U.S. patent application number 13/035833 was filed with the patent office on 2012-08-30 for inground drill string housing and method for signal coupling.
Invention is credited to Albert W. Chau, Benjamin John Medeiros.
Application Number | 20120218863 13/035833 |
Document ID | / |
Family ID | 46718923 |
Filed Date | 2012-08-30 |
United States Patent
Application |
20120218863 |
Kind Code |
A1 |
Chau; Albert W. ; et
al. |
August 30, 2012 |
INGROUND DRILL STRING HOUSING AND METHOD FOR SIGNAL COUPLING
Abstract
An inground housing is insertable in at least one joint of a
drill string extending from a drill rig. The inground housing
supports an electronics assembly for processing a data signal
relating to the inground operation and a signal coupling
arrangement for transferring the data signal between the
electronics assembly and the drill rig by electromagnetically
coupling the data signal between the signal coupling arrangement
and the drill string such that the data signal is electrically
conducted as an electrical data signal along at least a portion of
the drill string that extends from the inground housing. In another
feature, a current transformer is resiliently supported to isolate
the current transformer from mechanical shock and vibration that is
produced by an inground operation that is performed using the drill
string. In another feature, a drill string repeater is
described.
Inventors: |
Chau; Albert W.;
(Woodinville, WA) ; Medeiros; Benjamin John;
(Orting, WA) |
Family ID: |
46718923 |
Appl. No.: |
13/035833 |
Filed: |
February 25, 2011 |
Current U.S.
Class: |
367/82 |
Current CPC
Class: |
E21B 47/01 20130101;
E21B 47/12 20130101 |
Class at
Publication: |
367/82 |
International
Class: |
E21B 47/16 20060101
E21B047/16 |
Claims
1. In a system in which an inground tool is moved through the
ground in a region for performing an inground operation, said
system including a drill rig and a drill string which extends
between said inground tool and said drill rig and is configured for
extension and retraction from said drill rig, said drill string
being made up of a plurality of electrically conductive drill pipe
sections, each of which includes a section length and each of which
is configured for removable attachment to the inground tool at one
joint and to one another at other joints that are formed between
adjacent ones of the drill pipe sections such that the drill string
includes a plurality of joints to facilitate the extension and
retraction of the drill string by one section length at a time, an
apparatus comprising: an inground housing that is removably
insertable at one of the joints as the drill string is extended to
thereafter form part of the drill string and said inground housing
defines a housing cavity that is configured for receiving an
electronics assembly that processes a data signal relating to the
inground operation; and a signal coupling arrangement supported by
the inground housing and configured at least for electrical
communication with the electronics assembly when received in the
housing cavity and for transferring the data signal between the
electronics assembly in the housing cavity and the drill rig at
least in part by electromagnetically coupling the data signal
between the signal coupling arrangement and the drill string such
that the data signal is electrically conducted as an electrical
data signal along at least a portion of the drill string that
extends from the inground housing and at least some of the
electrically conductive drill pipe sections forming said portion of
the drill string cooperate as an electrical conductor for carrying
the electrical data signal.
2. The apparatus of claim 1 wherein said portion of the drill
string extends at least partially from the inground housing to the
drill rig such that the signal coupling arrangement couples the
data signal between the signal coupling arrangement and said
portion of the drill string.
3. The apparatus of claim 1 wherein said signal coupling
arrangement is configured for electromagnetically receiving the
electrical data signal from said portion of the drill string as the
data signal and thereafter electrically transferring the data
signal to the electronics assembly such that the apparatus serves
as a receiver.
4. The apparatus of claim 1 wherein said signal coupling
arrangement is configured for electromagnetically transferring the
data signal from said electronics assembly to said portion of the
drill string to produce the electrical data signal in the drill
string such that the apparatus serves as a transmitter.
5. The apparatus of claim 1 wherein said signal coupling
arrangement is configured for bidirectional coupling of the data
signal between the electronics assembly and the drill string such
that the apparatus serves as a transceiver.
6. The apparatus of claim 1 wherein said signal coupling
arrangement includes a current transformer supported by the
inground housing and in electrical communication with the
electronics package when received in the housing cavity for
electromagnetically coupling the data signal between the drill
string and said current transformer.
7. The apparatus of claim 6 wherein said inground housing includes
an outer surface configuration that defines an annular groove for
receiving said current transformer therein.
8. The apparatus of claim 7 further comprising: a support
arrangement for resiliently supporting said current transformer
within said annular groove on said inground housing such that the
current transformer is isolated at least to some extent from a
mechanical shock and vibration environment to which the housing is
subjected responsive to said inground operation.
9. The apparatus of claim 8 wherein said support arrangement
includes a plurality of resilient spacers that are distributed
around a peripheral configuration of the current transformer for
supporting the current transformer in the annular groove and a
resilient potting compound that is received in said annular groove
between said resilient spacers for further supporting the current
transformer in said annular recess groove to isolate the current
transformer from the mechanical shock and vibration
environment.
10. The apparatus of claim 8 wherein said support arrangement
includes a resilient potting compound surrounding the current
transformer in said annular recess groove to isolate the current
transformer from the mechanical shock and vibration
environment.
11. The apparatus of claim 1 wherein said electronics package
includes a sensor section and the electronics package is configured
for producing said data signal responsive to a sensor signal from
at least one sensor in the sensor section such that the signal
coupling arrangement electromagnetically couples the sensor signal
onto the drill string for transfer to the drill rig using at least
some of the electrically conductive drill pipe sections as said
electrical conductor and said electronics package includes a
locating signal antenna for electromagnetically transmitting an
electromagnetic locating signal and said inground housing is
configured for emanating said electromagnetic signal into the
ground surrounding the inground housing.
12. The apparatus of claim 1 wherein each drill pipe section
includes a box fitting at one end and a pin fitting at an opposing
end and wherein said inground housing includes said box fitting at
one end and said pin fitting at an opposite end.
13. The apparatus of claim 12 wherein each drill pipe section
defines a through passage to provide for a flow of drilling fluid
through the drill string and wherein said inground housing defines
an internal passage which provides for said flow of drilling fluid
through the inground housing between the box fitting and the pin
fitting of the inground housing.
14. The apparatus of claim 1 wherein each drill pipe section
includes a box fitting at one end and a pin fitting at an opposing
end and wherein said inground housing includes said box fitting at
each end and said apparatus includes a box to pin adapter that is
removably attached to one of the box fittings of the inground
housing to form part of said drill string.
15. The apparatus of claim 14 wherein said signal coupling
arrangement is positioned nearest to a selected one of the box
fittings of the inground housing and the box to pin adapter is
removably attached to the other box fitting at an opposite end of
the inground housing from the selected fitting.
16. The apparatus of claim 1 wherein said signal coupling
arrangement includes a current transformer supported by the
inground housing and in electrical communication with the
electronics package when received in the housing cavity for
electromagnetically coupling the data signal between the drill
string and said current transformer, and the current transformer
includes a winding having a first current transformer electrical
lead that is electrically connected to the electronics
assembly.
17. The apparatus of claim 16 wherein said winding includes a
second current transformer lead that is electrically connected to
the electronics package such that the first current transformer
lead and the second current transformer lead are in electrical
isolation from the drill string.
