U.S. patent application number 09/908949 was filed with the patent office on 2001-11-22 for method and apparatus for multilateral well entry.
Invention is credited to Leising, Lawrence J..
Application Number | 20010042621 09/908949 |
Document ID | / |
Family ID | 23623457 |
Filed Date | 2001-11-22 |
United States Patent
Application |
20010042621 |
Kind Code |
A1 |
Leising, Lawrence J. |
November 22, 2001 |
Method and apparatus for multilateral well entry
Abstract
In one embodiment, the invention relates to a method for
location, or location and entry, of a lateral wellbore from a main
wellbore of a multilateral hydrocarbon well, the method being
characterized by unique operation of a controllably bent sub. The
invention further relates to a system for location, or location and
entry of a lateral wellbore, including a specialized controllably
bent sub, and most preferably, to a controllably bent sub designed
for efficient lateral wellbore location and/or entry.
Inventors: |
Leising, Lawrence J.; (Sugar
Land, TX) |
Correspondence
Address: |
Trop, Pruner & Hu, P.C.
Suite 100
8554 Katy Freeway
Houston
TX
77024
US
|
Family ID: |
23623457 |
Appl. No.: |
09/908949 |
Filed: |
July 19, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09908949 |
Jul 19, 2001 |
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09410153 |
Sep 30, 1999 |
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Current U.S.
Class: |
166/255.1 ;
166/113; 166/50 |
Current CPC
Class: |
E21B 41/0035 20130101;
E21B 23/03 20130101; E21B 47/09 20130101 |
Class at
Publication: |
166/255.1 ;
166/113; 166/50 |
International
Class: |
E21B 047/09 |
Claims
What is claimed is:
1. A method for locating a lateral wellbore from a main wellbore of
a hydrocarbon well with a working tool comprising providing a
wellbore working tool on a work string, the working tool
terminating in a multi-segment work-locator sub adapted to
semi-flexibly position the terminal segment of the sub, and to
semi-flexibly deflect the terminal segment at an acute angle with
respect to the longitudinal axis of the string, the terminal
segment being of a length adapted for lateral wellbore incursion;
lowering the tool in the main wellbore to a location proximate the
lateral wellbore to be entered and at which the end of the terminal
segment is below or posterior to the lateral wellbore to be
entered; positioning the terminal segment of the sub in said main
wellbore at an acute angle with respect to the longitudinal axis of
the work string; raising or retrieving the work string in the main
wellbore, while maintaining a section of the terminal segment in
contact with a wall of said main wellbore, and locating the lateral
wellbore by increase of the acute angle between the terminal
segment and the longitudinal axis of the work string and by entry
of a section of the terminal segment into the lateral wellbore.
2. The method of claim 1 in which the sub is oriented in the main
wellbore before raising the work string.
3. The method of claim 2 in which the work string comprises coiled
tubing.
4. The method of claim 3 in which surface fluid pressure is
measured while raising or retrieving the work string, and the
location of the lateral wellbore is determined by a change in
pressure.
5. The method of claim 3 in which the terminal segment includes
means for well treatment and/or analysis.
6. A method for locating a lateral wellbore from a main wellbore of
a hydrocarbon well with a working tool comprising providing
wellbore working tool on a work string, the working tool
terminating in a multi-segment work-locator sub adapted to
semi-flexibly position the terminal segment of the sub, and to
semi-flexibly deflect the terminal segment at an acute angle with
respect to the longitudinal axis of the string, the terminal
segment being of a length adapted for lateral wellbore incursion;
lowering the tool in the main wellbore to a location proximate the
lateral wellbore to be entered and at which the end of the terminal
segment is above or anterior to the lateral wellbore to be entered;
positioning the terminal segment of the sub in said main wellbore
at an acute angle with respect to the longitudinal axis of the work
string; lowering or advancing the work string in the main wellbore,
while maintaining a section of the terminal segment in contact with
a wall of said main wellbore, and locating the lateral wellbore by
increase of the acute angle between the terminal segment and the
longitudinal axis of the work string and by entry of a section of
the terminal segment into the lateral wellbore.
7. The method of claim 6 in which the sub is oriented in the main
wellbore before lowering or advancing the work string.
8. The method of claim 7 in which the work string comprises coiled
tubing.
9. The method of claim 8 in which surface fluid pressure is
measured while lowering or advancing the work string, and the
location of the lateral wellbore is determined by a change in
pressure.
10. The method of claim 8 in which the terminal segment includes
means for well treatment and/or analysis.
11. A method for locating and entry of a lateral wellbore from a
main wellbore of a hydrocarbon well with a working tool comprising
providing a wellbore working tool on a work string, the working
tool terminating in a multi-segment work-locator sub adapted to
semi-flexibly position the terminal segment of the sub, and to
semi-flexibly deflect the terminal segment at an acute angle with
respect to the longitudinal axis of the string, the terminal
segment being of a length adapted for lateral wellbore incursion;
lowering the tool in the main wellbore to a location proximate the
lateral wellbore to be entered and at which the end of the terminal
segment is below or posterior to the lateral wellbore to be
entered; positioning the terminal segment of the sub in said main
wellbore at an acute angle with respect to the longitudinal axis of
the work string; raising or retrieving the work string in the main
wellbore, while maintaining a section of the terminal segment in
contact with a wall of said main wellbore, and locating the lateral
wellbore by increase of the acute angle between the terminal
segment and the longitudinal axis of the work string and by entry
of a section of the terminal segment into the lateral wellbore;
guiding the remainder of the terminal segment of the sub into the
lateral wellbore; and positioning the terminal segment of the sub
with respect to the longitudinal axis of the sub so that the sub
may be advanced or retrieved in the lateral wellbore.
12. The method of claim 11 in which the sub is oriented in the main
wellbore before raising the work string.
13. The method of claim 12 in which the work string comprises
coiled tubing.
14. The method of claim 13 in which surface fluid pressure is
measured while raising the work string, and the location of the
lateral wellbore is determined by a change in pressure.
15. The method of claim 13 in which the lateral wellbore is
treated.
16. The method of claim 13 in which well or formation analysis is
performed in the lateral wellbore.
17. A method for locating and entry of a lateral wellbore from a
main wellbore of a hydrocarbon well with a working tool comprising
providing a wellbore working tool on a work string, the working
tool terminating in a multi-segment work-locator sub adapted to
semi-flexibly position the terminal segment of the sub, and to
semi-flexibly deflect the terminal segment at an acute angle with
respect to the longitudinal axis of the string, the terminal
segment being of a length adapted for lateral wellbore incursion;
lowering the tool in the main wellbore to a location proximate the
lateral wellbore to be entered and at which the end of the terminal
segment is above or anterior to the lateral wellbore to be entered;
positioning the terminal segment of the sub in said main wellbore
at an acute angle with respect to the longitudinal axis of the work
string; lowering or advancing the work string in the main wellbore,
while maintaining a section of the terminal segment in contact with
a wall of said main wellbore, and locating the lateral wellbore by
increase of the acute angle between the terminal segment and the
longitudinal axis of the work string and by entry of a section of
the terminal segment into the lateral wellbore; guiding the
remainder of the terminal segment of the sub into the lateral
wellbore; and positioning the terminal segment of the sub with
respect to the longitudinal axis of the sub so that the sub may be
advanced or retrieved in the lateral wellbore.
18. The method of claim 17 in which the sub is oriented in the main
wellbore before lowering the work string.
19. The method of claim 18 in which the work string comprises
coiled tubing.
20. The method of claim 19 in which surface fluid pressure is
measured while lowering the work string, and the location of the
lateral wellbore is determined by a change in pressure.
21. The method of claim 19 in which the lateral wellbore is
treated.
22. The method of claim 19 in which well or formation analysis is
performed in the lateral wellbore.
