U.S. patent application number 14/032905 was filed with the patent office on 2014-03-27 for reliability for electromagnetic data telemetry for downhole application on well drilling operations.
This patent application is currently assigned to Nabors International, Inc.. The applicant listed for this patent is Nabors International, Inc.. Invention is credited to Vadim Minosyan, Matthew White.
Application Number | 20140083773 14/032905 |
Document ID | / |
Family ID | 50337788 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140083773 |
Kind Code |
A1 |
Minosyan; Vadim ; et
al. |
March 27, 2014 |
Reliability for Electromagnetic Data Telemetry for Downhole
Application on Well Drilling Operations
Abstract
A tool and associated methods for transmitting electromagnetic
data telemetry from a downhole sensor during drilling operations.
The tool may include a pressure housing, the pressure housing
including an EM transmitter, receiver, or transceiver. A conductive
element electrically coupled to the EM transmitter, receiver, or
transceiver is positioned between an upper and a lower signal
conductor positioned coaxially around the conductive element. The
upper and lower signal conductors support the pressure housing and
conductive element within the inner diameter of a drill collar and
provide electrical connection between the conductive element and a
section of the drill collar on either side of an insulated gap. In
some embodiments, the conductive element is tensioned between the
upper and lower signal conductors.
Inventors: |
Minosyan; Vadim; (Conroe,
TX) ; White; Matthew; (Spring, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nabors International, Inc. |
Houston |
TX |
US |
|
|
Assignee: |
Nabors International, Inc.
Houston
TX
|
Family ID: |
50337788 |
Appl. No.: |
14/032905 |
Filed: |
September 20, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61706030 |
Sep 26, 2012 |
|
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|
Current U.S.
Class: |
175/40 |
Current CPC
Class: |
E21B 47/13 20200501;
E21B 47/00 20130101 |
Class at
Publication: |
175/40 |
International
Class: |
E21B 47/00 20060101
E21B047/00 |
Claims
1. A tool for transmitting electromagnetic data telemetry from a
downhole sensor during drilling operations comprising; a pressure
housing, the pressure housing including an EM transmitter,
receiver, or transceiver; a conductive element electrically coupled
to the EM transmitter, receiver, or transceiver; a lower signal
conductor positioned coaxially around the conductive element, the
lower signal conductor supporting the pressure housing and
conductive element within the inner diameter of a drill collar and
providing electrical connection between the conductive element and
a section of the drill collar on one side of an insulated gap; and
an upper signal conductor positioned coaxially around the
conductive element, the upper conductor supporting the conductive
element within the inner diameter of the drill collar and providing
electrical connection between the conductive element and a section
of the drill collar on the other side of the insulated gap.
2. The tool of claim 1 wherein the conductive element is surrounded
by one or more nonconductive sleeves.
3. The tool of claim 1 wherein the conductive element is supported
along its length by one or more centralizers.
4. The tool of claim 3 wherein the centralizers are formed from a
rigid material.
5. The tool of claim 3, wherein the conductive element is supported
every 18 inches along its length.
6. The tool of claim 2 wherein the non-conductive sleeve is sealed
at the ends against the conductive element to prevent contaminants
entering between the sleeve and the conductive element.
7. The tool of claim 3 wherein the centralizer is sealed at the
ends against the conductive element to prevent contaminants
entering between the centralizer and the conductive element.
8. The tool of claim 1 wherein the upper and lower conductors are
rigid cylindrical conductors with a plurality of through openings
allowing fluid passage through the drill collar around the
transmission assembly.
9. The tool of claim 1 wherein the length of the conductive element
is less than 36 inches in length.
10. The tool of claim 1 wherein the upper and lower conductors are
fixed at specific distances within the drill collar, and at least a
portion of the conductive element is tensioned between the upper
and lower signal conductors within the drill collar.
11. The tool of claim 2 wherein the upper and lower conductors are
fixed at specific distances within the drill collar, and a portion
of the nonconductive sleeve is compressed between the upper and
lower conductors within the drill collar.
