Note: Descriptions are shown in the official language in which they were submitted.
CA 02260616 1999-02-03
LATERAL WELLBORE CONNECTION
BACKGROUND OF THE INVENTION
The present invention relates generally to operations performed in
conjunction with subterranean wells and, in an embodiment described herein,
more particularly provides apparatus and methods for achieving a lateral
wellbore connection.
Wher a it is desired to drill a lateral wellbore from a parent wellbore, it
is common practice to position a whipstock in casing lining the parent
wellbore, and then mill a window thr ough the casing. The lateral wellbore
may then be drilled outward from the parent wellbore by passing drill bits
through the window. Unfor tunately, these operations are usually very time-
consuming and, therefore, very expensive to perform.
It would be advantageous to provide an exit joint made of a drillable
material in the parent wellbore casing string, so that the time involved in
milling through the casing would be virtually eliminated. For operational
efficiency and str uctural integrity of the lateral wellbore connection, it
would
be desir able for the exit joint to be configured as a cementing shoe or other
portion of a typical casing string.
Since passage of tools, tubular members and other equipment from the
parent wellbore to the lateral wellbore generally requires some rotational
orientation, it would also be advantageous to provide apparatus which reduces
the time required to rotationally orient items of equipment in the well. For
example, one deflection device may be used to guide a drill bit to cut through
the casing string, and thereafter another deflection device may be used to
CA 02260616 1999-02-03
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guide other equipment from the parent wellbore to the lateral wellbore. The
second deflection device could be rotationally oriented using the rotational
orientation of the first deflection device.
It would also be advantageous to provide methods of modifying
properties of for mations or subterranean strata surrounding lateral wellbore
junctions, or otherwise stabilizing the lateral wellbore junctions. In this
manner, lateral wellbore connections which do not include materials which
must be milled through to form lateral wellbores may nevertheless be
stabilized. Such stabilized formations might have reduced permeability,
increased fracture gradient and leak-off pressures, increased tensile and
compressive strength, increased ductility, and/or otherwise modified
properties.
Accordingly, it is an object of the present invention to provide a lateral
wellbore connection which does not require time-consuming milling
operations, and which does not require repetitive downhole rotational
orientation of items of equipment used therein. It is another object of the
present invention to provide methods of stabilizing formations intersected by
wellbore junctions, or otherwise modifying properties of subterranean strata
surrounding wellbore connections.
SUMMARY OF THE INVENTION
In carrying out the principles of the present invention, in accordance
with an embodiment thereof, a lateral wellbore connection is provided which
is efficient and economical in its construction and operation. Apparatus and
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methods provided by the present invention provide wellbore junctions which
are stabilized without the need for using non-drillable materials.
In broad terms, the invention encompasses apparatus and methods for
achieving a lateral wellbore connection. In one embodiment of the present
invention, a material is disposed within a radially enlar ged portion of a
first
wellbore and permitted to harden therein. The material is then drilled
through to form a wellbore junction. In one aspect of the present invention,
the material may be forced into pores of a formation or subterranean strata
sure ounding the wellbore junction. The material may be forced therein before
or after a second wellbore is drilled intersecting the first wellbore.
In another aspect of the present invention, the material may be a
har denable epoxy composition having flexibility upon har dening, such as an
epoxide containing liquid selected from the group of diglycidyl ethers of 1,4-
butanediol, neopentyl glycol and cyclohexane dimethanol, and a har dening
agent selected from the group of aliphatic amines and carboxylic acid
anhydrides. The composition is forced into a subterranean stratum by way of
a wellbore penetrating it and by way of the porosity of the stratum. The epoxy
composition is then allowed to harden in the stratum.
Upon hardening, the resulting flexible epoxy composition reduces the
permeability of the stratum and increases its resistance to shear failure
adjacent to the wellbore whereby the fracture gradient of the stratum is
appreciably increased.