18. The apparatus of claim 16 wherein said electronics assembly
includes a case that serves as one electrical terminal for the
electronics package and inground housing is configured to cooperate
with the case such that the case is electrically coupled to the
inground housing and wherein said winding includes a second current
transformer lead that is electrically connected to the inground
housing for electrical communication with the electronics
assembly.
19. In a system in which an inground tool is moved through the
ground in a region for performing an inground operation, said
system including a drill rig and a drill string which extends
between said inground tool and said drill rig and is configured for
extension and retraction from said drill rig, said drill string
being made up of a plurality of electrically conductive drill pipe
sections, each of which includes a section length and each of which
is configured for removable attachment to the inground tool at one
joint and to one another at other joints that are formed between
adjacent ones of the drill pipe sections such that the drill string
includes a plurality of joints to facilitate the extension and
retraction of the drill string by one section length at a time, a
method comprising: arranging an inground housing for removable
insertion at one of the joints as the drill string is extended to
thereafter form part of the drill string and defining a housing
cavity within the inground housing that is configured for receiving
an electronics assembly that processes a data signal relating to
the inground operation; supporting a signal coupling arrangement
using the inground housing; and configuring said signal coupling
arrangement for electrical communication with the electronics
assembly, when received in the housing cavity, and for transferring
the data signal between the electronics assembly in the housing
cavity and the drill rig at least in part by electromagnetically
coupling the data signal between the signal coupling arrangement
and the drill string such that the data signal is electrically
conducted as an electrical data signal along at least a first
portion of the drill string that extends from the inground housing
and at least some of the electrically conductive drill pipe
sections forming said first portion of the drill string cooperate
as an electrical conductor for carrying the electrical data
signal.
20. The method of claim 19 wherein said portion of the drill string
extends at least partially from the inground housing to the drill
rig and the method includes electromagnetically coupling the data
signal between the signal coupling arrangement and said portion of
the drill string.
21. The method of claim 19 including configuring said signal
coupling arrangement for electromagnetically receiving the
electrical data signal from said portion of the drill string as the
data signal and thereafter electrically transferring the data
signal to the electronics assembly such that the electronics
assembly serves as a receiver.
22. The method of claim 19 including configuring said signal
coupling arrangement for electromagnetically transferring the data
signal from said electronics assembly to said portion of the drill
string to produce the electrical data signal in the drill string
such that the electronics assembly serves as a transmitter.
23. The method of claim 19 including configuring said signal
coupling arrangement for bidirectional coupling of the data signal
between the electronics assembly and the drill string such that the
electronics assembly serves as a transceiver.
24. The method of claim 19 including supporting a current
transformer using the inground housing as part of the signal
coupling arrangement and electrically connecting the current
transformer in communication with the electronics package when
received in the housing cavity for electromagnetically coupling the
data signal between the drill string and said current
transformer.
25. The method of claim 24 wherein said inground housing includes
an outer surface configuration and defining an annular recess as
part of the outer surface configuration and receiving said current
transformer in said annular recess.
26. The method of claim 25 further comprising: resiliently
supporting said current transformer within said annular recess on
said inground housing such that the current transformer is isolated
at least to some extent from a mechanical shock and vibration
environment to which the inground housing is subjected responsive
to said inground operation.
27. The method of claim 26 wherein resiliently supporting includes
arranging a plurality of resilient spacers in a spaced apart,
distributed way around a peripheral configuration of the current
transformer for supporting the current transformer in the annular
groove and applying a resilient potting compound in said annular
recess between said resilient spacers for further supporting the
current transformer in said annular groove to isolate the current
transformer from the mechanical shock and vibration
environment.
28. The method of claim 26 including applying a resilient potting
compound in said wherein said support arrangement includes a
resilient potting compound in said annular recess to surround the
current transformer in said annular recess to isolate the current
transformer from the mechanical shock and vibration
environment.
29. The method of claim 19 wherein said electronics package
includes a sensor section and the electronics assembly is
configured for producing said data signal responsive to a sensor
signal from at least one sensor in the sensor section such that the
signal coupling arrangement electromagnetically couples the sensor
signal onto the drill string for transfer to the drill rig using at
least some of the electrically conductive drill pipe sections as
said electrical conductor and said electronics assembly includes a
locating signal antenna for electromagnetically transmitting an
electromagnetic locating signal and including configuring said
inground housing for emanating said electromagnetic locating signal
into the ground surrounding the inground housing.
30. The method of claim 19 wherein each drill pipe section includes
a box fitting at one end and a pin fitting at an opposing end and
including configuring said inground housing to include said box
fitting at one end and said pin fitting at an opposite end.
31. The method of claim 30 wherein each drill pipe section defines
a through passage to provide for a flow of drilling fluid through
the drill string and including configuring said inground housing to
define an internal passage which provides for said flow of drilling
fluid through the inground h
32. The method of claim 19 wherein each drill pipe section includes
a box fitting at one end and a pin fitting at an opposing end and
said method includes configuring said inground housing including
said box fitting at each end and providing a box to pin adapter
that is removably attachable to one of the box fittings of the
inground housing to form part of said drill string.
33. The method of claim 32 including positioning said signal
coupling arrangement nearest to a selected one of the box fittings
of the inground housing and removably attaching the box to pin
adapter to the other box fitting at an opposite end of the inground
housing from the selected fitting.
34. The method of claim 19 including supporting a current
transformer on said inground housing as part of said signal
coupling arrangement and connecting the current transformer in
electrical communication with the electronics assembly when
received in the housing cavity for electromagnetically coupling the
data signal between the drill string.
35. The method of claim 34 wherein said current transformer
includes a winding having a first current transformer electrical
lead that is electrically connected to the electronics assembly by
said connecting.
36. The method of claim 35 wherein said winding includes a second
current transformer lead and connecting further includes
electrically connecting the second current transformer lead to the
electronics assembly such that the first current transformer lead
and the second current transformer lead are in electrical isolation
from the drill string.
37. The method of claim 35 wherein said electronics assembly
includes a case that serves as one electrical terminal for the
electronics assembly and connecting includes configuring the
inground housing to cooperate with the case such that the case is
electrically coupled to said inground housing and wherein said
winding includes a second current transformer lead and connecting
includes electrically connecting the second current transformer
lead to the inground housing for electrical communication with the
electronics assembly.
38. A repeater for use in a system in which an inground tool is
moved through the ground in a region for performing an inground
operation, said system including a drill rig and a drill string
which extends between said inground tool and said drill rig and is
configured for extension and retraction from said drill rig, said
drill string being made up of a plurality of electrically
conductive drill pipe sections, each of which includes a section
length and each of which is configured for removable attachment to
the inground tool at one joint and to one another at other joints
that are formed between adjacent ones of the drill pipe sections
such that the drill string includes a plurality of joints to
facilitate the extension and retraction of the drill string by one
section length at a time, said repeater comprising: an inground
housing including a housing body that defines a housing cavity and
said inground housing is removably insertable at any selected one
of the joints as the drill string is extended to thereafter form
part of the drill string and said inground housing includes a
signal coupling arrangement for providing bidirectional
electromagnetic coupling between the inground housing and the drill
string for receiving a data signal that is carried by electrical
conduction by at least some of the electrically conductive drill
pipe sections making up one portion of the drill string by
electromagnetically coupling the data signal from the drill string
to the inground housing as a received data signal; and a repeater
electronics package received in said housing cavity of the inground
housing and which is in electrical communication with the signal
coupling arrangement for producing a repeater signal based on the
received data signal, but which is distinguishable from the
received data signal and for providing the repeater signal to the
signal coupling arrangement such that the signal coupling
arrangement electromagnetically couples the repeater signal back to
the drill string for transfer of the repeater signal as another
electrical signal along the drill string such that the repeater
signal is electrically conducted by at least some of the
electrically conductive drill pipe sections making up a different
portion of the drill string.
