U.S. patent number RE30,055 [Application Number 05/893,569] was granted by the patent office on 1979-07-24 for apparatus for transmitting well bore data.
This patent grant is currently assigned to Schlumberger Technology Corporation. Invention is credited to Jackson R. Claycomb.
United States Patent |
RE30,055 |
Claycomb |
July 24, 1979 |
Apparatus for transmitting well bore data
Abstract
In the representative embodiments of the present invention
described herein, a drilling mud is circulated through a drill
string at a sufficient rate to effectively operate an
impeller-driven electrical generator arranged on a tool coupled in
the drill string for supplying power to downhole electrical
circuits and one or more downhole condition-measuring devices on
the tool. By selectively controlling the flow of drilling mud past
the impeller in accordance with the conditions being monitored by
the condition-measuring devices, data-encoded acoustic signals are
produced in the circulating fluid and transmitted to the surface
for detecting and decoding as power is simultaneously supplied to
the downhole system by the generator.
Inventors: |
Claycomb; Jackson R. (Houston,
TX) |
Assignee: |
Schlumberger Technology
Corporation (New York, NY)
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Family
ID: |
27042963 |
Appl.
No.: |
05/893,569 |
Filed: |
April 5, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
470081 |
May 15, 1974 |
03949354 |
Apr 6, 1976 |
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Current U.S.
Class: |
367/84 |
Current CPC
Class: |
E21B
41/0085 (20130101); E21B 47/24 (20200501); E21B
47/18 (20130101); E21B 47/20 (20200501) |
Current International
Class: |
E21B
47/12 (20060101); E21B 41/00 (20060101); E21B
47/18 (20060101); G01V 001/40 () |
Field of
Search: |
;340/18NC,18LD |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Buczinski; S. C.
Attorney, Agent or Firm: Moseley; David L. Sherman; William
R. Langer; Thomas
Claims
What is claimed is:
1. Apparatus adapted for producing signals at the surface
representative of at least one downhole condition occurring while
drilling a borehole and comprising:
a body adapted to be tandemly coupled into a tubular drill string
and defining a fluid passage for carrying drilling fluids being
circulated to a borehole-drilling device dependently coupled
therebelow;
data-signaling means on said body and including circuit means for
producing digitally-encoded electrical data signals;
power-supply means on said body and including an electrical
generator adapted to be rotatively driven for producing electrical
power for said circuit means; .Iadd.and .Iaddend.
impeller means coupled to said generator and cooperatively arranged
in fluid passage for rotatively driving said generator upon flow of
drilling fluids through said fluid passage and said impeller means;
.[.and.]. .Iadd.said impeller means including
.Iaddend.signal-producing means .[.cooperatively arranged on said
impeller means and.]. adapted for .Iadd.at least .Iaddend.partially
obstructing the flow of drilling fluids through said .[.impeller
means.]. .Iadd.fluid passage .Iaddend.in response to said
electrical data signals to selectively produce
correspondingly-encoded acoustic signals in drilling fluids
circulating through said body.
2. The apparatus of claim 1 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured downhole condition during
the drilling of a borehole.
3. The apparatus of claim 1 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured formation characteristic
during the drilling of a borehole.
4. The apparatus of claim 1 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured characteristic of the
drilling fluids circulating through a borehole exterior of said
body during the drilling thereof.
5. The apparatus of claim 1 wherein said impeller means include a
reaction-type turbine impeller having a plurality of flow passages
cooperatively arranged therein for rotatively driving said
impeller; and said signal-producing means include a
passage-obstructing member cooperatively mounted on said impeller
for movement between one operating position where flow of drilling
fluids through at least one of said flow passages is at least
substantially blocked and another operating position where flow of
drilling fluids through said flow passages is at least
substantially unimpeded, and actuating means cooperatively arranged
for selectively moving said passage-obstructing member between its
said operating positions in response to said electrical data
signals.
6. The apparatus of claim 5 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured downhole condition during
the drilling of a borehole to correspondingly move said
passage-obstructing member between its said operating positions and
produce said encoded acoustic signals.
7. The apparatus of claim 5 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured formation characteristic
during the drilling of a borehole to correspondingly move said
passage-obstructing member between its said operating positions and
produce said encoded acoustic signals.
8. The apparatus of claim 5 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured characteristic of the
drilling fluids circulating through a borehole exterior of said
body during the drilling thereof to correspondingly move said
passage-obstructing member between its said operating positions and
produce said encoded acoustic signals.
9. The apparatus of claim 1 wherein said impeller means include a
multi-bladed impeller having a plurality of selectively-adjustable
impeller blades cooperatively arranged for movement between
selected pitch angles; and said signal-producing means include
blade-positioning means cooperatively coupled to said impeller
blades for movement between one operating position where said
impeller blades are shifted to one pitch angle substantially
blocking flow of drilling fluids through said fluid passage and
another operating position where said impeller blades are shifted
to another pitch angle substantially facilitating flow of drilling
fluids through said fluid passage, and actuating means
cooperatively arranged for selectively moving said
blade-positioning means between said operating positions in
response to said electrical data signals.
10. The apparatus of claim 9 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured downhole condition during
the drilling of a borehole to correspondingly move said
blade-positioning means between said operating positions and
produce said encoded acoustic signals.
