between said first and
second ports, said connecting chamber being elongated
longitudinally of said tool to interconnect said first and second
ports in a selected range of relative positions of the mandrel and
the assembly, but out of communication with said first ports except
when said packer is at least partially expanded.
13. In an earth borehole tool mountable on the lower end of a
string to be raised and lowered therewith, and including an
elongated member attachable to said lower end, a packer telescoped
with said member and having one end attached thereto and its other
end slidable along the member, said packer being expandable in
response to movement of said other end toward said one end and
collapsible in response to extending movement of said other end
away from said one end, the improvement comprising:
a retractor secured to said other end and movable therewith along
said member;
first means acting between said retractor and said member to latch
the two together when said packer is extended along said
member;
second means selectively movable along said member toward said
other end to expand said packer, said second means including a
release element operable during such movement to unlatch said
retractor for movement of said other end in a direction to expand
the packer;
and third means acting between said second means and said retractor
to positively return the retractor along said member as the packer
is collapsed.
14. The improvement defined in claim 13 in which said second means
is a sleeve assembly telescoped over said member for movement
relative thereto toward and away from said other end of said
packer, said retractor being disposed between said member and said
sleeve assembly and having a latching element movable into
engagement alternately with said member and with said sleeve
assembly.
15. The improvement defined in claim 14 in which said retractor is
a sleeve telescoped over said member and into the sleeve assembly,
said latching element comprising a plurality of lugs disposed
around said member and carried on said sleeve by resiliently
flexible fingers urging the lugs toward said member.
16. The improvement defined in claim 15 in which said first means
includes said lugs and a first detent on said member, and in which
said third means includes a second detent inside said sleeve
assembly receiving said lugs when the latter are away from said
first detent.
17. The improvement defined in claim 16 in which said release
element is a cam inside said sleeve assembly movable along said
member and operable to shift said lugs into said second detent.
18. The improvement defined in claim 15 in which first and second
washover locks are mounted respectively on said other packer end
and on the adjacent end of said sleeve assembly, said retractor
being secured to said first washover lock and extending into said
second washover lock.
19. The improvement defined in claim 13 including at least one
stabilizer rotatably mounted on said tool adjacent said packer,
said stabilizer having an outside diameter substantially larger
than the collapsed diameter of said packer thereby to prevent the
latter from rubbing against the wall of the borehole.
20. The improvement defined in claim 19 in which first and second
washover locks are mounted respectively on said stabilizer and on
the adjacent end of said sleeve assembly for locking said
stabilizer to said sleeve assembly.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to earth borehole drilling
apparatus and, more particularly, to drilling apparatus of the
general type disclosed in Lynes Pat. Nos. 3,233,676 and 3,235,017
with which the earth formations being penetrated can be sealed off
and the contents tested or treated during the drilling operation
without removing the drilling apparatus from the borehole. Testing
involves the taking of samples of fluids from the penetrated
formation, and treating involves the introduction of fluids, such
as an acid, into the lower end portion of the borehole.
As explained in detail in the aforesaid patents, conventional
formation testing has required the removal from the borehole of the
entire drilling apparatus, including the drilling tool and the stem
or the string of pipe from which the tool is suspended and by which
it is driven, followed by insertion of a separate tool for making
the test, removal of the testing tool, and reinsertion of the
drilling apparatus. Needless to say, these were time-consuming and
costly operations with many disadvantages, particularly in view of
the fact that many wells are as deep as 20,000 feet or more.
The disadvantages of such conventional testing techniques led to
the development of drilling apparatus of the type disclosed in the
Lynes patents with a so-called packer incorporated in the drilling
tool above the drill bit and having a packer-setting mechanism
actuated by manipulation of the drill string to expand the packer
radially into sealing engagement with the wall of the borehole
preparatory to testing the formation at the bottom of the borehole,
and then radially contracting the packer after the test is
completed. In this way, the lower end portion of the borehole can
be isolated from the remainder of the hole and from the drilling
fluid that is circulated through the hole during the drilling
operation, and formation testing of treating can be accomplished
through the drilling apparatus while the latter remains in the
borehole.
The Lynes packer takes the form of an elongated cylinder of
resiliently flexible material, such as rubber, telescoped over an
elongated, tubular extension of the drilling string, called the
mandrel, and longitudinally secured at its upper end to the mandrel
and abutting at its lower end against a tubular drive sleeve
assembly telescoped over the mandrel and carrying a drill bit on
its lower end. Below the packer is a spline connection between the
mandrel and the sleeve assembly for drivingly coupling the two
together in different angular positions in which the packer is
either longitudinally extended and radially contracted (the normal
drilling condition), or longitudinally contracted and radially
expanded (the packing condition), the drilling tool being driven
through the spline connection with the packer radially collapsed
during normal operation.
