Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02444443 2007-02-28
CLAMP MECHANISM FOR I - E
FIELD OF THE INVENTION
The present invention relates generally to a clamp mechanism for an in-well
seismic sensor and, more particularly to a clamp mechanism for a fiber optic
based
sensor mechanism. The clamp mechanism is capable of coupling to production
tubing
for deployment in the well and is actively capable of acoustically coupling a
sensor with
the casing of the well. The clamp mechanism is capable of releasing the sensor
mechanism towards the casing when subjected to a predetermined pressure within
the
well or when subjected to fluid in the well for a predetermined amount of
time.
BACKGROUND OF THE INVENTION
Seismic surveying is a standard tool for the exploration of hydrocarbon
reservoirs. Vertical seismic profiling (VSP) is one method employed in the art
of seismic
surveying. VSP can be used within a single well or can be used in multiple
wells, i.e., in
a cross-well arrangement, which are well known techniques. VSP uses a
plurality of
sensors arranged within the well. Various types of acoustic and/or pressure
sensors
known in the art are used in seismology. A seismic generator arranged at the
surface or
in another well transmits waves, which are reflected by the geologic
formations or
transmitted through them. The sensors then receive these waves.
It is generally preferred to permanently position the sensors within the well,
and
further preferred that such sensing not substantially interfere with normal
production
operation of the well. Various techniques exist in the art to mechanically
couple sensors
to a borehole structure, such as the production tube, the well casing, or a
production
packer. In the art, the sensors are typically arranged outside the casing and
are
surrounded by cement injected into the annular space between the casing and
the
borehole of the well. Embedding the sensors in this manner is beneficial in
that acoustic
waves used in the seismic analysis can easily travel to the sensors without
attenuation.
In addition, different types of acoustic waves (e.g., shear waves) can be
sensed using
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CA 02444443 2003-10-06
this method. Unfortunately, mechanically coupling the sensors to the casing
can be
generally difficult and costiy to perform. Furthermore, the sensors are not
recoverable.
According to other approaches of vertical seismology in the art, sensors are
only
temporarily located within the well. During temporary placement, the sensors
are used
to take readings and then retrieved from the well. In addition, the position
of the sensors
can be changed within the well to take into account alterations of the earth
strata under
analysis, resulting from production of effluents. Moreover, deployment or
retrieval of
temporary sensors disrupts production from the well, which can be particularly
costly if
measurements are periodically made to assess strata conditions over a given
time
period. Furthermore, preparing the sensors for insertion into the well,
properly
positioning the sensors, and retrieving the sensors can require tedious
preparation and
execution.
The present invention is directed to overcoming, or at least reducing the
effects
of, one or more of the problems set forth above.
SUMMARY OF THE INVENTION
A clamp mechanism for actively coupling an in-well seismic sensor to the
casing
of a well is disclosed. The clamp mechanism is capable of coupling to the
production
tubing for deployment in the well and is capable of actively coupling the
sensor to the
casing of the well. The clamp mechanism includes a body capable of being
coupled to
the production tubing. The sensor is mounted in a carrier mechanism, which
positions
adjacent the body. A biasing mechanism is disposed between the body and the
carrier
mechanism. When released, the biasing mechanism is capable of displacing the
carrier
mechanism with the mounted sensor towards the surface of the casing. A release
mechanism is capable of releasing the carrier mechanism when subjected to a
predetermined pressure within the well or when subjected to fluid in the well
for a
predetermined amount of time. A guiding mechanism on the body and the carrier
mechanism guides the displacement of the carrier mechanism towards the surface
of
the casing. Once coupled to the casing, the sensor is substantially
acoustically
decoupled from the clamp mechanism and production tubing.
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BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing summary, a preferred embodiment, and other aspects of the
present invention will be best understood with reference to a detailed
description of
specific embodiments of the invention, which follows, when read in conjunction
with the
accompanying drawings, in which:
Figure 1 schematically illustrates a seismic system according to the present
invention deployed in a well having a casing.
Figure 2 schematically illustrates a seismic station having a clamp mechanism
and a sensor mechanism of the present invention in an annulus formed between a
casing and a production tube in a weif.
Figure 3 schematically illustrates an embodiment of the sensor mechanism for
use with the clamp mechanism of the present invention.
Figures 4A-C respectively illustrate a plan view, a side view, and an end view
of
an embodiment of an in-well seismic station having a clamp mechanism and a
sensor
mechanism according to the present invention.
Figure 5 illustrates a plan view of the body of the clamp mechanism of Figures
4A-C.
Figure 6 illustrates an exploded view of the clamp mechanism and the sensor
mechanism of Figures 4A-C.
Figure 7 illustrates a graph showing eight tensile force versus separation
curves
for magnetic materials of various dimensions.
Figure 8 illustrates a graph estimating the stiffness for an -ring.
Figures 9 A-D illustrate various views of the clamp mechanism depicting an
embodiment of a release mechanism according to the present invention.
Figures 10 A-B illustrate the clamp mechanism and the sensor mechanism of the
present invention in stages of use in a well.
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CA 02444443 2003-10-06
Figure 11 illustrates a plan view of another embodiment of a clamp mechanism
according to the present invention.
Figure 12 illustrates a side cross-section of the clamp mechanism of Figure
11.
Figures 13 A-D illustrate various end cross-sections of the clamp mechanism of
Figure 11.
Figures 14 A-B illustrate a detailed cross-section of a portion of the clamp
mechanism of Figure 11, showing another embodiment of a release mechanism
according to the present invention.
Figures 15 A-D illustrate various embodiment of release mechanisms composed
of a dissolvable polymer.
DETAILED DESCRIPTION OF THE INVENTION
In the interest of clarity, not all features of actual implementations of a
clamp
mechanism for actively coupling an in-well seismic station to the casing of a
well are
described in the disclosure that follows. It will of course be appreciated
that in the
development of any such actual implementation, as in any such project,
numerous
engineering and design decisions must be made to achieve the developers'
specific
goals, e.g., compliance with mechanical and business related constraints,
which will
vary from one implementation to another. While attention must necessarily be
paid to
proper engineering and design practices for the environment in question, it
should be
appreciated that the development of a clamp mechanism for actively coupling an
in-well
seismic station to the casing of a well would nevertheless be a routine
undertaking for
those of skill in the art given the details provided by this disclosure.
Referring to the schematic illustration in Figure 1, a fiber optic in-well
seismic
array 20 used in the exploration of a hydrocarbon reservoir is depicted. The
array 20
has a plurality of seismic stations 30 interconnected by inter-station cables
40. The
array 20 is shown deployed in a well 10, which has been drilled down to a
subsurface
production zone and is equipped for the production of petroleum effluents.
Typically, the
well 10 includes a casing 12 coupled to the surrounding formations by injected
cement.
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Production tubing 14 is lowered into the cased well 10. The well 10 can be
fifteen to
twenty thousand feet or more in depth, and the annulus 16 can be filled with a
drilling
fluid (not shown) having a high temperature and pressure, which presents an
extremely
corrosive and hostile environment.
The seismic stations 30 include sensor mechanisms 32 and clamp mechanisms
34. The sensor mechanisms 32 are interconnected by the inter-station cables 40
to a
source/sensing/data collection apparatus 22, which typically includes a
demodulator
and optical signal processing equipment (not shown). The inter-station cables
40 are
typically'/-inch diameter cables housing optical fibers between the sensor
mechanisms
32 and the apparatus 22.
The sensor mechanisms 32 include one or more sensors (not shown), among
other components disclosed in more detail below. The clamp mechanisms 34
couple
the sensor mechanisms 32 to the production tubing 14, which is then lowered to
a
desired depth in the well 10. A preferred system and method for transporting,
deploying, and retrieving the sensor mechanism 32 and the clamp mechanism 34
of the
present invention is disclosed in U.S. Patent Publication No. 2004-0065443,
published
April 8, 2004. Once deployed in the well 10, the sensors of the sensor
mechanisms 32
are actively coupled to the casing 12 using the clamp mechanisms 34 of the
present
invention.
As is known in the art, seismology involves the detection of acoustic waves to
determine the strata of geologic features, and hence the probable location of
petroleum
effluents. A seismic generator (not shown) arranged at the surface or in
another well is
used to generate acoustic waves. Acoustic waves radiate from the source along
direct
paths and reflected paths through the various layers of earth. The seismic
waves cause
the surrounding earth layers to react, and the motion is detected by the
sensors in the
sensor mechanisms 32 through the casing 12 coupled to the earth. Resulting
signals
are transmitted through the inter-station cable 40 to the source/sensing/data
collection
apparatus 22, which interrogates the sensor mechanisms 32.
As is known in the art of fiber optic based seismic sensing, each sensor
mechanism 32 can include one or more fiber optic based sensors, such as fiber
Bragg
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CA 02444443 2003-10-06
gratings (FBG5), that reflect a narrow wavelength band of light having a
central
wavelength. If each sensor has a different reflection wavelength, the
reflected signals
may be easily detected using Wavelength Division Multiplexing (WDM)
techniques. If
the sensors have the same wavelength, reflected sigrials can be resolved in
time using
Time Division Multiplexing (TDM) techniques. Sucih multiplexing technologies
and
mixtures thereof are well known in the art. For brevity, well-known additional
steps,
devices, and techniques employed in the methods of seismic sensing are
omitted.