11. The apparatus of claim 9 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured formation characteristic
during the drilling of a borehole to correspondingly move said
blade-positioning means between said operating positions and
produce said encoded acoustic signals.
12. The apparatus of claim 9 further including:
condition-responsive measuring means on said body and coupled to
said circuit means for supplying input signals thereto
representative of at least one measured characteristic of the
drilling fluids circulating through a borehole exterior of said
body during the drilling thereof to correspondingly move said
blade-positioning means between said operating positions and
produce said encoded acoustic signals.
13. Apparatus adapted for measuring at least one downhole condition
while drilling a borehole and comprising:
a body tandemly coupled in a tubular drill string having a
borehole-drilling device independently coupled thereto and defining
a fluid passage for circulating drilling fluids between the surface
and said borehole-drilling device;
data-signaling means on said body and adapted for providing
digitally-encoded data signals representative of at least one
downhole condition;
power-supply means on said body and including an electrical
generator adapted to be rotatively driven for producing electrical
power for said data-signaling means;
a multi-ported reaction-type turbine impeller coupled to said
generator and cooperatively journalled in said fluid passage for
rotatively driving said generator upon circulation of drilling
fluids through the ports of said impeller;
signal-producing means including a port-obstructing member
cooperatively mounted on said impeller for movement between one
operating position where flow of drilling fluids through said
impeller ports is at least substantially unimpeded and another
operating position where flow of drilling fluids through at least
one of said impeller ports is at least substantially blocked for
producing a pressure pulse in drilling fluids circulating through
said fluid passage, and actuating means coupled to said
port-obstructing member and operable in response to said data
signals for selectively moving said port-obstructing member between
its said operating positions to produce corresponding
digitally-encoded pressure pulses in drilling fluids circulating
through said fluid passage; and
pulse-detecting means cooperatively coupled to the surface end of
said drill string for detecting said pressure pulses to provide
indications at the surface representative of of said downhole
condition.
14. The apparatus of claim 13 wherein said port-obstructing member
is cooperatively arranged upstream of said impeller for blocking
entrance of drilling fluids into said one impeller port upon
movement of said port-obstructing member to its said other
operating position.
15. The apparatus of claim 13 wherein said actuating means include
an electro-mechanical actuator cooperatively arranged for moving
said port-obstructing member between its said operating positions
in response to electrical signals from said data-signaling
means.
16. The apparatus of claim 15 wherein said data-signaling means
include circuit means coupled to said actuator and cooperatively
arranged for supplying digitally-encoded electrical output signals
thereto, and condition-responsive means on said body and coupled to
said circuit means for supplying electrical input signals thereto
representative of said downhole condition.
17. The apparatus of claim 15 wherein said downhole condition is a
selected formation characteristic and said data-signaling means
include circuit means for supplying electrical input signals
thereto representative of said formation characteristic.
18. The apparatus of claim 15 wherein said downhole condition is a
selected characteristic of drilling fluids circulating through a
borehole exterior of said body and said data-signaling means
include circuit means for supplying electrical input signals
thereto representative of said drilling fluid characteristic.
19. Apparatus adapted for measuring at least one downhole condition
while drilling a borehole and comprising:
a body tandemly coupled in a tubular drill string having a
borehole-drilling device dependently coupled thereto and defining a
fluid passage for circulating drilling fluids between the surface
and said borehole-drilling device;
data-signaling means on said body and adapted for providing
digitally-encoded electrical data signals representative of at
least one downhole condition;
power-supply means on said body and including an electrical
generator adapted to be rotatively driven for producing electrical
power for said data-signaling means;
a multi-bladed turbine impeller coupled to said generator and
cooperatively journalled in said fluid passage for rotatively
driving said generator upon circulation of drilling fluids through
the openings between the blades of said impeller, said impeller
blades being cooperatively arranged for movement between selected
pitch angles;
signal-producing means including cam means cooperatively associated
with said impeller blades for simultaneously shifting said impeller
blades between one operative pitch angle where flow of drilling
fluids through said impeller openings is at least substantially
unimpeded and another operative pitch angle where flow of drilling
fluids through said impeller openings is at least substantially
impeded for producing a pressure pulse in drilling fluids
circulating through said fluid passage, and actuating means coupled
to said cam means and operable in response to said data signals for
selectively moving said impeller blades between their said
operative pitch angles to produce corresponding digitally-encoded
pressure pulses in drilling fluids circulating through said fluid
passage; and
pulse-detecting means cooperatively coupled to the surface end of
said drill string for detecting said pressure pulses to provide
indications at the surface representative of said downhole
condition.
20. The apparatus of claim 19 wherein said actuating means include
an electro-mechanical actuator cooperatively arranged for moving
said impeller blades between their said operative pitch angles in
response to said electrical data signals from said data-signaling
means.
21. The apparatus of claim 20 wherein said data-signaling means
include circuit means coupled to said actuator and cooperatively
arranged for supplying digitally-encoded electrical output signals
thereto, and condition-responsive means on said body and coupled to
said circuit means for supplying electrical input signals thereto
representative of said downhole condition.
