Note: Descriptions are shown in the official language in which they were submitted.
CA 02563145 2006-10-11
SAND BARRIER FOR A LEVEL 3 MULTILATERAL
WELLBORE JUNCTION
BACKGROUND OF THE INVENTION
A multilateral wellbore system by definition includes at least a
primary wellbore and a lateral wellbore extending therefrom. The junction
between the primary wellbore and the lateral wellbore in some cases is an
avenue for sand and other particulate matter infiltration into the wellbore
system which generally results in the entrainment of such particulate matter
with the production fluid. Clearly, it is undesirable to entrain particulate
matter
in production fluid since those particulates would then need to be removed
from the production fluid adding expense and delay to a final release of a
product. The reasons for particulate infiltration through a junction in a
multilateral wellbore are many, including the not entirely controllable window
size and shape which is generated by running a milling tool into the primary
wellbore and into contact with a whipstock whereafter the mill tool mills a
window in the casing of the primary wellbore. The milling process itself is
not
precise and thus it is relatively unlikely that a precise window shape and
size
can be produced. Lateral liners run in to extend through a milled window and
into a lateral borehole are constructed with regular patterns and sizes at the
surface. When a regular pattern at the top of such a liner is seated against a
milled window in the downhole environment, it is relatively unlikely that the
liner flange will seat correctly in all regions of a milled window. This
leaves
gaps between the flange of the liner and the milled casing in the primary
wellbore resulting in the aforesaid avenue for infiltration of particulate
matter
to the wellbore system. A device and method capable of reducing the amount
of particulate matter infiltrating the wellbore system at a junction in a
multilateral wellbore will be beneficial to downhole arts.
SUMMARY OF THE INVENTION
Sand and other particulate matter is significantly excluded from
junctions in level 3 multilateral wellbore systems by employing a thin walled
sleeve having a premachined window therein in conjunction with the
conventional milling of a window in the primary wellbore casing. The
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premachined window exhibits a known and easily controlled shape and size
which lends itself to assurance that a commercially available liner hanger
will
seal thereagainst since the liner hanger and the sleeve are machined in
controlled conditions at the surface for the purpose of seating with one
another. The installation of the sleeve with the premachined window ensures
that at the ID of the wellbore casing, the window surFace "seen" by the liner
hanger system is one against which the liner hanger system is sealable. The
seal of the liner hanger may be by any number of methods, two preferred
methods being by an elastomeric seal placed between the flange of the liner
hanger and the sleeve, and a metal-to-metal interference fit resulting in
deformation of the window sleeve outward during installation of the liner. In
addition a hook liner hanger embodiment is disclosed. All of these alternate
methods of providing a seal are effective and each have benefits which are
attractive for certain applications. The sleeve is preferably swaged at an
uphole end thereof, a downhole end thereof, both or in its entirety depending
upon the application and desires of the operator. In one embodiment, the
casing itself of the primary wellbore is provided with a cylindrical recess
capable of receiving the sleeve such that the ID of the sleeve is
substantially
the same diameter as the ID of the casing.