23. A segmented work-locator sub adapted to semi-flexibly deflect
its terminal segment at an acute angle with respect to the
longitudinal axis of a string or another segment of the sub, the
terminal segment being of a length adapted for lateral wellbore
incursion.
24. A segmented work-locator sub adapted to semi-flexibly position
its terminal segment, and to semi-flexibly deflect its terminal
segment at an acute angle with respect to the longitudinal axis of
a string or another segment of the sub, the terminal segment being
of a length adapted for lateral wellbore incursion.
25. A segmented work-locator sub comprising an attaching sub
segment adapted for attachment to a work string or tool at one end
thereof; and a nose segment coupled to the attaching sub segment at
the other end thereof, the attaching segment and the nose segment
being coupled in such manner that the nose segment may be
semi-rigidly positioned so that its longitudinal axis coincides at
least substantially with that of the attaching segment, or may be
semi-rigidly pivoted and positioned at an acute angle with respect
to the longitudinal axis of the attaching segment, the nose segment
being of a length adapted for lateral wellbore incursion.
26. The sub of claim 25 comprising means for well treatment in the
nose segment.
27. A system for location or location and entry of a lateral
wellbore from a main wellbore of a hydrocarbon well comprising a
wellbore working tool suspended on a work string, the working tool
terminating in a segmented work-locator sub adapted to
semi-flexibly position its terminal segment, and to semi-flexibly
deflect its terminal segment at an acute angle with respect to the
longitudinal axis of the string or another segment of the sub, the
terminal segment being of a length adapted for lateral wellbore
incursion.
28. Apparatus comprising a first housing adapted for wellbore
insertion and provided at one end thereof with an apertured closure
and adapted at the other end thereof for connection to and
communication with a work string; a piston, having an internal
fluid passage, disposed in said first housing, at a location toward
the end of said first housing adapted for connection to a work
string, said piston adapted for longitudinal sliding displacement
in said first housing; a mandrel, having an internal fluid passage,
disposed in said first housing internally to said piston and
connected at or proximate one end to said piston for longitudinal
displacement with the piston in said first housing, the fluid
passage of the mandrel communicating with the fluid passage of the
piston at or proximate said one end of the mandrel and with a fluid
outlet or outlets in the terminal segment of the other end of the
mandrel, which outlet or outlets communicate with the interior of
the first housing; a cam member connected to the terminal segment
of said other end of the mandrel and disposed for longitudinal
sliding displacement in said first housing; a pivot shaft, having
an internal fluid passage, partially disposed in said first
housing, the pivot shaft comprising an extension arm which extends
through and beyond the aperture of said closure, said pivot shaft
having mounting means, and being mounted in said housing for
angular displacement of the extension arm of the pivot shaft in
said aperture, the pivot shaft being operatively connected to said
cam member for semi-flexible positioning and deflection of the
extension arm and in such manner that longitudinal sliding
displacement of the cam member in said first housing provides
angular displacement of the extension arm of pivot shaft in the
aperture; a second housing adapted for wellbore insertion having an
anchoring closure at one end thereof provided with a receiving
aperture adapted to receive the terminal section of said extension
arm, said receiving aperture and said anchoring closure positioned
for and said receiving aperture receiving the terminal section of
said extension arm; means disposed in said second housing
cooperating with said anchoring closure and said mounting means for
anchoring the terminal section of the extension arm of said pivot
shaft in said second housing, the internal fluid passage of the
pivot shaft communicating through outlets with the interior of the
first housing and with the interior of the second housing to
provide a fluid passage between the interior of the first housing
and the interior of the second housing; and means for egress of
fluid from the second housing.
29. The apparatus of claim 28 comprising a spring partially
surrounding the mandrel in said first housing and positioned to
resist the longitudinal displacement of the piston in the first
housing.
30. Apparatus comprising a first housing adapted for wellbore
insertion and provided at one end thereof with an apertured closure
and adapted at the other end thereof for connection to and
communication with a work string; a piston, having an internal
fluid passage, disposed in said first housing, at a location toward
the end of said first housing adapted for connection to a work
string, said piston adapted for longitudinal sliding displacement
in said first housing; a first mandrel, having an internal fluid
passage, disposed in said first housing internally to said piston
and connected at or proximate one end to said piston for
longitudinal displacement with the piston in said first housing,
the fluid passage of the first mandrel communicating with the fluid
passage of the piston at or proximate said one end of the first
mandrel and with a fluid outlet or outlets in the terminal segment
of the other end of the first mandrel; a second mandrel disposed in
said first housing, having an internal fluid passage with an inlet
at or proximate one end thereof and an outlet or outlets at the
other end thereof communicating with the interior of the first
housing; a cam member connected to the terminal segment of the
other end of the second mandrel and disposed for longitudinal
sliding displacement in said first housing; a pivot shaft, having
an internal fluid passage, partially disposed in said first
housing, the pivot shaft comprising an extension arm which extends
through and beyond the aperture of said closure, said pivot shaft
having mounting means, and being mounted in said first housing for
angular displacement of the extension arm of the pivot shaft in
said aperture, the pivot shaft being operatively connected to said
cam member for semi-flexible positioning and deflection of the
extension arm and in such manner that longitudinal sliding
displacement of the cam member in said first housing provides
angular displacement of the extension arm of the pivot shaft in the
aperture; means for coupling the first mandrel and the second
mandrel, providing a closed fluid passage between said first and
second mandrel, and in such manner that said second mandrel is
decoupled from said first mandrel if a fluid force exceeding a
predetermined threshold is applied to said piston, or if
significant constraining moment is applied to the pivot shaft when
deflected; a second housing adapted for wellbore insertion having
an anchoring closure at one end thereof provided with a receiving
aperture adapted to receive the terminal section of said extension
arm, said receiving aperture and said anchoring closure positioned
for and said receiving aperture receiving the terminal section of
said extension arm; means disposed in said second housing
cooperating with said anchoring closure and said mounting means for
anchoring the terminal section of the extension arm of said pivot
shaft in said second housing, the internal fluid passage of the
pivot shaft communicating through outlets with the interior of the
first housing and with the interior of the second housing to
provide a fluid passage between the interior of the first housing
and the interior of the second housing to provide a fluid passage
between the interior of the first housing and the interior of the
second housing; and means for egress of fluid from the second
housing.
31. The apparatus of claim 30 comprising a first spring partially
surrounding the first mandrel in said first housing and positioned
to resist the longitudinal displacement of the piston in the first
housing, and a second spring partially surrounding the second
mandrel in said first housing and positioned for decoupling the
second mandrel.
32. A method for locating a lateral wellbore from a main wellbore
of a hydrocarbon well with a working tool comprising providing a
wellbore working tool on a work string, the working tool
terminating in a multi-segment work-locator sub adapted to
semi-flexibly deflect the terminal segment at an acute angle with
respect to the longitudinal axis of the string, the terminal
segment being of a length adapted for lateral wellbore incursion;
lowering the tool in the main wellbore to a location proximate the
lateral wellbore to be entered and at which the end of the terminal
segment is below or posterior to the lateral wellbore to be
entered; positioning the terminal segment of the sub in said main
wellbore at an acute angle with respect to the longitudinal axis of
the work string; raising or retrieving the work string in the main
wellbore, while maintaining a section of the terminal segment in
contact with a wall of said main wellbore, and locating the lateral
wellbore by increase of the acute angle between the terminal
segment and the longitudinal axis of the work string and by entry
of a section of the terminal segment into the lateral wellbore.
33. The method of claim 32 in which the sub is oriented in the main
wellbore before raising the work string.
34. The method of claim 32 in which the work string comprises
coiled tubing.
35. The method of claim 34 in which the terminal segment includes
means for well treatment and/or analysis.
Description
FIELD OF THE INVENTION
[0001] The invention relates generally to the location and entry of
a lateral hydrocarbon well from a main wellbore in a subterranean
formation, and additionally to treatment and/or analysis of a
lateral hydrocarbon well after such location and entry.