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These and other features, advantages, benefits and objects of the
present invention will become apparent to one of ordinary skill in the art
upon
careful consideration of the detailed descriptions of representative
embodiments of the invention hereinbelow and the accompanying dr awings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic cross-sectional view of a first apparatus and
method of drilling a subterranean well, initial steps of the method having
been performed, and the first method and apparatus embodying principles of
the present invention;
FIG. 2 is a schematic cross-sectional view of a second apparatus, and in
which further steps of the first method have been performed, the second
apparatus embodying principles of the present invention;
FIG. 3 is a schematic cross-sectional view of the first method in which
optional steps in drilling a lateral wellbore are performed;
FIG. 4 is a schematic cross-sectional view of the first method in which
optional steps in drilling a parent wellbore are performed;
FIG. 5 is a schematic cross-sectional view of a third apparatus
embodying principles of the present invention; and
FIG. 6 is a schematic cross-sectional view of a fourth apparatus and
second method for drilling a subterranean well, initial steps of the method
having been performed, and the fourth apparatus and second method
embodying principles of the present invention.
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DETAILED DESCRIPTION
Representatively and schematically illustrated in FIG. 1 is a method 10
which embodies principles of the present invention. In the following
description of the method 10 and other methods and apparatus described
herein, directional terms, such as "above", "below", "upper", "lower", etc.,
are
used for convenience in referring to the accompanying drawings. Additionally,
it is to be understood that the various embodiments of the present invention
descr ibed her ein may be utilized in various orientations, such as inclined,
inverted, horizontal, vertical, etc., without departing from the principles of
the
present W vention.
As depicted in FIG. 1, initial steps of the method 10 have been
performed. A parent wellbore 12 has been drilled to a depth at which it is
desired to install a string of casing 14. The method 10 advantageously uses a
specially configured cementing shoe 16 as a part of the casing string 14. The
cementing shoe 16 may be threadedly or otherwise attached to the remainder
of the casing string 14 and is sealingly attached thereto.
The cementing shoe 16 is also configured for use as an exit joint for
drilling a lateral wellbore 18 (see FIG. 2). For this purpose, the cementing
shoe 16 is made of one or more drillable materials. For example, the
cementing shoe 16 may include an inner filler material 20 and an outer case
or container 22 enveloping the filler material. The inner filler material 20
may be cement or other cementitious material, may be reinforced, as with
graphite or polypropylene fibers, etc., and may be integrally formed with the
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outer case 22. The outer case 22 may be fiber-reinforced resinous material, or
it may be metallic) such as aluminum, etc. Of course, other materials may be
used to construct the cementing shoe 16 without departing from the principles
of the present invention.
As shown in FIG. l, the cementing shoe/exit joint 16 is positioned at or
very near the lower end of the casing string 14. This is an advantageous
position for the exit joint 16 in the method 10, since in normal practice the
lower end of a casing string is usually located in rock or other consolidated
and stable formation. Thus, when the cementing operation is performed and
the cementing shoe 16 is cemented in place as depicted in FIG. l, the lower
end of the casing string 14 is preferably in a stable formation and is at
least
somewhat protected from damage during subsequent drilling and completion
operations. For convenience and clarity of illustration, conventional steps
and
items of equipment used in the cementing operation are not shown in the
dr awings or described herein, these being well known to those of ordinary
skill
in the ar t.
Referring additionally now to FIG. 2, the method 10 is schematically
and representatively illustrated in which additional steps have been
performed. The parent wellbore 12 has been extended by drilling downward
through the casing string 14. Another casing or liner 24 has then been
installed in a lower portion 26 of the parent wellbore 12 and cemented in
place.
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Threadedly and sealingly attached at an upper end of the casing or
liner 24 is an orienting member 28. The orienting member 28 includes an
inter nal later ally inclined annular surface 30 and an internal annular
recess
or latching profile 32. Threadedly and sealingly attached above the orienting
member 28 is a seal bore or polished bore receptacle (PBR) 34.
