Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02452551 2003-12-22
PROTECTOR SYSTEM FOR FIBER OPTIC SYSTEM
COMPONENTS IN SUBSURFACE APPLICATIONS
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to the field of hydrocarbon exploration, drilling and
production. More particularly, the invention relates to subsurface systems
employing
fiber optic conductors, connectors and instrumentation and protection required
and
desirable for the same.
Prior Art
In recent years, the use of fiber optic technology has grown in many
industries. The benefits of using fiber optics where electric conductors were
used
previously has greatly improved communications in both the quality of
information
transmitted and received, and the speed of communication. Unfortunately
however,
many of the benefits of fiber optic technology have not heretofore been
available to
the hydrocarbon exploration, drilling and production industry due to the
extremely
unfavorable conditions downhole. These, of course, are high pressure, high
temperature, vibration, caustic fluids, etc. All of these conditions
collectively and
individually are significantly deleterious to delicate optic fibers and would
cause very
early failures requiring workovers in production wells if employed as they
have been
in other industries. Because of this, the incorporation of optic fibers
downhole, in all
but the most limited of circumstances, has been contraindicated. Due to the
technological benefits of fiber optic usage, the industry is in need of a way
to deploy
and employ fiber optics reliably in the downhole environment.
SUMMARY OF THE INVENTION
The above-identified drawbacks of the prior art are overcome, or alleviated,
by
the fiber optic protection system of the invention.
Fiber optic conductors, connectors, instrumentation, sensors and associated
control circuitry (hydraulic/electrical/optical), etc. are now employable in
the
downhole environment in connection with the invention disclosed herein. The
protection system insulates fiber optic technology from the unfavorable
conditions
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existing downhole so that such technology may be reliably employed, thus
allowing
the subsurface portion of the hydrocarbon industry to reap the benefit of
fiber optic
technology. Optical fibers allow greater accuracy and speed of determining
information downhole. Decisions are faster made and adjustments in different
zones
may be executed quicker to enhance production of desired fluids while
retarding
production of undesirable fluids.
The scope of the invention also includes the routing of surface supplied power
(hydraulic/electrical/optical) through a protected environment to the downhole
fiber
optic components to selectively supply said power to any number of a multitude
of
downhole tools, as desired.
In accordance with one aspect of the present invention there is provided a
downhole protector sub for a non-coiled production tubing string comprising:
a discrete manifold sub connectable axially in a non-coilable production
tubing
string, said discrete manifold sub including an axial flow passage which is
within an
outside diameter of said discrete manifold sub;
a plurality of recesses formed in said outside diameter of said discrete
manifold
sub; and
at least one fiber optic component mounted in an environmental condition
insulator in at least one of said plurality of recesses.
In accordance with another aspect of the present invention there is provided a
downhole oil well protector sub for optic fiber junctions and components in a
non-
coilable production tubing string comprising:
a discrete housing having an outer surface and an inner surface, said inner
surface defining a flow passage;
at least one radial recess formed in said outer surface, said recess adapted
to
receive an optic fiber component; and
at least one protected space, under a component protector, adapted to receive
an optic fiber component, said protected space being a radial recess formed in
said
outer surface and including a cover to cover said recess.
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BRIEF DESCRIIPTION OF THE DRAWINGS
Referring now to the drawings wherein like elements are numbered alike in the
several FIGURES:
FIGURE 1 is a schematic representation of the protection system of the
invention connected with the other tools.