BACKGROUND OF THE INVENTION
[0002] Multilateral hydrocarbon wells, i.e., hydrocarbon wells
having one or more secondary wellbores connecting to a main
wellbore, are common in the oil industry, and will continue to be
drilled in substantial numbers in the future. Location, or location
and entry of one or more of the secondary or lateral wellbores,
whether in completion or treatment procedures for a new well, or
for reconditioning or reworking of an older well, often poses a
problem for the well service operator.
[0003] A common approach for location and entry into lateral
wellbores, particularly in level 1 and level 2 well construction,
is to run jointed pipe from a service rig just barely into the
lateral wellbore using standard location and kickoff procedures.
Coilable tubing (commonly referred to in the industry as "coiled
tubing") carrying a service or work tool is then run through the
jointed pipe and into the lateral wellbore. In the usual approach,
however, the extra expense of a service rig adds significantly to
the cost of entry operations. Again, in some cases, even if the
cost of the service rig is accepted, procedures employed for
location of a particular lateral wellbore often lack precision and
can be time consuming. Accordingly, efforts have continued, and
there has been a need, to find an alternative to service rig
dependent and inefficient approaches, particularly for level 1 and
level 2 multilateral well reworking operations. In particular,
there has been a need to provide an effective location or location
and entry method and a locator, entry and servicing tool that would
reduce costs and allow use of relatively inexpensive coiled tubing
procedures. The invention addresses these needs, and provides a
method, system, and tool for location, entry or re-entry, and
service operations, each of which is particularly adapted to
"coiled tubing" usage.
SUMMARY OF THE INVENTION
[0004] Accordingly, in one embodiment, the invention relates to a
method for location, or location and entry, of a lateral wellbore
from a main wellbore of a multilateral hydrocarbon well, the method
being characterized by unique operation of a controllable or
controllably bent sub. In this embodiment, the working tool
employed, including the aforementioned sub, which possesses
particular required positioning and/or deflection characteristics,
is operated in the main wellbore in a manner such that location of
the desired lateral wellbore is facilitated. For conducting
wellbore treatment or servicing, the work tool will comprise well
treatment and/or analysis components, optionally in the "bent"
segment or arm of the sub. Advantageously, with well treatment
and/or analysis components provided in or near the sub, the
invention permits immediate treating operations in the located
lateral wellbore, tripping out and removal of the sub being
unnecessary.
[0005] In a further aspect, the invention relates to a novel system
for location or location and entry of a lateral wellbore from a
main wellbore of a hydrocarbon well, and which further includes
means for working or reworking the well, the system comprising a
work string and a unique wellbore working tool suspended on the
work string. The novel working tool terminates in a segmented
work-locator sub having a terminal segment which may be "bent"
according to predetermined design requirements. In particular, the
work-locator sub of the system is adapted to semi-rigidly or
semi-flexibly position its terminal segment or semi-rigidly or
semi-flexibly deflect its terminal segment at an acute angle with
respect to the longitudinal axis of the string or other segment of
the sub, the terminal segment further being of a length adapted for
lateral wellbore incursion. The terms "semi-rigidly" and
"'semi-flexibly", as utilized herein with respect to the
positioning or deflection of the sub terminal segment, are
understood to indicate a relative rigidity at which the directing
or positioning components of the sub are designed to maintain the
position of or deflection of the sub's terminal segment. This
degree of rigidity is unlike the rigidity or stiffness at which
common controllable bent subs are held during drilling operations.
Instead, the sub of the system is structurally adapted for, or
comprises structural components for, positioning the terminal
segment with sufficient rigidity for efficient wellbore entry, as
hereinafter described, while providing the capacity for, when the
terminal segment is deflected from the longitudinal axis of the
string or other segment of the sub, limited yield of deflection to
a predetermined force or constraint or to a reduction of the angle
of deflection in response to encounter of such force or constraint,
or to an increase or expansion of the angle of deflection in the
absence or elimination of such force or constraint. Accordingly,
when the terminal segment is "straight", i.e., at least a section
thereof is in or generally in a line coincident with the
longitudinal axis of the remainder of the sub or the string, the
sub's terminal segment positioning components will be designed to
hold the terminal segment with sufficient rigidity or firmness that
the terminal segment does not pendulate or "dangle" to any
significant extent due to gravity from the rest of the sub, a
firmness important, for example, in wellbore entry, advancement, or
retrieval. In the deflected posture of the terminal segment, the
positioning components of the sub will be designed not only to
provide the terminal segment with a certain moment to deflect or
position and maintain the segment in deflection, but will be
adapted yield somewhat to the wellbore wall's constraint, to adjust
to a limited increase of the angle of deflection upon removal of
any constraining force on the terminal segment, or to the de-crease
of or reduction of the angle upon encounter by the terminal segment
with a constraining force exceeding a pre-determined level. Thus,
for example, the sub components are adapted or structured, on one
hand, to maintain its terminal segment securely against the main
wellbore wall, even though constrained thereby to some extent from
further deflection, while, on the other hand, if the terminal
segment is further or fully deflected during open lateral wellbore
entry, being adapted for constraint and reduction of the degree of
deflection to some degree, if, for example, the work tool is raised
and the terminal segment again encounters the constraining wall of
the main wellbore. To accomplish this type of resilient positioning
or deflection, appropriate means are provided in the sub, as
hereinafter described. Again, as utilized herein, the phrase "of a
length adapted for lateral wellbore incursion" indicates that, in
sizing the terminal segment for use in a main wellbore of specified
width, the length of the termin-al segment is sized to that length
effective to protrude or project a section of the terminal segment
into a lateral wellbore if the deflection angle between the
longitudinal axis of the string or remainder of the sub and the
longi-tudinal axis of the terminal segment is increased from the
deflection angle determined by the intersection of the longitudinal
axis of the string or remainder of the sub and the terminal segment
when confined by a main wellbore wall. Importantly, the terminal
segment of the work-locator sub of the system, in its most
preferred aspect, further comprises means for well treatment and/or
analysis so that, once the lateral wellbore is located and entered,
the lateral may be worked, treated and/or measurements taken
without withdrawal of the sub. Finally, means for orient-ing the
work-locator sub in the wellbore and means cooperating with the
work-locator sub for signaling the location of a lateral wellbore
are provided in the system.
[0006] In a further particular aspect, the invention comprises a
work tool which is adapted for performance in the invention method
and which includes a combination of elements including a novel
segmented work-locator apparatus or sub. In this embodiment, the
novel segmented work-locator apparatus comprises a proximate
attaching sub segment, attachable to a work string or tool at one
end thereof, and a distal nose segment, preferably having a
wellbore treating section, coupled to the attaching sub segment at
the other end thereof, the two segments being coupled in such
manner that the nose segment may be semi-rigidly positioned so that
its longitudinal axis coincides at least substantially with that of
the attaching segment, or may be pivoted and semi-rigidly
positioned at an acute angle with respect to the longitudinal axis
of the attaching segment, the nose segment being of a length
adapted for lateral wellbore incursion. The terminal section may
optionally contain analysis or measurement components, although
commonly these will be located in the main body of the tool.
Indication that the axis of the terminal segment coincides at least
substantially with the axis of the work-string or another sub
segment merely indicates that, while perfect alignment is desirable
and included, it is not required, and that, with consideration of
the length of the terminal segment, deviation from coincidence does
not occur to the extent that entry into a main wellbore is
prevented. Accordingly, in each of the sub embodiments described
herein, the sub may be lowered into the main wellbore "bent" to
some degree if the main wellbore width is of such extent that the
widest angular extension of the terminal segment does not bring the
terminal segment into significant contact with the main
wellbore.