12. The tool of claim 10, wherein the upper signal conductor and
lower signal conductor comprise upper and lower hangers positioned
to transfer tension from the conductive element into the drill
collar.
13. The tool of claim 10, wherein the upper and lower signal
conductors further comprise toroidal contact springs to
electrically couple the transmission assembly and the drill
collar.
14. The tool of claim 1 wherein the electrical connections between
the signal conductors and the drill collar comprise one or more
toroidal springs seated around the outer diameter of the signal
conductor and compressed against the inner diameter of the drill
collar.
15. The tool of claim 14 wherein the signal conductor further
comprises one or more seals seated around the outer diameter of the
signal conductor and compressed against the inner diameter of the
drill collar, said seals positioned nearer the end of the signal
conductor than the toroidal springs.
16. A tool for transmitting electromagnetic data telemetry from a
downhole sensor during drilling operations comprising; a drill
collar, the drill collar including a first and second tubular, the
first and second tubulars formed from an electrically conductive
material and coupled by an insulated gap; a pressure housing, the
pressure housing including an EM transmitter, receiver, or
transceiver; a conductive element electrically coupled to the EM
transmitter, receiver, or transceiver; a lower hanger rigidly
coupled to the first tubular, the lower hanger positioned coaxially
around the conductive element, the lower hanger supporting the
pressure housing and conductive element within the inner diameter
of the first tubular and providing electrical connection between
the conductive element and the first tubular; and an upper hanger
rigidly coupled to the second tubular, the upper hanger positioned
coaxially around the conductive element, the upper hanger
supporting the conductive element within the inner diameter of the
second tubular and providing electrical connection between the
conductive element and the second tubular.
17. The tool of claim 16, wherein the conductive element is
tensioned between the upper and lower hangers.
18. The tool of claim 17, further comprising an insulating sheath
positioned around the conductive element, the insulating sheath
extending between the upper and lower hanger so that the upper and
lower hanger exert a compressive force on the insulating sheath as
the conductive element is tensioned.
19. The tool of claim 16, wherein the upper and lower hangers
further comprise toroidal contact springs to electrically couple
the transmission assembly and the drill collar.
20. The tool of claim 16 wherein the conductive element is
supported along its length by one or more centralizers.
21. The tool of claim 20 wherein the centralizers are formed from a
rigid material.
22. The tool of claim 20 wherein the centralizer is sealed at the
ends against the conductive element to prevent contaminants
entering between the centralizer and the conductive element.
23. The tool of claim 18, wherein the insulating sheath is sealed
at the ends against the conductive element to prevent contaminants
entering between the sheath and the conductive element.
24. The tool of claim 16 wherein the upper and lower hangers
include a plurality of through openings allowing fluid passage
through the drill collar around conductive element.
25. A tool for transmitting electromagnetic data telemetry from a
downhole sensor during drilling operations comprising; a drill
collar, the drill collar including a first and second tubular, the
first and second tubulars formed from an electrically conductive
material and coupled by an insulated gap; a pressure housing, the
pressure housing including an EM transmitter, receiver, or
transceiver; a conductive element electrically coupled to the EM
transmitter, receiver, or transceiver; a lower hanger rigidly
coupled to the first tubular, the lower hanger positioned coaxially
around the conductive element, the lower hanger supporting the
pressure housing and conductive element within the inner diameter
of the first tubular and providing electrical connection between
the conductive element and the first tubular; and an upper signal
conductor, the upper signal conductor positioned coaxially around
the conductive element, the upper signal conductor providing
electrical connection between the conductive element and the second
tubular.
26. The tool of claim 25, further comprising an insulating sheath
positioned around the conductive element, the insulating sheath
extending between the upper signal conductor and the lower hanger,
the insulating sheath being under compressive load between the
upper signal conductor and the lower hanger so that the conductive
element is under tension.
27. The tool of claim 25, wherein the lower hanger further
comprises a toroidal contact spring to electrically couple the
transmission assembly and the drill collar.
