Note: Descriptions are shown in the official language in which they were submitted.
CA 02549625 2006-06-06
FLOW NOZZLE ASSEMBLY
BACKGROUND OF THE INVENTION
Field of the Invention
Embodiments of the present invention generally relate to methods and
apparatuses for providing a more uniform gravel pack in a wellbore. More
particularly,
the invention relates to methods and apparatuses for providing an improved
nozzle for
a shunt tube.
Description of the Related Art
Hydrocarbon wells, especially those having horizontal wellbores, typically
have
sections of wellscreen comprising a perforated inner tube surrounded by a
screen
portion. The purpose of the screen is to block the flow of unwanted materials
into the
wellbore. Despite the wellscreen, some contaminants and other unwanted
materials like
sand, still enter the production tubing. The contaminants occur naturally and
are also
formed as part of the drilling process. As production fluids are recovered,
the
contaminants are also pumped out of the wellbore and retrieved at the surface
of the
well. By controlling and reducing the amount of contaminants that are pumped
up to the
surface, the production costs and valuable time associated with operating a
hydrocarbon well will likewise be reduced.
One method of reducing the inflow of unwanted contaminants is through gravel
packing. Normally, gravel packing involves the placement of gravel in an
annular area
formed between the screen portion of the wellscreen and the wellbore. In a
gravel
packing operation, a slurry of liquid, sand and gravel ("slurry") is pumped
down the
wellbore where it is redirected into the annular area with a cross-over tool.
As the gravel
fills the annulus, it becomes tightly packed and acts as an additional
filtering layer along
with the wellscreen to prevent collapse of the wellbore and to prevent the
contaminants
from entering the stream of production fluids pumped to the surface. Ideally,
the gravel
will be uniformly packed around the entire length of the wellscreen,
completely filling the
annulus. However, during gravel packing, the slurry may become less viscous
due to
Joss of fluid into the surrounding formations or into the wellscreen. The loss
of fluid
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causes sand bridges to form. Sand bridges are a wall bridging the annulus and
interrupting the flow of the slurry, thereby preventing the annulus from
completely filling
with gravel.
The problem of sand bridges is illustrated in FIG. 1, which is a side view,
partially
30 in section of a horizontal wellbore with a wellscreen therein. The
wellscreen 30 is
positioned in the wellbore 14 adjacent a hydrocarbon bearing formation
therearound.
An annulus 16 is formed between the wellscreen 30 and the wellbore 14. The
Figure
illustrates the path of gravel 13 as it is pumped down the production tubing
11 in a
slurry and into the annulus 16 through a crossover tool 33.
35 Also illustrated in FIG. 1 is a formation including an area of highly
permeable
material 15. The highly permeable area 15 can draw liquid from the slurry,
thereby
dehydrating the slurry. As the slurry dehydrates in the permeable area 15 of
the
formation, the remaining solid particles form a sand bridge 20 and prevent
further filling
of the annulus 16 with gravel. As a result of the sand bridge, particles
entering the
40 wellbore from the formation are more likely to enter the production string
and travel to
the surface of the well. The particles may also travel at a high velocity, and
therefore
more likely to damage and abrade the wellscreen components.
In response to the sand-bridging problem, shunt tubes have been developed
creating an alternative path for gravel around a sand bridge. According to
this
45 conventional solution, when a slurry of sand encounters a sand bridge, the
slurry enters
an apparatus and travels in a tube, thereby bypassing the sand bridge to
reenter the
annulus downstream.
FIG. 2 is a sectional view of a prior art nozzle assembly 50 disposed on a
shunt
tube 55. The construction for an exit point from the shunt tube 55 involves
drilling a
50 hole 80 in the side of the tube, typically with an angled aspect, in
approximate
alignment with the slurry flow path 75, to facilitate streamlined flow. The
nozzle
assembly 50, having a tubular outer jacket 65, and a tubular carbide insert
60, is held in
alignment with the drilled hole 80, and the outer jacket is attached to the
tube with a
weld 70, trapping the carbide insert 60 against the tube 55, in alignment with
the drilled
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55 hole 80. The nozzle assembly 50 also has an angled aspect, pointing
downward and
outward, away from the tube 55. Sand slurry exiting the tube 55 through the
nozzle 50
is routed through the carbide insert 60, which is resistant to damage from the
highly
abrasive slurry.