When performing vertical seismic profiling, the seismic stations 30 of the
array
20 are distributed over a known length, for example, 5000 feet. Over the known
length,
the seismic stations 30 can be evenly spaced at desii-ed intervals, such as
every 10 to
feet, for providing a desired resolution. Accordingly, the fiber optic in-well
seismic
array 20 can include hundreds of sensor mechanisms 32 and associated clamp
mechanisms 34. Because fiber optic connectors (not shown) on the inter-station
cables
40 between the sensor mechanisms 32 can generate signal loss and back
reflection of
15 the signal, the use of such connectors is preferably minimized or
eliminated in the array
20. The practical consequence of limiting the use of fiber optic connectors is
that all or
most of the sensor mechanisms 32 must be spliced with the inter-station cables
40
before being transported to the well 10.
The clamp mechanism 34 of the present invention facilitates the pre-assembly,
20 deployment, and retrieval of the array 20. The clamp mechanism 34 is
capable of
coupling to the tubing 14 and is capable of actively coupling the sensors of
the sensor
mechanism 32 to the inner wall of the casing 12. As will be evident herein,
the clamp
mechanism 32 reduces or eliminates problems set forth above. Namely, use of
the
clamp mechanism 32 may not significantly disrupt production from the well.
Furthermore, preparing the clamp mechanisms 32 for insertion into the well 10,
properly
coupling the sensor mechanisms 32 to the casing 12, and retrieving the sensors
and
clamp mechanisms 32 and 34 may not require tedious preparation and execution.
Referring to Figures 2-3, a clamp mechanism 15i0 and a sensor mechanism 200
according to the present invention are schematically illlustrated. As shown in
Figure 2,
the clamp mechanism 50 includes a body 60, an attachment device 70, mounting
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CA 02444443 2006-03-14
members 90, and a carrier mechanism 100. The clamp mechanism 50 also includes
a
biasing mechanisms 130, a guiding mechanism 140, and a release mechanism 150.
The attachment device 70 couples the body 60 of the clamp mechanism 50 to a
deployment member 14, such as production tubing. When lowered into the well
10, the
clamp mechanism 50 is disposed in an annulus 16 between the production tubing
14
and a casing 12 of the well. The body 60 defines a channel 80 for holding the
sensor
mechanism 200. Many different types of sensors can be used in conjunction with
the
disclosed clamping mechanism 50. For example, the sensor mechanism 200 can
constitute an electrically based or fiber optic based sensor. In a preferred
embodiment,
the sensor mechanism 200 includes one or more fiber optic based sensors. A
preferred
sensor mechanism for use with the present invention is disclosed in U.S.
Patent No.
6,888,972, issued May 3, 2005.
In Figure 3, the preferred sensor mechanism 200 for use with the clamp
mechanism of the present invention is schematically illustrated in an isolated
view. The
sensor mechanism 200 includes a first splice component 220, a sensor
component
250, and a second splice component 270. A first intra-station cable 230
connects the
first splice component 220 with the sensor component 250, and a second intra-
station
cable 260 connects the sensor component 250 with the second splice component
270.
The sensor mechanism 200 can also include another sensor component 280
connected
to the first splice component 220 with a third intra-station cable 240.
First and second inter-station cables 41 and 42 can be connected at both ends
of the sensor mechanism 200. Such a dual-ended sensor mechanism 200 allows
several sensors mechanisms to be multiplexed in series or allows the sensor
mechanism 200 to be multiplexed with other fiber optic measuring devices, such
as
pressure sensors, temperature sensors, flow rate sensors or meters, speed of
sound or
phase fraction sensors or meters, or other like devices. Examples of other
sensing
devices are disclosed in the following U.S. Patents: U.S. Patent No.
6,691,584, issued
February 17, 2004, entitled "Flow Rate Measurement Using Short Scale Length
Pressures"; U.S. Patent No. 6,354,147, issued March 12, 2002, entitled "Fluid
Parameter Measurement In Pipes Using Acoustic Pressures"; U.S. Patent No.
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CA 02444443 2006-03-14
6,601,458, issued August 5, 2003, entitled "Distributed Sound Speed
Measurements
For Multiphase Flow Measurement"; U.S. Patent No. 6,971,259, issued December
6,
2005, entitled "Fluid Density Measurement In Pipes Using Acoustic Pressures";
and
U.S. Patent No. 6,782,150, issued August 24, 2004, entitled "Apparatus For
Sensing
Fluid In a Pipe".
If only one sensor mechanism 200 is used or if the sensor mechanism 200 is the
last in an array of sensor mechanisms, the second intra-station cable 260, the
second
splice component 270, and the inter-station cable 42 need not be connected to
the end
of the sensor component 250. Ultimately, the inter-station cable 41 connects
to a
source/sensing/data collection apparatus (not shown), which is well known in
the art
and is capable of interrogating the sensors in the mechanism 200 and
interpreting data
retrieved therefrom.
The first splice component 220 houses a fiber organizer, splices, and other
devices (not shown) for optical fiber delivered from the inter-station cable
41. For
example, excess fiber from the cable 41 can be wound on a fiber organizer
within the,
splice component 220. The first intra-station cable 230 carries optical fiber
from the first
splice component 220 to the sensor component 250. The sensor component 250
houses one or more sensors (not shown). Many different types of sensor may be
used
in conjunction with the disclosed sensor mechanism 200. In a preferred
embodiment for
in-well seismic sensing, the sensor mechanism 200 preferably houses one or
more
accelerometers, such as disclosed in U.S. Patent No. 6,575,033, issued June
10, 2003
and entitled "Highly Sensitive Accelerometer," and U.S. Patent No. 6,891,621,
issued
May 10, 2005 and entitled "Highly Sensitive Cross Axis Accelerometer". The
accelerometers (not shown) can be arranged to measure acceleration from
acoustic
waves in any of three orthogonal axes (x, y, and z) and can transmit
respective sensing
light signals indicative of static and dynamic forces at their location on the
optical fiber.
The second intra-station cable 260 carries optical fiber from the sensor
component 250 to the second splice component 270. The second splice component
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270 is substantially similar to the first splice component 220 and houses a
fiber
organizer, splices, and other devices (not shown) for optical fiber. As noted
above, the
second interstation cable 42 can be connected to another sensor mechanism 200
of the
array. Otherwise, the second splice component 270 can have a terminated end or
can
be eliminated altogether. The third intra-station cable 240 can carry optical
fiber from
the first splice component 220 to the second sensor component 280, which can
be a
fiber optic based hydrophone, for example, of which several are well known.
The components 220, 250, and 270 of the sensor mechanism 200 preferably
have cylindrical housings, allowing the sensor mechanism 200 to have a small
profile
for use in the clamp mechanism 50 of the present invention. In Figures 2-3,
the sensor
mechanism 200 is depicted in a basic form to show the gross details of the
present
invention Relevant detail of the components, materials, and methods of
manufacture for
the sensor mechanism 200 can be obtained from U.S. Patent No. 6,888,972,
issued
May 3, 2005.
Although the present embodiment of the clamp mechanism 50 is used with the
multiple component sensor mechanism 200 having cylindrical housings, one
skilled in
the art will appreciate that the clamp mechanism 50 can be used with other
sensor
mechanisms having other configurations. Accordingly, the channel 80 defined in
the
clamp mechanism 50 of Figure 2 can have rectilinear or other shapes.
Furthermore, it is
understood that the sensor mechanism 200 preferably has temperature, pressure,
shock, and random vibration ratings suitable for deployment in a well.
Consequently,
the sensor mechanism 200 incorporated herein is suitable.
As shown in Figure 2, the first and second splice components 220 and 270 are
mounted in the channel 80 of the body 60 with the plurality of mounting
members 90.
The sensor component 250 is mounted within the carrier mechanism 100. The
carrier
mechanism 100 with the sensor component 250 mounted therein is biased towards
the
casing 12 with biasing mechanism 130 and is guided towards the casing 12 with
the
guiding mechanism 140. The guiding mechanism 140 guides the carrier mechanism
100 substantially perpendicular to the axis of the tubing 14. In addition, the
guiding
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CA 02444443 2003-10-06
mechanism 140 preferably allows the carrier mechanism 100 to shift
longitudinally and
laterally along a plane being substantially parallel to the axis of the tubing
14.
When deployed in the well, the release mechanism 150 holds the carrier
mechanism 100 adjacent the body 60 until released. After installation in the
well 10, the
release mechanism 150 is actuated to release the carrier mechanism 100 with
mounted
sensor component 250. The biasing mechanism 130 pushes the carrier mechanism
100 towards the casing 12, and the guiding mechanism 140 guides the carrier
mechanism 100 towards the casing 12. Preferably, the carrier mechanism 100
establishes acoustical contact with the surface 18 at a plurality of points P.
The intra-
station cables 230 and 260 are flexible and allow the serisor component 250 to
be
moved in relation to the splice components 220 and 270 connected thereto. When
the
carrier mechanism 100 establishes acoustical contact with the surface 18, the
sensor
component 250 is acoustically coupled to the casing for seismic sensing.