Accordingly, in one aspect of the present invention there is
provided a running tool having a dog thereon adapted to automatically move
outwardly upon reaching a window in a casing of a wellbore and orient itself
by finding a downhole vee in said window.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings wherein like elements are
numbered alike in the several Figures:
Figure 1 is a cross-section view of a thin walled sleeve with
premachined window;
Figure 2 is a cross-section view of the thin walled sleeve
installed on a running tool which is illustrated schematically, the running
tool
including a locating dog;
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Figure 3 is a schematic illustration of the thin walled sleeve
installed with the uphole and downhole sections of the sleeve swaged against
the ID of the casing;
Figure 4 is an illustration in cross-section of the thin walled
sleeve installed in a fully swaged condition against the ID of the casing
wherein an alternate casing segment is employed having a recess to accept
the thin walled sleeve;
Figure 5 is an illustration similar to Figure 4 with the lateral liner
installed;
Figure 6 is a view of a section of a primary casing with a
whipstock installed therein prior to milling the primary casing;
Figure 7 is an illustration similar to Figure 6 but illustrating the
drill bit being run downhole;
Figure 8 illustrates the primary casing after drilling creating a
window in the primary casing and a lateral borehole;
Figure 9 illustrates the view of Figure 8 after the whipstock is
removed;
Figure 10 is an illustration of the sleeve being located at the
junction interface with a running tool;
Figure 11 illustrates the running tool swaging and uphole end of
the thin walled sleeve against the casing ID;
Figure 12 illustrates the sleeve in position within the wellbore;
Figure 13 is a similar view to Figure 12 with the lateral liner
installed therein;
Figure 14 is a schematic view of an alternate embodiment of the
sleeve employing an orientation anchor;
Figure 15 is a view of the Figure 14 embodiment after swedging
of the uphole end; and
Figure 16 is a schematic section view of an embodiment
employing a hook liner hanger.
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DETAILED DESCRIPTION OF THE INVENTION
Referring to Figure 1, a thin walled sleeve 10 is illustrated
having a premachined window 12. Sleeve 10 is preferably constructed of
steel with a thickness of from 0.125 inch to 0.250 inch. A preferred thickness
of 0.197 inch is selected to facilitate relatively easy swaging yet provide
sufficient resiliency in the sleeve to ensure a close proximity of a liner
extending therethrough to said sleeve sufficient to facilitate bridging of a
particular matter which would otherwise pass between said sleeve and said
liner to contaminate produced fluids. In another preferred embodiment the
liner is sealed against said sleeve. In a preferred embodiment, bands 13 are
positioned around sleeve 10 to aid in sealing and anchoring sleeve 10 against
casing 20. Bands 13 are preferably elastomeric. It should be understood that
one or more bands 13 may be employed as desired. The bands are visible in
Figures 1, 2 and 10 but are not visible in other figures because they are
compressed between sleeve 10 and the casing of the borehole.
Figure 2 schematically illustrates a running tool 14 on which
sleeve 10 is mounted for being run into the hole (not shown). Running tool 14
may be any one of several commercially available running tools capable of
releasably retaining a sleeve to be run downhole. Running tool 14 does
however include a schematically illustrated locating dog 16 unique to
applications of the thin walled sleeve 10. Locating dog 16 preferably is
mounted on pin 18 which includes a torsional spring (not shown). Locating
dog 16 follows an ID of a casing 20 until it reaches a milled window 22
whereat locating dog 16 automatically protrudes through window 22 while
running tool 14 proceeds farther downhole. As locating dog 16 reaches a
lower vee 24 of window 22, it will orient itself both linearly and
rotationally to
window 22. Because sleeve 10 is carefully oriented on running tool 14 at the
surface to place locating dog 16 in a selected position relative to
premachined
window 12, the action of locating dog 16 in vee 24 linearly and rotationally
orients sleeve 10 to the milled window 22.
Once sleeve 10 is oriented properly within the hole, running tool
14 is used to swage an uphole end 26, a downhole end 28 or both 26 and 28
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into contact with an ID 30 of casing 20. One preferred method for swaging
sleeve 10 is to employ an inflatable swaging device incorporated into the
running tool. If both uphole end 26 and downhole end 28 are intended to be
swaged then preferably two inflatable tools will be utilized simultaneously.
Figure 3 illustrates, schematically, sleeve 10 swaged at uphole end 26 and
downhole end 28.
Referring to Figure 4, an alternate construction for new wells is
disclosed wherein casing 32 is premachined with a window and includes
recess 34 which is of sufficient dimension and configuration to receive a
preinstalled sleeve 10 while providing an ID 36 of sleeve 10 which
substantially equals ID 38 of casing 32. By employing such casing 32 there is
no restriction at the junction which might otherwise be problematic with
respect to tools passing through the junction. As best illustrated in Figures
3
and 4, window 12 in sleeve 10 is preferably of smaller dimension than the
window 22 (in Figure 3) and 42 (in Figure 4) so that a lateral liner being
urged
into a sealing engagement at the junction will seal against the ID 36 of
sleeve
10 at window 12.