22. The apparatus of claim 20 wherein said downhole condition is a
selected formation characteristic and said data-signaling means
include circuit means for supplying electrical input signals
thereto representative of said formation characteristic.
23. The apparatus of claim 20 wherein said downhole condition is a
selected characteristic of drilling fluids circulating through a
borehole exterior of said body and said data-signaling means
include circuit means for supplying electrical input signals
thereto representative of said drilling fluid characteristic.
24. Apparatus adapted for producing acoustic signals at the surface
representative of at least one downhole condition and
comprising:
a body having a fluid passage and adapted for mounting in a well
bore pipe string carrying flowing fluids between the surface and a
downhole location in a well bore;
data-signaling means on said body and cooperatively arranged for
producing digitally-encoded electrical signals representative of at
least one downhole condition;
power-supply means on said body and including an electrical
generator adapted to be rotatively driven for supplying electrical
power to said data-signaling means, and a multi-ported turbine
impeller coupled to said generator and cooperatively arranged in
said fluid passage for operatively driving said generator upon flow
of fluids through the ports of said impeller; and
signal-producing means including a member movably arranged on said
impeller and selectively operable in response to said electrical
signals for momentarily obstructing the flow of fluids through at
least one of said impeller ports to produce correspondingly-encoded
acoustic signals in such fluids.
25. The apparatus of claim 24 wherein said data-signaling means
include:
circuit means cooperatively arranged for producing said electrical
signals in response to input signals supplied thereto; and
condition-measuring means coupled to said circuit means and
cooperatively arranged for supplying input signals thereto
representative of at least one formation characteristic.
26. The apparatus of claim 25 further including:
detecting means adapted for coupling to the surface end of a well
bore pipe string carrying said body for detecting said acoustic
signals to provide indications at the surface representative of
said formation characteristic.
27. The apparatus of claim 24 wherein said data-signaling means
include:
circuit means cooperatively arranged for producing said electrical
signals in response to input signals supplied thereto; and
condition-measuring means coupled to said circuit means and
cooperatively arranged for supplying input signals thereto
representative of at least one characteristic of such fluids.
28. The apparatus of claim 27 further including:
detecting means adapted for coupling to the surface end of a well
bore pipe string carrying said body for detecting said acoustic
signals to provide indications at the surface representative of
said fluid characteristic.
29. Apparatus adapted for producing acoustic signals at the surface
representative of at least one downhole condition and
comprising:
a body having a fluid passage and adapted for mounting in a well
bore pipe string carrying flowing fluids between the surface and a
downhole location in a well bore;
data-signaling means on said body and cooperatively arranged for
producing digitally-encoded electrical data signals representative
of at least one downhole condition;
power-supply means on said body and including an electrical
generator having a tubular driving shaft and adapted to be
rotatively driven for supplying electrical power to said signaling
means, and a multi-ported turbine impeller coupled to said driving
shaft and cooperatively arranged in said fluid passage for
operatively driving said generator upon flow of fluids through the
ports of said impeller; and
signal-producing means on said body and including a
port-obstructing member cooperatively mounted on said impeller for
angular movement relative thereto between one operating position
where flow of fluids through said impeller ports is substantially
unimpeded and another operating position where flow of fluids
through at least one of said impeller ports is substantially
obstructed, an actuating shaft coaxially disposed in said driving
shaft and coupled to said port-obstructing member for moving said
port-obstructing member between its said operating positions upon
angular movement of said actuating shaft in relation to said
driving shaft, a tubular cam follower coaxially disposed around
said shafts and adapted for longitudinal movement in relation
thereto between one cam-actuating position where an
enlarged-diameter first internal bore portion of said cam follower
is adjacent to a lateral opening in said tubular shaft and another
cam-actuating position where a reduced-diameter second internal
bore portion of said cam follower is adjacent to said shaft
opening, a spiraling intermediate internal bore portion joining
said first and second internal bore portions, an electro-mechanical
actuator coupled to said data-signaling means and responsive to
said electrical data signals for selectively shifting said cam
follower between said cam-actuating positions, a rotatable cam
adapted for rolling movement along said internal bore portions in
first and second orbital paths around said shafts respectively
determined by the diameters of said first and second internal bore
portions, and linkage means cooperatively coupling said cam between
said shafts for angularly moving said actuating shaft in relation
to said tubular shaft and including a first linkage member secured
to said tubular shaft to one side of said shaft opening and a
second linkage member secured to said actuating shaft and disposed
within said shaft opening for angular movement therein in
accordance with radial movements of said cam between its said
orbital paths.
30. The apparatus of claim 29 wherein said data-signaling means
include:
circuit means cooperatively arranged for producing said electrical
data signals in response to input signals supplied thereto; and
condition-measuring means coupled to said circuit means and
cooperatively arranged for supplying input signals thereto
representative of at least one formation characteristic.
31. The apparatus of claim 30 further including:
detecting means adapted for coupling to the surface end of a well
bore pipe string carrying said body for detecting said acoustic
signals to provide indications at the surface representative of
said formation characteristic.
32. The apparatus of claim 29 wherein said data-signaling means
include:
circuit means cooperatively arranged for producing said electrical
data signals in response to input signals supplied thereto; and
condition-measuring means coupled to said circuit means and
cooperatively arranged for supplying input signals thereto
representative of at least one characteristic of such fluids.