28. The tool of claim 25 wherein the conductive element is
supported along its length by one or more centralizers.
29. The tool of claim 28 wherein the centralizers are formed from a
rigid material.
30. The tool of claim 28 wherein the centralizer is sealed at the
ends against the conductive element to prevent contaminants
entering between the centralizer and the conductive element.
31. The tool of claim 25, wherein the insulating sheath is sealed
at the ends against the conductive element to prevent contaminants
entering between the sheath and the conductive element.
32. The tool of claim 25, wherein the upper signal conductor
comprises at least one of a bow spring, wire, or bolt.
33. A method for providing improved reliability of electromagnetic
(EM) data telemetry to the well site surface from downhole EM
sensors in a tool assembly during drilling of a well, the method
comprising: providing a pressure housing, the pressure housing
including an EM transmitter, receiver, or transceiver; electrically
coupling a conductive element to the EM transmitter, receiver, or
transceiver; tensioning the conductive element between an upper
hanger and a lower hanger, the upper hanger and lower hanger
positioned within a drill collar, the drill collar including a
first and second conductive tubular, the tubulars separated by an
insulating gap.
34. The method of claim 33, further comprising: selecting the
diameter, length, and tension of the conductive element so that the
resonant frequency is increased.
35. The method of claim 33, wherein the upper and lower signal
conductors further comprise toroidal contact springs to
electrically couple the transmission assembly and the drill
collar.
36. The method of claim 33, wherein the tool is assembled prior to
delivery to the rig floor at the well site.
37. The method of claim 33, wherein the tool is shipped to the well
site in a substantially assembled configuration.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority from provisional
U.S. Patent Application Ser. No. 61/706,030, filed Sep. 26,
2012.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to the collection of data
from sensors within a drill collar as part of a bottom hole
assembly near the lower ends of a drill pipe stand while said pipe
is in use in a downhole environment.
BACKGROUND
[0003] Downhole logging aids in determine the structural, physical
and chemical properties of a formation being penetrated. Data is
collected in the borehole. Traditionally Logging While Drilling
(LWD) operations were recorded for later analysis while Measurement
While Drilling (MWD) operations were transmitted to the surface to
provide more immediate feedback. In many operations today the
difference between the two has blurred, with tools which commonly
log and transmit data to allow immediate feedback and still avoid
data loss. For purposes of this discussion, the term MWD will be
utilized and should be interpreted to indicate: MWD, LWD, and/or
MWD+LWD.
[0004] Methods of transmission known to those skilled in the arts,
may include but are not limited to: wireline transmission,
modulated pressure waves/mud pulsing, and electromagnetic (EM)
signal, wired drill pipe (i.e. intellipipe). Methods for
transmitting data to the surface depend on the formation and
drilling techniques utilized in a specific situation. For example,
if compressible fluids are used for drilling, mud pulse telemetry
data is lost in deeper wells. EM MWD technology may utilize earth
formation as the medium to propagate a communications signal for
the bottom of a wellbore to the surface. EM MWD may allow large
quantities of real time data about a wellbore to be gathered during
drilling operations. EM may be useful in environments where
substantially incompressible drilling mud cannot be utilized for
various reasons, which prevents to use of mud pulse telemetry as a
data propagation medium.
[0005] Reliability of an EM MWD tool and specifically the
communications system to the surface may be a significant factor in
the effectiveness of the tool. A major application of EM MWD
technology may involve wells where it is not possible to use liquid
(termed drilling fluid or "mud") to flush cuttings to surface. In
such environments compressed gas or foam is used in place of the
mud. EM MWD may be useful in such situations due to the absence of
mud as a transition medium to the surface for data. However,
drilling mud may provide a significant dampening of shock and
vibration in traditional well operations. Drilling without mud
causes the levels of shock and vibration in the BHA to be
significantly higher.
[0006] Typically EM systems may be considered to be more reliable
and faster than mud pulse telemetry for transmission of down-hole
data to surface, assuming the formations outside the wellbore are
suitable for EM transmission. However, in rough drilling conditions
where high levels of shock and vibration are present, standard
narrow probe systems with rubber centralizers or metal spring
loaded centralizers are inadequate to maintain the required
reliability of the down-hole tool and communications channel for
the length of the operation.