To shift the mandrel and the sleeve assembly selectively from one
position to the other, a cam-clutch mechanism also is included
between the sleeve assembly and the mandrel of the later Lynes
patent, to index the assembly step by step about the mandrel in
response to up-and-down motion of the mandrel relative to the drive
sleeve assembly.
While the Lynes developments have been a breakthrough in the
drilling art, problems have been encountered at their use,
including wearing of the packer as a result of rubbing against the
borehole wall, primarily because of failure of the packer to return
to and remain in its fully collapsed condition. This may be
attributable to the setting of the packer in a partially expanded
condition, to the effect of fluid pressure acting on the packer
from below, or to the upward force exerted by the drilling fluid
circulating upwardly around the drill string. Another possible
cause of packer wear may be the lateral displacement of the drill
string in the borehole during drilling, the rotary mounting of the
Lynes packer being less than totally effective in preventing wear
as a result of the accompanying rubbing of the packer against the
borehole wall.
SUMMARY OF THE INVENTION
The present invention resides in a drilling apparatus equipped with
a packer and a packer-setting mechanism having the advantages of
the Lynes apparatus and, in addition, in which the packer is
positively returned to and held in its collapsed condition to
eliminate rubbing engagement with the borehole wall and resulting
wear on the packer in service use. In addition, the portion of the
tool including the packer is positively maintained in generally
centered relation in the borehole to prevent rubbing contact
between the packer and the wall that could result from lateral
displacement of the tool or the drill string within the hole during
drilling.
In the preferred embodiment of the invention disclosed herein for
purposes of illustration, a novel retractor is interposed between
the lower end of the packer and the upper end of the drive sleeve
assembly and is connected at its upper end to the packer and
normally latched at its lower end to the mandrel to hold the packer
in its longitudinally extended, radially contracted drilling
condition. During the relative movement of the drive sleeve
assembly used to set the packer against the borehole wall, the
retractor first is unlatched to free the lower end of the packer
for movement along the mandrel, and then is moved along the mandrel
with the packer as the latter is expanded into sealing engagement
with the borehole wall. During radial collapsing of the packer, the
retractor is latched to the drive sleeve assembly so that the
packer is pulled positively back to the longitudinally extended,
radially collapsed position, the retractor being automatically
relatched to the mandrel when it reaches its original position in
which the packer is stretched longitudinally along the mandrel.
In addition, the retractor is positioned between upper and lower
washover-locks which are disengageable to permit indexing of the
drive sleeve assembly and reengageable to connect the lower end of
the packer nonrotatably to the upper end of the drive sleeve
assembly, thereby to facilitate the fishing operation used to
recover a disconnected tool, and at least one rotary stabilizer
larger in diameter than the collapsed packer is mounted on the tool
adjacent the packer to keep the packer generally centered in the
borehole and prevent rubbing contact of the packer with the wall of
the borehole.
Further improvements have been made in the Lynes-type of drilling
apparatus by changing the spline connection to increase its
load-bearing capacity and avoid deformation of the load-bearing
elements of the connection, and by changing the arrangement of
circulating ports in the tool so that the ports are closed at all
times other than when the packer is expanded, while also insuring
that the ports are opened despite variations in the amount of
relative movement of the mandrel and the sleeve assembly required
to obtain complete sealing of the borehole around the tool.
Other objects and advantages of the invention will become apparent
from the following detailed description, taken in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an elevational view of an earth borehole drilling
apparatus embodying the novel features of the present invention,
the apparatus being shown suspended in a borehole preparatory to a
drilling or testing operation with the packer collapsed, portions
of the apparatus being broken out for compactness of
illustration;
FIG. 2 is an enlarged transverse cross-sectional view taken through
the drilling apparatus substantially along the line 2-2 of FIG. 1,
adjacent the upper end of the drive sleeve assembly, and also along
the line 2-2 of FIG. 8;
FIG. 3 is a sectional view similar to FIG. 2 taken substantially
along the line 3-3 of FIG. 1, and also along the line 3-3 of FIG.
8;
FIG. 4 is a sectional view similar to FIG. 2 taken substantially
along the line 4-4 of FIG. 1, and also along the line 4-4 of FIG.
8;
FIG. 5 is a sectional view similar to FIG. 2 taken substantially
along the line 5-5 of FIG. 1, and also along the line 5-5 of FIG.
8;
FIG. 6 is a sectional view similar to FIG. 2 taken substantially
along the line 6-6 of FIG. 1, and also along the line 6-6 of FIG.
8;
FIG. 7 is a sectional view similar to FIG. 2 taken substantially
along the line 7-7 of FIG. 1, and also along the line 7-7 of FIG.