Both the method of constructing the nozzle 50 and the nozzle itself suffer
from
60 significant drawbacks. Holding the nozzle assembly 50 in correct alignment
while
welding is cumbersome. A piece of rod (not shown) must be inserted through the
nozzle assembly 50, into the drilled hole 80, to maintain alignment. This
requires time,
and a certain level of skill and experience. During welding, the nozzle
assembly 50 can
shift out of exact alignment with the drilled hole in the tube due to either
translational or
65 rotational motion. After welding, exact alignment between the nozzle 50 and
the drilled
hole 80 is not assured. Because the carbide insert 60 actually sits on the
surface of the
tube 55, the hole 80 in the tube wall is part of the exit flow path 75.
Abrasive slurry,
passing through the hole, may cut through the relatively soft tube 55
material, and
bypass the carbide insert 60 entirely, causing tube failure.
70 Therefore, there exists a need for an improved nozzle assembly for a shunt
tube
and a method for attaching the nozzle to the shunt tube.
SUMMARY OF THE INVENTION
The present invention generally provides apparatuses and methods for an
improved shunt nozzle which is part of an alternative pathway for a slurry to
by-pass an
75 obstruction such as a sand bridge during gravel packing.
In one aspect of the invention, a nozzle assembly is provided for use in a
tool
having a hole through a wall of the tool, comprising: an insert configured to
at least
partially line the hole and seat on a surface of the wall proximate the hole,
thereby
restraining movement of the insert relative to the tool.
80 Preferably, the insert comprises a first portion; and a shoulder portion
between
the first portion and a lip portion, wherein the shoulder portion is
configured to seat on
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the surface of the wall proximate the hole. Further, the lip portion may be
configured to
at least partially line the hole and comprise a tapered portion that is
configured to form
an interference fit with a surface of the wall defining the hole. The nozzle
assembly
85 may further comprise a jacket having a bore therethrough and a recessed
portion for
receiving the first portion of the insert. The nozzle may be constructed from
a relatively
hard material, such as a carbide material. The insert may have a bore
therethrough
and may be configured so that a center of the bore will be substantially
aligned with a
center of the hole when the insert is seated on the wall of the tool.
90 In another aspect, a nozzle assembly is provided for use in a tool having a
hole
through the wall of the tool, comprising: an insert having a bore
therethrough, wherein
the insert is configured to mate with the tool so that a center of the bore is
held in
substantial alignment with a center of the hole.
In another aspect, a method is provided for attaching a nozzle assembly to a
95 tool, comprising: inserting an insert into a hole in a wall of the tool
until the insert seats
on a surface of the wall proximate the hole, thereby lining at least a portion
of the hole
with the insert and restraining movement of the insert relative to the tool.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the above recited features of the present
invention
100 can be understood in detail, a more particular description of the
invention, briefly
summarized above, may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted; however, that the
appended
drawings illustrate only typical embodiments of this invention and are
therefore not to
be considered limiting of its scope, for the invention may admit to other
equally effective
105 embodiments.
FIG. 1 is a side view, partially in section of a horizontal wellbore with a
wellscreen therein.
Figure 2 is a sectional view of a prior art flow nozzle configuration.
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Figure 3 is a top end view of a gravel pack apparatus, according to one
110 embodiment of the present invention, positioned within a wellbore. Figure
3A is a
sectional view, taken along line 3A-3A of FIG. 3, of the gravel pack apparatus
positioned within wellbore adjacent a highly permeable area of a formation.
FIG. 3B is
a schematic of one of the shunts showing the placement of nozzles along the
shunt.
FIG. 4 is a sectional view of a nozzle assembly, according to one embodiment
of
115 the present invention, disposed on one of the shunts. FIG. 4A is an
enlargement of a
portion of FIG. 4 indicated by the dotted oval labeled 4A.
FIG. 5 is a sectional view of a nozzle assembly, according to another
embodiment of the present invention, disposed on one of the shunts.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
120 FIG. 3 is a top end view of a gravel pack apparatus 100, according to one
embodiment of the present invention, positioned within wellbore 14. FIG. 3A is
a
sectional view, taken along line 3A-3A of FIG. 3, of the gravel pack apparatus
100
positioned within wellbore 14 adjacent the highly permeable area 15 of a
formation.
Although apparatus 100 is shown in a horizontal wellbore, it can be utilized
in any
125 wellbore. Apparatus 100 may have a "cross-over" sub 33 (see FIG. 1 )
connected to its
upper end which, in turn, is suspended from the surface on a tubing or work
string (not
shown). Apparatus 100 can be of one continuous length or it may consist of
sections
(e.g. 20 foot sections) connected together by subs or blanks (not shown).
Preferably,
all components of the apparatus 100 are constructed from a low carbon or a
chrome
130 steel unless otherwise specified; however, the material choice is not
essential to the
invention.