FIGURES 2-4 is an elongated longitudinal cross-section view of the manifold
sub of the invention;
FIGURES 5-7 is an elongated plan view of the top of the manifold sub of the
invention;
FIGURES 8-10 is an elongated plan view of the bottom of the manifold sub of
the invention;
FIGURE 11 is a cross-section view of the invention taken along section line
11-11 in FIGURE 2;
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FIGURE 12 is a cross-section view of the invention taken along section line
12-12 in FIGURE 2;
FIGURE 13 is a cross-section view of the invention taken along section line
13-13 in FIGURE 2;
FIGURE 14 is a cross-section view of the invention taken along section line
14-14 in FIGURE 2;
FIGURE 15 is a cross-section view of the invention taken along section line
15-15 in FIGURE 3;
FIGURE 16 is a cross-section view of the invention taken along section line
16-16 in FIGURE 3;
FIGURE 17 is a cross-section view of the invention taken along section line
17-17 in FIGURE 3;
FIGURE 18 is a cross-section view of the invention taken along section line
18-18 in FIGURE 3;
FIGURE 19 is a cross-section view of the invention taken along section line
19-19 in FIGURE 3;
FIGURE 20 is a cross-section view of the invention taken along section line
20-20 in FIGURE 4;
FIGURE 21 is a schematic view of a partial cross-section of the splice box of
the invention;
FIGURE 22 is an enlarged view of the circumscribed area of the splice box in
FIGURE 21; and
FIGURE 23 is a plan view of a splice box of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Fiber optic systems for downhole monitoring and control are most favorably
placed within a protected environment in a housing. The housings include
beveled
edges to avoid impact or shock loading on corners during running into the well
and
they include protective covers over all exposed openings for the same purpose.
Moreover, the fiber optic components being employed are preferably mounted in
a
vibration/shock load dampening material (for example, teflon, metal, or
similar),
* trade-mark
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which is chemically inert with respect to the well content, to guard them for
any
vibration or shock loading that does occur.
In order to provide one of skill in the art an understanding of the concept
embodied by the invention, FIGURE 1 illustrates several downhole tools and
optic
components in one possible configuration. The drawing is schematic but is apt
to
illustrate the concept of the invention. The manifold sub 7 houses many of the
fiber
optic components such as optic dry-mate connectors, optic splices, fiber optic
service
loops, optic hydraulic valves, optic-electric valves, fiber optic pressure
sensors, fiber
optic temperature sensors, optic wet-mate connectors, etc. and is an important
sub-
assembly of the protection system disclosed in more detail hereunder. Other
protective sub-assemblies are also illustrated in FIGURE 1 referring to the
splice box
6 (which may or may not be integral to the manifold sub), service loops 8 and
connector subs 3. Each provides protection against mechanical loading,
temperature
effects and pressure effects. The components also include outer features to
reduce the
occurrence of impacts with other structures while being run into the hole.
These too
are discussed hereunder.
In a particular embodiment of the manifold sub 7, referring to FIGURES 2-4,
control lines conveying optic fibers and hydraulic fluid, optic fiber
components and
associated control components are illustrated in various cross sectional and
plan
views. One of skill in the art will recognize that all of the conduits in the
manifold'
sub 7, be they optic fiber or hydraulic control lines, are protected within
the manifold
sub body 11 between a centrally located recessed channel 12 in the manifold
sub body
11 and the outer surface of the manifold sub body 1 l, or one of a series of
component
protectors 13-20.
In one embodiment, the component protectors 13-20 are designed so that they
are flush with, or below the outer surface of the manifold sub body 11. This
reduces
the risk of the component protectors 13-20 catching on another structure
downhole
and causing an impact or shock load to be transmitted to the components housed
within the manifold sub. The component protectors 13-20 have beveled edges to
ensure against impact loading on corners while running. The component
protectors
13-20 are secured over the various fiber optic components housed within the
manifold
sub 7 to form an interference fit, such that substantial load must be applied,
via a
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distributed load system comprising of a multitude of cap screws 21 being
threadedly
connected to the manifold sub body 11 through a series of clearance holes 70
(visible
in some views only) in the component protector 13-20, to deflect the component
protector material adequately to fully secure the component held therein
against
vibrational/load effects. The cap screws 21 are locked in place with locking
washers,
or thread locking adhesive, or similar, to ensure against load dissipation.
Additionally, the component protectors 13-20 are manufactured very accurately
to
form a very close fit between the component protectors 13-20 and the recessed
channels 12 and 29 in the manifold sub body 11 into which they are installed.
This
ensures against axial movement and lateral movement of the fiber optic
components
housed between the recesses in the manifold sub body 11 and the component
protectors 13-20 due to tension/vibration effects within the connections to
the fiber
optic components. All component protectors 13-20 are easily replaceable
without
detriment to the other components of the manifold sub 7. ~ther features of
specific
component protectors 13-20 will be discussed in depth later in this document.