SUMMARY
[0007] This disclosure provides for a tool for transmitting
electromagnetic data telemetry from a downhole sensor during
drilling operations. The tool may include a pressure housing, the
pressure housing including an EM transmitter, receiver, or
transceiver; a conductive element electrically coupled to the EM
transmitter, receiver, or transceiver; a lower signal conductor
positioned coaxially around the conductive element, the lower
signal conductor supporting the pressure housing and conductive
element within the inner diameter of a drill collar and providing
electrical connection between the conductive element and a section
of the drill collar on one side of an insulated gap; and an upper
signal conductor positioned coaxially around the conductive
element, the upper conductor supporting the conductive element
within the inner diameter of the drill collar and providing
electrical connection between the conductive element and a section
of the drill collar on the other side of the insulated gap.
[0008] This disclosure also provides for a tool for transmitting
electromagnetic data telemetry from a downhole sensor during
drilling operations. The tool may include a drill collar, the drill
collar including a first and second tubular, the first and second
tubulars formed from an electrically conductive material and
coupled by an insulated gap; a pressure housing, the pressure
housing including an EM transmitter, receiver, or transceiver; a
conductive element electrically coupled to the EM transmitter,
receiver, or transceiver; a lower hanger rigidly coupled to the
first tubular, the lower hanger positioned coaxially around the
conductive element, the lower hanger supporting the pressure
housing and conductive element within the inner diameter of the
first tubular and providing electrical connection between the
conductive element and the first tubular; and an upper hanger
rigidly coupled to the second tubular, the upper hanger positioned
coaxially around the conductive element, the upper hanger
supporting the conductive element within the inner diameter of the
second tubular and providing electrical connection between the
conductive element and the second tubular.
[0009] This disclosure also provides for a tool for transmitting
electromagnetic data telemetry from a downhole sensor during
drilling operations. The tool may include a drill collar, the drill
collar including a first and second tubular, the first and second
tubulars formed from an electrically conductive material and
coupled by an insulated gap; a pressure housing, the pressure
housing including an EM transmitter, receiver, or transceiver; a
conductive element electrically coupled to the EM transmitter,
receiver, or transceiver; a lower hanger rigidly coupled to the
first tubular, the lower hanger positioned coaxially around the
conductive element, the lower hanger supporting the pressure
housing and conductive element within the inner diameter of the
first tubular and providing electrical connection between the
conductive element and the first tubular; and an upper signal
conductor, the upper signal conductor positioned coaxially around
the conductive element, the upper signal conductor providing
electrical connection between the conductive element and the second
tubular.
[0010] This disclosure also provides for a method for providing
improved reliability of electromagnetic (EM) data telemetry to the
well site surface from downhole EM sensors in a tool assembly
during drilling of a well. The method may include providing a
pressure housing, the pressure housing including an EM transmitter,
receiver, or transceiver; electrically coupling a conductive
element to the EM transmitter, receiver, or transceiver; and
tensioning the conductive element between an upper hanger and a
lower hanger, the upper hanger and lower hanger positioned within a
drill collar, the drill collar including a first and second
conductive tubular, the tubulars separated by an insulating
gap.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present disclosure is best understood from the following
detailed description when read with the accompanying figures. It is
emphasized that, in accordance with the standard practice in the
industry, various features are not drawn to scale. In fact, the
dimensions of the various features may be arbitrarily increased or
reduced for clarity of discussion.
[0012] FIGS. 1A-1C are partial cross sections of an EM MWD/LWD
system consistent with at least one embodiment of the present
disclosure.
[0013] FIG. 2 is a partial cross section of the EM MWD/LWD system
of FIG. 1
[0014] FIG. 3 is a continuation of the partial cross section of
FIG. 2.
[0015] FIG. 4 is a continuation of the partial cross section of
FIG. 3.