8;
FIG. 8 is an enlarged fragmentary cross-sectional view taken
longitudinally of the drilling apparatus substantially along the
line 8-8 of FIG. 1 with parts of the apparatus shown in side
elevation;
FIG. 9 is a view similar to FIG. 8 with parts in moved positions
showing the drilling condition of the apparatus;
FIG. 10 is a view similar to FIG. 8 with parts in moved positions
showing the condition of the drilling apparatus as the packer is in
the process of being collapsed;
FIG. 11 is a view similar to FIG. 8 with the parts in moved
positions showing the condition of the drilling apparatus when the
packer is fully expanded;
FIG. 12 is a perspective view of the retractor, the central portion
being broken away for compactness of illustration;
FIG. 13 is a developed diagrammatic view of the spline and
cam-clutch elements illustrating the indexing of the drive sleeve
assembly about the mandrel;
FIG. 14 is an enlarged cross section taken within the arc 14-14 of
FIG. 9 and showing the retractor latched to the mandrel and about
to be unlatched;
FIG. 15 is a view similar to FIG. 14 showing the unlatched
condition while the packer is expanded, the view being taken within
the arc 15-15 of FIG. 11; and
FIG. 16 is a view similar to FIG. 14 showing the condition of the
latching elements as the packer is being collapsed, the view being
taken within the arc 16-16 of FIG. 10.
DETAILED DESCRIPTION
As shown in the drawings for purposes of illustration, the
invention is embodied in an apparatus indicated generally at 20
(FIG. 1) for drilling an earth borehole 21, typically an oil well
borehole, and generally comprising a hollow drill stem or string 22
suspended in the borehole from the surface of the earth, and a
drilling tool mounted on the lower end of the string and including
a hollow mandrel 23 (FIGS. 8--11) fastened to the lower end of the
drill string by a connector 24, a flexible and radially expandable
packer 25 telescoped over the mandrel for expansion into sealing
engagement with the wall of the borehole, and a drive sleeve
assembly 27 telescoped over the mandrel below the packer and
carrying a conventional drill bit 28 on its lower end beyond the
lower end of the mandrel. The packer 25 is secured at its upper end
to the mandrel 23, through the connector 24, and is freely slidable
along the mandrel below the connector, and the drive sleeve
assembly, which is suspended below the lower end of the packer, is
both rotatable and longitudinally slidable relative to the
mandrel.
To couple the drive sleeve assembly 27 to the mandrel 23 for the
transmission of driving force, both rotary and vertical, from the
drill string 22 and the mandrel to the drill bit 28, interfitting
spline elements 29 and 30 (FIGS. 4, 6, 8--11 and 13) are mounted
respectively on the interior of an intermediate portion 31 of the
drive sleeve assembly 27 and upon the adjacent portion of the
mandrel, the sleeve element 29 herein comprising a set of
elongated, angularly spaced spline bars and the mandrel element 30
comprising a corresponding number of similarly spaced spline slots
or grooves formed in a barrel 32 fast on the mandrel above the
spline bars, for example, by welding. The spline grooves have open
lower ends (see FIG. 8) for receiving the bars in snug fitting
relation, and have closed upper ends 33 for abutting against the
upper ends of the spline bars when the mandrel and the drive sleeve
assembly are in a predetermined longitudinal relation constituting
the drilling position of the various parts. Although various
numbers of grooves 30 and bars 29 may be used, herein there are
three of each.
Between each pair of drilling grooves 30 is a similar but longer
groove 34 (see FIGS. 3, 4 and 8--11) which extends a substantially
greater distance upwardly into the barrel 32, beyond the ends 33 of
the drilling grooves 30. Three longer grooves thus alternate with
the drilling grooves to receive the spline bars 29 of the drive
sleeve assembly 27 when the latter is turned a preselected amount
about the mandrel, and permit the sleeve assembly to move upwardly
relative to the mandrel, beyond the drilling position to a packing
position when the spline bars are angularly aligned with the longer
grooves 34.
The relative longitudinal movement of the mandrel 23 and the sleeve
assembly 27 beyond the drilling position is used to compress the
packer 25 longitudinally and thus to expand it radially into
sealing engagement with the borehole wall for testing. For this
purpose, the upper end of the packer, which is an elongated sleeve
of suitable material such as rubber or a selected synthetic
material, is secured to the mandrel by means of bolts 35 embedded
in the upper end of the packer sleeve and extending upwardly
through a bolting ring 37 bonded to the end of the packer sleeve,
and also through a flange 38 on the lower end of the connector 24.
The connector is threaded onto the lover end of the drill string 22
and onto the upper end of the mandrel. An O-ring 39 prevents
leakage of fluid from the annulus 40 in the borehole around the
tool into the space between the packer and the mandrel. On the
lower end of the packer is a second ring 41 which is secured by
bolts 42 to a head 43 which is slidable along the mandrel and is
positioned to abut against a similar head 44 mounted on the upper
end of the drive sleeve assembly 27 to transmit the relative upward
motion of the drive sleeve assembly to the lower end of the
packer.