The release mechanism 150 can be activated by telemetry, electrical signal,
pressure differential, a rupture disc, or other method. Due to daily rig costs
and risks
inherent in coiled-tubing and wire-line intervention of electrically activated
release, the
release mechanism 150 is preferably activated without intervention. One method
for
interventionless activation of the release mechanism 150 involve the use of
pressure
pulses to actuate the release mechanism 150. For example, pressure pulses can
be
transmitted down the fluid column of the annulus 16 from a surface unit (not
shown). An
electronic module (not shown) of the release mechanism 150 can detect the
pressure
pulses. When a pre-programmed pattern of pulses is detected, the release
mechanism
150 is actuated and is set by hydrostatic pressure of the well to release the
carrier
mechanism 100.
A preferred method for interventionless activation of the release mechanism
150
uses the absolute pressure of the well to effectuate release the carrier
mechanism 100
with the mounted sensor component 250. As best described below with reference
to
Figures 9A-D, the release mechanism 150 in a preferred embodiment includes a
rupture disc, which eliminates the need for a separate hydraulic, electrical,
or telemetry
system to activate the mechanism 150.
CA 02444443 2003-10-06
Another preferred method for interventionless activation of the release
mechanism 150 uses the fluid in the well. As best described below with
reference to
Figures 14A-15D, the release mechanism 150 in another preferred embodiment
includes a member composed of dissolvable polymE:r to hold the carrier
mechanism
100 until a predetermined amount of exposure to fluid in the well.
Once released, the sensor component 250 is not substantially mechanically
coupled to the body 60 of the clamp mechanism 50, as will be evident in the
disclosure
that follows, and hence is substantially acoustically decoupled from the body
60 once
released. The carrier mechanism 100 with mounited sensor component 250 is
substantially free-moving relative to the body 60, is guided towards the
casing 12, and
is biased to acoustically couple to the casing 12.
With the benefit of the above description of the clamp mechanism 50 and sensor
mechanism 200 of the present invention, additional components, features, and
aspects
of the clamp mechanisms 50 will now be discussed in more detail.
Referring to Figures 4A-7, an embodiment of an in-well seismic station having
a
clamp mechanism 50 and a sensor mechanism 200 according to the present
invention
is illustrated in a number of views. In Figures 4A-C, tihe clamp mechanism 50
and the
sensor mechanism 200 are shown in a plan view, a side view, and an end view,
respectively. In Figure 5, the body 60 of the clamp mechanism 50 of the
present
invention is shown in a plan view. In Figure 6, the clamp mechanism 50 and the
sensor
mechanism 200 are shown in an exploded view.
As best shown in Figures 4A-C, the clamp mechanism 50 includes the body 60,
attachment devices 70, a plurality of brackets 90, carrier mechanisms;100a-
b,and
biasing mechanisms 130a-b. The body 60 has first and second sides 62 and 64
and
first and second ends 66 and 68. The body 60 is approximately 70 to 100-cm in
length
and is capable of fitting in the aimulus formed between 5, 5.5, and 7-inch
production
tubing positioned inside 9 5/8-inch casing. One of ordinary skill in the art
will appreciate
that the dimensions provided above are only exemplary and can be changed
depending
on the sizes of casing, tubing, and sensors for the intended application of
the present
invention.
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As best shown in the end view of Figure 4C, the first side 62 of the body 60
defines a curvilinear shape. The first side 62 is intended to position
adjacent the casing
(not shown) of the well, as described below. The shape of the side 62 enables
the body
60 to fit the various casing dimensions. A similar shape can be used for the
second side
64 to accept various dimensions and tolerances of tubing (not shown) to be
encountered. Physical contact between the second side 64 and the tubing is
preferably
close to the outer edges 65 adjacent where the attachment devices 70a-b are
connected to the body 60. The shape of the first and second sides 62 and 64
thus
accommodate the cylindrical surfaces of the tubing and casing to be
encountered and
minimize the obstruction of the annulus formed between them. It is understood
that
other variations in the topology of the body 60 are possible to allow for
fluid in the
annulus to flow around the body 60. The body 60 can define a groove (not
shown) in
the second side 64 adjacent the tubing. In this way, a cable can be disposed
along the
groove between the body 60 and the tubing, which allows the clamp mechanism 50
to
also be used as an ordinary cable clamp for other in-well systems.
As evidenced herein, the clamp mechanism 50 of the present invention has a
low profile, allowing the clamp mechanism 50 to be associated to production
tubing. In
the art of seismic sensing, seismic sensors are typically installed in the
well using
conventional wire line. By using the low profile clamp rnechanism 50, the
sensor
mechanism 200 can be coupled to the tubing and installed in the well with the
production tubing. Thus, the clamp mechanism 50 can be used for seismic
sensing
during production so that operations are not greatly affected. In addition,
the clamp
mechanism 50 and sensor mechanism 200 can be retrieved for reuse.
The body 60 can be fcrmed by casting, machining, or a number of techniques or
combinations thereof known in the art. Using a combination of flat surfaces
angled from
one another to form the curvilinear shape for the first and second sides 62
and 64 can
be easily machined, which is an advantage for rnanufacturing. The body 60 is
preferably made from austinitic stainless steel with reference AISI 316, which
is suitable
for casting and has sufficient strength and resistance to high temperature and
corrosion
for use in conditions of a well. Using this material and the dimensions set
forth above,
the body 60 can weigh about 20-40-kg. However, other materials, metals, or
alloys can
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CA 02444443 2003-10-06
be used depending on the desired strength of the body 60 and its expected
environment (i.e., the annulus of a well). The materials of the body 60 and
other
components of the clamp mechanism 50 can be modified depending on the intended
environment, which can vary from well to well in terms of pressure,
temperature, and
caustic chemicals. For example, the materials of the clamp mechanism 50 may
need to
be modified if sufficient amounts of hydrogen sulfide or "sour gas" are
present in the
well. As is known in the art, the presence of hydrogen sulfide having a
concentration as
low as 10-ppm can weaken metals by causing sulfide stress cracking.
Metallurgical
techniques and materials resistant to such sour gas are well known to those of
ordinary
skill in the art.
As mentioned previously, the body 60 couples to the production tubing (not
shown) with the attachment devices 70. The attachment devices 70 can include
components commonly used with ordinary cable clamps. The attachment devices 70
each include a clamping component 72 and a coupling component 74. The clamping
components 72 are hingedly connected to the body 60 for encompassing the
tubing,
while the coupling components 74 are hingedly connected to the other edge of
the body
60 for connecting to an end of the clamping component 72 using a bolt 76.
Pivot pins
78 are used for the hinged connections of the components 72 and 74 to the body
60.
The pivot pins 78 allow the components 72 and 74 to move laterally thereon,
which
accommodates the effects of thermal expansion and deformation of the tubing
and
body 60 when in the well.
In addition to the use of the attachment devices 70 to couple the clamp
mechanism 50 to the tubing, the body 60 preferably includes a plurality of
support rods
52 in one or both of the ends 66 or 68 of the body 60. The support rods 52 are
threaded
into holes 67 and extend from the ends 66 or 68 of the body 60. As best
described
below and shown in Figures 10A-B, the distal ends of the support rods 52 have
stops
and are held within standard anchor clamps coupled to the production tubing.
The rods
52 are movable in the anchor clamps to allow for shifting and adjustment due
to the
effects of temperature and deformation in the well.
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The body 60 protects of the sensor mechariism 200 during installation and
retrieval. Accordingly, the first side 62 defines a channel 80. As best shown
in Figure 5,
which shows the body 60 without the sensor mechanism placed therein, the
channel
includes end recesses 82a-b, intermediate recesses 84a-b, and a central recess
86.
The channel 80 can also include an auxiliary recess 81 for an auxiliary sensor
component (not shown), such as a hydrophone.
As best shown in Figure 4A, the end recesses 82a-b respectively communicate
with the ends 66 and 68 of the body 60 and house the splice components 220 and
270.
The intermediate recesses 84a-b respectively connect the end recesses 82a-b
with the
central recess 50. The intermediate recesses 84a-b primarily house the intra-
station
cables 230 and 260, the carrier mechanisms 100a-.b, and the biasing mechanisms
130a-b, which are best shown in Figure 6.
As best shown in the plan view of Figure 5, each of the intermediate recesses
84a-b includes a guide pin 144a-b. The guide pins 144a-b are disposed in
opposite
corners of the recesses 84a-b. In addition, the recesses 84a-b each define
indentations
132a-b for the biasing mechanisms 130a-b described below. As best shown in
Figure
4A, the central recess 86 houses a major portion of the sensor component 250.
In the
present embodiment, the central recess 86 is substantially wider than the
sensor
mechanism 250, and ancillary side members 88a-b are disposed in the central
recess
86 along the sides of the sensor mechanism 250. The side members 88a-b are
attached to the body 60 with bolts and can be removed so that the clamp
mechanism
50 can be used with other devices or for applications other than fiber optic
in-well
seismic sensing explicitly disclosed herein. One of the side members 88a-b
also
preferably holds components of a release mechanismi (not shown). Relevant
details of
an embodiment of a release mechanism according to the present invention are
provided below with reference to Figures 9A-D.