39. The apparatus of claim 38 wherein said inground housing
includes a current transformer in electrical communication with the
inground tool for receiving the data signal and electromagnetically
coupling the data signal at least onto said portion of the drill
string and said coupling adapter further includes an adapter body
assembly having an outer surface configuration that defines an
annular recess for receiving said current transformer therein.
40. A method for use in a system in which an inground tool is moved
through the ground in a region for performing an inground
operation, said system including a drill rig and a drill string
which extends between said inground tool and said drill rig and is
configured for extension and retraction from said drill rig, said
drill string being made up of a plurality of electrically
conductive drill pipe sections, each of which includes a section
length and each of which is configured for removable attachment to
the inground tool at one joint and to one another at other joints
that are formed between adjacent ones of the drill pipe sections
such that the drill string includes a plurality of joints to
facilitate the extension and retraction of the drill string by one
section length at a time, said method comprising: configuring an
inground housing to include a housing body that defines a housing
cavity and said inground housing is removably insertable at any
selected one of said joints as the drill string is extended to
thereafter form part of the drill string and arranging said
inground housing to include a signal coupling arrangement for
providing bidirectional electromagnetic coupling between the
inground housing and the drill string for receiving a data signal
that is carried by electrical conduction by at least some of the
electrically conductive drill pipe sections making up one portion
of the drill string by electromagnetically coupling the data signal
from the drill string to the inground housing as a received data
signal; and supporting a repeater electronics package in said
housing cavity of the inground housing in electrical communication
with the signal coupling arrangement for producing a repeater
signal based on the received data signal, but which is
distinguishable from the received data signal and providing the
repeater signal to the signal coupling arrangement such that the
signal coupling arrangement electromagnetically couples the
repeater signal back to the drill string for transfer of the
repeater signal as another electrical signal along the drill string
such that the repeater signal is electrically conducted by at least
some of the electrically conductive drill pipe sections making up a
different portion of the drill string.
41. The method of claim 40 including configuring the housing body
of the inground housing to include a current transformer in
electrical communication with the inground tool for receiving the
data signal and electromagnetically coupling the data signal at
least onto said portion of the drill string and further configuring
the housing body to include an outer surface configuration that
defines an annular recess for receiving said current transformer
therein.
42. In a system in which an inground tool is moved through the
ground in a region during an inground operation, said system
including a drill rig and a drill string which extends between said
inground tool and said drill rig and is configured for extension
and retraction from said drill rig, said drill string being made up
of a plurality of electrically conductive drill pipe sections, each
of which includes a section length and each of which is configured
for removable attachment to the inground tool at one joint and to
one another at other joints that are formed between adjacent ones
of the drill pipe sections such that the drill string includes a
plurality of joints to facilitate the extension and retraction of
the drill string by one section length at a time, an apparatus
comprising: an electronics package that is configured for inground
operation; a current transformer configured for inductively coupled
communication with said drill string as part of providing for
communication between said electronics package and said drill rig
on said drill string by using the drill string as an electrical
conductor; a housing having a housing body that is removably
insertable at one of the joints as the drill string is extended to
thereafter form part of the drill string and said housing is
configured at least for receiving said current transformer with the
current transformer inductively coupled to the drill string and
said housing defines a housing cavity for receiving said
electronics package therein; and a support arrangement for
resiliently supporting said current transformer on said housing
body such that the current transformer is isolated at least to some
extent from a mechanical shock and vibration environment to which
the housing is subjected responsive to said inground operation.
43. In a system in which an inground tool is moved through the
ground in a region during an inground operation, said system
including a drill rig and a drill string which extends between said
inground tool and said drill rig and is configured for extension
and retraction from said drill rig, said drill string being made up
of a plurality of electrically conductive drill pipe sections, each
of which includes a section length and each of which is configured
for removable attachment to the inground tool at one joint and to
one another at other joints that are formed between adjacent ones
of the drill pipe sections such that the drill string includes a
plurality of joints to facilitate the extension and retraction of
the drill string by one section length at a time, a method
comprising: providing an electronics package that is configured for
inground operation; configuring a current transformer for
inductively coupled communication with said drill string as at
least part of providing for communication between said electronics
package and said drill rig on said drill string by using at least a
portion of the drill string as an electrical conductor; arranging a
housing having a housing body for removable insertion at one of the
joints as the drill string is extended to thereafter form part of
the drill string and configuring said housing at least for
receiving said current transformer with the current transformer
inductively coupled to the drill string and defining a housing
cavity within the housing for receiving said electronics package
therein; and resiliently supporting the current transformer on said
housing body for said inductive coupling to the drill string such
that the current transformer is isolated at least to some extent
from a mechanical shock and vibration environment to which the
housing is subjected responsive to said inground operation.
Description
RELATED APPLICATION
[0001] The present application is related to U.S. patent
application Ser. No. ______, (Attorney Docket No. DCI-54) entitled
DRILL STRING ADAPTER AND METHOD FOR INGROUND SIGNAL COUPLING,
sharing the filing date of the present application and which is
hereby incorporated by reference in its entirety.
BACKGROUND
[0002] The present application is generally related to inground
operations and, more particularly, to a system, apparatus and
method for electromagnetically coupling an electrical signal onto
an electrically conductive drill string to produce a corresponding
electrical signal on the drill string.
[0003] Generally, an inground operation such as, for example,
drilling to form a borehole, subsequent reaming of a borehole for
purposes of installing a utility line, borehole mapping and the
like use an electrically conductive drill string which extends from
an above ground drill rig. The prior art includes examples of the
use of an electrically conductive drill string as an electrical
conductor for serving to electrically conduct a data signal from an
inground tool to the drill rig. The surrounding earth itself serves
as a signal return path for purposes of detecting the signal at the
drill rig. This type of system is often referred to as a
measurement while drilling, MWD, system. Applicants recognize,
however, that that there remains a need for improvement in MWD
systems.
[0004] The foregoing examples of the related art and limitations
related therewith are intended to be illustrative and not
exclusive. Other limitations of the related art will become
apparent to those of skill in the art upon a reading of the
specification and a study of the drawings.
SUMMARY
[0005] The following embodiments and aspects thereof are described
and illustrated in conjunction with systems, tools and methods
which are meant to be exemplary and illustrative, not limiting in
scope. In various embodiments, one or more of the above-described
problems have been reduced or eliminated, while other embodiments
are directed to other improvements.