[0016] FIG. 5 is a continuation of the partial cross section of
FIG. 4.
[0017] FIG. 6 is a continuation of the partial cross section of
FIG. 5.
[0018] FIG. 7 is a continuation of the partial cross section of
FIG. 6.
DETAILED DESCRIPTION
[0019] It is to be understood that the following disclosure
provides many different embodiments, or examples, for implementing
different features of various embodiments. Specific examples of
components and arrangements are described below to simplify the
present disclosure. These are, of course, merely examples and are
not intended to be limiting. In addition, the present disclosure
may repeat reference numerals and/or letters in the various
examples. This repetition is for the purpose of simplicity and
clarity and does not in itself dictate a relationship between the
various embodiments and/or configurations discussed.
[0020] Disclosed herein is a configuration of an EM MWD/LWD system
which may improve communication reliability through more secure
contact between the probe and the drill collar. Further, the
configuration may improve reliability by increasing shock and
vibration tolerance, and increasing electrical isolation between
upper and lower units to avoid signal shorting and attenuation
found in earlier derivations. Additionally, the disclosed
configuration may be optimized for shipping and movement between a
rig site and off-site maintenance and repair facilities to minimize
rig downtime and allow for service and maintenance in more optimal
and controlled conditions. The configuration may be utilized with
multiple fluid drilling configurations, including but not limited
to mud, air, and foam drilling.
[0021] In one embodiment, the MWD tool assembly is kept to the
minimum length possible. The MWD tool has multiple positive
electrical contacts both above and below the electrical isolation
in a Gap Sub via electrical conduction springs and solid metal
centralizers which may also may be further sealed against drilling
fluid flow by O-rings between the solid metal centralizers and the
inside diameter (ID) of the drill collar. Openings through the
metal centralizers allow fluid to flow past connection points
without interfering with the electrical connection. Additionally,
the MWD tool involves placing the components in either tension or
compression to help ensure the system is rigid and resistant to
movement during shock and vibration of the BHA with respect to the
EM tool assembly. By adjusting the tension of the system, the
natural frequency of the EM tool assembly can be adjusted to avoid
common frequencies and harmonics found in drilling operations.
[0022] FIGS. 1A-1C depict an EM MWD system 101 consistent with at
least one embodiment of the present disclosure installed in a
collar assembly 102. Here, collar assembly 102 is depicted as a
four collar set including an upper hanger collar 103, gap sub 105
(also called the upper to lower isolation), sensor collar 107, and
lower sub 109 (also called orientation collar). In at least one
embodiment, all electronics of MWD tool 101 and specifically the EM
Transmitter are installed in a pressure housing 113. In some
embodiments, pressure housing 113 may be approximately 31/4'' in
diameter, and approximately 5.4 feet in length. One having ordinary
skill in the art with the benefit of this disclosure will
understand that differing diameters and lengths may be utilized
depending on the size, shape, and configuration of the EM
transmitter. Although discussed herein as a transmitter, one having
ordinary skill in the art with the benefit of this disclosure will
understand that EM MWD system 101 could likewise be used to receive
signals from the surface within the scope of this disclosure.
[0023] By selecting the OD and length of pressure housing 113,
pressure housing 113 may be of a sufficient stiffness to counteract
the potential of pressure housing 113 contacting the wall of sensor
collar 107 during a mechanical shock event. Additionally, higher
stiffness may also increase the resonant frequency of EM MWD system
101. When the resonant frequency is increased, the chances of
causing EM MWD system 101 to oscillate at its natural frequency may
be reduced, and the potential for extremely high levels of
vibration may be lowered.
[0024] Pressure housing 113 is sealed both above and below the
electronics with end caps (coil housing 115, tail 117) as shown in
FIGS. 6 and 7 respectively. Tail 117 may include a flow diverter
119 to re-direct the drilling fluid from between pressure housing
113 and the ID of Sensor Collar 107 to the ID of lower sub 109.