The manifold sub 7 is tubular and may be either concentric or eccentric with
respect to the casing bore 4 within which the manifold sub 7 is located and
places all
of the control lines and fiber optic components (discussed hereunder) within
the
annular body thereof. The manifold sub 7 may be supplied with metal-to-metal
sealing threaded connections 22 at either end to allow connection to the
tubing l, or
other components of the system, as represented in FIGURE 1. The manifold sub
body
11 may in one embodiment be bored to accept certain components or may in
another
embodiment be milled radially to accept components which then are covered with
component protectors 13-20 as noted previously, or both concepts are
employable
together. Well fluids are permitted to flow through the internal bore of the
manifold
sub 7 and within the annulus between the casing bore and outer surface of the
manifold sub body 11.
Refernng to FIGURES 2-4, the fiber optic working control line 23 (denoted
thus as it contains the optic fibers which are connected to various fiber
optic
components housed within the manifold sub 7) is visible in the top half of the
drawings. The fiber optic working control line 23 is housed in a recess 12 in
the
manifold sub body 11 which can be viewed in FIGURE l l, which is a cross
section
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view of the manifold sub 7 of the invention taken along section line 11-11 in
FIGURE
2. Also within this recess 12 are contained spacer reds 24 constructed of
impact/vibrativn dampening material capable of withstanding downhole
temperature
and pressure and of being chemically inert with respect to the well content
(for
example, teflon, metal, or similar). On either side of the spacer rods 24 are
hydraulic
fluid input control lines 25 which may be connected to other devices within
manifold
sub 7, such as optic-hydraulic valves 26 as displayed in the particular
embodiment, or
pass therethrough, to another manifold sub 7 in the next well zone. Fiber
optic
working control line 23 is connected to other optic components within manifold
sub?
and is distributed within and without manifold sub 7. In the particular
embodiment
represented, fiber optic working control line 23 is connected to a number of
optic-
hydraulic valves 26 and a fiber optic pressure sensor 27, but various other
fiber optic
components could be employed within the manifold sub 7. Fiber optic connector
control line 28 is also visible in the bottom half of FIGURES 2-4, and FIGURES
8-11
Fiber optic connector control line 28 is also housed in a radially milled
recess 29 in
the manifold sub body 11. It should be appreciated that all the control lines
illustrated
in FIGURES 2-10 are protected by an upper gauge ring 30 and lower guage ring
31,
which preferably are annular portions of the manifold sub and are the maximum
outer
diameter of the manifold sub 7. Upper and lower guage rings 30 and 31 are
specifically configured, manufactured and treated utilizing close tolerance
fits and
geometry that yields low stress levels during impact/shock and axial and
rotational
loading while running the manifold sub 7 into or out of the well. Upper and
lower
guage ring 30 and 31 have beveled edges to ensure a smooth transition to the
maximum tool diameter and prevent shock loading on sharp corners. Upper and
lower guage ring 30 and 31 ensure that the manifold sub body 11 and component
protectors 13-20 are not subj ected to the mechanical forces enc~untered while
traversing a well. A preferred method of connection of upper and lower guage
ring 30
and 31 to manifold sub body 11 may be via a threaded connection 32 between
guage
ring 30 inner diameter and manifold sub body 11 outer diameter. An alternative
method of connection may also be to split the guage ring 31 and install it in
a turned
recess 33 in the manifold sub body 1 l, retaining it in situation via a number
of cap
screws 34 threadedly connected to the manifold sub body 11. Rotational
resistance
CA 02452551 2003-12-22
may be provided by set screws 35 threadedly connected to the guage ring 30 and
locked against manifold sub body 11, as shown in FIGURE 12, or by a key 36
installed between guage ring 31 and manifold sub body 11, as shown in FIGURE
19.