33. The apparatus of claim 32 further including:
detecting means adapted for coupling to the surface end of a well
bore pipe string carrying said body for detecting said acoustic
signals to provide indications at the surface representative of
said fluid characteristic. .Iadd. 34. Apparatus adapted for
producing acoustic signals for transmission to the surface
representative of at least one downhole condition occurring while
drilling a borehole, comprising:
a housing adapted to be positioned within a tubular body defining a
fluid passage that conducts drilling fluids being circulated to a
borehole-drilling device dependently coupled therebelow;
circuit means for producing encoded electrical signals
representative of a downhole measurement;
power generating means in said housing and including an electrical
generator adapted to be rotatively driven for producing electrical
power for said circuit means; and
impeller means coupled to said generator and cooperatively arranged
in said fluid passage for rotatively driving said generator upon
flow of drilling fluids through said fluid passage, said impeller
means including means responsive to said encoded electrical signals
for at least partially obstructing the flow of drilling fluids
through said passage to thereby produce correspondingly encoded
acoustic signals in said drilling fluids. .Iaddend. .Iadd. 35. The
apparatus of claim 24 wherein said impeller means includes a
reaction-type turbine impeller having a plurality of flow passages;
and said obstructing means includes a passage-obstructing member
mounted for movement between one operating position where flow of
drilling fluids through at least one of said flow passages is at
least substantially blocked and another operating position where
flow of drilling fluids through said flow passages is at least
substantially unimpeded. .Iaddend..Iadd. 36. The apparatus of claim
35 wherein said obstructing means further includes actuating means
cooperatively arranged for selectively moving said passage
obstructing member between its operating positions in response to
said encoded electrical signals. .Iaddend. .Iadd. 37. The apparatus
of claim 34 wherein said impeller means includes a multi-bladed
impeller having a plurality of selectively adjustable blades
cooperatively arranged for movement between selected pitch angles;
and said obstructing means includes blade-positioning means
cooperatively arranged coupled to said blades for movement between
one operating position where said blades are shifted to one pitch
angle substantially blocking flow of drilling fluids through said
fluid passage and another operating position where said blades are
shifted to another pitch angle substantially facilitating flow of
drilling fluids through said fluid passage. .Iaddend..Iadd. 38. The
apparatus of claim 37 wherein said obstructing means further
includes means cooperatively arranged for selectively moving said
blade-positioning means between said operating positions in
response to said encoded electrical signals. .Iaddend.
Description
Many systems have been proposed heretofore for transmitting data
representative of one or more measured downhole conditions to the
surface during the drilling of a borehole. In recent years,
however, it has become apparent that from the standpoint of
potential commercial utility, the most-promising data-transmission
system of this nature will employ the drilling mud circulating
through the drill string as a medium for transmitting encoded
acoustic signals to the surface.
Typical of these proposals is the new and improved downhole
signaling tool described in U.S. Pat. No. 3,736,558 which includes
a selectively-controlled valve that is operated for momentarily
interrupting the flow of drilling mud through the drill string so
as to produce sucessive data-encoded acoustic pulses in the mud
stream which can be readily detected at the surface. Alternatively,
other promising data-transmission systems of this nature employ a
similar-downhole signaling tool such as those described in U.S.
Pat. No. 3,309,565 and U.S. Pat. No. 3,764,970 in which a
motor-driven "siren signaler" is operated to transmit either
frequency-modulated or phase-encoded data signals at acoustic
frequencies to the surface by way of the mud stream in the drill
string. In either of these "siren-signaling" systems, it has been
found best to power the various downhole electrical components by a
typical self-contained turbine-generator unit which is steadily
driven by the mud stream flowing through the drill string.
As may be expected, there are, of course, countervailing advantages
and disadvantages between these two different types of downhole
data-transmission system. For instance, although the aforementioned
"pressure-pulse" signaling tools require a minimum of electrical
power and produce a stronger signal than the "siren-signaling"
tools, it has been found that the pressure-pulse signals sometimes
have an unfavorable signal-to-noise ratio in comparison to the
siren signals. On the other hand, since these signalers are driven
by a suitable electrical motor, these tools require significantly
more electrical power than the pressure-pulse tools. Thus, with the
siren-signaling tools which have been proposed to date, it has been
found that a larger turbine-generator unit is required and higher
mud flow rates must be supplied than is the case with an
otherwise-equivalent pressure-pulse signaling tool.
Accordingly, it is an object of the present invention to provide
new and improved apparatus to reliably produce coded acoustic
signals in a circulating well fluid, such as drilling mud, for
rapidly and accurately conveying data representative of one or more
downhole conditions to the surface but with minimum electrical
power requirements for the downhole components of the transmission
system.