[0006] Generally, an apparatus and associated method are utilized
in a system in which an inground tool is moved through the ground
in a region for performing an inground operation. The system
includes a drill rig and a drill string which extends between the
inground tool and the drill rig and is configured for extension and
retraction from the drill rig. The drill string is made up of a
plurality of electrically conductive drill pipe sections, each of
which includes a section length and each of which is configured for
removable attachment to the inground tool at one joint and to one
another at other joints that are formed between adjacent ones of
the drill pipe sections such that the drill string includes a
plurality of joints to facilitate the extension and retraction of
the drill string by one section length at a time. In one aspect of
the disclosure, an inground housing is removably insertable at one
of the joints as the drill string is extended to thereafter form
part of the drill string. The inground housing defines a housing
cavity that is configured for receiving an electronics assembly
that processes a data signal relating to the inground operation. A
signal coupling arrangement is supported by the inground housing
and configured at least for electrical communication with the
electronics assembly when received in the housing cavity and for
transferring the data signal between the electronics assembly in
the housing cavity and the drill rig at least in part by
electromagnetically coupling the data signal between the signal
coupling arrangement and the drill string such that the data signal
is electrically conducted as an electrical data signal along at
least a portion of the drill string that extends from the inground
housing and at least some of the electrically conductive drill pipe
sections forming said portion of the drill string cooperate as an
electrical conductor for carrying the electrical data signal.
[0007] In another aspect of the present disclosure, a repeater is
described for use in a system in which an inground tool is moved
through the ground in a region for performing an inground
operation. The system includes a drill rig and a drill string which
extends between the inground tool and the drill rig and is
configured for extension and retraction from the drill rig. The
drill string is made up of a plurality of electrically conductive
drill pipe sections, each of which includes a section length and
each of which is configured for removable attachment to the
inground tool at one joint and to one another at other joints that
are formed between adjacent ones of the drill pipe sections such
that the drill string includes a plurality of joints to facilitate
the extension and retraction of the drill string by one section
length at a time. The repeater includes an inground housing
including a housing body that defines a housing cavity and the
inground housing is removably insertable at any selected one of the
joints as the drill string is extended to thereafter form part of
the drill string. The inground housing includes a signal coupling
arrangement for providing bidirectional electromagnetic coupling
between the inground housing and the drill string for receiving a
data signal that is carried by electrical conduction by at least
some of the electrically conductive drill pipe sections making up
one portion of the drill string by electromagnetically coupling the
data signal from the drill string to the inground housing as a
received data signal. A repeater electronics package is received in
the housing cavity of the inground housing and can be in electrical
communication with the signal coupling arrangement for producing a
repeater signal based on the received data signal, but which is
distinguishable from the received data signal and for providing the
repeater signal to the signal coupling arrangement such that the
signal coupling arrangement electromagnetically couples the
repeater signal back to the drill string for transfer of the
repeater signal as another electrical signal along the drill string
such that the repeater signal is electrically conducted by at least
some of the electrically conductive drill pipe sections making up a
different portion of the drill string.
[0008] In addition to the exemplary aspects and embodiments
described above, further aspects and embodiments will become
apparent by reference to the drawings and by study of the following
descriptions.
BRIEF DESCRIPTIONS OF THE DRAWINGS
[0009] Exemplary embodiments are illustrated in referenced figures
of the drawings. It is intended that the embodiments and figures
disclosed herein are to be illustrative rather than limiting.
[0010] FIG. 1 is a diagrammatic view, in elevation, of a system
which utilizes an inground housing and signal coupling arrangement
of the present disclosure.
[0011] FIG. 2 is a diagrammatic partially cutaway view of one
embodiment of the inground housing and signal coupling arrangement
of the present disclosure, shown here to illustrate details of its
structure.
[0012] FIG. 3 is a diagrammatic exploded view, in perspective, of
the embodiment of the inground housing of FIG. 2, shown here to
illustrate details of its structure as well as an electronics
package that is receivable in the housing.
[0013] FIG. 4 is a further enlarged fragmentary view, in elevation
and partial cross-section, taken within a circle 4-4 in FIG. 2,
shown here to illustrate details at least with respect to
electrical connections in the embodiment of FIG. 2 of the inground
housing and signal coupling arrangement.
[0014] FIG. 5 is a diagrammatic view, in elevation, of one-half of
an overall current transformer that can be used in an embodiment to
provide for mechanical shock and vibration isolation of the current
transformer from an inground operation using support spacers or
donut members.
[0015] FIG. 6 is a diagrammatic view, in cross-section, partially
showing another embodiment of an inground housing of the present
disclosure including a pin fitting.
[0016] FIG. 7 is a block diagram which illustrates one embodiment
of an electronics section that can be used with embodiments of the
inground housing of the present disclosure.
[0017] FIG. 8 is a block diagram which illustrates one embodiment
of an electronics section that can be used at the drill rig or as
part of a drill string repeater in cooperation with the inground
housing of the present disclosure.
DETAILED DESCRIPTION
[0018] The following description is presented to enable one of
ordinary skill in the art to make and use the invention and is
provided in the context of a patent application and its
requirements. Various modifications to the described embodiments
will be readily apparent to those skilled in the art and the
generic principles taught herein may be applied to other
embodiments. Thus, the present invention is not intended to be
limited to the embodiment shown, but is to be accorded the widest
scope consistent with the principles and features described herein
including modifications and equivalents, as defined within the
scope of the appended claims. It is noted that the drawings are not
to scale and are diagrammatic in nature in a way that is thought to
best illustrate features of interest. Descriptive terminology such
as, for example, up, down, upper, lower, left, right and the like
may be used with respect to these descriptions, however, this
terminology has be adopted with the intent of facilitating the
reader's understanding and is not intended as being limiting.
Further, the figures are not to scale for purposes of illustrative
clarity.
[0019] Turning now to the figures wherein like components are
indicated by like reference numbers throughout the various figures,
attention is immediately directed to FIG. 1 which is an elevational
view that diagrammatically illustrates one embodiment of a
horizontal directional drilling system generally indicated by the
reference number 10 and produced in accordance with the present
disclosure. While the illustrated system shows the invention within
the framework of a horizontal directional drilling system and its
components for performing an inground boring operation, the
invention enjoys equal applicability with respect to other
operational procedures including, but not limited to vertical
drilling operations, pullback operations for installing utilities,
mapping operations and the like.
[0020] FIG. 1 illustrates system 10 operating in a region 12.
System 10 includes a drill rig 14 having a drill string 16
extending therefrom to a boring tool 20. The drill string can be
pushed into the ground to move inground tool 20 at least generally
in a forward direction 22 indicated by an arrow. While the present
example is framed in terms of the use of a boring tool, it should
be appreciated that the discussions apply to any suitable form of
inground tool including but not limited to a reaming tool, a
tension monitoring tool for use during a pullback operation in
which a utility or casing can be installed, a mapping tool for use
in mapping the path of the borehole, for example, using an inertial
guidance unit and downhole pressure monitoring. In the operation of
a boring tool, it is generally desirable to monitor based on the
advance of the drill string whereas in other operations such as a
pullback operation, monitoring is generally performed responsive to
retraction of the drill string.
[0021] With continuing reference to FIG. 1, drill string 16 is
partially shown and is segmented, being made up of a plurality of
removably attachable, individual drill pipe sections some of which
are indicated as 1, 2, n-1 and n, having a section or segment
length and a wall thickness. The drill pipe sections may be
referred to interchangeably as drill rods having a rod length.
During operation of the drill rig, one drill pipe section at a time
can be added to the drill string and pushed into the ground by the
drill rig using a movable carriage 30 in order to advance the
inground tool. Drill rig 14 can include a suitable monitoring
arrangement 32 for measuring movement of the drill string into the
ground such as is described, for example, in U.S. Pat. No.