[0007] In yet a further embodiment, a novel controllably bent sub
for location, location and entry, and treatment and/or analysis of
lateral wellbores is described, the sub being characterized by
unique operational capabilities. The sub of the invention is
adapted for maintaining semi-rigid or semi-flexible positioning of
its terminal member or segment in the manner described, and in its
preferred form, is provided with novel force relief means to
prevent damage to its components by excess fluid pressure generated
force or by accidental undue constraint of the "bent" arm or
terminal member of the sub. The novel sub of the invention is
further provided with means for alerting or signaling an operator
when the terminal segment of the sub is "bent" more than a
predetermined amount, i.e., the acute angle of the sub has
increased or become greater. Other novel and unique aspects of the
method, system, and apparatuses of the invention are set out more
fully in the following detailed description.
BRIEF DESCRIPTION OF THE DRAWING
[0008] FIG. 1 is a schematic representation illustrating entry of a
working tool in a lateral wellbore in a manner according to the
invention.
[0009] FIG. 2 is a schematic representation illustrating generally
the components of a controllably bent sub according to the
invention.
[0010] FIGS. 3a, 3b, and 3c are cross-sectional views of a
controllably bent sub of the invention in the plane of the sub's
bend illustrating sub orientation adapted for lowering or insertion
of the sub into a main wellbore.
[0011] FIGS. 4a, 4b, and 4c are cross-sectional views of a
controllably bent sub of the invention in the plane of the sub's
bend illustrating sub orientation adapted for location of and entry
of the sub into a lateral wellbore.
[0012] FIG. 5 is a sectional view along line A-A of FIG. 3a.
[0013] FIG. 6 is a sectional view along line B-B of FIG. 3b.
[0014] FIG. 7 is a sectional view along line C-C of FIG. 3b.
[0015] FIGS. 8a and 8b are sectional views of a plug and cam
structure employed in a sub of the invention along the longitudinal
axis L of the sub.
[0016] FIG. 9 is a sectional view along line D-D of FIG. 3b.
[0017] FIG. 10 is a sectional view along line E-E of FIG. 3b.
[0018] FIG. 11 is a cross-sectional view of the preferred unique
force limiting transmission means of the invention in a straight
sub orientation.
[0019] FIG. 12 is a cross-sectional view of the preferred unique
force limiting transmission means of the invention in a bent sub
orientation.
[0020] FIGS. 13a, 13b, 13c, and 13d are cross-sectional views of a
controllably bent sub of the invention in the plane of the sub's
bend containing the force limiting transmission means of the
invention.
[0021] FIGS. 14a, 14b, 14c, and 14d are cross-sectional views of a
controllably bent sub of the invention in the plane of the sub's
bend containing the force limiting transmission means of the
invention and illustrating sub terminal segment deflection at high
fluid flow.
DETAILED DESCRIPTION OF THE INVENTION
[0022] According to the method of the invention, a wellbore working
tool is provided on a work string, the working tool comprising and
terminating in a segmented work-locator sub comprising or having a
terminal segment adapted to semi-rigidly or semi-flexibly position
and/or to semi-rigidly or semi-flexibly deflect its terminal
segment at an acute angle with respect to the longitudinal axis of
the string, the terminal segment being of a length adapted for
lateral wellbore incursion. The terminal segment may also possess
some curvature, i.e., may be curved, as described more fully
hereinafter. In the method of the invention, any controllably bent
sub structure providing the required capabilities may be used,
although, as mentioned, the specific subs described herein are
preferred. Thus, subs designed with "knuckle joints" of different
structure than the particular subs of the invention, or having
restricted "ball joints" may be used if constrained to bend in the
required manner and if provided, as mentioned, with appropriate
force adjusting means, as well as the lateral incursion feature of
the in-vention, and, most preferably, with well treatment/and or
analysis features. Other means of accomplishing a "bend" include a
pin joint, bourdon tube, or asymmetrically slot-ted member with
internal pressurization means. Addition-ally, while the preferred
subs of the invention emphasize flow of the work and treating
fluids through the sub, e.g., through the terminal segment, other
designs may be em-ployed. For example, lateral ports in the sub may
be used, with fluid ejection occurring in the remainder section of
the sub or even in the main work tool body.
[0023] Accordingly, upon provision of a suitable working tool, in
the case of a vertical main wellbore, the tool is then lowered in
the main wellbore to a location proximate and below, or above, the
lateral wellbore to be located or located and entered. The terminal
segment of the sub of the tool will preferably be maintained, on
lowering, at an angle coincident with or at least substantially
coincident with the axis of the work string, minor deflection, as
indicated, being possible, depending on the main wellbore diameter.
In the case of a slanted or horizontal main wellbore, the tool is
advanced into the main wellbore to a position proximate the lateral
wellbore, either posterior to or anterior to the lateral wellbore.
In either situation, the terminal segment of the sub is then
positioned or deflected in the main wellbore at an acute or
increased acute angle with respect to the longitudinal axis of the
work string or other segment of the sub by applying a deflection
force or moment to the terminal segment in excess of that required
to thrust the distal or nose end of the terminal segment into
contact with a constraining wall or side of the main wellbore. The
effect of the application of excess deflection force or moment is
that the terminal segment possesses potential for further increase
or expansion of the acute angle of deflection should the constraint
of the main wellbore wall or side be eliminated or dissipated. In
this regard, for simplicity in description, the "wall" of a
wellbore is understood to include not only the surface of the
subterranean formation forming the wellbore, but may include
casing, liner, cement, etc., present in the wellbore. At this
point, operation of the sub to locate the lateral wellbore or
"profiling" of the main wellbore may be commenced. Optionally, and
preferably, however, the sub is then oriented in the main wellbore
in the correct azimuthal direction by any known procedure and
device. For example, the work string may include an indexing device
or a continuously run motor providing 360 degree coverage which may
be suitably employed by those skilled in the art to orient the sub.
In the case of an indexing device, the index range is preferably on
the order of 30 degrees.
[0024] To commence the profiling, in the case of a vertical main
wellbore, and depending on the location of the sub, either below or
above the lateral's junction with or entry to the main wellbore,
the string is raised or lowered in the main wellbore. With a
slanted or horizontal main wellbore, depending on the location of
the sub, either posterior or anterior to the lateral's entrance,
the string is retrieved or advanced. In both cases, the excess
deflection moment on the terminal segment is maintained during
movement or displacement of the string. In either case, the lateral
wellbore may be located according to the invention in the following
manner. As the sub is raised or lowered (or retrieved or advanced)
in the main wellbore, the distal end or nose of the terminal
segment of the sub, at an acute angle to the longitudinal axis of
the string, continues in contact with the main wellbore wall or
side. However, when the open lateral wellbore is reached, the
constraining or confining force of the main wellbore wall or side
is eliminated, and the tip force or excess potential energy in the
semi-flexibly maintained terminal segment is released, expanding
the acute angle made by the terminal segment with the longitudinal
axis of the working tool or sub. If the terminal segment is of a
length adapted for lateral wellbore incursion, the nose or end
section thereof will be forced or urged into the open lateral
wellbore, thereby "locating" the lateral. This expansion may be
sensed by an operator at the surface by a variety of sensing
mechanisms or means, and the terminal segment may then guided or
advanced further into the lateral wellbore. Upon location and entry
into the lateral wellbore, the terminal segment of the sub may be
returned to and semi-rigidly fixed at a position or angle allowing
advancement into the lateral. Normally, this will be a reduced
acute angle or, preferably, an angle that is at least substantially
coincident with that of the longitudinal axis of the work string or
attaching sub segment. Treatment operations and/or analysis may
then be commenced. The well treatment procedures which may be
carried out are any of those commonly undertaken, such as
acidizing, flushing, cementing, etc. In a particularly preferred
embodiment, surface fluid pressure in the system is measured while
raising the string, and the location of the lateral wellbore is
signaled by change in pressure.
[0025] The invention is especially useful for re-entry of level 1
and level 2 multilateral wells, although it is not limited thereto.
As employed herein, the expression "level 1" is used in the manner
commonly understood in the art, as referring to well construction
characterized by a "parent" or main wellbore with one or more
lateral wellbores branching from the main wellbore. In level 1
wells, the wellbores are openhole and the junction is unsupported.