In the method 10, the casing 24, orienting member 28 and PBR 34 are
installed in the parent wellbore 12, and the casing is cemented in place,
before
the lateral wellbore 18 is drilled. As shown in FIG. 2, the inclined surface
30
may be oriented to face radially toward the lateral wellbor e-to-be-drilled,
or it
may be otherwise directed, as will be explained in further detail below.
Additionally, note that the PBR 34 and an upper portion of the orienting
member 28 extend above the lower parent wellbore 26, with at least the PBR
extending into the cementing shoe 16. Thus, it is possible to place cement
about the PBR 34 and orienting member 28 to further isolate the formation
surrounding the lateral wellbore connection (see FIG. 4).
When it is desired to drill the lateral wellbore 18, an assembly 36 is
conveyed into the parent wellbore 12, for example, by lowering the assembly
via a work string, coiled tubing, etc. in a conventional manner. The assembly
36 includes a deflection device 38 and an orienting member 40. The deflection
device 38 has a laterally inclined upper surface 42 formed thereon for
deflecting cutting tools, such as drill bits, tubular members, other items of
equipment, etc., laterally with respect to the parent wellbore 12. The
deflection device 38 and orienting member 40 are representatively shown in
CA 02260616 1999-02-03
_g_
FIG. 2 as being solid, but it will be r eadily appreciated that these elements
could be made generally tubular, that is, having axial flow passages formed
therethrough.
When the assembly 36 is conveyed into the parent wellbore 12, the
deflection device 38 is free to rotate relative to the or Tenting member 40. A
release member or annular shear ring 44 attaches the deflection device 38 to
the orienting member 40 and permits relative rotation therebetween.
However, as shown in FIG. 2, the deflection device 38 has been downwardly
displaced relative to the orienting member 40, thus shearing the shear ring
44, and the deflection device is no longer permitted to rotate relative to the
orienting member.
Complementarily shaped mating splines 46 are formed on each of the
deflection device 38 and orienting member 40, so that, when the assembly 36
is being conveyed into the well, the splines are disengaged, thereby
permitting
relative rotation between the deflection device and the orienting member 40.
However, when the orienting member 40 is engaged with the PBR 34 and
orienting member 28, and a downwardly directed axial force is applied to the
deflection device 38 to shear the shear ring 44, such as by slacking off on a
work string attached thereto at the earth's surface to thereby apply a portion
of the work string's weight to the deflection device, the deflection device
will
displace axially downward and the splines 46 will engage, thereby preventing
relative rotation between the deflection device and the orienting member 40.
Of tour se, other types of rotational locks may be used in place of the
splines
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_g_
46, such as clutches, other cooperatively engageable projections and r
ecesses,
etc., and other types of release members may be used in place of the shear
ring
44, without departing from the principles of the present invention.
A latch member or snap ring 48 is carried externally on the deflection
device 38. When the deflection device 38 is downwardly displaced relative to
the orienting member 40 as described above, the snap ring 48 radially
outwardly extends into an annular recess or groove 50 formed internally on
the orienting member 40. The snap ring 48 prevents the deflection device 38
from displacing upwardly relative to the orienting member 40 after the
deflection device has displaced downwardly as shown in FIG. 2. Thus, the
snap ring 48 maintains the splines 46 in engagement, and thereby prevents
any relative rotation between the deflection device 38 and the orienting
member 40.
The orienting member 40 has a circumferential seal 52 carried
externally thereon, which sealingly engages the PBR 34 when the assembly 36
is installed. Use of the seal 52 is optional, since it may not be desired to
sealingly engage the assembly 36 with the orienting member 28, liner 24, etc.
In that case use of the PBR 34 would be optional as well.
Also carried on the orienting member 40 are a series of
circumferentially spaced apart keys or lugs 54 of conventional design for
latching engagement with the latching profile 32. Additionally, a laterally
inclined annular surface 56 is formed externally on the orienting member 40
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for complementary engagement with the inclined sur face 30 of the orienting
member 28.