In FIGURE 3 and FIGURE 14, a component protector 13 covers, protects and
further insulates the fiber optic 3-way angled junction 37, which distributes
various
optic fibers safely and without imparting excessive bending stresses within
the fiber to
the various optic components housed within the manifold sub 7. Also shown in
FIGURES 2-10 and FIGURES 14 and 1 S, component protector 19 protects the fiber
optic 3-way angled junction 38 and a multitude of optical connectors 39
connected to
it. It should be appreciated that all pressure resisting connections between
components of the protection system are of a non-elastomeric nature or metal-
to-
metal sealing and the protection system has been designed such that all
potential leak
paths have been optimized. Methods of eliminating potential leak paths include
welding of component sub-assemblies together. Component protector 19 includes
profiles such that the optical connectors 39 are prevented from rotational
movement
during threaded connection make-up to the mating end of the optical connector
40.
This feature assists in assembly procedures while running the protection
system into
the well and attaching the necessary ancillary optic fiber control equipment.
Referring now to FIGURES 2-7 and FIGURE 15, pressure sensor 27 is
illustrated between the radially milled recess 12 in the manifold sub body 11
and the
component protector 14. Fiber optic working control line 23 terminates at the
pressure sensor 27. Hydraulic fluid input control lines 25 continue through
the milled
recess 12 in manifold sub body 11 and are restrained from vibration and
protected
from mechanical loading by component protector 15, shown in FIGURES 2-7 and
FIGURE 16. Dependant on required length of hydraulic fluid input control lines
25
within manifold sub 7, and number of components to which they are attached, a
multitude of such component protectors 15 may be used. Prior to exiting the
manifold
sub body 11, below the lower guage ring 31, hydraulic fluid input lines 25
are, in this
embodiment, weldedly connected to angled junction pieces 41, shown in FIGURES
5-
7 and FIGURE 17. Angled junction pieces 41 are installed in the milled recess
12 in
the manifold sub body 1 l and covered by another component protector 17,
providing
the same function as previously described component protectors 13-20. Angled
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junction pieces 41 are used to reduce the otherwise unacceptable bend radius
of the
control line in order that it can be safely installed within the confines of
the milled
recess 12 within the manifold sub body 11. The angled junction piece 41 routes
hydraulic fluid, in this embodiment, to the input side of an optic-hydraulic
valve 26,
located between a recess 42 in the manifold sub body 11 and a component
protector
16. The recess 42 housing the optic-hydraulic valve 26 is connected to the
main
recess 12 in the manifold sub body 11 via a radially milled connecting slot
43.
Hydraulic fluid output lines 44 are connected to the output side of the optic-
hydraulic
valves 26 and exit the manifold sub body 11 via a continuation of the milled
recess 42
in which the optic-hydraulic valve 26 is housed. Component protector 18 is
installed
over the recess 42 to prevent vibration of the hydraulic fluid output control
line 44
and to protect it from mechanical loading, as shown in FIGURES 5-7 and FIGURE
18. Dependant on the configuration of the manifold sub 7, a multitude of
component
protectors 18 may be required.
Referring now to the bottom half of FIGURES 2-4, FIGURES 8-10 and
FIGURE 16, the optical connectors 39, installed in the recesses in the
manifold sub
body 11 are connected to the mating ends of the optical connector 40. This sub-
assembly is not part of the manifold sub 7 per se, but is ancillary control
equipment
installed during running of the manifold sub 7 into the well, and is shown for
illustrative purposes only. In order to connect the mating end of the optical
connector
40 to the optical connector 39, it is necessary to remove the component
protector 20.
The component protector 20 is secured by cap screws 21 which have been
selected for
ease of removal and installation in an offshore environment. The component
protector 20 is a one-piece assembly, again to assist in disassembly/assembly
procedures. The bottom half of the lower guage ring 31 is also removed from
it's
turned recess 33 in the manifold sub body 11 and the mating end of the optical
connector 40 is installed within the milled recess 29 in the manifold sub body
11.
Upon making up the threaded connection between the mating end of the optical
connector 40 and the optical connector 39, the bottom half of the lower gauge
ring 31
and the component protector 20 are replaced, the cap screws 21 and 34 locked
in
position, via locking washers, or thread adhesive, or similar.