6,035,951 (hereinafter the '951 patent), entitled SYSTEMS,
ARRANGEMENTS AND ASSOCIATED METHODS FOR TRACKING AND/OR GUIDING AN
UNDERGROUND BORING TOOL, which is commonly owned with the present
application and hereby incorporated by reference.
[0022] Each drill pipe section defines a through opening 34 (one of
which is indicated) extending between opposing ends of the pipe
section. The drill pipe sections can be fitted with what are
commonly referred to as box and pin fittings such that each end of
a given drill pipe section can threadingly engage an adjacent end
of another drill pipe section in the drill string in a well known
manner. Once the drill pipe sections are engaged to make up the
drill string, the through openings of adjacent ones of the drill
pipe sections align to form an overall pathway 36 that is indicated
by an arrow. Pathway 36 can provide for a pressurized flow of
drilling fluid or mud, consistent with the direction of arrow 36,
from the drill rig to the drill head, as will be further
described.
[0023] The location of the boring tool within region 12 as well as
the underground path followed by the boring tool may be established
and displayed at drill rig 14, for example, on a console 42 using a
display 44. The console can include a processing arrangement 46 and
a control actuator arrangement 47.
[0024] Boring tool 20 can include a drill head 50 having an angled
face for use in steering based on roll orientation. That is, the
drill head when pushed ahead without rotation will generally be
deflected on the basis of the roll orientation of its angled face.
On the other hand, the drill head can generally be caused to travel
in a straight line by rotating the drill string as it is pushed as
indicated by a double headed arrow 51. Of course, predictable
steering is premised upon suitable soil conditions. It is noted
that the aforementioned drilling fluid can be emitted as jets 52
under high pressure for purposes of cutting through the ground
immediately in front of the drill head as well as providing for
cooling and lubrication of the drill head. Boring tool 20 includes
an inground housing 54 that receives an electronics package 56. The
inground housing is configured to provide for the flow of drilling
fluid to drill head 50 past the electronics package, as will be
seen in a subsequent figure. In one embodiment, the electronics
package can be cylindrical in configuration and supported within
housing 54. Drill head 50 can include a pin fitting that is
received by a box fitting of inground housing 54. An opposing end
of the inground housing can include a box fitting that receives a
pin fitting of drill pipe section n which defines a distal,
inground end of the drill string. Of course, drill head 50 can be
replaced by any suitable inground tool having a pin fitting such
as, for example, a reaming tool, a reaming tool in combination with
a tension monitoring arrangement, a mapping arrangement or suitable
combinations thereof. It is noted that the pipe fittings of the
drill head and the inground housing are generally the corresponding
box and pin fittings as found on the drill pipe sections of the
drill string for facilitating removable attachment of the drill
pipe sections to one another in forming the drill string. Thus,
inground housing 54 can engage an inground tool such as, for
example, drill head 50 having a pin fitting while having an
opposing box fitting for removable engagement with the
inground/distal end of the drill string. For purposes of inserting
inground housing 54 into the drill string, for reasons yet to be
described, a box to pin adapter (not shown) can be used in order to
adapt box fitting 114 to a pin fitting. It is noted, in this
regard, that box to pin fitting adapters are well known in the art.
In another embodiment, yet to be described, the inground housing
can include a box fitting and an opposing pin fitting.
[0025] Inground electronics package 56 can include a transceiver 64
which, in some embodiments, can transmit a locating signal 66 such
as, for example, a dipole locating signal, although this is not
required. In some embodiments, transceiver 64 can receive an
electromagnetic signal that is generated by other inground
components as will be described at an appropriate point below. The
present example will assume that the electromagnetic signal is a
locating signal in the form of a dipole signal for descriptive
purposes. Accordingly, the electromagnetic signal may be referred
to as a locating signal. It should be appreciated that the dipole
signal can be modulated like any other electromagnetic signal and
that the modulation data is thereafter recoverable from the signal.
The locating functionality of the signal depends, at least in part,
on the characteristic shape of the flux field and its signal
strength rather than its ability to carry modulation. Thus,
modulation is not required. Information regarding certain
parameters of the boring tool such as, for example, pitch and roll
(orientation parameters), temperature and drilling fluid pressure
can be measured by a suitable sensor arrangement 68 forming part of
the electronics package which may include, for example, a pitch
sensor, a roll sensor, a temperature sensor, an AC field sensor for
sensing proximity of 50/60 Hz utility lines, a DC magnetic field
sensor for sensing yaw orientation and any other sensors that are
desired. Electronics package 56 further includes a processor 70
that is interfaced as necessary with sensor arrangement 68 and
transceiver 64. Another sensor that can form part of the sensor
arrangement is an accelerometer that is configured for detecting
accelerations on one or more axes. Power can be provided by a
battery 72.
[0026] A portable locator 80 can be used to detect electromagnetic
signal 66. One suitable and highly advanced portable locater is
described in U.S. Pat. No. 6,496,008, entitled FLUX PLANE LOCATING
IN AN UNDERGROUND DRILLING SYSTEM, which is commonly owned with the
present application and is incorporated herein by reference in its
entirety. As mentioned above, the present descriptions apply to a
variety of inground operations and are not intended as being
limiting, although the framework of horizontal directional drilling
has been employed for descriptive purposes. As discussed above, the
electromagnetic signal can carry information including orientation
parameters such as, for example, pitch and roll. Other information
can also be carried by the electromagnetic signal. Such information
can include, by way of example, parameters that can be measured
proximate to or internal to the boring tool including temperatures
and voltages such as a battery or power supply voltage. Locator 80
includes an electronics package 82. The electronics package is
interfaced for electrical communication with the various components
of the locator and can perform data processing. Information of
interest can be modulated on electromagnetic signal 66 in any
suitable manner and transmitted to locator 80 and/or an antenna 84
at the drill rig, although this is not required. Any suitable form
of modulation may be used either currently available or yet to be
developed. Examples of currently available and suitable types of
modulation include amplitude modulation, frequency modulation,
phase modulation and variants thereof. Any parameter of interest in
relation to drilling such as, for example, pitch may be displayed
on display 44 and/or on a display 86 of locator 80 as recovered
from the locating signal. Drill rig 14 can transmit a telemetry
signal 98 that can be received by locator 80. The telemetry
components provide for bidirectional signaling between the drill
rig and locator 80. As one example of such signaling, based on
status provided by drill rig monitoring unit 32, the drill rig can
transmit an indication that the drill string is in a stationary
state because a drill pipe section is being added to or removed
from the drill string.
[0027] Still referring to FIG. 1, an electrical cable 100 can
extend from inground electronics package 56 to an electromagnetic
signal coupling arrangement 110 such that any sensed value or
parameter relating to the operation of the inground tool can be
electrically conducted in either direction between the
electromagnetic coupling arrangement and the electronics package on
this cable. One of ordinary skill in the art will appreciate that
what is commonly referred to as a "wire-in-pipe" can be used to
transfer signals to the drill rig. The term wire-in-pipe refers to
an electrical cable/conductor that is housed within interior
passageway 36 that is formed by the drill string. In accordance
with the present disclosure, however, cable 100 extends only to
electromagnetic signal coupling arrangement 110, as will be further
described immediately hereinafter.