Thus, such motion acts to raise the lower end of the packer 25
along the mandrel 23 while the upper end of the packer is anchored
to the mandrel, thereby squeezing the packer longitudinally to
bulge it outwardly in the manner shown in an intermediate condition
in FIG. 10 and in a packing condition in FIG. 11, the spline bars
29 being angularly aligned with the longer, packing grooves 34
during this motion. Conversely, downward motion of the sleeve
assembly, from the packing position shown in FIG. 11, stretches the
packer back through the condition in FIG. 10 to the condition shown
in FIG. 8.
To align the spline bars 29 selectively with either the longer
packing grooves 34 or the shorter drilling grooves 29, a cam-clutch
indexing mechanism, indicated generally at 47 in FIG. 8--11, in
incorporated in the drilling apparatus to respond to successive
up-and-down movements of the mandrel 23 within the drive sleeve
assembly 27 and index and latter stepwise about the mandrel, one
full step for each up-and-down movement. Preferably, this
cam-clucth mechanism makes use of the elongated fingers 48 formed
between adjacent slots 29, 34 of the barrel 32, and also of the
lower ends of the spline bars 29, and further includes a clutch
cylinder 49 which is fast on the mandrel below the barrel, in
longitudinally spaced relation with the lower ends of the spline
fingers 48 to leave an annular space between the fingers and the
clutch cylinder at least as long as the spline bars. The clutch
cylinder herein is pinned to the lower end portion of the mandrel
at 50.
Formed on the upper end of the clutch cylinder 49 are a plurality
of indexing teeth 51 each having a longitudinally extending edge 52
on one side, the left side herein, and an inclined edge 53 on the
other side, and the tip of each such clutch tooth is generally
centered on one of the packing grooves 34 while the end of the
inclined side 53 at the bottom of the notch between two teeth 51 is
generally centered on the next drilling groove 30 to the right.
Moreover, the lower ends 54 of the fingers 48 are inclined upwardly
and to the right from their tips, each of which overlies one of the
inclined clutch edges 53. The lower ends of the spline bars 29
preferably are beveled to be parallel to these edges.
As the drilling apparatus 20 is lowered into the borehole 21 (FIGS.
1 and 8), the drive sleeve assembly 27 and the drill bit 28 are
suspended from the mandrel 23 by means of the spline bars 29, which
are seated in three of the notches between the clutch teeth 51,
thereby limiting the downward telescoping motion of the sleeve
assembly relative to the mandrel. After the drill bit engages the
bottom 57 of the borehole, continued downward motion of the drill
string lowers the mandrel through the drive sleeve assembly and
thus shifts the clutch cylinder 49 downwardly away from, and free
of, the spline bars 29.
Assuming that the spline bars 29 are angularly aligned with three
spline fingers 48 that are to the left of shorter, drilling grooves
30, as shown in FIG. 8, this lowering of the mandrel 23 brings the
beveled lower ends 54 of the spline fingers into engagement with
the upper ends of the spline bars to cam the bars to the right,
clockwise in FIG. 6, into alignment with the drilling grooves, thus
indexing the drive sleeve assembly 27 in the same direction. The
spline bars then slide into the drilling grooves and "bottom"
therein, as shown in FIG. 9, the accompanying longitudinal motion
being insufficient to initiate expansion of the packer 25. Then the
drill bit 28 is rotated and driven into the earth by rotary and
vertical driving forces applied through the barrel 32 to the spline
bars and thus to the drive sleeve assembly.
One important improvement in the present invention as compared to
the later Lynes apparatus is the squaring of both the upper ends 58
of the spline bars 29 and the upper ends 33 of the spline grooves
30 so that the opposed surfaces are substantially perpendicular to
the longitudinal axis of the drilling apparatus. It has been found
that the bevels on the upper ends of the Lynes spline bars were
unnecessary for proper indexing of the drive sleeve assembly 27
and, in fact, that such bevels reduced the load-bearing capacity of
the spline connection, sometimes became deformed in service use,
and subsequently interfered with proper operation of the drilling
apparatus. The squared ends distribute the load more effectively to
eliminate this problem.
When expansion of the packer 25 is desired, in order to seal off
the lower portion of the borehole 21 for testing or treating, the
drill string 22 is simply raised to raise the mandrel 23 within the
drive sleeve assembly 27 until the clutch cylinder 49 engages the
beveled lower ends of the spline bars 29 to cam the latter to the
right, and the drill string then is lowered to shift the beveled
lower ends 54 of the spline fingers 48 into engagement with the
squared upper ends of the spline bars. This cams the bars and the
sleeve assembly on to the right, and aligns the bars with the
longer packing grooves 34 so that continued downward motion of the
mandrel through the sleeve assembly shifts the bars upwardly into
and along the longer grooves, as shown in FIGS. 10 and 11.