The expression "level 2" is also used as commonly understood in the
art, as referring to well construction characterized by a "parent"
or main wellbore which is cased and cemented, with one or more
openhole lateral wellbores branching from the main wellbore that
may or may not include a drop-off liner. As employed herein, the
expression "main wellbore" in not to be taken as referring simply
to the principal or initial wellbore (whether vertical, slanted, or
horizontal) in a multilateral wellbore system, but is to be
understood to include a "secondary" wellbore, regardless of
orientation, from which it is desired to enter another joining
secondary wellbore.
[0026] In order to describe the invention more fully, reference is
made to the accompanying drawing. In the interest of clarity, many
features related to the manufacturing or maintenance of specific
apparatus features of the invention, such as sectioning, beveling,
or fileting, and common connection means, such as threading, which
are well known or fully realizable by those skilled in the art, and
which have no bearing on the essence of the invention, have not
been described. Again, the very specific description of steps or
elements herein are not to be taken as limiting, it being
understood that equivalent steps or means are contemplated to be
within the scope of the invention.
[0027] Accordingly, in FIG. 1 there is illustrated a typical
location and entry of a lateral wellbore which has been carried out
by the invention steps described previously. In particular, there
is shown a segment or portion of a multilateral wellbore 1 having a
vertical main well bore 2, with a lateral or slanted bore 3
connecting at a junction J. While a vertical main wellbore is
illustrated, those skilled in the art will recognize that wellbore
2, as indicated, may be slanted or horizontal, and that, commonly,
more than one lateral will be joining wellbore 1, although only one
lateral is shown. In FIG. 1, vertical main wellbore 2 is provided
with casing 4, but the connection of lateral bore 3 at junction J
is an open hole connection.
[0028] Designated generally as 5 is a working tool which embodies
aspects of the invention. Working tool 5 is suspended from work
string 6, the string in this case comprising coiled tubing, which
has been supplied from coil 7 via a surface injector through the
wellhead. The tool has been centered in the main wellbore with
centralizers 8, and a knuckle joint (not illustrated) may be
included in the assembly. The working or treating fluid is supplied
through the coiled tubing by means of pump or pumps 9, from an
appropriate supply source (not shown). While for profiling a common
wellbore fluid, such as water or hydrocarbon fluid, may be
utilized, for well treatment, such work fluids as acids, e.g.,
hydrochloric acid, flush liquids, spacers, and cements may be
supplied. Pump means 9, along with pressure measurement means 9a,
may also be used as a part of or a component of important means for
determining the location of lateral wellbore 3, as discussed more
fully hereinafter. Working tool 5 is comprised, importantly, of
segmented work-locator sub 10, shown as providing insertion of a
segment or portion thereof, or attachment thereto, into the lateral
wellbore 3. As illustrated, sub 10 comprises an attaching and
deflection section 11 and terminal or deflected segment 12.
Terminal or deflected segment 12 includes extension or segment 13
as well as optionally tapered or rounded nose section 14, and
segments 13 and 14 will preferably comprise structure for well
treatment and/or analysis. Segment 12 is shown as being extended at
an acute angle .alpha. with respect to the longitudinal axis of the
working tool or of segment 11, and is sized in a length sufficient
for lateral wellbore incursion. In the illustration of FIG. 1, the
angle .alpha. is the maximum deflection of terminal segment 12, the
angle having increased from its previous arc when the terminal
segment 12 was constrained by the main wellbore 2. While the
maximum value of the angle .alpha. may be varied depending on the
main wellbore size and on the size of terminal segment 12, suitable
deflection angles for practicing the method of the invention and
use of the sub of the invention, assuming the terminal section of
the sub to be "straight" will range from about 3 or 4 degrees to
about 30 degrees with a range of from about 4 degrees to about 15
degrees being preferred. In this regard, the shape of terminal
segment 12 may be varied or irregular to some extent, and, as
mentioned, may have some curvature or angularity (not illustrated),
so long as the angular and sizing parameters thereof are consonant
with the requirements described herein. In such case, the acute
angle of deflection may be considered to be defined by the
intersection of the longitudinal axis of the string or other
segment of the sub and a line from the beginning of the curve,
where the curve is tangent to the longitudinal axis of the string
or other segment of the sub, through the end or tip of the terminal
segment of the sub.
[0029] In the manner described previously, the lateral 3 has been
located by utilization of the excess deflection force approach of
the invention, and in this case, by proper orientation of the sub.
Segment 15 of tool 6 will include the appropriate orienting
equipment, such as indexing means, or an orienting motor, and may
include other analyzing and/or treating components as are common in
working tools, as well as telemetry components, and these may also
be present in the segments designated 16 and 13.
[0030] FIG. 2 is a schematic illustration of the arrangement of the
respective operating sections of the novel controllably bent sub of
the invention, shown in an orientation suitable for entry into a
main wellbore. In the assemblies of the sub shown in the additional
views of the drawing hereinafter, which, because of length and
complexity are provided in sections, it will be understood that the
arrangement of the sub follows the scheme of FIG. 2. Accordingly,
in FIG. 2, letter A designates a hydraulic pressure transmission
section, with conversion of fluid pressure to mechanical force, and
which may include an optional and preferred further load limiting
and back 2 force relieving section FR; letter B denotes a segment
or section which provides conversion of mechanical force
transmitted thereto to deflection of a locator or caliper segment
or arm, and may include structure responsive to a deflection of the
locator segment for signaling such deflection; and letter C denotes
a locator or caliper segment or structure N providing means for
lateral wellbore location or entry as well as structure for well
treatment (WT).
[0031] FIGS. 3a, 3b, 3c, 4a, 4b, and 4c illustrate the assembly of
a sub which may be bent in controlled manner to carry out the
lateral wellbore location, and location and entry aspects of the
invention, as well as being adapted to perform appropriate well
treatment and/or analysis once the lateral wellbore entry has been
achieved. As shown in FIGS. 3a, 3b, and 3c, there is provided a
housing section or pipe 50 which comprises means, not illustrated,
such as a box end, for attaching one end thereof to a pin for
suspending on a work string. Commonly, such a string may include,
anterior to the connection with 50, and not illustrated, check
valves, a disconnect (in the event the tool gets stuck), and a
circulation sub. At the opposite end, housing section 50 is
connected, suitably with threads or other suitable means 51, and
communicates with chamber 52 in housing member 53, to form a first
or principal housing for containing the components of A and B of
FIG. 2. The housing 53 is adapted for wellbore insertion, being
sized in light of the diameter of the wellbore to be entered, and
will preferably be shaped externally, as shown, in a generally
cylindrical or tubular shape, although this is not required. A seal
or seals 54 are provided for a fluid tight arrangement.
Alternatively, a proper seal may also be achieved by other means,
such as a metal to metal seal (not shown), or in some cases,
eliminated if not required by the application.
[0032] Mounted in housing section 50 proximate its entry into
chamber 52 is an optional flow directing and limiting orifice rod
component. In particular, there is shown a flow directing and
mounting member 55 which is shaped to provide flow paths or ports
56 for fluid transmission, a cross-section thereof being shown in
FIG. 5. The position of member 55 is determined by shoulder, as
shown, with a set screw 57 or by other suitable means employed for
retention. Member 55 is also provided with a bore 58 in which is
mounted an orifice reduction means or rod 59. Rod or member 59
comprises pin section 60, and is suitably mounted for movement in
extension 61 of bore 58 formed by retainer section 62 of member 55.
Rod 59 is threaded in member 55, with set screw 63 in slot 64, or
other suitable means, provided for stability, and the longitudinal
axis of rod 59 preferably coincides with the longitudinal axis L of
the housing 53.
