U.S. patent application number 13/171127 was filed with the patent office on 2013-01-03 for milling assembly.
This patent application is currently assigned to Halliburton Energy Services, Inc.. Invention is credited to David Joe Steele.
Application Number | 20130000907 13/171127 |
Document ID | / |
Family ID | 47389418 |
Filed Date | 2013-01-03 |
United States Patent
Application |
20130000907 |
Kind Code |
A1 |
Steele; David Joe |
January 3, 2013 |
Milling Assembly
Abstract
A milling assembly and methods for milling an opening for a
lateral wellbore in a section of casing or in a cement liner.
Inventors: |
Steele; David Joe;
(Arlington, TX) |
Assignee: |
Halliburton Energy Services,
Inc.
Houston
TX
|
Family ID: |
47389418 |
Appl. No.: |
13/171127 |
Filed: |
June 28, 2011 |
Current U.S.
Class: |
166/298 ;
166/55 |
Current CPC
Class: |
E21B 29/06 20130101 |
Class at
Publication: |
166/298 ;
166/55 |
International
Class: |
E21B 29/00 20060101
E21B029/00 |
Claims
1. A milling assembly, comprising: a tubular body with an opening
at an upper end and another opening at a lower end, the lower end
having an inside diameter and an outside diameter; and a cutting
surface on the lower end extending from the inside diameter up to,
but not including, the outside diameter.
2. The milling assembly of claim 1, further comprising a
retractable retaining element positioned within the tubular body
between another opening at the lower end and the opening at the
upper end.
3. The milling assembly of claim 2, further comprising a filter
positioned within the tubular body between the retaining element
and the opening at the upper end.
4. The milling assembly of claim 3, further comprising another
retractable retaining element positioned within the tubular body
between the retaining element and the filter.
5. The milling assembly of claim 1, further comprising: a side
opening in the tubular body between the opening at the upper end
and the another opening at the lower end; and another side opening
in the tubular body between the side opening and another opening at
the lower end or the opening at the upper end.
6. The milling assembly of claim 4, wherein the retaining element
and the other retaining element are closed and extend into an
annulus of the tubular body when there is no circulation of fluid
through the annulus.
7. The milling assembly of claim 6, wherein the retaining element
and the other retaining element are open and substantially parallel
to an axis of the tubular body when there is circulation of fluid
through the annulus.
8. The milling assembly of claim 1, further comprising another
cutting surface on the inside diameter of the lower end.
9. The milling assembly of claim 1, further comprising a whipstock
positioned to engage the cutting surface and redirect the cutting
surface toward an adjacent section of casing.
10. The milling assembly of claim 9, wherein the whipstock is
substantially solid.
11. A milling assembly, comprising: a tubular body with an opening
at an upper end and another opening at a lower end, the lower end
having an inside diameter and an outside diameter; a cutting
surface on the lower end; and a whipstock positioned to engage the
cutting surface and redirect the cutting surface toward an adjacent
section of casing.
12. The milling assembly of claim 11, further comprising a
retractable retaining element positioned within the tubular body
between the other opening at the lower end and the opening at the
upper end.
13. The milling assembly of claim 12, further comprising a filter
positioned within the tubular body between the retaining element
and the opening at the upper end.
14. The milling assembly of claim 13, further comprising another
retractable retaining element positioned within the tubular body
between the retaining element and the filter.
15. The milling assembly of claim 11, further comprising: a side
opening in the tubular body between the opening at the upper end
and the another opening at the lower end; and another side opening
in the tubular body between the side opening and the other opening
at the lower end or the opening at the upper end.
16. The milling assembly of claim 14, wherein the retaining element
and the other retaining element are closed and extend into an
annulus of the tubular body when there is no circulation of fluid
through the annulus.
17. The milling assembly of claim 16, wherein the retaining element
and the other retaining element are open and substantially parallel
to an axis of the tubular body when there is circulation of fluid
through the annulus.
18. The milling assembly of claim 11, wherein the cutting surface
extends from the inside diameter up to, but not including, the
outside diameter.
19. The milling assembly of claim 18, further comprising another
cutting surface on the inside diameter of the lower end.
20. The milling assembly of claim 11, wherein the whipstock is
substantially solid.
21. A method for milling an opening for a lateral wellbore in a
section of casing or in a cement liner, comprising: lowering a
milling assembly on a drilling string toward a whipstock in a
wellbore partially lined with the section of casing and the cement
liner; milling the opening in the section of casing or in the
cement liner when the milling assembly engages the whipstock;
circulating a fluid through the milling assembly during the milling
of the opening in the section of casing or in the cement liner; and
retaining cuttings within the milling assembly when the fluid stops
circulating through the milling assembly.