This and other objects of the present invention are broadly
attained by selectively controlling the flow of a circulating well
fluid past a fluid-driven generator unit arranged in a pipe string
carrying the flowing fluid so as to produce encoded acoustic
signals in the fluid which are representative of downhole
conditions as monitored by one or more measuring devices which are
powered by the downhole generator. In a preferred embodiment of new
and improved apparatus arranged in accordance with the principles
of the present invention, a generator is driven by an otherwise
typical turbine-type impeller which is cooperatively associated
with selectively-operable flow-obstructing means adapted for
movement between one position where little or no obstruction is
presented to the fluid flowing through the ports of the turbine
impeller and another position where this flow is at least
momentarily retarded for producing an acoustic signal in the
flowing fluid. An alternative embodiment of new and improved
apparatus of the present invention employs a generator which is
driven by an impeller with variably-positionable blades. Means are
provided for selectively shifting the impeller blades between a
minimum flow-obstruction position and an increased flow-obstruction
position and an increased flow-obstruction position for producing
an acoustic signal in the flowing fluid. Both embodiments of the
new and improved apparatus of the present invention further include
means for selectively operating the apparatus for momentarily
obstructing the flowing fluid to transmit data-encoded acoustic
signals through the fluid stream which are representative of one or
more downhole conditions.
The novel features of the present invention are set forth with
particularity in the appended claims. The invention, together with
further objects and advantages thereof, may be best understood by
way of the following description of exemplary apparatus employing
the principles of the invention as illustrated in the accompanying
drawings, in which:
FIG. 1 shows a new and improved well tool arranged in accordance
with the present invention as it will appear while coupled in a
drill string during the course of a typical drilling operation;
FIGS. 2A and 2B are successive enlarged cross-sectioned views of a
preferred embodiment of a selectively-operable acoustic signaler
employed with the well tool shown in FIG. 1 to produce data-coded
acoustic signals;
FIGS. 3A-3C are cross-sectional views respectively taken along the
lines "3A--3A", "3B--3B" and "3C--3C" in FIGS. 2A and 2B;
FIGS. 4A and 4B are views similar to those depicted in FIGS. 2A and
2B, but showing the new and improved acoustic signaler in a
different operating position;
FIGS. 5A-5C are cross-sectional views similar to FIGS. 3A-3C but
which are respectively taken along the lines "5A--5A", "5B--5B" and
"5C--5C" in FIGS. 4A and 4B to illustrate the operation of the
acoustic signaler shown in FIGS. 2A and 2B;
FIGS. 6 and 7 are enlarged cross-sectioned views of an alternative
embodiment of a new and improved selectively-operable acoustic
signaler which can also be employed with the well tool shown in
FIG. 1, with FIG. 7 being drawn to a larger scale to better
illustrate this alternative embodiment;
FIG. 8 is an isometric view of one of the significant features of
the new and improved signaler shown in FIGS. 6 and 7;
FIG. 9 is a cross-sectional view taken along the lines "9--9" in
FIG. 7 to illustrate additional features of that alternative
embodiment of the apparatus of the present invention; and
FIG. 10 graphically represents the operating characteristics of the
signaler shown in FIGS. 6-9.
Turning now to FIG. 1, a new and improved well tool 20 arranged in
accordance with the present invention is depicted coupled in a
typical drill string 21 having a rotary drill bit 22 dependently
coupled thereto and adapted for excavating a borehole 23 through
various earth formations. As the drill string 21 is rotated by a
typical drilling rig (not shown) at the surface, substantial
volumes of a suitable drilling fluid or so-called "mud" are
continuously pumped downwardly through the tubular drill string and
discharged from the drill bit 22 to cool the bit as well as to
carry earth borings removed by the bit to the surface as the mud is
returned upwardly along the borehole 23 exterior of the drill
string. It will be appreciated, therefore, that the circulating mud
stream flowing through the drill string 21 serves as a transmission
medium that is well suited for transmitting acoustic signals to the
surface at the speed of sound in the particular drilling fluid.
In accordance with the principles of the present invention,
data-signaling means 24 are arranged on the tubular body 25 of the
well tool 20 and include one or more condition-responsive devices,
as at 26 and 27, coupled to appropriate electrical circuitry 28
operatively arranged in the tool body for sequentially producing
digitally-coded electrical data signals that are representative of
the measurements being obtained by the condition-responsive
devices. It will, of course, be appreciated that these
condition-responsive transducers 26 and 27 will be adapted as
required for measuring such downhole measurements as the pressure,
the temperature, or the resistivity or conductivity of either the
drilling mud or adjacent earth formations as well as various other
formation conditions or characteristics which are typically
obtained by present-day wireline logging tools.
To provide electrical power for operation of the data-signaling
means 24, a typical rotatively-driven generator 29 is coupled, as
by a shaft 30, to an otherwise-typical reaction-type turbine
impeller 31. As will be subsequently explained, the turbine
impeller 31 is uniquely arranged to serve as one element of an
acoustic signaler 32 which selectively interrupts or obstructs the
drilling fluid flowing through the drill string 21 for producing
digitally-encoded acoustic signals or pressure pulses at a
corresponding pulse rate. Briefly stated, the signaler 32 is
selectively operated in response to the data-encoded electrical
signals from the downhole circuitry 28 as required for producing a
correspondingly-encoded acoustic output signal as well as for
continuously driving the generator 29 to supply the electrical
power requirements of the data-transmission means 24. This encoded
signal is successively transmitted to the surface through the mud
stream flowing within the drill string 21 as a series of discrete
signal portions or successive pressure pulses which, preferably,
are encoded binary representations or data signals indicative of
the downhole borehole or formation conditions respectively sensed
by the condition-measuring devices 26 and 27. When these encoded
signal pulses reach the surface, they are sequentially decoded and
converted into meaningful data-conveying indications or records by
suitable signal detecting-and-recording apparatus 33 such as that
shown in U.S. Pat. No. 3,488,629 or U.S. Pat. No. 3,555,504 or U.S.