The splice components 220 and 270 can be held firmly within the end recesses
82a-b by several methods or structures known in the art. As best shown in
Figures 4A-
B, a plurality of mounting members 90 hold the splice components 220 and 270
in the
recesses 82a-b. As best shown in Figure 6, the mounting rnembers 90 each
define a
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CA 02444443 2003-10-06
cylindrical surface 92 to match the cylindrical housings of the splice
components 220
and 270. Fasteners 94 on each mounting member 90 connect the member to
countersinks 83 formed in the first side 62 of the body 60. The fasteners 94
are
preferably held within the mounting members 90 so they cannot be separated
therefrom, which eases assembly.
When attached in the countersinks 83, the mounting members 90 are preferably
flush with the first side 62 of the body 60, as best shown in the side view of
Figure 4B.
Because the first splice component 220 has the inter-station cable 41
connected
thereto, the splice component 220 must be able to withstand any forces that
may be
imposed on it during assembly, transport, or operation. Therefore, the first
splice
component 220 preferably has three mounting members 90a-c holding the
component
220 in the end recess 82a. The second splice component 270 has two mounting
members 90d-e.
In an alternative embodiment, the plurality of mounting members 90 can be
hingedly connected to the body 60 at one end and can fasten to the body 60 at
the
other end. In yet another alternative, a single mountirig member can be used
for each
splice housing 220 and 270. If a single mounting rnember is used for each
splice
component 220 or 270, the single mounting member, such as a curved plate, can
be
made to span substantially the entire length of the splice component 220 or
270 to
provide a substantial amount of protection and a flush outer surface to the
body 60. As
one of ordinary skill in the art will recognize, a nurriber of techniques and
methods
known in the art can be used to mount the splice components 220 and 270 to the
body
60.
The carrier mechanisms 100a-b hold the sensor component 250. As best shown
in Figure 6, the carrier mechanisms 100a-b each include a support 11 a-b
connecting
to a bracket 120a-b, which clamp around respective ends of the sensor
component 250.
Each of the supports 110a-b defines a cylindrical surFace 112 to match the
cylindrical
housing of the sensor component 250. Each of the supports llOa-b also defines
threaded holes 116, a guide hole 142, and bored holes 119. The threaded holes
116
mate with fasteners 126 to connect the supports 110a-b with the brackets 120a-
b. The
CA 02444443 2006-03-14
guide holes 142 mate with one of the guide pins 144a-b in the intermediate
recesses
84a-b. The bored holes 119 are on the underside of the supports 110a-b and
receive
portions of the biasing mechanisms 130a-b. The supports 110a-b are held
adjacent the
body 60 by the release mechanism (not shown), as described below.
The brackets 120a-b each includes a cover portion 122 with wings 124. The
fasteners 126 are held within the wings 124 so that they cannot be removed
from the
bracket 120a-b. To assemble the carrier mechanisms 100a-b, the ends of the
sensor
component 250 are positioned in the cylindrical surfaces 112 of the supports
110a-b.
The brackets 120a-b are then positioned adjacent the ends of the sensor
component
250. The fasteners 126 on the brackets 120a-b are threaded into the threaded
holes
116 in the supports 110a-b.
The use of brackets 120a-b and fasteners 126 as the attachment technique is
simple and can reduce the amount of time to mount the sensor component 250 in
the
clamp mechanism 50 during well completion, if necessary. Furthermore, the use
of
brackets 120a-b with fasteners 126 can be compatible with the requirements for
a
transportation receptacle for the sensor mechanism 200 disclosed in U.S.
Patent
Publication No. 2004-0065443, published April 8, 2004.
Although the intra-station cables 230 and 260 of the sensor mechanism 200
preferably include capillary tubes made from INCONEL or MONEL alloys with an
outer
diameter between 1/16" and 1/8", the cover portions 122 of the brackets 120a-b
preferably extend beyond the ends of the sensor component 250 to provide
additional
protection to the intra-station cables 230 and 260. The cover portions 122 can
also help
to reduce the probability of clogging of loose materials, such as mud or
sludge, inside
the recesses 84a-b. For example, the brackets 120a-b preferably have an open
structure to prevent clogging and can define holes (not shown). To further
reduce the
risk of clogging, the cover portions 122 can completely cover and form a seal
with the
recesses 84a-b of the body 60. The cover portions 122 also reduce the risk of
jamming
when the clamp and sensor mechanism 50 and 200 are retrieved together from a
well.
For example, the cover portions 122 have curved surfaces.
16
CA 02444443 2003-10-06
The first bracket 120a includes two contact points Pi and P2 for coupling to
the
casing of the well. The second bracket 120b includes a single contact point
P3. which
has a hemispherical shape and is integrally formed on the second bracket 120b.
The
contact points P, and P2 are positioned with a wide separation to achieve
maximum
stability when coupled to the casing. In the present embodiment, the contact
points P,
and P2 constitute extensions of the fasteners 126 of the first bracket 120a.
Alternatively,
the contact points P, and P2 can be extended metall portions integral to the
bracket
120a, such as on the second bracket 120b.
The brackets 120a-b and three contact points P1_3 are subject to wear as they
contact the casing and may rub against the casing. Consequently, the three
contact
points Pl_3 are made of the same material as the brackets 120a-b and supports
110a-b,
which are preferably made of martenistic, precipitation hardened stainless
steel IJNS
S1 7400 to reduce the wear during installation and operation.
The biasing mechanisms 130a-b are disposed between the clamp mechanism
50 and the carrier mechanisms 100a-b. The biasing mechanisms 130a-b push the
carrier mechanisms 100a-b with mounted sensor component 250 away from the body
60 towards
the casing. In the present embodiment, the biasing rr,echanisms 130a-b include
two springs for each carrier mechanism 100a-b. The pairs of springs 130a-b are
respectively positioned in indentations 132a-b formed in the intermediate
recesses 84a-
b. The bored holes 119 on the undersides of the supports 11 a-b receive the
other
ends of the springs 130a-b.
A great variety of springs 130a-b can be used to optimize the force and the
location of the pushing force on the carrier mechanisms 100a-b. Furthermore,
the
springs 130a-b can easily fit into the recesses 84a-b in the body 60. For the
conditions
found in the annulus of the well, the springs 130a-b are preferably composed
of non-
corrosive materials. In addition, the material of the springs 130a-b
preferably does not
degrade during repetitive movements. Examples of suitable corrosion resistant
metal
alloys for the springs 130a-b include, but are not limited to stainless steel,
INCONEL,
17
CA 02444443 2003-10-06
and INCOLOY. Other mechanical biasing mechanisms, such as leaf springs, could
also
be used.
In an alternative embodiment to the use of springs for the biasing mechanisms
130a-b, the required pushing force can be generated with magnetic elements
(not
shown). In this alternative embodiment, magnets are placed on the underside of
the
supports 110a-b and are place within the recesses 84a-b. The required pushing
force to
deploy the sensor component 250 away from the body 60 can be achieved by
orienting
the magnets to face poles of the same polarity (e.g., riorth to north).
Biasing the carrier
mechanisms 100a-b with magnets can allow for even better acoustical decoupling
of
the sensor component 250 from the body 60 and hence from the production
tubing.
Selection of appropriate characteristics and types of miagnetic elements for
use with the
present invention requires consideration of temperature effects and tensile
force versus
separation of the magnetic elements, among other considerations.
As is known in the art, substantially strong magnetic elements can achieve a
large force, but attention must be paid to the Curie temperature of the
magnetic
elements. Curie temperature represents the thermal limit for the atoms of the
magnetic
element to retain their magnetic alignment. Substantially strong magnetic
elements can
have Curie temperatures as low as only 80-degrees Celsius, for example.
Because the
biasing mechanisms 130a-b will be subject to high temperatures in the well,
magnetic
materials with a high Curie temperature have to be used. The Curie
temperatures for
three exemplary and suitable ferromagnetic elements are as follows: cobalt =
1,130
degrees C; iron = 770 degrees C; nickel = 358 degrees C.
In addition to a high Curie temperature, the magnetic elements must have an
appropriate tensile force versus separation for elevated temperatures.
Referring to
Figure 7, a graph shows eight local stiffness versus separation curves for
various
magnets, such as Neodymium Neo35 and ordinary ferrite (Y28) magnets of
differing
dimensions. As is known in the art, the tensile force from magnetic elements
decreases
very rapidly with increased separation of the elements. Typically, magnetic
elements
with Curie temperatures of about 250-degrees Celsius can have considerably
lower
tensile forces than desirable. For the present invention, Neodymium Neo35
having a
18
CA 02444443 2003-10-06
maximum temperature of 250 C can be used for high temperature applications.
Ordinary ferrite (Y28) having a maximum temperature of 80 C can be used for
low
temperature applications. One of ordinary skiii in the art would find it a
routine
undertaking to select appropriate dimensions, number, and composition of
magnets to
provide a sufficient pushing force for use with the clamp mechanism 50 to
press the
sensor component 250 against the casing, even at the sensor component's
maximum
displacement from the body of 10 to 15-mm.