Referring to Figure 5, the depiction of Figure 4 has been
repeated but with a lateral liner installed. Thus, it is illustrated that
flange 44
of lateral liner 46 is seated against the window 12 in sleeve 10 and is sealed
thereto. It should be noted that at the interface (arrow 48) may be an
elastomeric sealing material such as polyurethane or a metal sealing material
such as bronze or steel. It should also be noted that it is possible to
machine
the premachined window 12 slightly smaller than liner 46 to provide an
interference fit with the liner 10. Because of the proximity of the sleeve to
the
liner in the area of the premachined window, sand and other particulate matter
from the area of the junction 50 is substantially excluded from the wellbore
system. This can be by one of bridging or sealing depending upon the
tightness of the liner against the sleeve.
Referring to Figures 6-13, a sequential illustration of one
embodiment for installing the sand device is illustrated. In Figure 6, casing
20
is illustrated with a whipstock 52 therein oriented and maintained in place by
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anchor 54. In Figure 7, a drill string 56 is illustrated being introduced to
the
downhole environment just prior to contact with whipstock 52. Referring to
Figure 8, a milled window 22 and lateral borehole 58 are illustrated.
Referring
to Figure 9, the whipstock 52 has been removed from the wellbore leaving
anchor 54 in place. It should be noted that anchor 54 is not required for
installation of the sand exclusion device described herein but could be used
if
desired as a locating device. Referring to Figure 10, a running tool 14 as
described hereinabove, has been introduced to the downhole environment
and into the vicinity of lateral borehole 58. Dog 16 orients linearly and
rotationally to milled window 22. Once dog 16 has landed in vee 24, as
described above, the sleeve 10 is swaged with inflatable packer 60 which is
illustrated in Figure 11. Referring to Figure 12, the swaged sleeve 10 is left
in
position within the wellbore and anchored to casing 20 with window 12
oriented linearly and rotationally to borehole 58. Figure 13 illustrates a
lateral
liner 60 installed with flange 62 firmly seated against sleeve 10 and creating
a
seal thereagainst with either an elastomeric sealant such as polyurethane,
metal-to-metal seal or other suitable seal.
The above discussed method for orienting rotationally and
linearly using dog 16, while a preferred embodiment, is but one embodiment.
Another preferred embodiment referring to Figures 14 and 15 is to stab into
anchor 54 with a running tool 80 having an orientation anchor 82 so that
sleeve 10 is orientable to the milled window (not shown in subject figure)
based upon the original whipstock anchor 54 and not the vee 24 of the
window. The orientation anchor 82 further seals the downhole end and thus
removes the need to swage the downhole end of sleeve 10. The uphole end
therefore is the only end needing swaging. Figure 15 illustrates the uphole
end swaged as has been previously described herein.
In another embodiment referring to Figure 16, a schematic
illustration carrying identical numerals for identical components is provided
for
understanding of another preferred arrangement where the sand exclusion
sleeve 10 is employed in connection with a hook hanger liner 70 having hook
72 to engage with vee 24. Although a flange 44 is not available in this
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embodiment, an interference fit between liner 70 and sleeve 10 is
nevertheless crated which causes the bridging of particulates and thus their
exclusion from the junction.
It should be noted that while the foregoing method for creating a
sand excluding junction is effective, it is only necessary to place the sleeve
10
at a desired location, and run a liner through the premachined winds and into
close enough proximity therewith to facilitate bridging of particulate matter.
Swaging the sleeve in place is a preferred operation as well. Milling of a
window in the primary casing and drilling a lateral borehole may have been
accomplished as part of an earlier operation.
While preferred embodiments of the invention have been shown
and described, various modifications and substitutions may be made thereto
without departing from the spirit and scope of the invention. Accordingly, it
is
to be understood that the present invention has been described by way of
illustration and not limitation.