[0028] Attention is now directed to FIG. 2 in conjunction with FIG.
1. FIG. 2 is a diagrammatic partially cutaway view which
illustrates one embodiment of boring tool 20 in further detail. In
particular, the boring tool includes inground housing 54 which
forms box fittings 112 and 114 at each of its opposing ends. Box
fitting 112 is configured for engaging the distal end of drill
string 16 while box fitting 114 is configured for receiving drill
head 50. It should be appreciated that, in other embodiments,
either one or both of these box fittings can be replaced by a pin
fitting depending on a particular application. The inground housing
can be formed from any suitable material such as, for example, from
nonmagnetic alloys including nonmagnetic stainless steels and from
magnetic alloys such as, for example, 4140, 4142, 4340 or any
suitable high strength steel. If the inground housing is to include
a magnetometer as part of sensor arrangement 68, the use of a
nonmagnetic material for the housing and related components avoids
potential field disturbance. A fluid passage 116 extends between
box fittings 112 and 114 such that fluid communication is provided
from the drill string leading into drill head 50 which defines a
passage 118 for emitting fluid jets 52. Housing 54 defines a
housing cavity for receiving electronics package 56, as will be
further described. For the moment, it is sufficient to note that
the electronics package is received in an off-centered manner in
order to provide sufficient space for fluid passage 116. In the
present embodiment, transceiver 64 is made up of a printed circuit
board 122 and a dipole antenna 126 which transmits electromagnetic
locating signal 66. Cable 100 can be routed from electromagnetic
signal coupling arrangement 110 to printed circuit board 122 for
purposes of sending data to the signal coupling arrangement and/or
receiving data from the electromagnetic signal coupling
arrangement. In some embodiments, transceiver 64 can be replaced by
a transmitter that is configured for providing signals to the
coupling arrangement without the need for receiver functionality.
Further, in some embodiments, transmission of locating signal 66 is
optional along with associated features of the inground housing,
yet to be described. Electrical connections are formed between the
various components as needed, but have not been individually
designated in FIG. 2 for purposes of illustrative clarity.
[0029] Turning now to FIG. 3 in conjunction with FIG. 2, the former
is an exploded perspective view of boring tool 20, shown here for
illustrating further details with respect to its structure. In
particular, inground housing 54 is configured for receiving a cover
140 above the electronics package in the view of FIG. 2. As seen in
the latter figure, a tab 142 extends from one end of the cover to
be received in a notch which is defined by the inground housing. An
opposite end of the cover defines an opening 144 for receiving a
fastener 146 such that the fastener can threadingly engaged the
inground housing in an installed condition of the cover. It should
be appreciated that any suitable expedient can be used to install
the cover on the inground housing. Cover 140 defines a slot 148
that is configured for enhancing the emission of the locating
signal while one or more additional slots 150 can be defined by the
inground housing for the same purpose. In this regard, such slots
are not needed in embodiments that do not utilize locating signal
66. FIG. 3 illustrates details with respect to one embodiment of
electronics package 56 wherein a first end cap 154 is received by a
cylindrical body 156 which itself can house dipole antenna 126 and
printed circuit board 122 of FIG. 2 wherein body 156 is essentially
transparent to locating signal 66. An opposing end of cylindrical
body 156 is connected to a battery compartment 158 which receives
battery 72 of FIG. 2. The battery compartment can be metallic and
electrically conductive. Any suitable battery cell or cells can be
used to make up the battery such as, for example, a pair of
standard C size battery cells. A second end cap 160 is received on
the free end of the battery compartment. It should be appreciated
that this end cap can define an indexing feature 162 such that the
electronics package can be received in a selected orientation
within the inground housing. In this way, certain sensor signals
such as that of roll orientation can accurately correspond to some
selected orientation of the inground housing or inground tool as
selectably received in the inground housing to provide selectable
orientations in quadrature. The electronics package can be received
in the housing first and second spacer arrangements 166 and 168,
respectively, first spacer arrangement 166 includes a first end
block 172 that defines a cylindrical recess (not visible) and
complementary indexing features (not visible) for being received
within indexing slot 162. First end block 172 can be formed, for
example, from thermal plastic. One or more filler spacer blocks 174
can be provided in view of the lengthwise extents of the cavity
defined by the inground housing and further in view of the length
of electronics package 56. The filler blocks can be formed, for
example, from urethane foam or silicone foam and can be suitably
dimensioned. Accordingly, first end spacer block 172 accommodates
any one of four user selectable orientations of the electronics
package within the cavity of the inground housing. Second spacer
arrangement 168, at the opposite end of the electronics package,
can include a second end block 172' that can be identical to first
end block 172 for receiving the opposite end of the electronics
package within a cylindrical recess 178, although complementary
indexing features may not be needed. One or more filler blocks 174
can also be positioned adjacent to second end block 172', as
needed.
[0030] With primary reference to FIG. 3, electromagnetic signal
coupling arrangement 110 includes a current transformer 200 which
can be formed using a split core as described in above incorporated
co-pending U.S. patent application Ser. No. ______ (Attorney Docket
No. DCI-54), entitled DRILL STRING ADAPTER AND METHOD FOR INGROUND
SIGNAL COUPLING. The current transformer includes first and second
current transformer leads 202a and 202b which can be connected, for
example, in electrical communication with electronics package
56.
[0031] In one embodiment, the electronics package can include a
cable pigtail 100 that is internally electrically connected, for
example, to printed circuit board 122 (FIG. 2). Cable 100 can
include either one or two electrical conductors. In one embodiment,
cable 100 includes one electrical conductor that is electrically
connected, for example, to current transformer lead 202a. Current
transformer lead 202b can be electrically connected to the inground
housing which is electrically conductive, for example, using a
fastener (not shown) within an annular recess 204 such as an
annular groove or slot. At the same time, battery compartment 158
can also be electrically connected to the battery as well as
inground housing 54 such that the latter forms part of the
electrical circuit to connect current transformer lead 202b with
the electronics package. In another embodiment, cable 100 can
include two conductors such that each one of current transformer
leads 202a and 202b can be electrically connected to one of the
cable conductors in electrical communication with electronics
package 56. In this embodiment, the current transformer can be
electrically isolated from inground housing 54 and the drill string
itself when the electronics package housing is electrically
isolated from the inground housing. The split core configuration of
the current transformer provides for installation into annular slot
or groove 204 that is defined by inground housing 54, as will be
described in further detail immediately hereinafter. Moreover, the
above incorporated Application entitled DRILL STRING ADAPTER AND
METHOD FOR INGROUND SIGNAL COUPLING, (Attorney Docket No. DCI-54)
describes an embodiment in which the current transformer is
electrically connected to the drill string by one lead and another
embodiment in which the current transformer is completely
electrically isolated from the drill string. This isolation can
reduce common mode noise that may be coupled onto the drill string,
for example, as the result of the presence of 50 Hz or 60 Hz noise
in an inground environment.
[0032] Referring to FIG. 4 in conjunction with FIGS. 2 and 3, FIG.