Apparatus 100 includes a wellscreen assembly 105. As shown, wellscreen
assembly 105 comprises a base pipe 110 having perforations 120 through a wall
thereof. Wound around an outer side of the base pipe 110 is a wire wrap 125
135 configured to permit the flow of fluids therethrough while blocking the
flow of
particulates. Alternatively, wellscreen assembly 105 may be any structure
commonly
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used by the industry in gravel pack operations which permit flow of fluids
therethrough
while blocking the flow of particulates (e.g. commercially-available screens,
slotted or
perforated liners or pipes, screened pipes, prepacked screens and/or liners,
or
140 combinations thereof).
Also disposed on the outside of the base pipe 110 are two shunts 145. The
number and configuration of shunts 145 is not essential to the invention. The
shunts
145 may be secured to the base pipe 110 by rings (not shown). At an upper end
(not
shown) of the apparatus 100, each shunt 145 is open to the annulus. Each one
of the
145 shunts 145 is rectangular with a flow bore therethrough; however, the
shape of the
shunts is not essential to the invention. Disposed on a sidewall of each shunt
is a
nozzle 150.
FIG. 3B is a schematic of one of the shunts 145 showing the placement of
nozzles 150 along the shunt 145. As shown, a plurality of nozzles 150 are
disposed
150 axially along each shunt 145. Each nozzle 150 provides slurry fluid
communication
between one of the shunts 145 and an annulus 16 between the wellscreen 105 and
the
wellbore 14. As shown, the nozzles 150 are oriented to face an end of the
wellbore 14
distal from the surface (not shown) to facilitate streamlined flow of the
slurry 13
therethrough.
155 Disposed on the outside of the base pipe 110 are a plurality of
centralizers 130
that can be longitudinally separated from a length of the base pipe 110 that
has the
perforations 120 and the wire wrap 125. Additionally, a tubular shroud 135
having
perforations 140 through the wall thereof can protect shunts 145 and
wellscreen 105
from damage during insertion of the apparatus 100 into the wellbore. The
perforations
160 140 are configured to allow the flow of slurry 13 therethrough.
In operation, apparatus 100 is lowered into wellbore 14 on a workstring and is
positioned adjacent a formation. A packer 18 (see FIG. 1 ) is set as will be
understood
by those skilled in the art. Gravel slurry 13 is then pumped down the
workstring and out
the outlet ports in cross-over sub 33 to fill the annulus 16 between the
wellscreen 105
165 and the wellbore 14. Since the shunts 145 are open at their upper ends,
the slurry 13
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will flow into both the shunts and the annulus 16. As the slurry 13 loses
liquid to the
high permeability portion 15 of the formation, the gravel carried by the
slurry 13 is
deposited and collects in the annulus 16 to form the gravel pack. If the
liquid is lost to a
permeable stratum 15 in the formation before the annulus 16 is filled, the
sand bridge
170 20 is likely to form which will block flow through the annulus 16 and
prevent further
filling below the bridge. If this occurs, the gravel slurry will continue
flowing through the
shunts 145, bypassing the sand bridge 20, and exiting the various nozzles 150
to finish
filling annulus 16. The flow of slurry 13 through one of the shunts 145 is
represented by
a rrow 102.
175 FIG. 4 is a sectional view of a nozzle assembly 150, according to one
embodiment of the present invention, disposed on one of the shunts 145. FIG.
4A is an
enlargement of a portion of FIG. 4 indicated by the dotted oval labeled 4A.
The nozzle
assembly 150 comprises an insert 160 with a flow bore therethrough, that
features a lip
160a that extends into a drilled hole 170 in a wall of the shunt 145, thereby
lining a
180 surface 145a of the shunt wall that defines the hole 170. Preferably, the
insert is made
from a hard material, e.g., carbide, relative to the material of the shunt
145. As shown,
the length of the lip 160a is substantially the same as the wall thickness of
the shunt
145. However, the lip 160a may be substantially longer or shorter than the
wall
thickness of the shunt 145. Preferably, the lip 160a features a slight taper
on an outer
185 surface 160c for seating on the surface 145a of the shunt wall, thereby
providing a
slight interference fit; however, the taper is not essential to the invention.
The insert
160 also features a shoulder 160b which seats with a surface 145b of the shunt
wall
proximate the hole 170, thereby providing a rigid stop limiting the depth to
which lip
160a can penetrate the shunt 145. An outer jacket 155 having a flow bore
therethrough
190 and a recess configured to receive a portion of the insert 160 may then be
easily
slipped on and secured to the shunt 145 with a weld 165. Preferably, the outer
jacket
155 and insert 160 are tubular members; however, their shape is not essential
to the
invention. Preferably, the hole 170 is not perpendicular to the surface 145b
of the shunt
proximate the hole; however, the hole may be perpendicular to the surface of
the shunt
195 proximate the hole.