Tail 117 may also include a lower signal conductor 121 coupled to
lower sub 109. FIG. 7 depicts lower signal conductor 121 as an
external tapered thread for interfacing with an internal tapered
thread of lower sub 109. This connection constitutes one of two
potential locations EM MWD system 101 is electrically connected to
collar assembly 102 wall below gap sub 105 and the rest of the BHA
(not shown) through this metal to metal mounting. Tail 117 may
include rubber spacers 123 between the ID of sensor collar 107 and
the OD of tail 117 to, for example, buffer EM MWD system 101
against shock.
[0025] Pressure housing 113, as depicted in FIGS. 5, 6, also
includes coil housing 115. Coil housing 115 may in some embodiments
include a transformer coil (not shown) positioned between the
transmitter of EM MWD system 101 and conductive element 139. Coil
housing 115 may be connected to lower hanger 125. Lower hanger 125
may have an OD just under the ID of sensor collar 107. Lower hanger
125 and coil housing 115 are conductive and may be utilized to
transfer an electrical signal from EM MWD system 101 to a second
point on collar assembly 102. Lower hanger 125 may include seals
127, 129 between the OD of lower hanger 125 and the ID of sensor
collar 107 to form a sealed portion 131 from drilling fluid present
in collar assembly 102. Seals 127, 129 are depicted in FIG. 5 as 0
rings, but one having ordinary skill in the art with the benefit of
this disclosure will understand that any suitable seal may be
utilized within the scope of this disclosure.
[0026] In sealed portion 131, at least one toroidal contact spring
133 electrically couples the body of lower hanger 125 and sensor
collar 107 in the absence of drilling fluid, foam, gas, or other
invasive medium. In some embodiments, two such toroidal contact
springs 133 are utilized, but one skilled in the art would
appreciate that other numbers of contact springs may be utilized. A
plurality of contact springs 133 may decrease the chance of contact
loss. One skilled in the art would appreciate additional materials
may be utilized to establish reliable electrical contact in the
space between lower hanger 125 and sensor collar 107. For example,
when a nonconductive fluid is utilized, fluid, or nonconductive
contaminants could lodge between a conducting member and the collar
wall in the absence of seals 127, 129, causing an electrical
disconnection.
[0027] Lower hanger 125 may thus serve as a contact from EM MWD
system 101 to the collars below gap sub 105. Isolating toroidal
contact springs 133 from fluid invasion may help ensure the
designed contact point stays consistent in electrical conductivity
throughout the operation of EM MWD system 101 regardless of the
drilling fluid utilized. Lower hanger 125 may also serve as a
centralizer and support point for pressure housing 113. Sensor
collar 107 is installed around lower hanger 125. Sensor collar 107
may be threaded onto lower sub 109 at the same location the tapered
thread on tail 117 mates to lower sub 109 from the ID.
[0028] Coupling EM MWD system 101 to the collars below gap sub 105
at both lower hanger 125 and tail 117 may increase resilience of
the electrical connection by providing two paths to make electrical
contact. This redundancy may reduce the possibility of losing
contact with the wall of the collars below gap sub 105 under severe
shock and vibration.
[0029] Lower hanger 125 is coupled to a probe isolation component
135, which serves to electrically isolate pressure housing 113 and
lower hanger 125 from antenna housing 137 on the other end of probe
isolation component 135 utilizing an internal non-conductive
material.
[0030] A sheathed wire (not shown) is run internally from coil
housing 115 through probe isolation component 135 and connected to
conductive element 139 located within antenna housing 137 (see FIG.
4), allowing the electronics to induce an electrical signal across
probe isolation component 135 and eventually gap sub 105 via upper
hanger 141 shown in FIG. 2. Conductive element 139 includes an
electrical conductor 140 which is surrounded by a non-conductive
sleeve 143. One having ordinary skill in the art with the benefit
of this disclosure will understand that electrical conductor 140
may be any suitable conductive structure, including but not limited
to a wire, rod, cable, etc. In some embodiments, sleeve 143 is
formed from fiberglass. Sleeve 143 prevents conductive fluids from
allowing signal leakage between electrical conductor 140 and collar
assembly 102. Sleeve 143 also eliminates the need to align probe
isolation component 135 with gap sub 105 to avoid shorting or
signal attenuation.