As the upper orienting member 40 engages the PBR 34 and lower
orienting member 28, several functions are performed. The seal 52 sealingly
engages the PBR 34. The inclined surfaces 30, 56 engage each other. If the
upper orienting member 40 is not radially aligned with the lower orienting
member 28, the surfaces 30, 56 will cooperate to cause the upper orienting
member to rotate into radial alignment with the lower orienting member. At
this point, the upper orienting member 40 is free to rotate relative to the
deflection device 38. When the upper orienting member 40 is radially oriented
with respect to the lower orienting member 28, the keys 54 engage the
latching profile 32, thereby latching the orienting members together, with the
surfaces 30, 56 preventing further rotation of the orienting members relative
to each other.
After the orienting members 28, 40 have been radially aligned and
latched together, the deflection device 38 is oriented so that the surface 42
faces toward the lateral wellbore-to-be-drilled using conventional methods,
such as by using a gyroscope included in the work string used to convey the
assembly 36 into the parent wellbore 12. An axially downwardly directed
force is then applied to the deflection device 38, such as by applying a
portion
of the work string's weight to the deflection device. This force causes the
shear ring 44 to shear, releasing the deflection device 38 for displacement
relative to the orienting member 40. The deflection device 38 displaces
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downward, engaging the splines 46 and engaging the snap ring 48 in the
groove 50. At this point, the deflection device 38 is rotationally locked with
respect to the wellbore 12, and will remain in this position indefinitely,
with
the surface 42 facing toward the lateral wellbore-to-be-drilled.
One or more cutting tools, such as drill bits, may be lowered through
the casing string 14 and deflected by the surface 42 to cut laterally through
the cementing collar 16. In this manner, no milling is required to cut a
window through the casing string 14. An opening 58 is drilled through a
sidewall of the cementing collar 16 and extended outward from the parent
wellbore 12 to form the lateral wellbore 18.
Due to wear or other reasons, it may be desired to install another
deflection device or other item of equipment at the lateral wellbore
connection.
The method 10 and apparatus shown in FIGS. 1 & 2 and described above are
particularly well suited for repetitive rotational alignment of items of
equipment relative to the wellbore 12 in these circumstances. The upper
orienting member 40 may be unlatched from the lower orienting member 28,
such as by applying an axially upwardly directed force to the assembly 36 to
disengage the keys 54 from the latching profile 32, and the upper orienting
member may be retrieved to the earth's surface with the deflection device 38
attached thereto.
Note that the deflection device 38 remains rotationally locked to the
orienting member 40 as they are retrieved. At the earth's surface, an operator
may note the orientation of the deflection device 38 relative to the orienting
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-12-
member 40. The operator may then attach another deflection device or other
item of equipment to the orienting member 40 in the same orientation as the
previously attached deflection device 38.
Thus, when the newly-attached item of equipment and the upper
orienting member 40 are installed in the well and the orienting members 40,
28 are again engaged with each other, the newly-attached item of equipment
may have the same radial orientation relative to the wellbore 12 as the
deflection device 38 previously had. Of course, the newly-attached item of
equipment might also be attached to the upper orienting member 40 with a
different radial orientation, without departing from the principles of the
present invention. Additionally, the newly-attached item of equipment might
be attached to another upper orienting member, similar to the upper orienting
member 40, but not necessarily including the features which permit rotation
and then rotational locking between the item of equipment and the upper
orienting member) since radial orientation of the newly attached item of
equipment relative to the upper orienting member may be fixed before
conveyance into the well.
Referring additionally now to FIGS. 3 & 4, optional steps of the method
are schematically shown, which may be utilized when relatively high
pressure drilling or other operations are performed through the lateral
wellbore connection. In FIG. 3, a liner 60 or other tubular member is shown
inserted through the opening 58 formed through the cementing shoe 16
sidewall. The upper end of the liner 60 is sealingly disposed within the
parent
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wellbore 12 in the interior of the casing 14. The lower end of the liner 60 is
sealingly disposed within the lateral wellbore 18.