The accompanying relative longitudinal motion of the mandrel 23
relative to the drive sleeve assembly 27, beyond the motion that
occurs during seating of the spline bars 29 in the drilling grooves
30, is applied to the packer 25 as longitudinal contracting or
compressing motion which expands the packer into sealing engagement
with the borehole wall. After testing its completed, another
up-and-down motion of the drill string 22 raises and then lowers
the mandrel, the spline barrel 32, and the clutch cylinder 49 to
return the packer to its axially elongated, radially collapsed
condition while indexing the drive sleeve assembly 27 to the
position in which the spline bars 29 are seated in the shorter
grooves 30 for resumption of drilling.
In accordance with the primary aspect of the present invention, the
lower end of the packer 25 normally is latched to the mandrel 23 in
a manner that holds the packer longitudinally extended and radially
collapsed, is unlatched automatically as an incident to the
movement of the spline bars 29 along the longer spline grooves 34
past the ends of the shorter grooves 30, thereby permitting the
lower end portion of the packer to be moved along the mandrel to
set the packer, and subsequently is positively returned to its
extended position and relatched to the mandrel to insure that the
packer is fully collapsed during drilling. To these ends, a
retractor 60 is incorporated in the drilling apparatus between the
packer and the upper end portion of the drive sleeve assembly 27
and is secured to the lower end of the packer and slidably mounted
on the mandrel. This retractor is provided with at least one latch
element 61 which is engageable with a detent 62 positioned on the
mandrel within the drive sleeve assembly to receive the latch
element when the packer is fully extended. On the inside of an
upper end portion 63 of the drive sleeve assembly is a release
element 64 that is engageable with the latch element, during
downward motion of the mandrel, and is operable to disengage the
latch element from the mandrel at a preselected point in the
relative motion. Moreover, the release element simultaneously
shifts the latch element into a second detent 65 on the sleeve
assembly so that the retractor 60 can be positively pulled back
along the mandrel to stretch and collapse the packer during the
raising of the mandrel and the downward relative motion of the
sleeve assembly.
In the present instance, the retractor 60 is an elongated,
generally cylindrical sleeve, shown most clearly in FIG. 12, having
an inside diameter selected for a close sliding fit with the
mandrel 23, and having a plurality of angularly spaced fingers 67
extending downwardly from its lower end to lie alongside the
mandrel below the upper end of the drive sleeve assembly. On the
lower end of each finger is a latch element 61 in the form of a lug
having an upwardly facing shoulder 61a on its inner side for
seating in an annular groove forming the detent 62 (FIGS. 8--11 and
14) in the mandrel.
The retractor fingers 67 herein are integral with the lower end
portion of the retractor sleeve and preferably are made resiliently
flexible to urge the latch lugs 61 radially inwardly toward the
mandrel and into the detent groove 62 therein. For convenience of
manufacture, the upper and lower portions of the retractor sleeve
may be separately formed and the joined into a unitary element by a
weld 68.
Encircling the upper end of the retractor 60 is a radial flange 69
which overhangs an upwardly facing shoulder 70 (FIGS. 8, 10 and 11)
in the head 43 fast on the lower end of the packer 23, the
underside of the bolting ring 41 being spaced above this flange so
that the retractor is secured to the packer by a lost-motion
connection permitting relative motion of the retractor within the
limits defined by the shoulder 70 and the underside of the bolting
ring. This accommodates a limited degree of change in the length of
the packer. An O-ring 71 prevents leakage of fluid past the flange
69 and through the lower end of the packer.
It will be seen in FIG. 8 that the retractor 60 extends downwardly
into the head 44 on the upper end of the drive sleeve assembly 27,
the detent groove 62 of the mandrel 23 being located adjacent the
underside of the head during lowering of the drilling apparatus 20
into the borehole 21. Immediately beneath the head 44 is an
elongated cylinder constituting the upper portion 63 of the drive
sleeve assembly, this cylinder being threaded at 27 into the head
and telescoped slidably over the retractor, extending beyond the
latch fingers 67 and along the mandrel with a clearance fit. The
interior of this cylinder bears against the outer sides of the
latch lugs 61 and normally holds the latter positively in the
detent groove 62.
The release element 64 is disposed inside the cylinder 63 a
selected distance below the latch lugs 61, as shown in FIG. 8, and
herein is in the form of an annular cam which slides along the
outside of the mandrel 23 and has an outwardly and downwardly
inclined outer surface 73 for passing inside the lower sides of the
lugs 61 and camming them out of the detent groove 62. The inner
surface of the release cam is relieved to avoid marring of the
mandrel.