[0033] In the configuration illustrated in FIGS. 3a, 3b, 3c, pin 60
extends in chamber 52 into an orifice insert 70, which may comprise
more than one element, and which defines a orifice chamber 70a,
having a defined orifice 71. Extension of the tip 60a of pin 60
into orifice area 71 causes a larger flow area and thus a lower
pressure drop when the area 71 is in its lowermost position. The
insert 70 is mounted in a body or member 72. Body 72 extends in
housing 53, being slidably mounted therein for longitudinal
displacement, and is fixed to a mandrel 73 by threading and by
screws 74 or other suitable means. Retainer ring 75 holds orifice
insert 70 in place in member 72. As will be evident to those
skilled in the art, orifice insert 70 and body 72 combine to form a
piston (designated generally as H) which is employed for
longitudinal displacement of mandrel 73 in housing 53, and which is
thus adapted to transmit fluid force applied. In particular, piston
H includes the hollow chamber sections 75a and 70a and throat 71.
Chambers 75a and 70a connect through throat or bore 71, section 70a
communicating through the aperture or inlet 75b with a bore 76 in
mandrel 73. Body 72 is preferably provided with a hex cross-section
at 75c, the hex section allowing torquing of member 72 on to
mandrel 73. Accordingly, if the mandrel 73 is not constrained,
piston H and mandrel 73 may be displaced along the longitudinal
axis of housing 53 by suitable application of fluid pressure acting
on the piston H.
[0034] However, resisting the movement of piston H and mandrel 73
is spring 77, which surrounds mandrel 73 over a portion of its
length. Spring 77 abuts the end 78 of piston H at one end and at
its other end abuts shoulder 79 of crossover sleeve 80 (FIG. 3b).
Various constructions, including making 79 an integral abutment in
53, may be employed, but as shown, shoulder 79 is formed by a
sleeve 80, the sleeve 80 having a bore 81 through which mandrel 73
may translate. Accordingly, spring 77 provides a resistance to the
movement of piston H and mandrel 73, to the end that diminished
force is translated from the piston H to further components of the
tool. While selection of a spring of appropriate characteristics,
e.g., size and spring preload, will depend on a variety of factors,
such as mandrel size and the desired resistance, etc., and is well
within the ambit of those skilled in the art, a suitable spring
preload, for example, might range from 150 to 600 lbs for a 21/8"
outside diameter tool. The spring preload is calculated as the free
length minus the assembled length of the spring, i.e., the
deflection, times the spring rate. The spring 77 preload determines
the pressure drop required to overcome the spring preload force and
causes the terminal segment to deflect. The net orifice flow area
60a,71 may be varied in order to allow the sub to deflect only at a
flow rate higher than a predetermined threshold.
[0035] In this embodiment, the mandrel 73 translates the hydraulic
force acting on piston H to a deflection section D where that
hydraulic force is converted and utilized in section 53a of housing
53 by appropriate structure to deflect a locator-work member at an
acute angle in a plane passing through the longitudinal axis L of
the tool. More particularly, mandrel 73 passes through the
connecting sleeve 80 which is joined to or forms part of housing
53. Sleeve 80 is provided at each end with suitable connecting
means, such as threads 82 at one end and threads 83 at the other.
Seals 84 and 85 are provided as shown. A further sleeve member 90
is mounted in the housing as shown, mandrel 73 passing through
member 90 in the bore 91 thereof. Sleeve 90 is provided with seal
92. Mandrel 73 is provided with an outlet or outlets, such as ports
93 for egress of fluid from the interior or bore 76 of the mandrel.
As will be evident, sleeve 90 is shaped to allow fluid from ports
93 to exit mandrel 73 and into the bore or space 94. The bore 76 of
the mandrel is plugged or closed at a location proximate the ports
93 with plug section 96, illustrated in FIG. 6, of cam member 100.
Cam member 100, including plug 96, is shown in additional detail in
FIGS. 7 and 8a and 8b. The plug section or member 96 closes the
internal fluid passage 76 of mandrel 73. Plug member 96 is threaded
into mandrel 73. The plug member 96 is preferably connected
integrally to the cam member or section 100, the latter having a
slot guide 101, although the sections may be joined by other means
of assembly. Alternatively, cam member 100 may be integral with
mandrel 73 (not shown). Cam member 100 is mounted for sliding
displacement in the bore of section 53a, receiving, as indicated,
the longitudinal thrust from mandrel 73. The slot guide 101 is
preferably substantially rectangular and converts the longitudinal
movement of mandrel 73 and cam member 100. In particular, there is
provided a pivot shaft 102 with cam pin 103 mounted securely on an
end portion of the pivot shaft 102 for movement in cam slot guide
101. A square slider 104 is mounted on the cam pin 103 for sliding
movement in the cam slot 101. Slider 104 increases the bearing
area, although the cam pin may be run directly in cam slot 101. For
simplicity, the expression "pin member", as employed herein, is
taken to include either of these arrangements, as well as
equivalent means. A curved cam is also possible with a round cam
follower. The connecting end of pivot shaft 102 may be of generally
solid construction, but the segment 102a of pivot shaft 102
contains a bore or internal fluid passage 105 which communicates
with the bore or internal space of housing section 53a through an
outlet or outlets such as ports 106. In addition, anti-debris
turbulence creating ports 107 provide flow into bore 105.
Accordingly, fluid may flow through ports 93, through the bore or
space 94 of housing 53, into the ports 106 and 107, and through
bore 105, as described more fully hereinafter.
[0036] Housing section 53a terminates in an apertured enclosure
110. In the illustration, closure 110 comprises a specially
designed arcuately shaped, apertured structure, which may be
integral with housing 53a (preferably), or which may also be
provided as a cap (not shown), suitably attached. The exterior of
arcuate closure 110 provides an apertured segment of a sphere or
"ball" which cooperates with a closure 138, as discussed more fully
hereinafter. As shown, closure 110 is provided with a
longitudinally outwardly expanding aperture 111 whose center axis
is preferably located at least substantially coincident with the
longitudinal axis of housing 53a, although this is not required.
The interior wall of closure 110 is also arcuately shaped (not
necessarily the same arc as that of the exterior wall), as
indicated by numeral 112.
[0037] Pivot shaft 102 is provided with a circumferentially
disposed mounting shoulder 113 which defines a segment of a sphere
which is sized and shaped for cooperation with the interior arcuate
surface 112 of closure 110. A seal 114 is provided in shoulder 113
for preventing passage of fluid through aperture 111. The segment
or extension arm 115 of pivot shaft 102 extends from shoulder 113
through and beyond aperture 111. Member 115 and aperture 111 are
sized appropriately for substantial clearance between them to
permit variable acute angle generation by member 115 through the
aperture 111.
[0038] Extension arm 115 of pivot shaft 102 is joined with the sub
segment designated generally as N by appropriate means, as
exemplified hereinafter. The terminal segment N is adapted for
wellbore insertion and is multifunctional, in that it comprises the
culminating component for lateral wellbore location and further may
be adapted for well treatment and/or analysis. For example, in
addition to design features related to its caliper or locator
function, the segment N may include, and preferably will, means,
such as ports, for ejection or egress of treating fluids, as well
as a subsection or subsections for measurements or analysis.
[0039] Accordingly, as shown, the end of extension arm 115 extends
into segment N, terminating in an anchoring closure sub-section 130
thereof. The sub-section 130 preferably comprises a generally
cylindrical housing 131, although this shape is not required, which
is suitably attached to, as by threads 132, and forms a portion or
section of, housing 133. Housing 133 may include, or be
appropriately coupled at a location distal from housing 131, with a
sub-section 134 which may contain, for example, an instrument and
telemetry package 135. Subsections 130 and 134 are adapted to
provide fluid flow therethrough from the bore of extension arm 115,
to the end that fluid may be transmitted to a nose sub-section 136,
which joins and communicates with subsection 134, and to egress or
ejection through outlets or ports 137.