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Refernng now to FIGURES 2-7, the hydraulic fluid input lines 25 and
hydraulic fluid output lines 44 may terminate in special connection ports 45,
welded
onto the end of each of the lines. These connection ports 45 accept control
lines
connected to downhole tools, such as the Hydraulic Sliding Sleeve 9, as shown
in
FIGURE 1, below the manifold sub 7, and provide a method of sealing the
conduit
against well conditions such as temperature, pressure and well content.
Typically,
such seals will be of a metal-to-metal nature.
Within the context of the invention, the manifold sub 7 protects optic fiber
component assemblies from the unfavorable conditions existing downhole.
However,
as the system is designed to protect hardwired optic components and fibers,
there is
also a need to provide a protected environment in which to house the required
splices
between individual optical fibers. While splicing of separate optical fibers
together is
common practice in many industries, and provisions exist for housing said
splices,
there are no existing enclosures which protect against the unfavorable
conditions
experienced downhole. Refernng to FIGURE l, the optic fiber splice box sub 6
of
the invention houses these splices in a secure environment., providing
protection from
the conditions within the well, be they temperature, pressure, or mechanical
loading,
or a combination thereof. While the drawing is schematic, it is apt to
illustrate the
concept of the invention. The optic fiber splice box sub 6 is an important sub-
assembly of the protection system disclosed in more detail hereunder.
In order to provide one of skill in the art an understanding of the concept
embodied by this aspect of the invention, FIGURES 21-23 illustrate a
particular
embodiment of the optic fiber splice box sub 6. The splice box sub 6 is
tubular and
may be either concentric or eccentric with respect to the casing bore 4 within
which
the splice box sub 6 is located. The splice box sub body 46 may be supplied
with
metal-to-metal sealing threaded connections 47 at either en.d to allow
connection to
the tubing 1, or to other components of the system, as represented in FIGURE
5, or it
may be supplied as an integral part of the manifold sub 7, being located above
the
upper gauge ring 30 of said manifold sub, as represented in FIGURE 1. The
splice
box sub body 46 may be bored to accept certain components or may be milled
radially
to accept components which are then covered with an enclasure cover 48. Well
fluids
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are permitted to flow through the internal bore of the splice box sub 6 and
within the
annulus between the casing bore 4 and outer surface of the splice box sub 6.
The splice box sub body 46 and follower nut 49 include beveled edges to
provide a smooth transition to the maximum tool diameter and to avoid impact
or
shock loading on corners during traverse of the well. Splice box body 46 and
follower nut 49 are specifically designed, manufactured (precision machining)
and
treated (hardened surface preparation) utilizing close tolerance fits and
geometry that
yields low stress levels during impact/shock and axial and rotational loading
while
running the splice box sub 6 into or out of the well. Splice box sub body 46
and
follower nut 49 ensure that enclosure cover 48 is not subjected to the
mechanical
forces encountered while traversing a well.
Fiber optic working control line 23 and fiber optic connector control line 28
are connected to the splice box sub fiber optic enclosure 50 via ports 51
drilled into
the fiber optic enclosure 50, through the splice box sub body 46. These
connections
are sealable by a metal-to-metal sealing Jam Nut and Ferrule arrangement 52.
The
fiber optic conveying control line 53, housing the fibers to which the fibers
within the
fiber optic working control line 23 and fiber optic connector control line 28
must be
spliced is connected to the fiber optic enclosure using the same general
method.
Moreover, additional ports 51 may be provided for the purpose of pressure
testing the
fiber optic enclosure 50 upon completion of the splicing procedure; or for the
purpose
of filling the void within the fiber optic enclosure with a chemically inert
material,
unaffected by temperature and pressure effects (for example, epoxy resin or
similar)
for the purpose of providing further resistance to vibrational effects within
the fiber
optic enclosure 50. Upon completion of said procedures, said ports 51 will be
metal-
to-metal sealed using Blanking Plugs, or similar.