As best shown in Figure 6, the intermediate recesses 84a-b respectively
include
guiding pins 144a-b, which extend substantially perpendicular to the axial
dimension of
the body 60. One guide pin 144a-b is provided for each support 11 a-b so that
the
supports llOa-b and pins 144a-b can accommodate variations in tolerances,
elongation, and angular orientation of the sensor component 250. The guide
holes 142a-
b have a larger dimension than the guide pins 144a-b.
Elastomeric elements (not shown), such as 0--rings, are disposed between the
guide pins 144a-b and the guide holes 142a-b. The elastomeric elements are
used as
buffers between the guide pins 144a-b and guide holes 142a-b, substantially
eliminating any metal-to-metal contact therebetween. The elastomeric elements
also
centralize the carrier mechanisms 100a-b in the channel 80 by allowing the
supports
110a-b to move laterally with respect to the pins 144a-b.
Because the tubing is subjected to vibrations that are induced by the
production
of effluents and undesired noise waves produced from the seismic source, the
sensor
mechanism 250 must be sufficiently acoustically decoupled from the production
tubing.
The flexibility of the elastomeric elements is used to minimize the acoustic
coupling
between the carrier mechanisms 100a-b and the clamp mechanism 50. Hence, use
of
the elastomeric elements can substantially acoustically decouple the sensor
component
250 from the production tubing. As shown in Figure 4A, the guide pins and
guide holes
can allow the carrier mechanisms 100a-b to move small distances in lateral
directions
La and Lb within the intermediate recesses 84a-b.
Referring to Figure 8, a graph illustrates a first curve 146 of displacement
versus
load for an exemplary 0-ring. Also illustrated on the graph is a second curve
147 of
19
CA 02444443 2003-10-06
local stiffness versus load. The exemplary O-ring has an inner diameter of
approximately 8-mm and a thickness of approximately 3-mm. As evidenced by the
graph, the displacement versus load curve 146 is not a linear relationship. On
the other
hand, the "local stiffness" increases with the total load in an almost linear
as shown by
curve 147. As evidenced by the slope of line 148, which represents a "best
fit" line of
line 147, the graph shows that the effective "spring constant" of an 0-ring
squeezed
between to flat surfaces can be approximately 21-N/mm, which is the slope of
line 148.
The material of the elastomeric elements is preferably soft but capable of
withstanding the environment present in the annulus for an extended period of
time.
Suitable materials for the elastomeric elements include, but are not limited
to, polymer
materials resistant to high temperatures, such as silicone, Viton, TORLON
(Polyamidimide), or PEEK (Polyetheretherketone). These materials can serve
long-term
temperatures higher than 250 C and are suitable for in-well applications.
During assembly, the guide pins 144a-b respectively position in the guide
holes
142a-b in the supports 110a-b. The guide pins 144a-b assure that the sensor
component 250 is physically aligned inside the central recess 86. Contact of
the guide
pins 144a-b with the elastomeric elements and contact of the biasing members
130a-b
with the supports llOa-b substantially assure that the sensor mechanism 250 is
acoustically decoupled from the body 60 of the clamp mechanism 50.
The guide pins 144a-b include stops, shoulders, or widened portions (not
shown)
on their distal ends to keep the supports 11 a-b of the carrier mechanisms
100a-b from
coming out of the intermediate channels 84a-b during retrieval of the clamp
mechanism
50. When the carrier mechanisms 100a-b are released from the body 60 so as to
couple to the casing, the guide pins 144a-b allow the carrier mechanisms 100a-
b to
respectively shift or move in radial directions Ea and Eb, as shown in Figure
4B. The
carrier mechanisms can respectively move approximately 10 to 15-mm in
directions Ea
and Eb. With each carrier mechanism 100a-b able to move radially (Ea and Eb)
and
laterally (La and Lb), the carrier mechanisms 100a-b including the sensor
component
250 can slightly tilt and rotate when released and adjust to changes in the
well due to
temperature or irregularities in the casing. The sliglit tilting and rotating
allows the
CA 02444443 2003-10-06
sensor component 250 to be brought into contact with the casing even under
imperfect
conditions. One of ordinary skill in the art will appreciate that the
dimensions provided
herein are only exemplary and can be readily altered depending on the
requirements of
an intended application of the present invention.
Referring to Figures 9A-D, an embodiment of a release mechanism 150 with its
surrounding components are shown for the disclosed clamp mechanism. In Figures
9A
and 9C, plan views of portions of the clamp mechanism and release mechanism
150
are shown, with Figure 9A showing the release mechanism 150 in an unreleased
state
and Figure 9C showing the clamp in a released state. Figures 9B and 9D are
respective
cross-sections of Figures 9A and 9C, which better reveal the details of the
release
mechanism 150.
In Figures 9A and 9C, the portions of the clamp mechanism include first and
second sides members 88a-b and first and second supports 11 a-b. The second
side
member 88b and the first and second supports 110a-b are shown in cross-section
to.
reveal internal components of the release mechanism 150. As best described
above,
the first and second side members 88a-b attach to the body 60 of the clamp
mechanism with the sensor component (not shown) positioned therebetween. As
also
described above, the first and supports llOa-b position adjacent the body 60
of the
clamp mechanism and are used to support ends of the sensor component. The
supports 11 a-b define bores 119 for the springs 130a-b, guide holes 142 for
the guide
pins (not shown), and holes 116 for attaching to the carrier brackets (not
shown).
The release mechanism 150 in the present emibodiment uses the absolute well
pressure to remotely release the supports 11 a-b with sensor component
attached
thereto. As best shown in Figures 9A-B, the second side member 88b includes
components of the release mechanism 150 installed therein. The release
mechanism
150 includes a movable piston 160, a replaceable canister 170, and a sliding
plate 180.
The piston 160 is movably positioned in a bore 152 defined within the side
member
88b. The piston 160 includes first and second heads 162a-b, first and second
activating
members 164a-b, and a stem 166. 0-rings 163 are used on the heads 162 a-b to
promote smooth movement of the heads 162a-b in the bore 152.
21
CA 02444443 2003-10-06
The replaceable canister 170 is threaded in a wide portion 158 of the bore 152
adjacent the stem 166. The replaceable canister 170 includes a chamber 172, a
rupture
disc 174, and a threaded cap 176. The rupture disc 174 is welded to the end of
the
canister 170 so that the chamber 172 is hermeticaily sealed and filled with
air at
substantially one atmosphere. The threaded cap 176 holds the canister 170 with
rupture disc 174 within the wide portion 158 of the bore 152.
The sliding plate 180 is movably positioned adjacent the body 60 and between
the first and second side members 88a-b. A side portion 181 of the plate 180
is
positioned underneath the piston 160 in the second side member 88b. The side
portion
181 defines first and second slots 186a-b, which receive the activation
members 1 64a-
b of the piston 160 therein.
A first end 182a of the plate 180 is positioned underneath the first support
110a,
and a second end 182b is positioned underneath the seccnd support 110b. The
first
and second ends 182a-b each include a pair of holding members or keys 184a-b,
which
engage key slots 111 a-b defined in the supports 110a-b.
In Figures 9A-B, the release mechanism 150 is shown in an unreleased state
holding the first and second supports 110a-b adjacent the body 60. Hence, the
sensor
component (not shown), which is mounted between the supports llOa-b is also
not
released, which is suitable when the clamp mechanism is being transported and
deployed.
As best shown in Figure 9B, the activating members 164a-b extend from the
piston 160 and position in the slots 186a-b defined in the side portion 181 of
the plate
180. The stem 166 of the piston 160 is positioned through a narrow portion 156
of the
bore 152. An 0-ring 167 is provided about the stem 166 adjacent the first head
162a for
reducing shock when the piston 160 is released. The end of the bore 152
adjacent the
narrow portion 156 defines a port 154 for fluid to escape when the piston 160
is moved.
Another 0-ring 168 is provided adjacent the distal end of the stem 166 to
promote
smooth movement of the stem 166.
22
CA 02444443 2003-10-06
In the unreleased state of Figures 9A-B, the keys 184a-b on the ends 182a-b of
the plate 180 are engaged in the key slots ill a-b defined in the supports
110a-b.
Consequently, the supports 110a-b with the mounted sensor component (not
shown)
are held adjacent the body 60 of the clamp mechanism. Although two keys 184a-b
and
two slots 111a-b are used in the present embodiment, it is understood that
more or
fewer keys or slots can be used depending on the space available, the sizes of
the keys
and slots, and the amount of engagement required between the keys and slots.
Once deployed in the well, fluid in the well impregnates the unsealed passages
and crevices of the release niechanism 150. Only the chamber 172 of the
canister 170
is hermetically sealed from the well fluid. Thus, fluid pressure can seep
through the port
154, into the bore 152, past the 0-ring 168 via the narrow portion 156. In
this regard,
the 0-rings 163, 167, and 168 are primarily used for guiding the piston 160
and stem
166 and are not used for sealing out the high pressure well fluid. This means
that fluid
may also be able to seep past the 0-rings 163, which may be of no consequence.