4 is an enlarged diagrammatic view of a region 4-4 that is shown
within a dashed circle in the view of FIG. 2, shown here to
illustrate further details of one embodiment of the apparatus
proximate to current transformer 200 and its connection to
electronics package 56. As described above, current transformer 200
is configured for installation in transformer recess or groove 204
that is defined by inground housing 54. The current transformer
includes a coil that is wound upon an annular or toroidal core such
that the end portions of the coil can form leads 202a and 202b of
FIG. 3. In this regard, the core can include any suitable
cross-sectional shape such as, for example, rectangular, square and
circular. As is also shown in FIG. 2, the core can be split in
order to facilitate installation of the current transformer into
transformer groove 204. It should be appreciated that any suitable
current transformer can be used and that the particular current
transformer that is described here is not intended as limiting.
[0033] The current transformer can be designed with at least the
following in mind: [0034] a. Shock and vibration. The material
selection and construction can provide for withstanding the shock
and vibration for the downhole drilling environment. [0035] b.
Magnetic material selection can be based on low core loss at the
operating frequency, high flux saturation and mechanical
robustness. [0036] c. High flux saturation of the core can permit a
reduction in cross-sectional area of the magnetic core, to provide
for increasing the cross-sectional area of the adapter coupling
main body for torque and power transmission. [0037] d. Low inter
winding capacitance for high frequency response.
[0038] In view of the foregoing, in one embodiment and by way of
non-limiting example, a tape wound core can be used. As will be
familiar to one of ordinary skill in the art, such cores are less
susceptible to shock and vibration than ferrite cores. Such a tape
wound core can be produced using a thin, high magnetic flux
saturation tape in order to avoid eddy current losses in the core.
In different embodiments, the tape thickness can range from
0.00025'' to 0.001''. One suitable thickness is 0.0007''. The tape
wound core can be finished, for example, using powder coating or
epoxy coating. In one embodiment, additional vibration and shock
protection can be provided for the current transformer and its core
based on the manner by which the current transformer is mounted in
groove 204, as will be described at an appropriate point
hereinafter.
[0039] One or both of current transformer leads 202a and 202b (FIG.
3) can be electrically connected to electronics package 56 by cable
100, for example, with connections such as crimp connections
received in recess 204 adjacent to the current transformer. Cable
100 can be routed through a passage arrangement that is made up of
a first passage portion 240 and a second passage portion 242 each
of which can be formed, for example, by drilling and/or suitable
machining. Passage portion 242 can be configured to receive a plug
244 that can be held in threading engagement, so as to prevent high
pressure drilling fluid from entering the passage arrangement. It
should be appreciated that any suitable arrangement can be used to
provide information coupling between the current transformer and
the electronics package including electrical connections and
electrical connections in combination with inductive coupling. As
an example of the latter embodiment, the electronics package can
include a coupling transformer having a first transformer coupling
coil 250 that is built-in to the electronics package and a second
transformer coupling coil 252 that is connected to current
transformer leads 202a and 202b (or to a cable extending therefrom)
and mounted within passage 242, for example, using a potting
compound. In the embodiment using the coupling transformer,
components of the electronics package housing and second spacer
arrangement 168 can provide for electromagnetic coupling between
the subject transformer coils. It should be appreciated that one of
ordinary skill in the art can develop many other embodiments in
view of the present disclosure while still remaining within the
scope of the teachings herein.
[0040] Referring to FIGS. 1-4, current transformer 200 can use the
drill pipe in the manner of a single turn secondary and the
surrounding soil to form a complete current path. The primary
winding of the current transformer can convert a low current output
from the drive electronics to a high current signal on the drill
pipe with the drill pipe itself serving as the single turn
secondary. Of course, the terms, primary and secondary can be used
interchangeably based on the direction of signal coupling and have
been applied here for descriptive and non-limiting purposes. The
current ratio is proportional to the number of turns on the
primary. For example, if the current into the primary is 10 mA rms,
the current induced on the drill pipe will be 1000 mA which is one
hundred times higher than the input current if the ratio of primary
to secondary turns is 100/1. As discussed above, a tape wound core
can be encapsulated in an epoxy 280 (FIG. 4) for added mechanical
strength, using any suitable thermal plastic or epoxy. The finished
core or toroid can be cut, for example, with a diamond saw into two
half cores for installation purposes with the transformer windings
applied to each core half. A small gap, for example, of about
0.001'' can be formed between the confronting surfaces of the core
half ends by bonding a piece of non-magnetic material, such as
Mylar.RTM., a strong polyester film between the confronting
surfaces, to create a magnetic gap. This gap helps to prevent
magnetic saturation of the core. As is well known in the art, the
cross-section of the core can be determined by the frequency, flux
density, number of turns of magnet wire (for example, an insulated
copper wire), saturation flux density and applied voltage to the
current transformer. With frequency from a few kilohertz to a
hundred kilohertz, the cross-section, by way of example, can be
approximately 0.2'' by 0.2'' for a square-shaped cross-sectional
embodiment. In some embodiments, the current transformer can be
shock mounted in the annular groove, as will be further described
at one or more points hereinafter.
[0041] Assembly of one embodiment can proceed, for example, by
installing current transformer 200 into annular groove 204. Cable
100 can be extended into through passages 240 and 242 from the
electronics package to the current transformer. Electrical
connections can be made between the current transformer leads and
cable 100, for example, using crimp connections or any other
suitable connections. It should be appreciated that the current
transformer, cylindrical ring and high pressure electrical
connector assembly are readily replaceable/repairable in the
field.
[0042] Referring to FIG. 5, one-half of current transformer 200 is
shown for purposes of illustrating another embodiment for isolating
the current transformer from mechanical shock and vibration. It is
noted that edges of annular recess 204 are diagrammatically shown
by dashed lines proximate to the current transformer. In
particular, current transformer 200 can be shock mounted using any
suitable number of donut or spacer members 300. Three spacer
members can be used with a suitable or at least approximately even
distribution around the periphery of the current transformer. Each
spacer member can define a center aperture for receiving the
current transformer. Since the current transformer can be provided
in two halves, spacer members 300 can readily be installed on each
current transformer half prior to installation of the current
transformer into groove 204. When the current transformer is
provided in two halves, each half can support two or more shock
mitigation spacer members. The spacer members can have any suitable
shape in view of the shape of the current transformer and annular
recess into which they are to be received. Moreover, the spacer
members can have any suitable arc width in the annular recess. The
spacer ring members can be formed from any suitable material such
as, for example, a resilient foam material. In one embodiment, a
high temperature foam material can be used. Such foam materials,
either currently available or yet to be developed, can be resistant
to temperatures up to and including 120 degrees Centigrade and can
include, by way of example, a silicone foam. As seen in FIGS. 4 and
5, a potting compound 302 can be used to at least partially fill
the entirety of annular recess 204 or spaces between any of spacer
members 300 that are used. A separate layer 304 of protective
material can be provided outward of potting compound 302 as well as
outward from the spacer members in the annular recess. The potting
compound can be a soft or resilient potting compound, such as, for
example, polyurethane or electronic grade RTV for purposes of
providing at least partial mechanical shock and vibration isolation
of the current transformer from inground operations. Protective
layer 304, for example, can be an epoxy compound that is harder
than the underlying potting compound. Current transformer 200 can
be potted in position, as described above, using spacer members 300
as centering devices during application of the resilient potting
compound, however, it should be appreciated that the spacer members
are not required.