Formed in the cylinder 63 immediately above the release cam 64 is
the second detent 65, which is an annular internal groove in the
cylinder for receiving the lugs 61 in the unlatched condition, this
detent groove having a downwardly facing upper side that overlies
upwardly facing shoulders 61b on the outer sides of the lugs to
latch the retractor 60 to the cylinder as shown in FIGS. 10 and 16.
Thus, as the mandrel is raised within the drive sleeve assembly 27
after a testing operation, the shoulders 61 are positioned to abut
against the upper side of the detent groove 65 and maintain the
retractor stationary relative to the sleeve assembly until the
detent groove 62 moves back into alignment with the latch lugs 61.
Then the lugs snap into the detent groove in the mandrel and out of
the groove in the cylinder, thereby to latch the packer 25 in the
extended position as the mandrel continues to rise within the drive
sleeve assembly. The packer and retractor thereafter remain
stationary relative to the mandrel while the drive sleeve is
indexed into the drilling position.
For convenience of manufacture, the cylinder 63 herein is formed in
two sections that are welded together at 74 below the detent groove
65, the upper section being threaded into the head 44 and the lower
section being threaded at 75 into the upper end of a cylinder 77
hereafter referred to as the upper drive sleeve. As viewed in FIG.
8, the barrel 32 of the mandrel 23 is disposed within this drive
sleeve.
It will be evident that the packer 23 is secured against rotation
relative to the drilling string, in contrast to the rotary packers
of the Lynes patents. Such rotation was not completely effective in
preventing rubbing wear as a result of contact with the borehole
wall, so the rotary mounting has been eliminated and such contact
is prevented, first, by the positively acting retractor 60 and,
second, by positively centering the packer section of the drilling
tool in the borehole. For this purpose, at least one rotary
stabilizer 78 is included in the drilling apparatus close to the
packer 25, herein on the upper end of the drive sleeve assembly 27.
Such stabilizers have been used conventionally to assist in keeping
a borehole going straight during drilling, and are formed with
maximum outside diameters slightly smaller than the borehole
diameter and substantially greater than the collapsed diameter of
the packer. The stabilizer 78 used herein comprises a tough,
longitudinally grooved sleeve 79 of wear-resistant material fast on
a metal cylinder 80 that is telescoped onto the cylinder 63 and
confined thereon beneath a wear ring 81 below the head 44 and above
an annular member 82 fast on the outside of the lower section of
the cylinder 63.
Although only one stabilizer 78 is shown, a second can be similarly
mounted immediately above the packer 25. It will be apparent that
such a stabilizer or stabilizers limit the lateral deflection that
is possible in the adjacent sections of the drilling tool, and thus
protect the collapsed packer against engagement with the borehole
wall.
If the drilling tool should, for any reason, become disconnected
from the drill string 22, it often is desirable to be able to
"fish" the tool out of the borehole 21 before normal drilling is
resumed. Such fishing is a complicated and highly developed art
involving special methods and special tools that are well known to
those skilled in the art. The present apparatus is designed so that
it can be "washed over" and fished out and, for this purpose, the
heads 43 and 44 are formed as so-called "washover locks" having
ratchet teeth 83 on their adjacent ends. These teeth are engaged
when the two heads are pressed together, and thus lock the lower
end of the packer 25 to the upper end of the drive sleeve assembly
27. Similarly, teeth 84 (FIGS. 8--11) are formed on the lower end
of the stabilizer 78 to mesh with opposed teeth on the annular
element 82 below the stabilizer, thus constituting two additional
washover locks for holding the stabilizer against rotation.
During testing, the drill bit 28 is pressed against the bottom 57
of the borehole 21 as a result of the manipulation of the drilling
apparatus 20 with which the packer 25 is expanded. Accordingly, it
is possible, or even likely, that the normal fluid circulation
ports (not shown) in the bit will be plugged, and it is desirable
to provide an auxiliary path for the flow of fluids into and out of
the drilling apparatus below the packer, the direction of flow
depending upon whether a sample is being taken from a formation or
a treating fluid is being introduced into the formation. Although
ports have been provided for this general purpose before, the
present invention, in one of its secondary aspects, contemplates
the provision of auxiliary ports 85 in the drive sleeve assembly 27
above the bit 28, which are open only when the apparatus is in the
testing and treating condition, the ports being reliably opened
during expansion of the packer 25 regardless of variations in the
extent of motion of the mandrel 23 required to expand the packer
into full sealing engagement with the borehole wall.
As shown in FIGS. 1 and 8, an annular series of such ports 85 is
formed in a lower portion 87 of the drive sleeve assembly 27,
hereafter called the lower drive sleeve, and a second annular
series of ports 88 is formed in the mandrel 23 in communication
with the interior of the mandrel and, therefore, with the interior
of the drill string 22. These latter ports open at their outer ends
through the clutch cylinder 49 into an elongated annular connecting
chamber 89 around the clutch cylinder formed by reducing a
substantial portion of the outside diameter of the cylinder within
the lower drive sleeve. The connecting chamber extends both above
and below the ports 85.