Consequently, fluid pressure of the well acts on the side of the rupture disc
174
adjacent the stem 166, and the atmospheric pressure in the chamber 172 acts
against
the other side of the disc 174. A considerable pressure differential develops
across the
rupture disc 174 as the clamp mechanism is deployed in the well. When the
absolute
pressure in the well exceeds the differential pressure rating of the rupture
disc 174, the
disc 174 bursts.
As is known in the art of rupture discs, the rupture disk 174 is designed to
rupture at a predetermined pressure differential. A combination of material
thickness,
material selection, surface area, and geometry of the disc 174 are used to
regulate the
predetermined pressure differential at which it will rupture. Rupture disks
174 can have
a non-fragmenting design and may not require vacuum support. Rupture disks can
be
made of numerous materials known in the art and can range in sizes from 1/2"
(12-mm)
to 60" (1200-mm), for example. Furthermore, rupture disks are known in the art
that can
be resistant to corrosion, can withstand operating temperatures up to 400 F
or even
800 F, can be designed for a wide range of burst pressures, can have tight
burst
pressure tolerances, and can have low flow resistance,
23
CA 02444443 2003-10-06
Consequently, a suitable rupture disk 174 for the disclosed clamp mechanism
can be selected for a given application and differential pressure rating,
which can vary
from application to application. Thus, depending on the intended final
position of the
clamp mechanism and the pressure levels in the well, an appropriate canister
170 with
an appropriate rupture disc 174 can be installed in the wide portion 158 and
held
therein with the cap member 176 so that the release rnechanism 150 is
activated when
subjected to a predetermined pressure or depth in the well.
Referring the Figures 9C-D, the rupture disk 174 is shown ruptured. When
rupturing, metal segments of the disk 174 can fold back to provide an opening
therethrough. After the disc 174 ruptures, well pressuire rushes to fill the
low pressure
chamber 172, causing the piston 160 to move in direction A in the bore 152. It
should
be noted that the pressure differential is sufficient -to --move the piston
160 without-the-
use of additional springs or mechanical mechanisms. As the first head 162a is
moved in
direction A, well fluid in the bore 152 is allowed to escape from the port
154. The 0-ring
167 adjacent the first head 162a can be used to lessen the shock produced when
the
piston 160 is moved with considerable force in direction A. Iri addition, the
port 154 can
have a small, predetermined cross-section to limit the escape of well fluid
from the bore
152 so that the well fluid can also act to dampen the movement of the piston
160 in
direction A.
With the movement of the piston 160, the activating members 164a-b shift
position and cause the sliding plate 180 to also shift position. The holding
members or
keys 184a-b are moved within the key slots 111 a-b. The supports 110a-b are
released,
and the compressed biasing members 130a-b push the supports 11 a-b away from
the
body 60. As a result, the shift of the release mechanism 150 in the single
direction A
releases both supports 11 a-b simultaneously, which reduces risks of tilting
and
jamming of the release mechanism 150, supports 110a-b, and sensor component
during release.
Any resonance created by the components of the release mechanism 150 can
be minimized with the numerous 0-rings 163, 167, and 168 used. The friction
from the
0-rings 163, 167, and 168 can help to secure the piston 160 and stem 166 in
the
24
CA 02444443 2006-03-14
unreleased and released positions. The sliding plate 180 can be provided with
devices
for facilitating and dampening its movements, as well.
After the release mechanism 150 is activated, it is understood that the keys
184a-b should not interfere with the supports 110a-b. Consequently, the keys
184a-b
preferably have a low profile above the surface of the plate 180. It is
understood that
the release mechanism 150 can be designed to accommodate the effects of
pressure
and temperature within the well. In addition, it is understood that the
chamber 152 and
the port 154 can be designed to reduce the potential of clogging or other
problems
associated with well fluid.
Referring to Figures 10A-B, the seismic station having a clamp mechanism 50
and sensor mechanism 200 is illustrated in stages of use in a well.
Preferably, the
sensor mechanism 200 is pre-assembled and installed in the clamp mechanism 50
prior to transportation to the well 10. Furthermore, the clamp mechanism 50
with
installed sensor mechanism 200 is preferably transported, deployed, and
retrieved
using a system and method as disclosed in U.S. Patent Publication No. 2004-
0065443,
published April 8, 2004.
In Figure 10A, the seismic station is shown during deployment in the annulus
16
of the well 10. As is known in the art, devices or portions thereof that
become loose or
break off in the annulus 16 can be extremely difficult and expensive to
retrieve, if even
possible, and can even render a well unusable. Consequently, the clamp
mechanism
50 with installed sensor mechanism 200 preferably includes redundant
techniques for
coupling the clamp mechanism 50 to the tubing 14. The clamp mechanism 50 is
coupled to the tubing 14 using the clamp members 70, as described earlier. In
addition,
first and second anchor clamps 54 and 56 connect to the rods 52 extending from
the
body 60. The rods 52 are slidable within the anchor clamps 54 and 56 to allow
for
thermal expansion and deformation during use. The rods 52 include stops 53 on
their
distal ends to prevent removal from the anchor clamps 54 and 56.
During deployment, the clamp mechanism 50 is preferably capable of only
coming in contact with the casing 12 along one or two lines or at a couple of
points
depending on the orientation inside the casing 12. This is facilitated by the
curved
CA 02444443 2003-10-06
surface profile of the clamp mechanism 50 discussed above. Also, the clamp
mechanism 50 is situated primarily on one side of the tubing 14, and is
approximately
70 to 100-cm in length. Placing most of the clamp rnechanism 50 on one side of
the
production tubing 14 helps to open the cross-section of the annulus 16 to
prevent
clogging. Additional cable tracks (not shown) can be included on both sides of
the
clamp mechanism 50 for running additional cables and devices along the tubing
14.
During deployment, the release mechanism (not shown) maintains the carrier
mechanisms 100a-b locked in the channel defined in the body 60. The sensor
component 250 mounted in the carrier mechanisms 100a-b is kept in correct
position
and is protected by the channel and the carrier mechanisms 100a-b. Preferably,
the
three contact points P1_3 on the carrier mechanisms 1 OOa-b do not touch the
casing 12
during deployment to minimize the risk of wear and damage to them.
Referring to Figure 10B, the clamp mechanism 50 is lowered to a predetermined
depth within the annulus 16. Hydrostatic pressure iri the annulus 16,
indicative or a
particular depth, triggers the release mechanism on the clamp 50 as described
in detail
above. The biasing mechanisms (not visible) disposed between the body 60 and
the
carrier mechanisms 100a-b move the carrier mechanisms 100a-b with mounted
sensor
component 250 approximately 10 to 15-mm towards the casing 12 to make contact
with
and to acoustically couple to the casing 12. Once acoustically coupled to the
casing 12,
the carrier mechanisms 100a-b can be used to transfer seismic signals from the
casing
12 to the sensor component 250 mounted therein.
As noted above, the biasing mechanisms 130a-b push the carrier mechanisms
100a-b with mounted sensor component 250 towards the casing 12. Determining
the
required and optimal pushing force of the biasing members 130a-b requires
consideration of a number of constraints, incfudincl consideration of
achieving an
acceptable seismic coupling in both vertical and horizontal wells and of
avoiding
unacceptable shock during the release of the carrier mechanisms 100a-b and
sensor
component 250. The minimum required force from the biasing members 130a-b also
depends on the weight of the assembled carrier mechanisms 100a-b and sensor
component 250, the stiffness of the intra-station cables 230 and 260 coupled
to the
26
CA 02444443 2003-10-06
sensor component 250, the viscosity of any material in the well, and the type
of well in
which the mechanisms are deployed (e.g., a vertical, deviated, or horizontal
well),
among other variables. There is an obvious trade-off between reliable
clamping, force
from the guiding pins, and risk of resonance and shock during the release
operation.
Based on evaluations, the use of springs is preferred for the biasing
mechanisms 1
30a-b for the high temperature applications in a well.
The positioning of the biasing mechanisms 130a-b with respect to the contact
points Pl_3 provides stability and reduces the risk of unwanted resonance. In
this
regard, it can be preferable to position the contact points P1_3 at a further
lateral
distance than the biasing mechanisms 130a-b. 'The resonance of the biasing
mechanisms 130a-b must also be taken into consideration. The pushing force of
the
biasing mechanisms 130a-b is also preferably optimized to minimize the risk of
vibration of the sensor mechanism 250 when deployed against the casing 12. In
the
present embodiment, the assembled carrier mechanisms 100a-b and sensor
component 250 weigh approximately 2 to 3-kg. The biasing mechanisms 130a-b are
preferably capable of providing a pushing force that is approximately three to
four times
the weight of the sensor component 250 with the assembled carrier mechanisms
100a-
b to ensure adequate coupling with the casing 12, which is believed to reduce
the
probability of resonance without reducing sensor sensitivity. This level of
force is also
sufficient to overcome the usually insignificant resistancE: of the thin,
intra-station
cables. One of ordinary skill in the art will appreciate that the stiffness
and pushing
force of the biasing mechanisms 130a-b provided above are only exemplary and
can be
readily altered depending on the requirements of an intended application of
the present
invention.