22. The method of claim 21, further comprising retrieving the
cuttings within the milling assembly when the milling assembly is
removed from the wellbore.
23. The method of claim 21, further comprising filtering the
cuttings within the milling assembly during circulation of the
fluid through the milling assembly.
24. The method of claim 21, wherein the cuttings are retained
within the milling assembly by a retaining element.
25. The method of claim 24, wherein the retaining element is in an
open position when the fluid is circulating through the milling
assembly.
26. The method of claim 24, wherein the retaining element is in a
closed position when the fluid stops circulating through the
milling assembly.
27. The method of claim 21, further comprising pre-milling a
portion of the section of casing to form an opening representing a
pre-milled window.
28. The method of claim 21, wherein the fluid circulating through
the milling assembly enters an opening at one end of the milling
assembly and exits through a side opening in the milling assembly
into an annulus between the milling assembly and the section of
casing or another section of casing.
29. The method of claim 28, wherein the fluid circulating through
the milling assembly enters another opening at another end of the
milling assembly and exits through another side opening in the
milling assembly into the annulus between the milling assembly and
the section of casing or the another section of casing.
30. The method of claim 27, further comprising positioning the
whipstock within the section of casing below the pre-milled window.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not applicable.
FIELD OF THE INVENTION
[0003] The present invention generally relates to a milling
assembly and methods for milling an opening for a lateral wellbore
in a section of casing or in a cement liner using the milling
assembly.
BACKGROUND OF THE INVENTION
[0004] Wellbores are typically drilled using a drilling string with
a drill bit secured to the lower free end and then completed by
positioning a casing string within the wellbore and cementing the
casing string in position. The casing increases the integrity of
the wellbore and provides a flow path between the surface and a
selected subterranean formation for the injection of treating
chemicals into the surrounding formation to stimulate production,
for receiving the flow of hydrocarbons from the formation, and for
permitting the introduction of fluids for reservoir management or
disposal purposes.
[0005] During conventional milling and/or drilling operations for
completion of a lateral wellbore, drilling fluid is typically
pumped downhole through a conventional milling assembly on the
drilling string until it exits the bottom of the drilling string
and circulates back up through the annulus between the drilling
string and the casing as illustrated in FIG. 1. In FIG. 1, a
cross-sectional elevation view of a conventional wellbore 100
illustrates the typical path of drilling fluid during milling
and/or drilling operations. The drilling fluid passes through the
drilling string 102, exits an opening 104 at the bottom of the
drilling string 102 and circulates back up through the annulus 106
between the drilling string 102 and the intermediate casing 108.
During the milling and/or drilling operations, cuttings 110 may be
captured within the drilling fluid and deposited at various
positions within the wellbore 100 as illustrated in FIG. 1. For
example, cuttings 110, may be deposited where the intermediate
casing 108 joins the surface casing 112, at the wellhead 114 and/or
in a blowout preventer 116. The cuttings 110 may include casing
remnants, cement and/or formation debris from the milling and/or
drilling operations. Due to a low annular velocity in the annulus
106 above the intermediate casing 108, the cuttings 110 may
accumulate more around the wellhead 114 and the blowout preventer
116. As a result, cuttings 110 may become severely compacted
causing failure of the wellhead 114 and/or blowout preventer 116.
This problem is compounded when the drilling fluid stops pumping
through the drilling string 102 after the milling and/or drilling
operations.
[0006] Although there are conventional tools that reverse circulate
the drilling fluid in a manner that captures cuttings within the
tool, these tools are typically designed for retrieving other stuck
tools in the drilling string. These conventional "fishing" tools
are often designed to avoid cutting the casing while other tools
that become stuck within the wellbore are cut free with the use of
a fishing tool. As a result, this type of conventional fishing tool
cannot be used to mill an opening for a lateral wellbore in a
section of the casing.
SUMMARY OF THE INVENTION
[0007] The present invention overcomes one or more of the prior art
disadvantages by using an improved milling assembly to retain
cuttings within the milling assembly during completion of a lateral
wellbore.
[0008] In one embodiment the present invention includes a milling
assembly, comprising: i) a tubular body with an opening at an upper
end and another opening at a lower end, the lower end having an
inside diameter and an outside diameter; and ii) a cutting surface
on the lower end extending from the inside diameter up to, but not
including, the outside diameter.