The upper end of the liner 60 is sealingly engaged with the casing
str ing 14 by a packer or liner hanger 62 attached to the liner. The lower end
of the liner 60 is sealingly engaged with a PBR 64 attached to another liner
or
other tubular member 66 cemented in the lateral wellbore 18. Of course,
many other ways of sealing the liner 60 in the parent and lateral wellbores
12,
18 may be used in the method 10 without departing from the principles of the
present invention.
It will be readily appreciated that such sealing engagement of the liner
60 operates to isolate the lateral wellbore connection from fluid pressures
present in the casing string 14 above the liner 60, such as those that might
be
experienced when the lateral wellbore 18 is drilled further outward from the
parent wellbore 12. Thus, drill bits or other equipment may be conveniently
transported through the lateral wellbore connection via the liner 60, and
fluid
pressures present in the parent wellbore 12 above the lateral wellbore
connection will be isolated from the lateral wellbore connection during these
operations. When there is no longer a need for the liner 60, it may be
retrieved using conventional methods.
In FIG. 4, another liner or other tubular member 68 is positioned
extending through the lateral wellbore connection, but in this case the liner
is
used before the lateral wellbore 18 is drilled. However, it is to be clearly
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understood that the liner 68 could also be used after the lateral wellbore 18
has been drilled.
As shown in FIG. 4, the liner 68 is inserted through the cementing shoe
16 after the casing 24, orienting member 28 and PBR 34 are installed and
cemented within the lower parent wellbore 26. The liner 68 is sealingly
engaged within the casing string 14 above the cementing shoe 16 using a
packer or liner hanger 70. The lower end of the liner 68 is sealingly engaged
with the PBR 34. In this manner, the parent wellbore 12 may be extended by
passing drill bits, etc. through the casing string 14, liner 68 and casing 24,
without applying any excessive fluid pressure to the lateral wellbore
connection.
Referring additionally now to FIG. 5, an apparatus 80 embodying
principles of the present invention is representatively and schematically
illustrated. The apparatus 80 may be used in the method 10 described above,
and may be used in other methods as well. In many respects, the apparatus
80 is similar to the cementing shoe 16 described above, but differs in some
respects also.
The apparatus 80 includes a float collar 82 similar to float collars of
conventional design and well known to those skilled in the art. The float
collar 82 includes a float valve 84, which permits flow of cement or other
material downwardly through an axial flow passage 86 formed therethrough,
but prevents flow upwardly through the float collar. At least the float valve
84 portion of the float collar 82 is made of drillable material, such as
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aluminum, etc., and an annular area 88 between the float valve and an outer
tubular housing 90 may be filled with the same or another drillable material,
such as cement. An upper end of the housing 90 is configured for threaded
and sealing attachment to a tubular member, such as casing of the casing
string 14 shown in FIG. 1.
Threadedly and sealingly attached below the float collar 82 is a
cementing shoe 92. An axial flow passage 94 formed through the cementing
shoe 92 is aligned with the flow passage 86 of the float collar 82. When the
float valve 84 is open, fluid or other material may flow from the flow passage
86 to the flow passage 94.
The flow passage 94 is lined with a tubular flow conductor 96, which
limits erosion of a filler material 98 radially outwardly surrounding the flow
passage. The filler material 98 may be similar to the filler material 20 used
in
the cementing shoe 16 described above. The filler material 98 is shown in
FIG. 5 as being made of cement, but it is to be understood that it may
actually
be a resinous material, a polymer, a fiber-reinforced material, an elastomer,
or
any of a variety of drillable materials.
The cementing shoe 92 is attached to the float collar 82 by means of an
outer tubular housing or case 100. The case 100 at least partially radially
outwardly surrounds the filler material 98 and may include retaining
structures, such as annular recesses 102, etc.) formed internally thereon or
attached thereto, for preventing movement of the filler material 98 relative
thereto. The case 100 is preferably made of a drillable material, such as
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aluminum, etc., so that an opening, such as opening 58 shown in FIG. 2, may
be easily drilled laterally therethrough.