Pat. No. 3,747,059, each of which is hereby incorporated herein by
reference.
Turning now to FIGS. 2A and 2B, successive elevational views, in
cross-section, are shown of the preferred embodiment of the
acoustic signaler-generator driver 32 employed in the present
invention. In general, this embodiment of the new and improved
acoustic signaler 32 includes the reaction-type fluid-driven
turbine 31 which is cooperatively coupled to the generator shaft 30
by an elongated tubular shaft 34 coaxially disposed within a
tubular housing 35 that is, in turn, coaxially mounted within the
tubular body 25 of the tool 20. As will be subsequently explained
in further detail, the new and improved signaler 32 further
includes selectively-operable fluid-obstructing means, such as an
alternately-positionable obstructing member 36, cooperatively
arranged for momentarily blocking or impeding the flow of drilling
mud through the turbine 31 upon the controlled operation of
actuating means, such as a typical solenoid actuator 37, in
response to coded electrical signals from the encoder 28 (FIG.
1).
As best illustrated in FIGS. 2A and 3A, the turbine impeller 31 is
typically arranged with a plurality of reaction passages, as at 38
and 39, having upwardly-facing inlet ports, as at 40 and 41, and
appropriately-directed, laterally-facing outlet ports, as at 42 and
43. In this manner, as drilling mud is pumped downwardly through
the tool body 25, the flowing mud will impart a rotative torque to
the impeller 31 and the turbine shaft 34 as the mud leaves the
laterally-directed discharge ports, as at 42 and 43, of the
impeller.
To accommodate the flow of the drilling mud downstream of the
signaler 32, the tubular housing 35 and the tool body 25 are
cooperatively sized and shaped to define adequately-sized annular
mud passages, as at 44 and 45, for conducting the mud on through
the tool 20 and the drill bit 22 (FIG. 1). Similarly, to prevent at
least significant bypassing of the turbine impeller 31, a tubular
guard or mud shroud 46 is mounted on top of the rotatable impeller
and extended upwardly as illustrated in FIG. 2A to a sliding and
generally-sealing engagement with the underside of an
inwardly-directed fixed shoulder 47 formed around the open upper
end of the signaler housing 35. To minimize wear at that point, it
is preferred to cooperatively mount opposed seal rings, as at 48
and 49, of a hardened material on the co-engaged surfaces of the
shroud 46 and the shoulder 47 respectively. Accordingly, it will be
appreciated that as drilling mud is pumped downwardly through the
tool 20, it will be directed through the shroud 46; and, after
being discharged from the turbine passages 38 and 39 to impart
rotative torque to the impeller 31, the mud will flow on through
the annular mud passages 44 and 45 in and around the housing
35.
It will, of course, be recognized by those skilled in the art that
with any given drill string, as at 21, and a given flow rate of
drilling mud, there will be a corresponding mud pressure at the
surface end of the drill string. Moreover, it will be appreciated
that an increased pressure will result if the flowing drilling mud
is even partially obstructed; and the increase in this pressure
differential will be directly related to the degree of
obstruction.
Accordingly, in keeping with the principles of the present
invention, the port-obstructing member 36 is cooperatively arranged
on the upper face of the turbine impeller 31 for controlled rocking
or arcuate movement between a non-obstructing position (as shown in
FIG. 3A) where all of the inlet ports, as at 41, are at least
substantially unblocked and a port-obstructing position (as shown
in FIG. 5A) where one or more of the inlet ports are at least
partially blocked. As depicted in the preferred embodiment of the
acoustic signaler 32, it is preferred that the movable
port-blocking member 36 be arranged for rotative movement in a
relatively-short arc between a first operating position where all
of the inlet ports, as at 41, are substantially uncovered and a
second operating position where two of these ports are completely
obstructed. It should, however, be understood that other
arrangements of the port-blocking member 36 could be provided to
either vary the number of affected ports or provide different
degrees of non-obstruction or obstruction without departing from
the broad conceptual scope of the present invention.
It will, of course, be recognized that the port-obstructing member
36 needs only to be shifted through a relatively-small arc of
travel to accomplish its unique signal-producing function.
Accordingly, an elongated shaft 50 is dependently secured to the
port-obstructing member 36 and coaxially disposed inside of the
tubular turbine shaft 34. To support the elongated shaft 50, one or
more bearings, as at 51, are coaxially arranged within the turbine
shaft 34 to facilitate the arcuate movement of the elongated shaft;
and a thrust bearing, as at 52, is arranged on the turbine shaft
for supporting the elongated shaft against the unbalanced axial
forces imposed by the downwardly-flowing mud on the
port-obstructing member 36.