[0031] At one or more locations along sleeve 143, a centralizer 145
is used to support conductive element 139 and help minimize
movement with respect to collar assembly 102. Centralizer 145 may
be constructed from a hard, nonconductive material. In some
embodiments, centralizer 145 is formed from fiberglass. In at least
one embodiment, multiple centralizers 145 are positioned as close
as possible to, for example, prevent vibration of conductive
element 139, and provide adequate support for horizontal
operations. Centralizers 145 may also be spaced enough to eliminate
needless turbulence in the fluid flow which may add to wear on
sleeve 143 and centralizers 145.
[0032] In some embodiments, centralizers 145 could be lengthened to
the point that one or more run the length of conductive element
139, serving the function of both centralizer 145 and sleeve 143.
In such a configuration, care would need to be taken to orient
wings or protrusions 147 on centralizer 145 with respect to an
abutting centralizer to avoid fluid turbulence or blockage.
[0033] In at least one embodiment, both centralizer 145 and sleeve
143 are sealed to solid conductor 140 of conductive element 139
with the use of O-rings or other sealing systems to further prevent
exposure of large areas of conductor 140 to the invasive medium at
high pressure. Ideally spacers and sleeves are also abutted in such
a manner as to create an additional seal between the neighboring
spacers/sleeves.
[0034] By creating a non-conducting sleeve 143 around conductive
element 139, the system can be assembled within varying lengths of
collars without the need to adjust the placement of the probe
isolation components 135. Without non-conducting sleeve 143, if the
probe isolation components 135 are not aligned with gap 149 of gap
sub 105, the annular space between conductive element 139 OD and
collar assembly 102 ID could carry conductive drilling fluid which
could shunt the EM signal across the fluid. Any shunting may, for
example, reduce the effectiveness of the system by applying
additional load to the transmitting system. Furthermore, any signal
shunted across the conductive fluid would not aid in transmitting
the EM signal from down hole to surface.
[0035] In addition, the use of a hard centralizer 145 compared with
current technology's use of rubber or spring loaded metal may
increase the rigidity of conductive element 139 by rigidly coupling
it to the surrounding collar assembly 102. Thus, shock resulting
from hard impacts may be reduced, and vibration may be dampened.
Reduction in shock and vibration to pressure housing 113 and
conductive element 139 may lead to improved reliability.
[0036] Gap Sub 105 is threaded onto sensor collar 107 around
conductive element 139. In some embodiments, compression stack 151
may be positioned within sensor collar 107, such that compression
stack 151 is compressed between the pin of gap sub 105 and the top
of lower hanger 125 as gap sub 105 is screwed into sensor collar
107 (FIG. 5). Compression stack 151 may include a hard rubber body
positioned to, for example, dampen shock and vibration to EM MWD
system 101 while retaining it within sensor collar 107.
[0037] In some embodiments, as depicted in FIG. 2, upper hanger
collar 103 is coupled to gap sub 105. Upper hanger 153 is installed
in upper hanger collar 103, and may be secured in place with hanger
retention nut 155 to the ID of upper hanger collar 103. Upper
hanger 153 has a center hole (not shown) to accommodate conductive
element 139, which may traverse through upper hanger 153.
Conductive element 139 may be secured to upper hanger 153 by
conductive element tensioning nut 157. Conductive element
tensioning nut 157 may serve to tension conductor 140 by pulling it
against lower hanger 125. At the same time, sleeve 143 is put in
compression as it is pinched between upper and lower hangers 131,
153.
[0038] Applying tension on conductor 140 may add to the stiffness
of conductive element 139. Increased tension may also increase the
fundamental harmonic frequency of conductive element 139, thereby
reducing the chance for high levels of vibration caused by
resonance. Compression of sleeve 143 may amplify this effect.
