Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DEVICE AND METHO~ FOR
SHIFTIN~ A PORT COLLAR SLEEVE
The invention relates to a tool for shifting
a sleeve positioned slideably inside of a tubular
member, such as a well casing. In a specific application,
the tool is designed for shifting a slidable sleeve
inside of a port collar, of the type used in well
cementing operations.
When boreholes are drilled to recover oil or
gas, a well casing is lowered into the hole and cemented,
usually at the lower end of the hole and frequently at
other locations above the lower end. When the lower
end of the casing is cemented, usually referred to as
primary cementing, a cement slurry is passed down
through the casing and up into the annular space defined
between the casing and the borehole. Cementing above
the lower end of the borehole is usually done later
than the primary cementing job, that is, during the
productive life of the well. The later operations are
sometimes referred to as secondary cementing, or stage
; cementing.
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One of the devices commonly used in stage
cementing operations is a port collar. A port collar
can be generally described as a coupling between sections
of well casing which has openings (ports) in the collar
wall. Positioned inside the collar is a sliding sleeve,
referred to as a port collar sleeve, which also has
ports in the sleeve wall. Prior to cementing, the
sleeve is in a position such that it closes off the
collar ports. When it is desired to pump cement into
the borehole annulus through the openings in the port
collar, a shifting tool is used to slide the sleeve to
a position in which the sleeve ports and collar ports
are in direct alignment.
Some of the known shifting tools are described
in U.S. Patents 2,667,926 (Alexander~, 3,768,562 (Baker),
and 3,948,322 (Baker). In general, the shifting tools
described in these patents require a mechanical opera-
tion which give the tools several disadvantagesO For
example, the mechanical linkage of the tool can sometimes
"hang up" inside the port collar-sleeve a~sembly. When
this happens, it makes it difficult to disengage the
tool between each shifting se~uence. Another problem
is that some of the tools are designed to engage and
shift only one port collar at a time, that is, the
engaging mechanism is not capable o being retracted to
enable the tool to pass through one port collar to
engage another. Another undesirable feature is that
some of the tools require rotating the drill pipe to
which the tool is fastened to latch the tool into the
port collar sleeve.
The shifting tool of this invention overcomes
the problems mentioned above, by providing an engaging
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mechanism which operates by hydraulic fluid pressure,
rather than by mechanical linkage. The tool described
herein is also simpler to operate than the prior tools
because of fewer moving parts. In addition, this tool
can pass through any number of port collars in a given
drill string. This feature enables the tool to engage
and shift each port collar sleeve an indefinite number
of times in a given operation.
In its broadest application, the tool of this
invention is useful for shifting a sleeve positioned
slideably inside a tubular section, such as a well
casing. As a specific application, the present tool is
designed for shifting a port collar sleeve to open and
close the ports in the collar. The port collar is
coupled between sections of a well casing and it has
fluid outlet ports therein. The port collar sleeve,
which is slideable inside the collar also has fluid
outlet ports therein.
This device includes a shifting tool assembly
which, in an operating position, sets or locks inside
of the port collar sleeve. The shifting tool assembly
is made up of a housing member and a piston assembly.
Inside the housing member is a lengthwise bore, which
is intersected by a transverse bore. The bottom end of
a tubing string, which is positioned in the well casing
is connected to the housing member and in fluid com-
munication with the lengthwise bore. At the top end,
the tubing string is connected to a source of an operating
fluid. The piston assembly is made up of at least one
piston section which is slideable along the transverse
bore of the housing member.
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Each piston section includes an inner piston
section and an outer piston section. The inner piston
section has an operating face, and the outer piston
section has a seating face. When the operating fluid
is directed through the tubing string, under pressure,
it engages the operating face of the inner piston
causing the piston assem~ly to move outwardly so that
the seating face of the outer piston section can seat
within the groove in the port collar sleeve.
The shifting tool also includes a hollow
mandrel, a packing sleeve assembly, and a check valve
assembly. The mandrel is connected to the housing
member in 1uid communication with the lengthwise bore
in the housing member. Fluid outlet ports are provided
in the mandrel. The packing sleeve assembly is posi-
tioned on the outside of the mandrel such that it
normally covers the fluid outlet ports in the mandrel.