As the drilling apparatus 20 is being lowered into the borehole 21,
the connecting chamber 89 is spaced well above the level of the
ports 85 in the lower drive sleeve 87, as shown in FIG. 8, and is
sealed therefrom by an O-ring 90 encircling the clutch cylinder 49
below the chamber. Thus, the ports 85 are closed. Another O-ring 91
below the ports prevents leakage past the lower end of the mandrel,
on which a locking nut 92 is threaded, and locked in place by a
double ring 92a of the type sold under the name "Spirolox" beneath
the end of the clutch cylinder. In the drilling position of the
parts shown in FIG. 9, the ports 85 remain below the connecting
chamber 89 and thus remain closed.
During the additional relative longitudinal motion used to expand
the packer 25, however, the ports 85 in the lower drive sleeve 87
are shifted into alignment with the connecting chamber 89, and in
this manner are brought into communication with the ports 88
through the clutch cylinder and the mandrel 23 and, therefore, with
the interior of the mandrel. If there is a variation in the amount
of endwise mandrel movement required to set the packer and seal the
borehole 21, the ports 85 may be spaced somewhat above or below the
exact center of the connecting chamber 89, but the elongation of
the chamber insures the opening of the ports despite such
variation.
It has been pointed out that the retractor 60 preferably is
fabricated in two parts that are joined together by the weld 68,
and that the cylinder 63 carrying the release cam 64 and the detent
groove 65 similarly is made in two welded parts. To facilitate the
manufacture of the drive sleeve assembly 27 with the spline bars 29
in the intermediate section 31, the sleeve assembly also comprises
a plurality of separately formed parts that are coaxially joined by
a weld 93 between the upper drive sleeve 77 and the intermediate or
spline portion 31, and by a second weld 94 between the intermediate
portion and a cylinder 95 which may be called the middle drive
sleeve. This sleeve is threaded at 97 onto the lower drive sleeve
87, which has a sleeve connector 98 threaded into its lower end for
coupling the sleeve assembly through one or more drill collars to
the drill bit 28. O-rings are shown at appropriate places for
sealing the fluids in or out of appropriate parts of the apparatus,
and provision has been made for lubrication where this is
desirable. These details need not be specifically described, as
they are illustrated generally and are within the skill of those
acquainted with this general type of apparatus.
SUMMARY OF OPERATION
Although the manner of operation of the drilling apparatus 20,
including the packer 25, should be readily apparent from the
foregoing detailed description, a brief recapitulation of the steps
and procedures should be worthwhile to emphasize more clearly the
features of the invention. Assuming that the borehole 21 has been
started in the conventional manner and that the drilling apparatus
is spaced above the bottom 57 of the hole, the drill bit 28 is
lowered into the hole until it reaches the bottom, the drive sleeve
assembly 27 being suspended from the mandrel 23 as shown in FIG. 8
as a result of the engagement of the spline bars 29 with the
toothed upper end of the clutch cylinder 49 pinned to the
mandrel.
In this condition, the retractor 60 is latched to the mandrel 23 by
the engagement of the lugs 61 with the detent groove 62, the packer
25 is longitudinally stretched to its full length and thus is
radially collapsed to its smallest diameter, and the ports 85 in
the lower drive sleeve 87 are out of communication with the
connecting chamber 89 so as to be closed. If fluid is to be
circulated through the drilling apparatus, its only exit path from
the apparatus is through the bit 28.
After the bit 28 reaches the bottom 57 of the borehole 21, downward
motion of the drive sleeve assembly 27 ceases and continued
lowering of the drill string 22 pushes the mandrel 23 down through
the sleeve assembly to disengage the clutch teeth 51 from the
spline bars 29 and then shift the spline fingers 48 into engagement
with the squared upper ends 58 of the bars so that the latter are
cammed to the right (FIG. 8) into alignment with one set of the
grooves 30, 34. Assuming that the aligned set is the set of
shorter, drilling grooves 30 and that drilling is to be resumed
without a test or treatment, the drill string is lowered until the
squared upper ends of the bars seat against the squared upper ends
33 of the drilling grooves. Then the apparatus is in the drilling
condition shown in FIG. 9 so that the tool can be rotated through
the spline connection and simultaneously pressed into the
earth.