[0039] Upper hanger 153, similarly to lower hanger 125, may also
utilize two seals 159, 161 to seal a section 163 of the OD of upper
hanger 153 from the drilling fluid, or other invasive medium. In
some embodiments, at least one toroidal contact spring 165 is
positioned to electrically couple upper hanger 153 to upper hanger
collar 103. As with lower hanger 125, making electrical contact in
an uncontaminated location ensures continuous conduction across the
contact in the presence of drilling fluid within the collar.
[0040] In at least one embodiment, upper hanger 153 is installed
directly into Gap Sub 105. The length of conductive element 139 may
be less than 36 inches in length. Conductive element 139 may be
supported at the midpoint, whereby conductive element 139 is
supported at approximate 18 inch increments with a hard
non-conductive centralizer 145. The drawings included in this
disclosure illustrate an embodiment which utilizes an upper hanger
collar 103 to allow testing of various gap subs without
modification of the gap sub body itself. One having ordinary skill
in the art with the benefit of this disclosure will understand that
any length conductive element may be substituted without deviating
from the scope of this disclosure, and that stabilizer positioning
may be carried as previously discussed and otherwise.
[0041] In at least one other embodiment, conductive element 139 is
not rigidly coupled to upper hanger collar 103 by an upper hanger.
Instead, conductive element 139 is electrically coupled to upper
hanger collar 103 by a traditional connection such as, for example
and without limitation, a bow spring, wire, or bolt. Conductive
element 139 is thus held rigidly to collar assembly 102 by lower
hanger 125. In certain embodiments, conductive element 139 may be
held in tension by compressing sleeve 143.
[0042] Due to the nature of this assembly, it may be desirable that
EM MWD system 101 be assembled in a shop as opposed to the rig
floor. For example, excessive rig down time may not be required
while the system is installed in the collar on the rig floor, since
EM MWD system 101 may be inserted as a complete unit into the
bottom hole assembly as it is made up on the rig floor.
Additionally, the shop assembly process may be easier to accomplish
with better quality control than is possible using the rig floor
assembly process.
[0043] The diagrams provided are in accordance with exemplary
embodiments of the disclosure, and are provided as examples. They
should not be construed to limit other embodiments within the scope
of the disclosure. For instance, the size of certain sections
should not be taken as absolutes with respect to other elements.
Additional element may be added or subtracted from the
configuration illustrated. Further some elements may vary in count,
orientation, or position within the scope of the disclosure.
Further, plurality of elements rendered as separate elements may be
joined into single elements, and elements illustrated individually
may be divided into a plurality of sub-elements. Further yet,
specific numerical data values (such as specific quantities,
numbers, categories, etc.) or other specific information should be
interpreted as illustrative for discussing exemplary embodiments.
Such specific information is not provided to limit the
disclosure.
[0044] The diagrams in accordance with exemplary embodiments of the
present disclosure are provided as examples and should not be
construed to limit other embodiments within the scope of the
disclosure. For instance, heights, widths, and thicknesses may not
be to scale and should not be construed to limit the disclosure to
the particular proportions illustrated. Additionally some elements
illustrated in the singularity may actually be implemented in a
plurality. Further, some element illustrated in the plurality could
actually vary in count. Further, some elements illustrated in one
form could actually vary in detail. Further yet, specific numerical
data values (such as specific quantities, numbers, categories,
etc.) or other specific information should be interpreted as
illustrative for discussing exemplary embodiments. Such specific
information is not provided to limit the disclosure.
[0045] Multiple figures have been provided for many pieces, the
views, sizes, and angles of the illustrations may vary, such
variance should not be construed in a manner that is would limit
the disclosure. Where multiple views, illustrations, photographs,
renderings, or drawings have been provided of a single piece, any
inconsistencies should be interpreted as different embodiments of
the disclosure.
[0046] The above discussion is meant to be illustrative of the
principles and various embodiments of the present disclosure.
Numerous variations and modifications will become apparent to those
skilled in the art once the above disclosure is fully appreciated.
It is intended that the following claims be interpreted to embrace
all such variations and modifications.
* * * * *