[0009] In another embodiment, the present invention includes a
milling assembly, comprising: i) a tubular body with an opening at
an upper end and another opening at a lower end, the lower end
having an inside diameter and an outside diameter; ii) a cutting
surface on the lower end; and iii) a whipstock positioned to engage
the cutting surface and redirect the cutting surface toward an
adjacent section of casing.
[0010] In yet another embodiment, the present invention includes a
method for milling an opening for a lateral wellbore in a section
of casing or in a cement liner, comprising: i) lowering a milling
assembly on a drilling string toward a whipstock in a wellbore
partially lined with the section of casing and the cement liner;
ii) milling the opening in the section of casing or in the cement
liner when the milling assembly engages the whipstock; iii)
circulating a fluid through the milling assembly during the milling
of the opening in the section of casing or in the cement liner; and
iv) retaining cuttings within the milling assembly when the fluid
stops circulating through the milling assembly.
[0011] These and other objects, features and advantages of the
present invention will become apparent to those skilled in the art
from the following description of the various embodiments and
related drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention will be described with reference to the
accompanying drawings, in which like elements are referenced with
like reference numbers, and in which:
[0013] FIG. 1 is a cross-sectional elevation view of a conventional
wellbore illustrating the typical path of drilling fluid during
milling and/or drilling operations.
[0014] FIG. 2 is a cross-sectional elevation view illustrating one
embodiment of the milling assembly according to the present
invention.
[0015] FIG. 3 is a cross-sectional elevation view of the milling
assembly illustrated in FIG. 2 as it engages a whip stock within a
section of casing.
[0016] FIG. 4 is a cross-sectional elevation view of the milling
assembly illustrated in FIG. 3 as it traverses the whip stock
within the section of casing.
[0017] FIG. 5 is a cross-sectional elevation view of the milling
assembly illustrated in FIG. 4 as it traverses the whip stock and
exits a pre-milled window in the section of casing.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] In the following detailed description of the preferred
embodiments, references to the accompanying drawings that form a
part hereof, and in which is shown by way of illustration specific
preferred embodiments in which the invention may be practiced.
These embodiments are described in sufficient detail to enable
those skilled in the art to practice the invention, and it is to be
understood that other embodiments that may be utilized and that
logical changes may be made without departing from the spirit and
scope of the present invention. The claimed subject matter thus,
might also be embodied in other ways, to include structures, steps
and combinations similar to the ones described herein, in
conjunction with other present or future technologies. The
following detailed description is therefore, not to be taken in a
limiting sense, and the scope of the present invention is defined
only by the appended claims.
[0019] Referring now to FIG. 2, a cross-sectional elevation view
illustrates one embodiment of an improved milling assembly 200
according to the present invention. The milling assembly 200
includes a tubular body 202 with an annulus 203 and an axis 207.
The body 202 further includes an opening 204 at an upper end and
another opening 206 at a lower end. The lower end of the body 202
has an inside diameter 208 and an outside diameter 210. A cutting
surface 212 on the lower end of the body 202 extends from the
inside diameter 208 up to the outside diameter 210. Another cutting
surface 224 may be included on the inside diameter 208 of the lower
end of the body 202. And, another cutting surface 225 may be
included above the lower end of the body 202 on the outside
diameter 210.
[0020] The milling assembly 200 includes a retractable retaining
element 214 positioned within the body 202 between another opening
206 at the lower end of the body 202 and the opening 204 at the
upper end of the body 202. A filter 216 may be positioned within
the body 202 between the retaining element 214 and the opening 204
at the upper end of the body 202. Another retractable retaining
element 218 may be positioned within the body 202 between the
retaining element 214 and the filter 216. As illustrated in FIGS.
2-5, the retaining element 214 and the another retaining element
218 are closed and extend into the annulus 203 of the body 202 when
there is no circulation of fluid through the annulus 203. However,
the retaining element 214 and the another retaining element 218 may
be open and substantially parallel to the axis 207 of the body 202
when there is circulation of fluid through the annulus 203. The
retaining element 214 and the another retaining element 218 may be
closed and extend into the annulus 203 of the body 202 when there
is no circulation of fluid through the annulus 203 by means of a
spring-loaded mechanism or other well known means to force the
retaining element 214 and the another retaining element 218 into a
closed position. As such, the means or mechanism used to place the
retaining element 214 and the another retaining element 218 in the
closed position may be retractable so that when there is
circulation of fluid through the annulus 203 of the body 202, the
retaining element 214 and the another retaining element 218 are
open and substantially parallel to the axis of the body 202.