If the spline bars 29 have entered the set of longer grooves 32,
the apparatus is shifted to the drilling condition simply by
raising the mandrel 23 and the clutch cylinder 49 until the spline
bars are engaged by the aligned clutch teeth 51, thus indexing the
drive sleeve assembly 27 one-half step, and then again lowering the
mandrel until the upper ends 58 of the spline bars are engaged by
the beveled fingers 48 to index the drive sleeve assembly the
remaining one-half step. The bars then slide into the shorter
grooves 30 and bottom therein as previously described. During all
of this motion, the retractor 60 remains latched to the mandrel 23
to maintain the packer 25 stretched to the radially collapsed
condition.
To convert the apparatus 20 from the drilling condition (FIG. 9) to
the testing and treating condition (FIG. 11), the mandrel 23 is
raised until the aligned clutch teeth 51 engage the lower ends of
the spline bars 29 and index the bars and the sleeve assembly 27
one-half step away from the shorter grooves 30, and then is lowered
so that the beveled fingers 48 engage the upper ends of the spline
bars and complete the indexing of the sleeve assembly to bring the
bars into alignment with the longer, packing grooves 34. Continued
lowering of the mandrel then slides the barrel 32 along the spline
bars past the normal drilling position, and thus begins shifting
the release cam 64 along the mandrel toward engagement with the
latch lugs 61, beyond the position shown in FIG. 14, so that
continued upward motion of the release cam along the mandrel
results in spreading of the fingers 67 away from the mandrel to
remove the lugs from the inner detent groove 62 while swinging them
into the outer detent groove 65.
Accordingly, the retractor 60 is unlatched from, and pushed
upwardly along, the mandrel as the washover locks 43 and 44 are
engaged and the lower end of the packer 25 is raised relative to
the upper end, all as shown in FIG. 10. This expands the packer
radially within the borehole 21 until the periphery of the packer
is pressed sufficiently tightly against the borehole wall to seal
off and isolate the lower portion of the hole, as shown in FIG. 11.
When this condition is achieved, the spline bars 29 typically are
adjacent the upper ends of the longer slots 34, as shown in FIG.
11, and the connection chamber 89 is in overlapping relation with
the annular series of ports 85 in the lower drive sleeve, thus
establishing communication with the ports 88 for a bypass flow of
liquid through the two sets of ports around the drill bit 28. In
case a tight seal has been obtained before the spline bars 29 move
the full extent into the longer grooves, expansion can be
terminated with the ports 85 in a different position along the
connecting chamber but reliably opened to communicate with the
ports 88.
As described in Lynes Pat. No. 3,233,676, a bailer or swab (not
shown) may be run into the drill string to remove sufficient
drilling fluid to lower the pressure in the sealed-off lower
portion of the borehole 21, thereby permitting formation fluids to
enter the borehole for removal through the drill string, or a
selected fluid can be pumped down through the drill string before
the packer is set to displace the drilling fluid from the
apparatus. In the latter case, the pumping pressure is released
after the packer is set, and the fluid is bled off as a gas to
permit the test or treatment to be made.
When the test or treatment is completed, the drill string 22 is
again raised relative to the sleeve assembly 27, thus shifting the
mandrel 23 and the barrel 32 upwardly relative to the spline bars
29. The upper end of the packer 25 is raised with the mandrel 23
while the lower end is latched through the retractor 60 to the
outer detent 65 in the cylinder 63 which, of course, is part of the
drive sleeve assembly 27 and thus remains stationary. Accordingly,
the packer is stretched longitudinally by this positive separation
of its ends until the detent groove 62 of the mandrel is raised
into alignment with the latch lugs 61.
At this time, the resilience of the fingers 67 of the retractor 60
cause the lugs 61 to snap inwardly into the inner detent groove 62,
at the same time leaving the outer detent groove 65 so that the
cylinder 63 is freed for movement relative to the retractor. Thus,
the cylinder slides over the latch lugs to the position shown in
FIG. 8 as the upward stroke of the mandrel is completed.
In this manner, the packer 25 is returned positively to its
radially collapsed condition despite any tendency it may have to
set in a partially expanded condition. Moreover, it is positively
latched in the collapsed condition against inadvertent expansion by
fluid pressure acting from below or by any other expanding force.
This, together with the positive centering action of the stabilizer
78, insures against rubbing contact of the collapsed packer with
the borehole wall during drilling.
From the foregoing, it will be evident that the present invention
overcomes the problems encountered with prior drilling apparatus of
the same general type, and does so in a novel, relatively simple
and highly effective manner which makes the Lynes-type of apparatus
commercially practical. Moreover, the invention is useable in
special drilling situations as a down-hole blowout preventer to
seal the annulus around the drill string and prevent oil from
rising within the annulus and escaping through fissures toward the
surface, thus overcoming serious problems that have been
encountered in recent drilling operations.
It also will be evident that, while a particular embodiment of the
invention has been illustrated and described, and a specific use
has been suggested, various modifications and other uses can be
made without departing from the spirit and scope of the
invention.
* * * * *