[0040] In the embodiment shown, the portion of housing 131
enclosing the end of arm 115 and proximate the segment 53a
terminates in an apertured recessed anchoring closure surface 138,
with the aperture 139 sized and adapted to receive the terminal
section of extension arm 115 with a relatively close tolerance and
in a manner which prevents relative rotation. For anchoring
extension arm 115 in housing 131, there is first provided a dual
taper bushing 140 with angularly offset bore 141, the bushing 140
being secured from rotation by a dowell pin 142 and being provided
with seals 143 and 144. A threaded terminus 145 of extension arm
115 is secured to segment N by a hollow nut 146 which does not
interfere with fluid flow from the bore of extension arm 115.
Compression means 147, such as Belleville washers or a spring, are
provided, as well as shim or backup washer or washers 148.
Accordingly, closure 110, shoulder segment 113, pivot shaft 102,
extension arm 115, recessed closure 138, and related anchoring
components thus provide an effective "knuckle" joint arrangement
which, in cooperation with the cam 100, cam slot 101, and pin 103,
as will be evident, provide displacement in a plane passing
perpendicular to the central axis of pin 103. The structure
described thus provides limited flexible deflection of the terminal
segment. That is, the cam slot-pivot shaft arrangement permits
travel of the slider and pin (and thus the pivot shaft movement in
the housing) to the end that, if the terminal segment is
constrained, or if the constraint is removed, the terminal segment
has a limited degree or freedom of movement. Preferably, a line
bisecting and connecting the short sides of the rectangular slot
101, if coplanar with the longitudinal axis of the mandrel 73,
would make an acute angle with the longitudinal axis of mandrel 73
of from 25 to 60, most preferably 35 to 45 degrees.
[0041] Operation of the embodiment illustrated in FIGS. 3a,3b,3c
and 4a,4b,4c is described, as follows. The sub is mounted by
attachment of the pipe 50 or housing 53 to the end, for example, of
a work string, such as a coiled tubing work string 6 providing an
assembly comprising an indexing/orienting tool or motor, and the
string and assembly with sub is lowered into or positioned in a
main wellbore. In preparation, the length of section N of the tool,
including the nose section 136, is selected based on the diameter
of the main wellbore, as described previously. When there is little
or no fluid flow through the tool, the force of spring 77 keeps the
mandrel 73 at its resting or inactive position, as shown in FIGS.
3a,3b. This corresponds to the straight position of segment N in
FIG. 3c, i.e., there is little or no pivot or deflection of segment
N. This orientation of segment N allows introduction of the tool
into the main wellbore to the desired depth while flowing at a low
rate through the tool. In the preferred operational configuration,
working or treating fluid from a workstring will flow through
section 50, passing through openings 56 into chamber 52, through
the internal fluid passage formed by 75a, 71, and 75b, and into the
bore or internal fluid passage 76 of mandrel 73. From the bore of
mandrel 73, fluid will continue through outlet or outlets 93 into
the internal or inner space 94 of housing 53, past the cam member
100, entering the bore or internal fluid passage 105 of pivot shaft
section 102a via ports 106, through the bore of nut 146 and into
the housing 131, sub section 136, and out ports 137.
[0042] Upon reaching the desired depth or a locus proximate the
lateral to be located, for example, at a site below or past the
lateral, preferably the sub is rotated by suitable means in the
string, such as the indexing means mentioned, or by a continuous
rotation motor. Upon reaching the desired orientation, fluid flow
rate through the tool is increased. As the flow rate is increased,
a pressure drop occurs across the annular gap between the orifice
rod 60 and the orifice 71. This pressure drop generates a force
acting on the piston, the force acting in a direction away from the
fixed orifice rod mount 55. In the case of a vertical main
wellbore, this will, of course, be "downward"; in a slanted or
horizontal main wellbore, directed "down hole". When the flow rate
exceeds a threshold flow rate, the acting force due to pressure
drop across the orifice rod/orifice exceeds the force of spring 77,
causing the piston H to move longitudinally, as illustrated in FIG.
4a, and, since the piston H and mandrel 73 are joined, as
described, the mandrel 73 moves correspondingly (FIGS. 4a, 4b). The
pressure drop also may be sensed by gages at the surface, providing
a signal to the operator.
[0043] The longitudinal movement or displacement of the mandrel 73
correspondingly moves the cam 100 and its cam slot 101, forcing the
slider 104 and the cam pin 103 to move angularly to the
longitudinal axis of the sub (FIG. 4b). This movement of the
slider/cam pin causes the pivot shaft 102 to move laterally in the
housing. Because the "ball" surface 113 is longitudinally fixed in
place by arcuate recess 112 and the tensioned anchoring of
extension arm 115 in segment N, the pivot shaft 102 is translated
or deflected in a plane perpendicular to the longitudinal axis of
pin 103. The deflection of pivot shaft 102 forces a corresponding
deflection of the terminal segment 115 in the opposite direction,
the fixed anchoring of terminal segment 115 in segment N allowing
the deflection of segment N in10 cluding section 136 to the side or
wall of a main wellbore (FIGS. 4b and 4c). If the flow rate of the
driving fluid is, and is maintained sufficiently great (and thus
the pressure drop acting on piston H), the tip force or energy
acquired by segment N is greater than that required to reach the
main wellbore side or wall. In a given case, for example, this
profiling flow rate might be maintained at 2 barrels per minute.
Because the wellbore wall constrains the section 136, this excess
energy or tip force may be utilized for location of the lateral
wellbore. In this circumstance, the pivot shaft 102 does not reach
contact with interior surface of housing 53a or rectangular opening
111.
[0044] The tool is then raised or moved uphole (in the direction of
the surface) in the main wellbore while maintaining fluid flow
rate, thus maintaining excess tip force in the terminal segment.
When the opening of the lateral wellbore is reached, the constraint
of the main wellbore is eliminated, and because the length of the
section N is of a length adapted for lateral wellbore incursion,
excess energy maintained or present in the segment urges or forces
the tip 136 into the lateral wellbore, thus locating and providing
entry into the lateral. In this case, the release of segment N may
cause pivot arm 102 to contact with the inner surface of housing
53a.
[0045] FIGS. 11 and 12 illustrate a preferred force relief
mechanism which may be incorporated into a sub according to the
invention. In particular, the relief structure of FIGS. 11 and 12
may be incorporated in the device described in FIGS. 3a,3b,3c and
4a,4b,4c, in the manner illustrated in FIGS. 13a,13b,13c,13d and
FIGS. 14a,14b,14c,14d. Additionally, the embodiments of FIGS.
13a,13b,13c,13d and FIGS. 14a,14b,14c,14d employ a unique pressure
change signaling structure, to the end that the tool operator may
be alerted when the lateral wellbore has been reached. In FIGS. 11
through 15d, like numbers indicate like features.
[0046] Accordingly, there is shown in FIG. 11 a force relief
section, designated generally as FR, which comprises a housing 200
adapted for wellbore insertion, preferably being cylindrical or
tubular, which may, as mentioned, and, as illustrated hereinafter,
form or comprise part of first housing 53. Housing 200 is joined by
suitable connection to and communicates with sleeve 80, such as by
threads or equivalent means 201. At the opposite end of housing
200, housing 200 is connected to and communicates with sleeve 202,
which may be identical to or analogous to sleeve 80. However,
mandrel 73, rather than terminating in section D, terminates in
section FR in a hollow sleeve 203. Sleeve 203 is fixed by suitable
means, such as retaining ring 204 and seal 205, to the end of
mandrel 73, which further comprises an expanded shoulder section
207. A retaining ring 208 is provided, with the end 209 of the
mandrel 73 being tapered to the size of bore 76. Additionally,
rather than abutting shoulder 79 of sleeve 80, as illustrated
previously in FIG. 3b, the spring 77 is provided a stop sleeve 210
with shoulder 210a, while the mandrel 73 has a range limiting stop
211 restricted by the shoulder 206 of sleeve 83.