[0043] Accordingly, a shock isolated and mounted current
transformer and associated method have been brought to light
herein. The housing which supports the current transformer includes
a housing body that can be removably insertable at one of the
joints of the drill string as the drill string is extended to
thereafter form part of the drill string. The housing is configured
at least for receiving the current transformer with the current
transformer inductively coupled to the drill string. A support
arrangement resiliently supports the current transformer on the
housing body such that the current transformer is isolated at least
to some extent from a mechanical shock and vibration environment to
which the housing is subjected responsive to the inground
operation. In some cases, a drill pipe section can be configured to
support a current transformer in a manner that is consistent with
the descriptions above, for example, when the drill pipe section
includes a sidewall thickness that is sufficiently thick for
purposes of defining a support groove for the current transformer
without unduly weakening the drill pipe section. Additionally, a
drill pipe section having a sidewall of sufficient thickness can
support the electrical connections, passages and assemblies
described above with limited or no modification as will be
recognized by one having ordinary skill in the art with this
overall disclosure in hand.
[0044] Referring to FIG. 6, in another embodiment, an inground
housing 54', partially shown, can be configured as essentially
identical to inground housing 54, as described above, except that
box fitting 114 (FIG. 2) is replaced by a pin fitting 400. It is
noted that threads have not been shown in the figure but are well
known and understood to be present. Thus, inground housing 54' can
include a box fitting at one end nearest to the current
transformer, as seen in FIG. 2, and pin fitting 400 at the opposing
end such that inground housing 54' can be inserted directly into
the drill string in removable engagement with adjacent ones of
drill pipe sections or engaging a drill head or other tool having a
box fitting.
[0045] FIG. 7 is a block diagram which illustrates one suitable
embodiment of electronics package 56, that can be supported in
inground housing 54 or 54'. The electronics package can include an
inground digital signal processor 710 which can facilitate all of
the functionality of transceiver 64 and processor 70 of FIGS. 1 and
2. Sensor arrangement 68 is electrically connected to digital
signal processor 710 via an analog to digital converter (ADC) 712.
Any suitable combination of sensors can be provided for a given
application and can be selected, for example, from an accelerometer
720, a magnetometer 722, a temperature sensor 724 and a pressure
sensor 726 which can sense the pressure of drilling fluid. Current
transformer 200 can be connected for use in one or both of a
transmit mode, in which data is modulated onto the drill string,
and a receive mode in which modulated data is recovered from the
drill string. For the transmit mode, an antenna driver section 730
is used which is electrically connected between inground digital
signal processor 710 and current transformer 200 to drive the
antenna. Generally, the data that can be coupled into the drill
string can be modulated using a frequency that is different from
any frequency that is used to drive antenna 126 (FIG. 2) that can
emit aforedescribed signal 66 (FIG. 1) in order to avoid
interference. When antenna driver 730 is off, an On/Off Switcher
(SW) 750 can selectively connect current transformer 200 to a band
pass filter (BPF) 752 having a center frequency that corresponds to
the center frequency of the data signal that is received from the
drill string. BPF 752 is, in turn, connected to an analog to
digital converter (ADC) 754 which is itself connected to digital
signal processing section 710. Recovery of the modulated data in
the digital signal processing section can be readily configured by
one having ordinary skill in the art in view of the particular form
of modulation that is employed.
[0046] Still referring to FIG. 7, dipole antenna 126 can be
connected for use in one or both of a transmit mode, in which
signal 66 is transmitted into the surrounding earth, and a receive
mode in which an electromagnetic signal such as, for example, a
signal from a tension monitoring arrangement is received. For the
transmit mode, an antenna driver section 760 is used which is
electrically connected between inground digital signal processor
710 and dipole antenna 126 to drive the antenna. Again, the
frequency of signal 66 will generally be sufficiently different
from the frequency of the drill string signal to avoid interference
therebetween. When antenna driver 760 is off, an On/Off Switcher
(SW) 770 can selectively connect dipole antenna 126 to a band pass
filter (BPF) 772 having a center frequency that corresponds to the
center frequency of the data signal that is received from the
dipole antenna. BPF 772 is, in turn, connected to an analog to
digital converter (ADC) 774 which is itself connected to digital
signal processing section 710. Transceiver electronics for the
digital signal processing section can be readily configured in many
suitable embodiments by one having ordinary skill in the art in
view of the particular form or forms of modulation employed and in
view of this overall disclosure.
[0047] Referring to FIGS. 1 and 8, the latter is a block diagram of
components that can make up one embodiment of a transceiver
arrangement, generally indicated by the reference number 800, that
is coupled to drill string 16. An aboveground current transformer
802 is positioned, for example, on drill rig 14 for coupling and/or
recovering signals to and/or from drill string 16. Current
transformer 802 can be electrically connected for use in one or
both of a transmit mode, in which data is modulated onto the drill
string, and a receive mode in which modulated data is recovered
from the drill string. A transceiver electronics package 806 is
connected to the current transformer and can be battery powered.
For the transmit mode, an antenna driver section 810 is used which
is electrically connected between a digital signal processor 820
and current transformer 802 to drive the current transformer.
Again, the data that can be coupled into the drill string can be
modulated using a frequency that is different from the frequency
that is used to drive dipole antenna 126 (FIG. 2) in order to avoid
interference as well as being different from the frequency at which
current transformer 200 (FIG. 7) couples a signal onto the inground
end of the drill string. When antenna driver 810 is off, an On/Off
Switcher (SW) 820 can selectively connect current transformer 802
to a band pass filter (BPF) 822 having a center frequency that
corresponds to the center frequency of the data signal that is
received from the drill string. BPF 822 is, in turn, connected to
an analog to digital converter (ADC) 830 which is itself connected
to digital signal processing section 820. It should be appreciated
that digital signal processing section 820 and related components
can form part of processing arrangement 46 (shown using a dashed
line) of the drill rig or be connected thereto on a suitable
interface 832. Transceiver 806 can send commands to the inground
tool for a variety of purposes such as, for example, to control
transmission power, select a modulation frequency, change data
format (e.g., lower the baud rate to increase decoding range) and
the like. Transceiver electronics for the digital signal processing
section can be readily configured in many suitable embodiments by
one having ordinary skill in the art in view of the particular form
or forms of modulation employed and in view of this overall
disclosure.
[0048] Referring to FIG. 1, in another embodiment, inground housing
54 or 54', along with current transformer 200, a box to pin adapter
(if needed), and transceiver 806 (FIG. 11) can be inserted as a
unit into one of the joints of the drill string to serve in the
manner of a repeater, by way of example, 1000 feet from the
inground tool. For example, the repeater arrangement can be
inserted in the joint formed between drill pipe sections 1 and 2 in
FIG. 1. In any of these embodiments, of course, the
repeater/transceiver electronics can be electrically connected to
the current transformer of the inground housing in a manner that is
consistent with the descriptions above. In order to avoid signal
interference, the current transformer can pick up the signal
originating from the inground tool at one carrier frequency and the
repeater electronics can retransmit the signal up the drill string
from the current transformer at a different carrier frequency.
[0049] The foregoing description of the invention has been
presented for purposes of illustration and description. It is not
intended to be exhaustive or to limit the invention to the precise
form or forms disclosed, and other embodiments, modifications and
variations may be possible in light of the above teachings wherein
those of skill in the art will recognize certain modifications,
permutations, additions and sub-combinations thereof.
* * * * *