The three points of contact P1_3 can adjust to the surface of the casing 12
independent of curvature in the casing dimensions, deformations, roughness,
and
position. For illustrative purposes, the surface of the casing 12 in Figures
1OA-B is
shown as slightly irregular, although it is understood that the actual surface
of the
casing can be quite different. In this regard, those of ordinary skill in the
art will
recognize that the casing 12 may not have a perfectly uniform diameter,
because it is
subject to damage, stresses, and drift. Moreover, junctions between various
pieces of
27
CA 02444443 2003-10-06
the casing string might cause the casing diameter to be non-uniform. Thus, the
clamp
mechanism 50 may encounter irregularities on the surface of the casing 12 of
about 10-
mm, for example. Moreover, the inner surface of the casing 12 can be rough
after
production and can become even worse due to contarnination and corrosion. The
three
contact points P1_3 can adapt to variation in surface finish, casing
irregularities, and
diameters of the casing 12 in the well 10.
The clamp mechanism 50 can be retrieved from the annulus 16 of the well 10 by
raising the production tubing 14, even if the release mechanisms have released
the
sensor components. In this circumstance, the carrier mechanisms 100a-b,
specifically
the contact points PT_3, will remain biased towards the casing 12 and hence
will rub
against the casing 12 as the clamp mechanism 50 is retrieved. However, this
level of
friction between the contact points P1_3 and the casing 12 will not be so
severe as to
damage the casing 12 or significantly impede the ability to retrieve the
production
tubing 14. After retrieval, the clamp mechanism 50 or certain components
thereon (e.g.,
contact points P1_3, brackets, rupturing disk) may need to be replaced if a
subsequent
deployment is envisioned.
Referring to Figures 11-13D, another embodirnent of a clamp mechanism 350
according to the present invention is illustrated. In Figure 11, the clamp
mechanism 350
is illustrated in a plan view. In Figure 12, the clamp mechanism 350 of Figure
11 is
illustrated in a side cross-section. In Figures 13A-D, the clamp mechanism 350
of
Figure 11 is illustrated in various end cross-sections to reveal internal
components.
With exceptions noted below, the clamp mechanism 350 of the present
embodiment is substantially similar to the embodimen-t disclosed above.
Consequently,
the materials used for the clamp mechanism 350 of the present embodiment are
similar
to those disclosed above.
The clamp mechanism 350 includes a body 360, brackets 390a-b, carrier
mechanisms 400a-b, and biasing mechanisms 430a-b. The body 360 has first and
second sides 362 and 364 and has first and second ends 366 and 368. The clamp
mechanism 350 is approximately 27.875-inches from end 366 to end 368. As best
shown in the end cross-section of Figure 13A, the second side 364 defines a
radius
28
CA 02444443 2003-10-06
substantially equivalent to the radius of the intended production tubing 14.
In the
present example, the production tubing 14 has a diameter of approximately 4-
inches.
Therefore, the second side 364 defines a radius of about 2-inches. The second
side
364, however, can be modified to fit tubing of other diameters. The snug
contact
between the second side 364 and the tubing 14 cari be advantageous in
preventing
damage to the clamp mechanism 350 during deployment and retrieval.
The body 360 is attached to adjacent the production tubing 14 with the
attachment devices 370a-b. The attachment devices 370a-b are clamp rings
encompassing the body 360 and the tubing 14. The clamp rings 370a-b can
include a
hinge (not shown) allowing them to be positioned around the body 360 and the
tubing
14. The clamp rings 370a-b can then be welded closed about the body 360 and
tubing
14. The clamp rings 370a-b are robust and protect a major portion of the clamp
mechanism 350, yet still allow for a substantially open cross-section for the
passage of
well fluid past the clamp mechanism 350. In addition to using the attachment
devices
370a-b to attach the clamp mechanism 350 to the tubing 14, the body 360 can be
held
by support rods (not shown) and anchor clamps (not shown), such as described
above.
As another robust feature, a plurality of steel ribs 372, 374, and 376 are
interconnected between the clamp rings 370a-b. The ends of the ribs 372, 374,
and 376
are preferably welded to the clamp rings 370a-b, which are also made of steel.
The use
of the ribs 372, 374, and 376 provides protection to the clamp mechanism 350
as it is
deployed and retrieved from the well. Moreover, the ribs 372, 374, and 376
provide an
open cross-section to allow well fluid to flow past the clamp mechanism 350.
As best shown in the end section of Figure 13B, the ribs 372, 374, and 376
extend different distances from the clamp rings 370a-b, The distances define a
substantially concentric diameter with respect to the diameter of the tubing
14. In the
present embodiment, all of the ribs 372, 374, and 376 extend approximately
4.198-
inches from the central axis C of the tubing 14. From the cover 450 to the
third rib 376,
the clamp mechanism 350 thus measures approxirnately 8.396-inches. With these
dimensions, the clamp mechanism 350 is capable of fitting in the annulus
formed
between the 4-inch production tubing 14 positioned inside an approximately 8.5-
inch
29
CA 02444443 2003-10-06
inner-diameter casing. The contact points P1_3 extend approximately 0.396-
inches
beyond the cover 450 when released as shown. Thus, the maximum lateral
dimension
from the contact points P1_3 to the rib 376 is approximately 8.792-inches. One
of
ordinary skill in the art will appreciate that the dimensions provided above
are only
exemplary and can be changed depending on the size of casing and tubing for
the
intended application of the present invention.
As best shown in Figure 12, a channel 380 is defined in the first side 362 of
the
body 360 from the first end 366 to the second end 368. The channel 380 is used
to
house a multiple component sensor mechanism (not shown), such as that
described
above. The channel 380 includes end recesses 382a-b, intermediate recesses
384a-b,
and a central recess 386. The end recesses 382a-b respectively communicate
with the
ends 366 and 368 of the body 360 and house the splice cornponents (not shown).
The
intermediate recesses 384a-b respectively communicate the end recesses 382a-b
with
the central recess 386. The intermediate recesses 384a-b house the carrier
mechanisms 400a-b and the biasing mechanisms 430a-b. The central recess 386
houses the sensor component (not shown), which is held by the carrier
mechanisms
400a-b. The intra-station cables (not shown) of the sensor mechanism are
housed
between the end recesses 382a-b and the intermediate recesses 384a-b.
For added protection to internal components, a cover 450 is positioned over
the
intermediate recesses 384a-b and the central recess 386. The cover 450
protects the
carrier mechanisms 400a-b and components of the sensor mechanism, such as the
intra-station cables (not shown) and the sensor component (not shown). As best
shown
in the end cross-section of Figure 13D, the cover 450 is attached to the body
360 using
a plurality of fasteners (not shown). The fasteners insert into holes 367 in
the second
side 364 of the body and attach to threaded holes 457 in the cover 450. The
fasteners
are preferably not exposed outside of the cover 450, vvhich reduces the
potential of the
fasteners being damaged.
As best shown in Figure 11, the cover 450 defines holes 454 through which the
three contact points P1_3 extend for potential contact with the casing of the
well. The
cover 450 preferably defines a plurality of slots 452 to allow well fluid to
flow through
CA 02444443 2003-10-06
the cover 450, which can reduce the potential of clogging problems. The cover
450 also
preferably has angled surfaces, which can reduce the potential of jamming
within the
casing when deployed.
As opposed to the numerous mounting rriembers used in the previous
embodiment, the clamp mechanism 350 of the present embodiment uses elongated
mounting members 390a-b to firmly hold the splice components within the end
recesses 382a-b. The elongated mounting members 390a-b substantially encompass
the length of the components and provide protection to them. As best shown in
the end
section of Figures 13-A, the mounting member 390a defines a cylindrical
surface 392 to
match the cylindrical housings of the splice component. Fasteners (not shown)
are
used to hold the mounting member 390a to the body 360. The fasteners mount
into
fastener holes 365 in the second side 364 of the body 360 and attach to the
mounting
member 390a. The other mounting member 390b for the other splice component is
substantially the same. Four fasteners are used for each mounting member 390a-
b.
Mounting the fasteners from the second side 364 prevents them from becoming
loose
in the annulus of the well if any damage to the clamp mechanism 350 occurs.
As best shown in Figure 12, the carrier mechanisms 400a-b are positioned in
the
intermediate recesses 384a-b respectively and are used to hold ends of the
sensor
component (not shown). The carrier mechanisms 400a-b include supports 410a-b
and
brackets 420a-b. The ends of the sensor component are respectively positioned
between the supports 410a-b and brackets 420a-b, as in the embodiment
disclosed
above. The supports 410a-b and brackets 420a-b define cylindrical surfaces to
match
the cylindrical housing of the sensor component. For example, the support 410a
and
bracket 420a in Figure 13C define an opening 412 to rnatch the circular cross
section of
the sensor component described above.
As best shown in Figure 13D, two fasteners (not shown for clarity) are used to
connect the support 410a to the bracket 420a. The fasteners mount into holes
416 in
the bottom of the support 410a and through aligned holes in the bracket 420a.
The
ends of these two fasteners thread into the contact portions Pi and P3
disposed in the
bracket 420a. The biasing mechanism 430a is disposed in the recess 384a and
31
CA 02444443 2003-10-06
engages the support 410a. The support 410a is locked ir, position with the
release
mechanism (not shown), as described in more detail below.