Note that the case 100 envelopes a substantial portion of the filler
material 98, but that a lower generally hemispherical-shaped portion 104 of
the filler material extends downwardly and outwardly therefrom. Thus, it is
not necessary for the case 100 to completely circumscribe the filler material
98
in keeping with the principles of the present invention. Of course, the lower
portion 104 may be otherwise shaped, and the case 100 may otherwise
envelope the filler material 98, or be integrally formed therewith, without
departing from the principles of the present invention.
The lower portion 104 has flow passages 106 formed therein, each of
which intersects the flow passage 94. As shown in FIG. 5, the flow passages
106 are formed through the filler material 98 and are unlined, but it is to be
understood that the flow passages may be lined with protective material, and
may be otherwise positioned, without departing from the principles of the
present invention.
Referring additionally now to FIG. 6, another apparatus 110 and
method 112 embodying principles of the present invention are
representatively and schematically illustrated. The apparatus 110 may be
used in the method l12, in any of the methods described above, or in any other
method, without departing from the principles of the present invention.
Additionally, the method 112 may use the apparatus 110, any of the other
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apparatus described above, or other apparatus, in keeping with the principles
of the present invention.
The apparatus 110 includes a float collar 114 and a cementing shoe or
float shoe 116, each of which is made of drillable material. As shown in FIG.
6, the float collar 114 and cementing shoe 116 are made of a molded plastic or
polymer material, but it is to be understood that the float collar and
cementing shoe may be made of other drillable materials, or combination of
drillable materials, without departing from the principles of the present
invention.
Each of the float collar l14 and cementing shoe 116 includes a float
valve 118. The float valves 118 permit flow from the interior of a casing or
other tubular string 120, from which the apparatus 110 is suspended, to an
annulus l22 between the casing string and a wellbore 124 of the well, but
prevent flow from the annulus to the interior of the casing string.
As shown in FIG. 6, initial steps of the method 112 have been
performed. The wellbore 124 has been drilled, at least to a point where it is
desired to drill a lateral wellbore 126 extending outwardly therefrom. The
wellbore 124 has been underreamed) that is, radially enlarged at the junction
of the parent wellbore and the lateral wellbore-to-be-drilled 126. The lateral
wellbore 126 is shown in dashed lines in FIG. 6, since it has not yet been
drilled.
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Radially outwardly extending tunnels or cavities 128 have been formed
in the under reamed portion of the wellbore 124, so that they extend into the
formation 130 surrounding the wellbore junction. The radial cavities 128 may
be formed by conventional techniques, such as jet cutting, using shaped
charges, fracturing the formation during pumping of material 134 thereinto,
etc. However, it is to be clearly understood that it is not necessary for the
wellbore 124 to be underreamed, or for the underreamed portion to have the
cavities 128 formed therein, in the method 112.
The apparatus 110 is then conveyed into the wellbore 124 suspended
from the casing string 120. The apparatus 110 is positioned at the wellbore
junction, so that the lateral wellbore 126 may be drilled therethrough
intersecting the parent wellbore 124, as described above.
Cement 132 is then pumped downwardly through the casing string 120,
through the apparatus l10, and upwardly into the annulus 122. Another
material 134 is tailed-in behind the cement 132, so that the cement is pushed
upwardly into the annulus 122 above the wellbore junction and the material
134 fills the annulus surrounding the apparatus 110, including the
underreamed portion of the wellbore 124 and the cavities 128. Of course, the
material 134 could also be cement, or another drillable material, without
departing from the principles of the present invention. Turbulence inducing
structures 136, of the type well known to those skilled in the art, may be
included on the apparatus 110 to aid in ensuring that the material 134
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"sweeps" through the entire annulus 122 at the wellbore junction. The cement
l22 and material 134 are then allowed to set and/or harden.
It will be readily appreciated that, by providing the underreamed
portion of the wellbore 124, and by filling the enlarged annulus 122
surrounding the wellbore junction with the material l34, the stability of the
wellbore junction is significantly improved. The wellbore junction is, thus,
made more resistant to collapse. Other benefits to the wellbore junction
provided by the method 112 are more fully described below.