[0047] Sleeve 203 extends into the hollow section 212 of sleeve
200, sleeve 203 being sized and adapted for longitudinal
displacement or movement inside the bore 212 of sleeve 200. At the
end of sleeve 203 there is provided a shoulder 213, which is in
contact with and receives the force of spring 214. The load
protection spring 214 surrounds a second hollow mandrel 215 over a
portion of its length and abuts shoulder or stop 216 on mandrel
215. The selection of a spring having the required characteristics
for spring 214 will depend on a variety of factors, such as the
desired resistance, etc., as discussed previously, and is within
the ability of those skilled in the art. Shoulder 216 may be
integral with mandrel 215, or may be provided separately, as
shown.
[0048] The second mandrel 215 is provided with a coupler sleeve 217
whose outer diameter is sized for sliding movement or displacement
in sleeve 203. Sleeve 217 is mounted on mandrel 215 in any suitable
fashion, such as by threads, and has a boss 218 which limits
longitudinal displacement of the mandrel 215 by cooperation with
the shoulder 213 of sleeve 203. Sleeve 217 is further provided with
O-ring seals 219 and 220. Accordingly, there is provided a chamber
221, bounded by the end of first mandrel 73, the proximate end of
second mandrel 215, and the sleeve 203, which will vary in length
depending on the displacement of mandrel 215, the chamber 221
providing a sealed fluid flow path from the bore of mandrel 73
through the bore or internal fluid passage 222 of mandrel 215.
[0049] In the preferred embodiment of the invention, the
above-described force relieving device is incorporated, as
indicated in FIG. 2, into the force conversion segment A, thus
providing a controllably bent sub with unique force relief and
deflection characteristics. Reference is made, in addition to FIGS.
11 and 12, to FIGS. 13a,13b,13c, 13d and 14a,14b,14c,14d which
illustrate the preferred sub operational configurations. The
preferred configurations additionally comprise a novel pressure
reducing and different signaling element, not used in the sub of
FIGS. 4a,4b,4c, and whose manner of operation is described in
connection with the description relating to FIGS. 14a, 14b,14c,14d.
Accordingly, in FIG. 13b, sleeve 80, as described previously,
rather than joining housing 53a, connects with and communicates
with the housing 200. Housing 53a is, instead, connected to and
communicates with sleeve 202. The mandrel 73, rather than
terminating in section D, terminates in a section designated
generally as FR and is in fluid communication with chamber 221.
[0050] In the preferred configuration, two modes of operation are
permitted. Depending on fluid flow rate through the sub, both first
mandrel 73 and second mandrel 215 may move as a single entity, or
the motion of the two mandrels may be decoupled from each other. If
mandrel 73 and mandrel 215 move as a unit, mandrel 215 simply
functions as mandrel 73 in the manner described in relation to
FIGS. 4a,4b,4c, moving the cam slot 101 and thereby causing the
slider 104 and the cam pin 103 to move angularly to the
longitudinal axis of the housing 53. Deflection of the segment N
occurs in the manner described previously with respect to FIGS.
4a,4b,4c.
[0051] On the other hand, if mandrel 215 is decoupled from mandrel
73, as described hereinafter, the result is significant limiting of
the force applied to the cam of the cam-deflection mechanism. This
decoupling permits deflection of the segment N, while limiting the
force applied and preventing overload on the cam member 100.
Conversely, decoupling insures that, if significant constraining
force is encountered by the terminal segment N, the cam mechanism
is protected. For example, in the circumstance where the operator
has located the lateral (the effective diameter measured is larger
than that of the main wellbore), but has continued movement of the
sub and has pulled the nose section 136 from the lateral upwardly
or anteriorly in the bent position, the constraining force of the
main wellbore on the cam is relieved by the decoupling. In such
case, the tip 136 will be forced back into the main wellbore while
allowing the angle of deflection a to be reduced.
[0052] Accordingly, with reference to FIGS. 13a,13b, 13c,13d, if
there is no significant fluid flow through the sub, the terminal
segment N is maintained in alignment with the other sections of the
sub, i.e., generally aligned with the longitudinal axis of the
housing 53. This alignment is accomplished by the spring force from
77 acting on the coupled first and second mandrels 73 and 215,
which pull the cam member 100 toward the housing section 50,
causing the pivot shaft 102 to be positioned in the manner shown in
13c. This position may advantageously be employed in main wellbore
entry or advancement in or retrieval from a wellbore.
[0053] If the fluid flow rate is below that which generates
sufficient hydraulic force to overcome the spring 77, the rod 60
will remain inside the orifice 71. The hydraulic force actuating
the cam mechanism is then a function of the small annular flow
passage between the orifice 71 and rod member 60. FIG. 11
illustrates the displacement of mandrel 73 and the relative
positions of the mandrels 73 and 215 in this circumstance. If the
flow is increased, causing the piston H and mandrel 73 to be
displaced in housing 53 away from section 50, the orifice will
translate with mandrel 73 and remain in loose proximity to rod 60,
similar to the position illustrated in 4a. However, the mandrel 73
and the mandrel 215 are displaced longitudinally in housing 53 as a
single entity, causing deflection of the segment N. This
circumstance is illustrated in FIGS. 14b,14c,14d.
[0054] At a high flow rate, e.g., greater that 2 barrels per
minute, the piston H moves longitudinally in housing 53, the
orifice 71 clearing rod 60. The resultant increase of flow area
reduces the relative pressure drop through piston H. The mandrel 73
moves longitudinally, compressing spring 77 and spring 214 and
translating until the stop or shoulder 211 on mandrel 73 abuts the
shoulder 206 of sleeve 80. As the mandrel 215 moves longitudinally,
the boss 95 moves to the position shown in FIG. 14c. That is, boss
95 (mounted on the mandrel 215) clears the end of sleeve 90
(fastened to the housing 53a). The pressure reduction when the tool
is bent acts as a signal to the surface that the lateral has been
entered. If the force on the piston H exceeds the preload force of
spring 77, and spring 214 is compressed, mandrel 215 is released
and decoupled from mandrel 73. The orifice rod position is as shown
in FIG. 14a, the length of chamber 221 in FIG. 14b being reduced
due to the displacement of the mandrel.
[0055] The decoupling of the second mandrel provides great
advantage. As indicated previously, if the operator continues to
pump at high flow rates, thereby generating sufficient force on the
piston H to keep it advanced in the bore of the sub, decoupling of
the mandrel 215 allows the angle .alpha. made by the segment N and
the longitudinal axis L to be reduced, so that the segment N may be
constrained without damage to the sub. Again, the spring 214
protects the cam mechanism from overload under high flow rate
situations when the sub is straight or is being closed at high flow
rate conditions.
[0056] Additionally, the boss 95 on mandrel 215 provides a valuable
signaling function similar to that performed by 60 and 71 in the
first sub. In particular, when the nose or tip 136 enters a lateral
wellbore, the additional deflection of segment N, acting through
the extension arm 115, pivot shaft 102, and slider 104 on the cam
100 and mandrel 215, opens up additional area for fluid flow past
boss 95 (FIG. 14c), thereby resulting in a pressure reduction which
may be sensed by suitable pressure measurement device and which is
observable to an operator at the surface. This pressure drop
provides an effective diameter threshold measurement or indicator
at the position of the tip 136 in the main wellbore, indicating to
the operator that the diameter of the bore exceeds the known main
wellbore diameter, and, in the absence of a washout, signaling the
location of a lateral.
[0057] If, after conducting the above described procedure, no
pressure change is observed in the retrieve or advance, the tool is
indexed, e.g., 30 degrees, the sub is returned to an appropriate
position, and the above-described procedure may be repeated.
Alternatively, the tool may be slowly rotated while moving the
tool. This would achieve 360 degree spiral coverage and reduce
fatigue on the coiled tubing and time required to locate the
lateral in addition to simplifying the operation.
* * * * *