Alternatively, each retaining element and/or additional retaining
elements may be designed to permit circulation of fluid through the
annulus 203 of the body 202 and retain various types of debris. The
retaining element 214 may be used to retain portions or remnants of
the sleeve 228 after the milling assembly 200 has milled an opening
there through and there is no longer any circulation of the fluid
through the annulus 203 of the body 202. Likewise, the another
retaining element 218 may be used to retain additional debris in
the form of cuttings from the casing, the cement liner and/or the
formation after the milling assembly 200 has completed milling
and/or drilling and there is no longer circulation of fluid through
the annulus 203 of the body 202. The filter 216 may be used to trap
cuttings during operation of the milling assembly 200 when there is
circulation of fluid through the annulus 203 of the body 202.
[0021] A side opening 220 is located between the opening 204 at the
upper end of the body 202 and the another opening 206 at the lower
end of the body 202. Another side opening 222 is located between
the side opening 220 and the opening 204 at the upper end of the
body 202.
[0022] The body 202 may be positioned within a section of casing
226 that includes a pre-milled window 230 through the casing 226. A
sleeve 228, preferably made of aluminum, may be connected to the
casing 226 around the pre-milled window 230 to protect the milling
assembly 200 from debris and cement as the casing 226 is secured
within a wellbore. Alternatively, the sleeve 228 may be made of a
fiberglass mesh.
[0023] The milling assembly described herein may be used to mill an
opening for a lateral wellbore in the manner described in reference
to FIGS. 3-5. The opening for the lateral wellbore may be formed by
milling and/or drilling through a section of casing, the cement
liner and/or the formation.
[0024] Referring now to FIG. 3, a cross-sectional elevation view of
the milling assembly 200 is illustrated as it engages a whip stock
302 within the section of casing 226. The milling assembly 200 may
be lowered on a drilling string toward the whip stock 302 in a
wellbore partially lined with the section of casing 226 and a
cement liner. As the milling assembly 200 is lowered, it may be
rotated before or during engagement with the whip stock 302. The
whip stock 302 may be positioned within the section of casing 226
at a predetermined depth in the wellbore, which may include below
the pre-milled window 230. The pre-milled window 230 may be formed
at the surface of the wellbore, before the casing is installed, by
pre-milling a portion of the section of casing 226 to form an
opening representing the pre-milled window 230.
[0025] Referring now to FIGS. 4-5, the milling assembly 200 is
rotated as it engages the whip stock 302 and begins to mill an
opening in the section of casing 226 through sleeve 228 and/or the
cement liner. If the section of casing 226 includes the pre-milled
window 230 and the sleeve 228 is not necessary, then the opening
may be milled in just the cement liner. In most situations,
however, the opening is milled in the section of casing 226 and in
the cement liner when the milling assembly 200 engages the whip
stock 302. During milling and/or drilling operations, a fluid
(e.g., drilling fluid) may be circulated through the milling
assembly 200. The fluid may carry cuttings and other debris through
the milling assembly 200. The fluid, for example, may enter the
opening 204 at the upper end of the body 202 and exit through the
side opening 220 in the body 202 into an annulus between the
milling assembly 200 and the section of casing 226 or another
section of casing. The fluid circulating through the milling
assembly 200 may enter another opening 206 at the lower end of the
body 202 and exit through another side opening 222 in the body 202
into the annulus between the milling assembly 200 and the section
of casing 226 or another section of casing. In this manner, the
fluid circulating through the milling assembly 200 is often
referred to as reverse circulation.
[0026] During circulation of the fluid through the milling assembly
200, cuttings and other debris may be filtered within the milling
assembly 200 by the filter 216. Further, the cuttings and other
debris may be retained within the milling assembly 200 when the
fluid stops circulating through the milling assembly 200. The
cuttings and other debris may be retained by the retaining element
214 and the another retaining element 218 when both are in a closed
position after the fluid stops circulating through the milling
assembly 200. The cuttings and other debris may be retrieved from
within the milling assembly 200 when the milling assembly 200 is
removed from the wellbore.
[0027] Although specific embodiments have been illustrated and
described herein, it will be appreciated by those of ordinary skill
in the art that any arrangement which is calculated to achieve the
same purpose may be substituted in the specific embodiments shown.
This application is intended to cover any adaptations or variations
of the present invention. Therefore, it is manifestly intended that
this invention be limited only by the following claims and
equivalents thereof.
* * * * *