Similarly, the turbine shaft 34 is rotatively-journalled within the
signaler housing 35 as by one or more bearings 53 and 54 which
support the turbine shaft 34 against unbalanced axially-directed
forces. The enlarged upper portion 55 of the shaft is provided with
an annular downwardly-facing shoulder 56 which is cooperatively and
rotatably engaged with the upper face of an inwardly-directed
shoulder 57 arranged around the intermediate portion of the
stationary signaler housing 35. Hereagain, to provide a suitable
fluid seal as well as to minimize the wear of these opposed
shoulders 56 and 57, complementary annular inserts 58 and 59 of a
hardened material are respectively arranged on the shoulders.
Those skilled in the art are, of course, well aware of the
undesirable effects of drilling mud on closely-fitted machine
parts. Accordingly, to isolate at least most of the interior of the
signaler 32 from the drilling mud in the tool body 25, the enlarged
upper portion 55 of the turbine shaft is cooperatively arranged to
define an oil-filled reservoir 60 which is communicated with the
interior of the signaler housing 35 below the housing shoulder 57
by way of the annular clearance gap between the shafts 34 and 50.
To maintain the oil in the housing 35 at borehole pressure as well
as to accommodate volumetric changes in the oil, an annular piston
member 61 is coaxially arranged in the reservoir 60 and slidably
sealed, as well as 62 and 63, with relation to the shafts 34 and
50. It will, of course, be appreciated that drilling mud will enter
the upper portion of the reservoir 60 above the piston 61 so as to
maintain the oil in the system at borehole pressure.
As previously mentioned, it is necessary only that the
port-obstructing member 36 be capable of being angularly shifted or
rocked through a relatively-small arc of travel which, in the
depicted preferred embodiment of the signaler 32, is in the order
of only about 30.degree.. Accordingly, to selectively shift or rock
the port-obstructing member 36 in an arcuate path between its two
operating positions, shaft-positioning means, as shown generally at
64, are arranged between the shafts 34 and 50 and the housing 35
and cooperatively associated with the solenoid actuator 37. In the
illustrated preferred embodiment of the signaler 32, the
shaft-positioning means 64 include a first pair of
radially-directed cam-supporting arms, as at 65 and 66, which, as
best seen in FIG. 3B, are mounted on opposite sides of the
elongated inner shaft 50 and respectively projected through a pair
of circumferentially-oriented slots 67 and 68 formed on opposite
sides of the tubular outer shaft 34. For reasons which will
subsequently be explained, a second pair of similar or identical,
oppositely-directed cam-supporting arms 69 and 70 (FIG. 3C) are
arranged on the elongated inner shaft 50 and projected through a
second opposed set of circumferentially-oriented slots 71 and 72 in
the wall of the turbine shaft 34 a short distance below the outer
slots 67 and 68.
The shaft-positioning means 64 further include first and second
pairs of oppositely-directed cam-supporting arms, as at 73-76 in
FIGS. 3B and 3C, which are secured on the exterior of the turbine
shaft 34 between the respective ends of the several slots 67, 68,
71 and 72 and in circumferential alignment with the other
cam-supporting arms 65, 66, 69 and 70 respectively. It should be
noted that although the upper and lower slots, as at 67 and 68, are
longitudinally aligned, the lower cam-supporting arms 75 and 76 are
angularly offset in relation to the upper arms 73 and 74. Rotatable
cam members 77-80 are respectively supported by an operative
linkage arrangement between the outer ends of the cam-supporting
arms 65, 66, 69, 70 and 73-76 so that radially-directed inward and
outward movements of the cam members 77-80 will be effective for
turning the elongated inner shaft 50 back and forth in relation to
the outer turbine shaft 34 through an arc of travel corresponding
to that required for selectively moving the port-obstructing member
36 between its two operating positions.
In the preferred embodiment of the signaler 32, this arcuate
rocking movement of the elongated shaft is accomplished by
rotatably journaling each cam member, as at 77, in an upright
position between the outer ends of a pair of toggle links, as at 81
and 82, and pivotally coupling the inner end of the first link to
the outer end of one of the cam-supporting arms, as at 73, on the
turbine shaft 34 and pivotally coupling the inner end of the second
link to the outer end of the adjacent cam-supporting arm, as at 65,
on the inner shaft 50. Accordingly, it will be appreciated that by
moving the cam rollers, as at 77 and 78, inwardly and outwardly
between their outermost positions (as viewed in FIG. 3B) and their
innermost positions (as viewed in FIG. 5B), the inner shaft 50 will
be correspondingly rocked in relation to the outer shaft 34 between
its respective angular positions.
From the preceding discussion, it will be recognized, therefore,
that the positioning of the port-obstructing member 36 is dependent
upon the radial positions of the cam rollers, as at 77 and 78.
Accordingly, to control the radial positioning of the several cam
rollers 77-80, a tubular cam follower 83 is coaxially disposed
within the housing 35 and adapted for limited longitudinal movement
therein between a lower operating position as illustrated in FIG.
2B and an upper operating position as illustrated in FIG. 4B. By
means, such as a longitudinal spline-and-groove arrangement 84, the
cam follower 83 is prevented from rotating relative to the housing
35. To selectively shift the cam follower 83 between its upper and
lower operating positions, the solenoid actuator 37 is provided
with a longitudinally-reciprocating tubular plunger 85 which is
coaxially disposed around the shafts 34 and 50 within an annular
solenoid coil 86 and coupled to the cam follower as by a
transversely-oriented spider 87.