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Assembly of the nozzle assembly 150 is as follows. The insert 160 is inserted
into the hole 170 until the taper of the outer surface 160c of the hard insert
160 is press
fit with the shunt surface 145a defining the hole 170 and the shoulder 160b is
seated on
the shunt surface 145b proximate the hole 170, so that the lip 160a lines the
surface
200 145a and the insert 160 is secured to the shunt 145. In other Words, the
smallest end
of the taper is inserted into the hole 170 first, and the tapered surface of
the insert 160
self-centers until it becomes snugly seated against the side of the hole 170
at the
surface 145a. This contact occurs in the approximate area of surface 160c on
the
carbide insert. The outer jacket 155 can be disposed over an outer surface of
the insert
205 160 and securely welded with minimal handling. Assembly time is greatly
reduced, as
is the required skill level of the assembler. Once seated, the nozzle assembly
150 is
restrained from translating or rotating relative to the shunt 145. Alignment
of the insert
bore and the jacket bore with the drilled hole 170 in the shunt 145 is
assured. Sand
slurry 13 exiting the tube, represented by arrows 175, passes through the lip
160a of
210 the hard insert, not the surface 145a of the hole 170. The possibility of
flow cutting the
surface 145a of the hole 170 is greatly diminished.
FIG. 5 is a sectional view of a nozzle assembly 250, according to another
embodiment of the present invention, disposed on one of the shunts 145. The
nozzle
assembly 250 comprises an insert 260 with a flow bore therethrough.
Preferably, the
215 insert 260 is made from a hard material, e.g., carbide, relative to the
material of the
shunt 145. A proximal lip 260a of the insert 260 extends into an aperture 270
in a wall
of the shunt 145, thereby lining a surface 245a of the shunt wall that defines
the
aperture 270. The proximal lip 260a can include any of the features described
above
with respect to the lip 160a of the nozzle assembly 150 illustrated in Figure
4 such that
220 the nozzle assembly 250 is assembled in the same manner with the proximal
lip 260a
serving the same functions.
An outer jacket 255 of the nozzle assembly 250 includes a bore therethrough
configured to receive the insert 260. Specifically, a recess 256 along an
inner diameter
of the outer jacket 255 proximate the aperture 270 accommodates an outer
diameter of
225 a medial length of the insert 260. A distal extension 260d extends from an
opposite
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end of the insert 260 than the proximal lip 260a and has a reduced outer
diameter with
respect to the medial length of the insert 260 to form an outward shoulder
261.
Accordingly, the outer jacket 255 easily slips over the insert 260 and secures
to the
shunt 145 with a weld 265. Once welded, an inward shoulder 258 defined by the
230 recess 256 of the outer jacket 255 mates with the outward shoulder 261 of
the insert
260 to prevent outward movement of the insert 260 with respect to the aperture
270.
The insert 260 and the outer jacket 255 preferably share a common terminus
due to a sufficiently sized length of the distal extension 260d of the insert
260. In other
words, the insert 260 concentrically disposed within the outer jacket 255
lines
235 substantially the entire length of the inner diameter of the outer jacket
255. Threads
259 on an outside end of the outer jacket 255 can replace inner threads to
enable
securing of a cap (not shown) to the nozzle assembly 250 if desired.
Preferably, the outer jacket 255 and insert 260 are tubular members; however,
their shape is not essential to the invention. As with other embodiments
described
240 herein, sand slurry 13 exiting the shunt 145, represented by arrows 275,
passes
through the proximal lip 260a of the insert in order to reduce wear on the
surface 245a
of the aperture 270. In addition, sand slurry 13 exiting the nozzle assembly
250 passes
through the distal extension 260d of the insert 260 without flowing through
and
contacting an end of the outer jacket 255, which may be made of a softer
material
245 similar to the shunt 145. In this manner, the distal extension 260d
protects the
shoulders 258, 261 that cooperate to keep the insert 260 from escaping and
causing
failure at the nozzle assembly 250. Thus, the insert 260 can provide a carbide
conduit
that protects all other portions of the nozzle assembly 250 from flow cutting
since sand
slurry exiting the shunt 145 passes substantially entirely through the carbide
conduit.
250 The possibility of flow cutting the surface 245a of the aperture 270 or
the end of the
outer jacket 255 is greatly diminished.
As shown, the nozzle assemblies 150, 250 are used with a shunt of a gravel
pack apparatus; however, the nozzle assemblies described herein may be used
with
various other apparatuses.
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255 While the foregoing is directed to embodiments of the present invention,
other
and further embodiments of the invention may be devised without departing from
the
basic scope thereof, and the scope thereof is determined by the claims that
follow.