In another position, the packing sleeve remains in
place in the well casing and the mandrel slides upwardly
through the sleeve to uncover the fluid outlet ports.
The check valve assembly is positioned within the
mandrel~ This valve has a closed position in which
fluid is blocked from flowing through the mandrel. In
additionl the check valve has an open position in which
fluid can flow through the mandrel.
The present invention resides in a well tool
for shifting a port collax sleeve, the sleeve being
slideably positioned inside a port collar, and the
sleeve having a groove defined on the inside wall
surface thereof, the tool comprising:
a housing member having therein a lengthwise
bore which is intersected by a transverse bore, the
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lengthwise bore being connected to a tubing string
adapted to carry an operating fluid into said length-
wise bore; and
a piston assembly including an inner piston
section and an outer piston section, the piston assembly
being slideably positioned within the transverse bore
of the housing member, the inner piston section having
an operating face adapted to operatively engage the
operating fluid, and the outer piston section having a
seating face adapted for seating engagement within a
groove defined on an inner wall of the port collar
sleeve;
the port collar and port collar sleeve each
having at least one fluid outlet port and said shifting
tool being adapted to shift the port collar sleeve to
an open position in which the fluid outlet ports in
said sleeve and said collar are in alignment with each
other, and to a closed position in which said fluid
outlet ports are out of alignment.
The invention also resides in a method for
shifting a port collar sleeve on a well tool comprising
the steps of:
coupling a port collar between sections of a
well casing, the collar having at least one fluid
2S outlet port therein;
positioning the port collar sleeve for slideable
movement within the port collar, the sleeve having at
least one fluid outlet port therein and a groove defined
on the inner wall surface of the sleeve;
positioning a shifting tool assembly within
the port collar sleeve, the shifking tool assembly
including a housing member and a piston assembly and
being in communication with a tubing string, the tubing
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string being positioned in said well casing and adapted
to carry an opexating fluid to the shifting tool assembly,
the piston assembly being positioned for slideable
movement within the housing member and having an operating
face adapted to be engaged by the operating ~luid, and a
seating face adapted on seating engagement within the
groove in the port collar sleevei
directing the operating fluid under pressure
through the tubing string and into the housing member
for pressure engagement with the operating face of the
piston assembly
thereby moving the piston assembly toward the
port collar sleeve such that the seating face of said
piston assembly seats within the groove in the port5 collar sleeve; and
pulling the shifting tool assembly upwardly
to move the port collar sleeve into a position in which
the fluid outlet port in the sleeve is in alignment
with the fluid outlet port in the collar.
FIGURE 1 is an eleva~ion view, in section,
illustrating the shifting tool of this invention as it
appears while being run into a well casing.
FIGURE 2 is a second elevation view, in
section, which illustrates schematically the position
of the shifting tool when the tool is in engagement
with a port collar sleeve, prior to shifting the sleeve.
FIGURE 3 is a third elevation view, in section,
which illustrates the position of the shifting tool
when it is being pulled out of the well casing.
FIGURE 4 is a detail view illustrating the
position of the shifting -tool and port collar sleeve
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before the sleeve is shifted to open the port collar.
FIGURE 5 is a second detail view showing the
position of the shifting tool and the port collar
sleeve after the sleeve has been shifted to a position
which opens the port collar.
In the drawing, the shifting tool assembly of
this invention is designated generally by the letter T.
The basic tool consists of a housing member 10 and a
piston assembly, which includes an outer piston section 11
and an inner piston se~tion 12. Inside the housing
membex 10 is a lengthwise bore 13, which is intersected
by a tranverse bore 14. The piston assembly is positioned
to slide laterally within the bore 14. The bore 14 is
indicated generally in FIGURES 1, 2 and 3, but it is
best shown in the detail views of FIGURES 4 and 5.