Refernng to FIGURE 23, the fibers within the various control lines are
introduced into the fiber optic enclosure 50 and the appropriate ends spliced
together,
to form a 'hardwired' continuous optic circuit. In order to achieve this, a
considerable
length of fiber is required, which must then be housed in a suitable
protective
enclosure 50, resistant to the deleterious effects of the inhospitable
downhole
environment (pressure, well content, etc.). Additionally, the internals of the
enclosure
50 must ensure that the optic fiber 55 is not excessively bent during
insertion into the
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enclosure, and that the bend radius of the fiber is kept to a maximum to
ensure optic
losses are kept to a minimum. This is especially critical at elevated
temperatures. In
order to achieve this desired aim of the invention, the optic fiber enclosure
50 is fitted
with a series of cylindrical guides 54 around which the fibers 55 are wrapped.
These
fiber guides 54 provide general positioning of the fiber 55 within the
confines of the
fiber optic enclosure 50 and are tightly toleranced with respect to the walls
of the
enclosure 50, to ensure that vibration effects will not cause excessive
movement and
cause damage to the fiber 55. The fiber guides 54 are manufactured from a
vibration/shock loading dampening material (for example, teflon, metal, or
similar).
In addition to the fiber guides 54, a number of fiber wrap subs 56 are
provided. The
fiber wrap subs 56 are profiled to mate with the inner surface of the fiber
optic
enclosure 50 to ensure against rotational movement. Additionally, they are
secured to
a boss 58 in the enclosure 50 inner surface via a tightly toleranced dowel pin
57. The
fiber wrap subs 56 have a shallow groove machined around the outer diameter to
assist in wrapping of the fiber 55 around them. Upon completion of the
wrapping
process, the fiber wrap sub cap 59 is installed and locked to the fiber wrap
sub 56 via
a key 60, preventing movement of the cap 59 and thereby preventing any damage
to
the fibers. Fiber wrap sub 56 and cap 59 are manufactured from a
vibration/shock
load dampening material (for example, teflon, metal, or similar).
In order to seal the optic fiber enclosure 50 from the downhole environment,
the enclosure cover 48 is then slid into place to seal on the non-elastomeric
or metal-
to-metal seals 61, housed within grooves in the splice box sub body 46. The
follower
nut 49 is then threadedly connected to the splice box sub body 49 until it
secures the
enclosure cover 48 tightly in place. The follower nut is then locked in place
via a lock
nut, or set screws, or thread locking adhesive, or similar.
At this stage, the seals 61 between the splice box sub body 46 and enclosure
cover 48 can be fully pressure tested to verify leak tightness. Confirmation
of
pressure integrity can be obtained via the additional ports 52 in the splice
box sub
body 46. The sealed optic fiber enclosure 50 can then be pumped full of void
filling,
vibration/shock load dampening material and the additional ports 52 sealed.
The
hydraulic fluid input control lines 25 are then placed over the bottom half of
the splice
box sub 46 and a protective cover 62 placed over the control lines. This
protective
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cover 62 includes beveled edges to provide a smooth transition to the maximum
tool
diameter and to avoid impact or shock loading on corners during traverse of
the well.
The protective cover 62 is specifically designed, manufactured utilizing close
tolerance fits and geometry that yields low stress levels during impact/shock
and axial
and rotational loading while running the splice box sub 6 into or out of the
well. The
cover is further preferably hardened to improved wear resistance.
The protective cover 62 ensures that the hydraulic fluid input control lines
25
are not damaged while traversing the well as they pass over the optic fiber
enclosure
cover 48. The protective cover may be secured in place via cap screws
threadedly
connected to the splice box sub body 46, or may be installed in a turned or
milled
groove in the splice box sub body 46, providing resistance to axial movement.
A key
installed between the protective cover 62 and splice box sub body 46 provides
resistance to rotational movement. Alternatively, the protective cover 62 may
be
1 S designed to fit closely between the mating threads of the threaded
connections 47 on
each end of the splice box sub body 46.
While preferred embodiments of the invention have been shown and
described, various modifications and substitutions may be made thereto without
departing from the spirit and scope of the invention. Accordingly, it is to be
understood that the present invention has been described by way of
illustration and
not limitation.