As best shown in Figure 13C, the support 41 0a defines a guide hole 442a. A
guide pin 444a is connected to the body 360 in the intermediate recess 384a
and is
disposed in the guide hole 442a. The guide pin 444a extends substantially
perpendicular to the axial dimension of the body 360. The guide hole 442a has
a larger
dimension than the guide pin 444a, allowing the supports 410a to move on the
pin
444a. The guide pin 444a has a stop on its distal end for engaging a shoulder
of the
guide hole 442a to limit movement of the support 410a in the recess 384a.
An elastomeric element 446a, such as an 0-ring, is disposed on the end of the
guide pin 444a. The 0-ring 446a engages the inner surface of the hole 442a to
acoustically decoupie the support 410a from the guide pin 444a and the body
360, as in
the embodiment disclosed above. The guide pin 444a extends into the
intermediate
recesses 3 84a-b a distance at least equivalent to the amount of required
movement of
the contact points P1_3 to couple with the casing of the well. The guide pin
444a includes
a shoulder on its distal ends to keep the supports 410a from coming out of the
intermediate channels 384a during retrieval of the clamp mechanism 350. The
guide
pin 444a allows the carrier mechanisms 400a to move approximately 10 to 15-mm.
The other support 410b defines a similar guide hole having a similar guide pin
disposed therein, but is positioned on the other side of the central axis C.
Consequently, the carrier mechanisms 400a-b and pins 444a-b can accommodate
variations in tolerances, elongation, and angular orientation of the sensor
component
mounted therein.
As in the first embodiment, the biasing mechanisms 430a-b are preferably
springs disposed between the intermediate recesses 384a-b and the supports
420a-b.
As earlier, two adjacent springs 430a-b are used for each carrier mechanism
400a-b,
which are disposed in partia0 bores (not shown) formed in the bottom of the
supports
420a-b. The biasing members 430a-b push the carrier mechanisms 400a-b with
attached sensor component away from the body 360 towards the casing when the
release mechanism is activated.
32
CA 02444443 2003-10-06
The first carrier 400a includes two contact points P1 and P2. As best shown in
Figure 13D, the contact points P, and P2 are positioned on either side of the
cylindrical
opening defined between the support 410a and the bracket 420a. The contact
points P,
and P2 are disposed in holes in the bracket 420a. Fasteners (not shown) are
used to
hold the contact points P1 and P2 from underneath the points so as not to be
damaged.
Ends of the contact points P, and P2 are capable of disposing through the
openings 454
defined in the cover 450 for coupling with the casing of the well. The second
carrier
mechanism 400b includes one contact point P3, which is substantially aligned
with the
central axis C of the clamp mechanism 350 and tubing 14. As best shown in
Figure 12,
the single contact point P3 is fastened to the second bracket 420b with a
fastener (not
shown) from underneath.
Referring to Figures 14A-B, a detailed cross-section of a portion of the clamp
mechanism 350 of Figure 11 along viewing line 14-14 is illustrated. The clamp
mechanism 350 includes a release mechanism 460. In Figure 14A, the release
mechanism 460 is shown installed in the cover 450 and holding the carrier
mechanism
410a adjacent the body 60. Thus, the contact point P2 is positioned
substantially within
and protected by the cover 450. This position is suitable for deployment of
the clamp
mechanism in a well so that the contact point P2 will not be damaged.
The release mechanism 460 is preferably a fastener, bolt, screw, or other like
mechanism. The release mechanism 460 has a threaded portion 462 and a head
portion 464. The threaded portion 462 is threaded through a threaded aperture
or hole
466 in the cover 450.
The release mechanism 460 is entirely or partially composed of a dissolvable
or
biodegradable polymer, such as thermoplastic polyvinyl alcohol (PVA) or
polyvinyl
acetate (PVAc) having a combination of additives. For example, Millennium
Plastics
Corporation produces dissolvable polymers using a technology described in U.S.
Patent No. 5,948,848. The technology is based on a method of manufacturing
thermoplastic polyvinyl alcohol (PVA) in combination with other approved food-
grade
additives commonly used in commercial and consumer plastic products.
Ordinarily,
PVA rapidly degrades in contact with water or moisture making it not very
useful for
33
CA 02444443 2003-10-06
typical industrial applications. However, PVA or similar polyrners can be made
that are
impervious to liquid dissolution for a desired amount of time. By using
different
combinations and ratios of the basic constituent ingredients, the firmness and
solubility
of the resulting polymer can be tailored to a particular application.
The polymer used with the release mechanism 460 is formulated to degrade in
the conditions of the well within a predetermined arnount of time. For
example, the
polymer may be designed to dissolve in a matter of hours or days of exposure
to the
well fluid. When the clamp mechanism 350 is assernbied, the intact fastener
460 is
threaded into the aperture 466 in the cover 450 to hold the carrier mechanism
400a
adjacent the body 360. A similar fastener is used for the other carrier
mechanism (not
shown) on the other end of the sensor mechanism (not shown). However, it is
understood that a single dissolvable fastener 460 can be centrally threaded in
the cover
450 and engage the midpoint of the sensor comporient, or that multiple
dissolvable
fasteners could be used.
When the clamp mechanism 350 is deployed in the well, the dissolvable fastener
460 remains intact until a predetermined amount of exposure to the well
conditions has
occurred. In Figure 14B, the release mechanism 460 has dissolved completely or
has
dissolved enough to be forced loose from the aperture 462. Consequently, the
compression springs 430a extend and push the carrier mechanism 400a towards
the
cover 450, and the contact point P2 extends beyorid the hole 454 for
acoustically
coupling with the casing of the well.
It is understood that the head portion 464 outside the cover 450 preferably
has a
small profile to reduce the chance of being damaged. It will also be
appreciated that the
release mechanism 460 need not be entirely composed of dissolvable polymer to
affect
release. However, the release mechanism 460 is preferably completely
dissolvable so
that components of the release mechanism 460 are not left loose in the annulus
of the
well or within the clamp mechanism 350 after release.
The release mechanism 460 need not be a fastener threaded in the cover 450.
Referring to Figures 15A- , various embodiments of release mechanisms 460,
470,
480, and 490 composed of dissolvable polymer are schematically illustrated. In
Figure
34
CA 02444443 2003-10-06
15A, the release mechanism 460 is a dissolvable fastener positioned in a bore
467 in a
support 420 of a carrier mechanism 400. The dissolvable fastener 460 is
threaded into
a threaded hole 468 in the body 360. Once the fastener 460 dissolves in the
well fluid,
the biasing mechanism 430 can move the carrier mechanism 400 away from the
body.
A substantially similar arrangement can be usedl for both carrier mechanisms
connected to the ends of the sensor component. The reverse arrangement can be
used, as well. For example, the dissolvable fastener 460 can be inserted from
the
bottom of the body through a hole 468 and can be threaded into the hole 467 in
the
support 420.
In Figure 15B, the release mechanism 470 is a pin or plate composed of
dissolvable polymer installed between the body 360 and the carrier mechanism
400 to
hold the carrier mechanism 400 adjacent the body 360. One end of the pin 470
is
inserted in an opening 472 in the body 360, and the other end is inserted in
to a slot
474 in the support 420. To assemble, the support 420 is positioned adjacent
the body
360. The pin 470 is positioned in the opening 472 and slot 474. The carrier
bracket 410
is then attached to the support 420 to hold the sensor component (not shown).
The pin
470 prevents the carrier mechanism 400 from being rnoved by the biasing
mechanism
430 until dissolved.
In Figure 15C, the release mechanism 480 is a band or strip of dissolvable
polymer attached to the body 360. Ends 482 and 484 of the band 480 are
attached to
the body 360, and the band 480 extends over the carrier mechanism 400 and
holds it
adjacent the body 360. The band 480 prevents the carrier mechanism 400 from
being
moved by the biasing mechanism 430 until dissolved.
In Figure 15D, the release mechanism 490 is a cap composed of dissolvable
polymer. The cap 490 is positioned between the contact point P and the hole
452 in the
cover 450. The cap 490 prevents the contact point P from extending beyond the
cover
450 until dissolved. The cap 490 could be threaded and screwed on to the cover
450,
as well.
It is understood that the dissolvable release mechanisms 460, 470, 480, and
490
according to the present invention preferably do not significantly interfere
with the
CA 02444443 2003-10-06
release of the carrier mechanism 400 and sensor cornponent once partially
dissolved.
However, attention should be paid to the location and size of the dissolvable
release
mechanism 460, 470, 480, and 490 relative to moving components. With the
benefit of
the above embodiments and the present disclosure, it will be appreciated that
a release
mechanism composed of dissolvable polymer can include a number of structures
and
can be positioned in a number of locations to temporarily hold the carrier
mechanisms
adjacent the body. As such, one of ordinary skill in the art will appreciate
that a
dissolvable release mechanism according to the present invention is not
strictly limited
to the explicit embodiments illustrated herein.
As used herein, "sensor system" denotes both a plurality of sensors or an
individual sensor.
It is intended that the invention include all modifications and alterations to
the full
extent that such modifications and alterations come within the scope of the
following
claims or the equivalents thereof.
36