During an operating sequence, such as cementing,
the tool T is lowered into a well casing 15. Sections
of the well casing 15 can be coupled togethPr by one or
more port collars 16. The poxt collar 16 is shown only
in the detail views of FIGURES 4 and 5. The top end of
the housing member 10 is coupled to the bottom end of a
tubing string 17, such that the tubing string communicates
with the bore 13 in the housing member. The other end
of the tubing string is connected to a source of an
operating fluid. The fluid source is not illustrated
herein. A hollow mandrel 18 is coupled to the bottom
end of the bore 13 in housing member 10. Near khe top
end of mandrel 18 are several fluid outlet ports 19.
A packing sleeve assembly is positioned to
slide up and down on the outside of mandrel 18 below
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the shifting tool assembly. A packing sleeve 20 defines
the main part of this assembly. An upper packing
element 21 is sandwiched between the sleeve 20 and
mandrel 18, to seal the upper end of the sleeve. At
the bottom end, the sleeve 20 is sealed by a lower
packing element 22. Packing element 21 is held in
place by a retainer ring 23. A similar retainer ring
24 holds the pac~ing element 22 in place. The packing
sleeve also includes several drag springs, which are
indicated by numeral 25. Each drag spring is fastened
to the top end of the packing sleeve 20 by a retainer
ring 26. At the bottom of the sleeve a second retainer
ring 27 clamps the springs to the sleeve.
A mule shoe 28 is fastened to the bottom end
of the mandrel 18 by a coupling 29. A check valve
assembly is positioned inside of the mule shoe. In
general, the check valve is made up of a nipple section
30, which has a lengthwise bore 31 therein, and a ball
32. A set o~ shear screws 33 holds the nipple section
30 in place inside the mule shoe 28. In its normal
position inside the mule shoe 28, as illustrated in the
drawing, the nipple section 30 seals off the fluid
outlet ports 28a in the mule shoe. When fluid from the
tubing string flows downwardly through the housing
member and the mandrel 18, the ball 32 will seat onto
the upper end of nipple section 30 to close bore 31 and
stop the fluid flow at that point (note FIGURES 2 and
3). Conversely, the pressure of fluid flowing upwardly
through the mule shoe 28 will cause the ball 32 to
unseat from the nipple section 30 to open bore 31, as
shown in FIGURE 1, and thereby allow unrestricted fluid
flow through the mandrel, the housing member, and the
tubing string.
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As shown in FIGURES 4 and 5, a port collar
sleeve 34 is positioned inside the port collar 16. The
port collar includes several fluid outlet ports 16a,
and similar fluid outlet ports 34a are defined in the
wall of sleeve 34. Numeral 35 refers to alternating
fingers and slots, which are machined into the top end
of sleeve 34. The fingers and slots 35 on sleeve 34
are adapted to mesh with a corresponding set of alternating
fingers and slots 36, which are machined into the
bottom end of a coupling 15a. The coupling 15a actually
connects the port collar 16, at its top end, to a
section of the well casing 15. As shown in FIGURE 5,
the upwardly-directed fingers and slots 35 mesh with
the downwardly-directed fingers and slots 36 only when
the port collar sleeve 34 is shifted upwardly.
The invention can be illustrated by describing
the use of the present shifting tool in a typical well
cementing operation. Prior to injecting cement into
the well casing 15, the shifting tool is run into the
casing 15 on the end of the tubing strin~ 17, until it
reaches a point just above the port collar 16. During
the running-in step, as illustrated in FIGURE 1, the
ball 32 is unseated from the bore 31 in nipple section
30. As explained earlier~ the ball is unseated ~y the
pressure of that part of the fluid which passes upwardly
through the mule shoe 18 and into the mandrel 18, the
housing member 10, and the tubing string 17. The rest
of the fluid in the well casing will remain on the
outside of the shifting tool, that is, between the
shifting tool and the casing, during the run-in step.
Referring again to FIGURE 1, as the shifting
tool is lowered into the casing, khe piston assembly is
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held in the retracted position by the hydrostatic
pressure of that part of the fluid which remains on the
outside of the tool. To explain further, the surface
area of the seating face lla of outer piston section 11
is greater than the surface area of the operating face
12a of inner piston section 12. For this reason, the
fluid pressure which bears against the seating face lla
of outer piston section 11, during the running-in step,
is greater than the 1uid pressure which bears against
the operating face 12a of inner piston section 12. The
result is that the piston assembly is pushed inwardly
and held in a "retract" position as the shifting tool
is lowered into the casing.