The material 134 may be cement, it may be cement with enhanced
properties, such as fiber-reinforced cement, or it may be any of a variety of
other materials, such as polymers, epoxy-type materials, etc. For example,
the material 134 may be a comparatively low viscosity material, which may be
pumped into the formation 130 surrounding the wellbore junction. Dashed
lines 138 in FIG. 6 indicate that the material 134 may be forced outwardly
into the for mation 130 surrounding the wellbore junction, in which case the
cavities 128 may be used to present increased surface area for admitting the
material into the formation.
In order to force the material 134 outwardly into the formation 130, a
conventional operation known as a "top-side squeeze" may be performed after
the material has been positioned in the annulus 122 surrounding the
apparatus 110. In this operation fluid pressure is applied to the annulus 122
at the earth's surface to squeeze the material 134 into the pores of the
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formation 130. Of course, the formation 130 preferably has at least a minimal
degree of permeability to permit the material l34 to flow thereinto.
Note that, by forcing the material 134 into the formation 130, several
benefits may be achieved. The collapse resistance at the wellbore junction
may be vastly improved. The tensile strength, compressive strength and
ductility of the formation 130 may be improved. The formation l30 may be
made impermeable in the area surrounding the wellbore junction by, for
example, filling its pores with the material 134. The leak-off and fracture
propagation pressures of the formation 130 may be increased. Resistance of
the formation 130 to chemicals may be improved. Of course, it is not
necessary in the method 112 for a11 of these benefits to be obtained, since a
choice of the material 134 to use in a particular situation may be tailored to
the specific well conditions, formation 130 composition and properties,
benefits
desired, etc.
An example of a material which may be used for the material 134 in the
method 112 is described in a copending application serial no. 08/914,594,
filed
August 18, 1997, entitled METHODS OF MODIFYING SUBTERRANEAN
STRATA PROPERTIES, attorney docket no. HES 97.0102. The disclosure of
that copending application is hereby incorporated by this reference. The
application describes a hardenable epoxy composition, such as an epoxide
containing liquid selected from the group of diglycidyl ethers of 1,4-
butanediol,
neopentyl glycol and cyclohexane dimethanol, and a hardening agent selected
from the group of aliphatic amines and carboxylic acid anhydrides. Aromatic
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amines may also be used as a hardening agent. Furthermore, the application
describes methods of pumping the epoxy composition into subterranean
stratum by way of a wellbore penetrating the stratum and by way of the
porosity of the stratum, and then allowing the epoxy composition to harden in
the str atum.
It will be readily appreciated that the above-described methods of
stabilizing a wellbore junction may be used in other types of junctions, and
may be utilized before or after drilling a wellbore at a junction. For
example,
the wellbore junctions representatively illustrated in FIGS. 2 & 6 may be
stabilized by for cing the material 134 into the formations surrounding the
junctions either befoga the lateral wellbores 18, 126 are drilled, or after
the
later al wellbores are drilled. Additionally, these operations may be
performed
in conjunction with wellbore stabilization methods described in the
incorpor ated application.
Once the cement 132 and material 134 (if a separate material is
utilized) have hardened in the representatively illustrated method 112, the
later al wellbore 126 is drilled in a similar manner as that described above
for
the method 10. The apparatus 110 may be drilled through and a deflection
device utilized to deflect cutting tools outwar dly therethrough to form the
later al wellbore 126. Thus, the method 112 does not require any time-
consuming milling operations and may be performed in the course of
substantially normal drilling and cementing operations.
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Of course, many modifications, additions, substitutions, deletions and
other changes may be made to the methods 10, 112 and various apparatus
descr ibed above, which changes would be obvious to a person skilled in the
art, and such changes are contemplated by the principles of the present
invention. Accordingly, the foregoing detailed description is to be clearly
understood as being given by way of illustration and example only, the spirit
and scope of the present invention being limited solely by the appended
claims.
WHAT IS CLAIMED IS:
