[0001] 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.
[0002] 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.
[0003] 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.
[0004] 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 operation which give the tools several disadvantages.
For example, the mechanical linkage of the tool can sometimes "hang up" inside the
port collar-sleeve assembly. When this happens, it makes it difficult to disengage
the tool between each shifting sequence. 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 of 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.
[0005] The shifting tool of this invention overcomes the problems mentioned above, by providing
an engaging 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.
[0006] 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.
[0007] 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
communication 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.
[0008] 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 assembly
to move outwardly so that the seating face of the outer piston section can seat within
the groove in the port collar sleeve.
[0009] 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 fluid communication
with the lengthwise bore in the housing member. Fluid outlet ports are provided in
the mandrel. The packing sleeve assembly is positioned 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 addition, the check valve has an open
position in which fluid can flow through the mandrel.
[0010] The present invention resides in a well tool for shifting a port collar 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 lengthwise bore being connected to a tubing string adapted to carry an operating
fluid into said lengthwise bore; and
a piston assembly including an inner piston section and an outer piston section, the
piston sections 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.
[0011] 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 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 shifting tool
assembly including a housing member and a piston assembly and 'being in communication with a tubing string, the tubing string being positioned in
said well casing and adapted to carry an operating 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 fluid, and a seating
face adapted on seating engagement within the groove in the port collar sleeve;
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 port 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 elevation 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 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.
[0012] 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 section 12. Inside the
housing member 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.
[0013] 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 together by one or more port
collars 16. The port 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 the top end of mandrel 18 are
several fluid outlet ports 19.
[0014] A packing sleeve assembly is positioned to slide up and down on the outside of mandrel
18 below 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 packing 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.
[0015] 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 of 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.
[0016] 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.
[0017] 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 string 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 by 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.
[0018] Referring again to FIGURE 1, as the shifting tool is lowered into the casing, the
piston assembly is 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 fluid 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.
[0019] 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 greater 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 forces 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.
[0020] Once the piston assembly is seated in the transverse groove 34b of the port collar
sleeve 34, an additional pressure of 500 psi is applied to the fluid 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 additional
means for properly locating the sleeve 34 relative to the port collar 16.
[0021] 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 (not shown) through the aligned open ports
34a and 16a in the sleeve and collar assembly.
[0022] 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 mandrel 18 thus slides upwardly through the packing sleeve and uncovers the outlet
ports 19 in the mandrel. The purpose in having ports 19 open is to permit the fluid
in the tubing string to circulate into the casing, as the string is pulled up, to
prevent a pressure build-up inside the string.
[0023] If a malfunction should occur in the packing sleeve assembly, so that the ports 19
are not uncovered when the tubing 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 to 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.
[0024] After the cementing operation, or other desired downhole operation is completed,
the next step is to close the outlet ports 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-engages
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.
1. A well tool for shifting a port collar 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 lengthwise bore being connected to a tubing string adapted to carry an operating
fluid into said lengthwise bore; and
a piston assembly including an inner piston section and an outer piston section, the
piston section 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.
2. The well tool of Claim 1, including a hollow mandrel having at least one fluid
outlet port therein, said mandrel being connected at one end to the lengthwise bore
of the housing member;
a packing sleeve assembly slideably positioned on the mandrel, said packing sleeve
assembly being slideable to a closed position in which the sleeve assembly covers
the fluid outlet port in the mandrel, and being slideable to an open position in which
said fluid outlet port is uncovered; and
a check valve assembly positioned within the mandrel, said valve assembly having a
closed position for blocking fluid flow through the mandrel and an open position for
allowing fluid to flow through the mandrel.
3. The well tool of Claim 1 or 2 in which the seating face of the outer piston section
has a greater surface area than the surface area of the operating face of the inner
piston section.
4. The well tool of Claim 1, 2 or 3, including integral slots and fingers defined
in the upper end of the port collar sleeve and in the lower end of a well casing section
positioned above said sleeve, wherein the respective fingers and slots of the well
casing section and the port collar sleeve are adapted to mesh when the port collar
sleeve is moved to a closed position.
5. The well tool of any one of the preceding Claims in which the groove in the port
collar sleeve is a transverse groove located below the fluid outlet port in the port
collar sleeve.
6. The well tool of Claim 2 in which the packing sleeve assembly includes a sleeve
which is slideably moveable on the mandrel, first and second packing elements positioned
between an inner wall surface of the packing sleeve and an outer wall surface of the
mandrel, and a set of drag springs mounted on the outside of the packing sleeve and
adapted to ride against an inner wall surface of a well casing section.
7. The well tool of Claim 2 in which the check valve assembly includes a mule shoe
coupled to the lower end of the mandrel, a nipple section positioned within the mule
shoe, and a ball member adapted to seat onto the upper end of the nipple section to
block the flow of fluid through a bore in the nipple section when the fluid flows
downwardly from the mandrel into the mule shoe, and the ball being adapted to unseat
from the nipple bore when fluid flows upwardly through the mule shoe into the mandrel.
8. 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 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 shifting tool
assembly including a housing member and a piston assembly and being in communication
with a tubing string, the tubing string being positioned in said well casing and adapted
to carry an operating 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 fluid, and a seating face adapted on seating
engagement within the groove in the port collar sleeve;
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 port 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.
9. The method of Claim 8 including the steps of:
reducing the operating fluid pressure sufficiently to cause the operating face of
the piston assembly to disengage from the groove in the port collar sleeve; and
pulling upwardly on the tubing string to remove the shifting tool from the well casing.