When the shifting tool reaches a point slightly
above the port collar 16, additional pressure is applied
to the fluid in the tubing string. As a typical example,
the additional pressure applied is about 500 psi above
the hydrostatic pressure of the fluid at that level.
This causes the pressure against the operating face 12a
of inner piston section 12 to be substantially grea-ter
than the normal hydrostatic pressure action against the
operating face lla. Therefore, when the shifting tool
is lowered into the port collar sleeve 34, the higher
pressure against the operating face 12a ~orces the
piston assembly to move outwardly. As the piston
assembly moves outwardly, the seating face lla seats
into a transverse groove 34b in the port collar sleeve
34. This sequence is illustrated schematically in
FIGURE 2 and in detail in FIGURE 4.
Once the piston assembly is seated in the
transverse groove 34b o~ the port collar sleeve 34, an
additional pressure of 500 psi is applied to the fluid
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in the tubing string 17. This is done to lock the
piston assembly into position with the port collar
sleeve. The port collar sleeve is then shifted upwardly
by pulling up on the tubing string. The upward travel
of the port collar sleeve 34 stops when the fingers and
slots 35 on the sleeve 34 are completely meshed with
the fingers and slots 36 on coupling 15a. At this stop
point the outlet ports 34a in sleeve 34 are directly
aligned with the outlet ports 16a in port collar 16, as
shown in FIGURE 5. Also, at the stop point, a set of
collet fingers 34c, which are mounted on sleeve 34,
latch into a recess 16b on the port collar 16. The
purpose of these collet fingers is to provide an addi-
tional means for properly locating the sleeve 34
relative to the port collar 16.
Referring particularly to FIGURE 3, after the
port collar sleeve 34 has been shifted to line up the
ports in sleeve 34 with the ports in collar 16, the
next step is to disengage the shifting tool from sleeve
34. This is done by releasing pressure on the fluid in
the tubing string, so that the piston assembly will
retract. After the shifting tool is disengaged from
sleeve 34, the tubing string 17 is pulled upwardly to
remove the shifting tool from the well casing. Cement
can then be pumped down the casing 15 and into the
borehole annulus Inot shown) through the aligned open
ports 34a and 16a in the sleeve and collar assembly.
When the shifting tool is pulled upwardly on
the end of the tubing string, the packing sleeve
assembly remains stuck in the well casing because of
the drag of springs 25 against the casing wall. With
the packing sleeve remaining "fixed" in the casing, the
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mandxel 18 thus slides upwardly through the packing
sleeve and uncovers the outlet ports l9 in the mandrel.
The purpose in having ports 19 open is to permit the
fluid in the tubing string to circulate i~to the casing,
as the string is pulled up, to prevent a pressure
build up inside the string.
If a malfunction should occur in the pac~ing
sleeve assembly, so that the ports 19 are not uncovered
when the tu~ing string is pulled upwardly, the pressure
build-up in the string can be prevented by another
means. For example, if such a malfunction takes place,
sufficient pressure is applied to the fluid in the
tubing string to shear the screws 33 which secure the
nipple section 30 to the mule shoe 28. Shearing the
screws 33 allows the nipple section 30 and ball 32 ~o
slide down past the outlet ports 28a in the mule shoe.
The fluid in the tubing string can then circulate into
the casing through the open ports 28a in the mule shoe.
After the cementing operation, or other
desired downhole operation is completed, the next step
is to close the ou~let por~s in the port collar 16.
This is done by running the shifting tool back into the
well casing 15 to re-engage the port collar sleeve 34
in the same manner as described earlier. Once the
piston assembly re-enyages port collar sleeve 34, and
is locked into place, enough weight is set on the
tubing string 17 to move the sleeve back down to its
original position (the position shown in FIGURE 4), so
that the sleeve again closes off the ports in collar
16.
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