It should be recognized that so long as mud is being pumped through
the tool 20, the turbine impeller 31 will be rotating the turbine
shaft 34 so as to continuously drive the generator 29 (FIG. 1).
Similarly, in either operating position of the port-obstructing
member 36, the elongated shaft 50 will also be rotating by virtue
of the engagement of the cam-supporting arms, as at 65, against one
or the other ends of the elongated slots, as at 67. Accordingly,
throughout the operation of the new and improved tool 20, the
several cam rollers 77-80 will also be rotating in their respective
coaxial orbits about the longitudinal axis of the tool. It should
also be noted that when the elongated shaft 50 is in the angular
position relative to the turbine shaft 34 depicted in FIGS. 3A-3C,
the upper cam rollers 77 and 78 will be rotating in their
maximum-diameter orbit and the lower cam rollers 79 and 80 will be
rotating in their minimum-diameter orbit. Conversely, when the
elongated shaft 50 is in its other angular position with respect to
the turbine shaft 34, the upper cam rollers 77 and 78 will now be
in their minimum-diameter orbit and the lower cam rollers 79 and 80
will be in their maximum-diameter orbit as shown in FIGS.
5A-5C.
Accordingly, it will be recognized that the internal bore of the
tubular cam follower 83 must be cooperatively arranged to
progressively move each associated pair of the orbiting cam rollers
77-80 inwardly and outwardly as the cam follower is selectively
shifted between its upper and lower operating positions. To
understand the cooperative operation of the shaft-positioning means
64, it is believed best to first consider the action of only of the
cam rollers, as at 77. First of all, as best illustrated in FIGS.
2B and 3B, the cam roller 77 is depicted there as being in its
maximum-diameter orbit. As a result, the immediately-adjacent
internal surface, as at 88, of the cam follower 83 must be of a
corresponding and uniform diameter that will allow the cam roller
77 to roll smoothly around this surface through a full circle. On
the other hand, after the cam follower 83 has been shifted upwardly
(by energization of the solenoid actuator 37) to its elevated
operating position shown in FIG. 4B, the cam roller 77 will now be
rotating in its minimum-diameter orbit and the adjacent internal
surface, as at 89, of the cam follower must have a
correspondingly-reduced uniform diameter as shown in FIG. 5B. It
will, of course, be recognized that both the maximum-diameter
cam-guiding surface 88 and the minimum-diameter cam-guiding surface
89 must be coaxially distributed around the longitudinal axis of
the tool 20.
It will, therefore, be appreciated that since the cam roller 77 is
continuously rotating within the non-rotating cam follower 83, the
cam roller must follow a spiraling path as it progressively moves
between the upper and lower cam-guiding surfaces 88 and 89 upon
shifting of the cam follower to one or the other of its operating
positions. Accordingly, a suitably-configured spiraling path or
cam-guiding surface, as at 90 and 91, is appropriately formed along
the internal surface of the cam follower 83 between the upper and
lower uniform-diameter cam-guiding surfaces 88 and 89. Thus, for
example, upon energization of the solenoid actuator 37, as the cam
follower 83 is shifted upwardly from its lower position to its
upper operating position, the cam roller 77 will be continuously
rotated through a steadily-reducing spiraling orbit as it
progressively moves from the large-diameter surface 88, along the
spiraling guide surfaces 90 and 91, and onto the intermediate
reduced-diameter cam-guiding surface 89.
Although only the cam roller 77 and its associated supporting
elements are essential for accomplishing the objects of the present
invention, it has been recognized that more-reliable or stable
operation can be achieved by providing the second
oppositely-directed cam roller 78 to work in conjunction with the
first roller. However, it will be appreciated that since the upper
cam rollers will always be rotating in precisely the same orbit,
the cam roller 78 cannot be rolled along the same spiral path, as
at 90 and 91, that the cam roller 77 is rolling over since the
rollers are on opposite sides of the shafts 34 and 50. Accordingly,
to accommodate the cam roller 78, a second spiraling path or
cam-guiding surface, as at 92 and 93, is formed along the internal
bore of the cam follower 83 between the enlarged-diameter and
reduced-diameter surfaces 88 and 89. This second spiraling path is
simply oriented 180.degree. out of phase with the first spiraling
path so that at any given longitudinal position of the cam follower
83, there will be an equal distance or radius between the
longitudinal axis of the tool 20 and the diametrically-opposite
points on the first and second spiraling paths.
It will be appreciated, therefore, that upon upward shifting of the
cam follower 83 by energization of the solenoid actuator 37, the
upward travel of the cam follower will be effective for positively
retracting the opposed cam rollers 77 and 78 as they respectively
roll along their associated cam-guiding paths, as at 90 and 92, to
the reduced-diameter cam-guiding surface 89. This action will, of
course, serve to positively shift the port-blocking member 36 from
its non-obstructing position shown in FIG. 3A to its
port-obstructing position shown in FIG. 5A.
On the other hand, upon return of the solenoid plunger 85 to pull
the cam follower 83 back to its lower operating position (along
with the assistance of a cam-follower spring 94 normally biasing
the cam follower toward that position) the opposed cam rollers 77
and 78 will not be positively returned to their respective extended
positions. Accordingly, should there be unwanted restraint of the
relative angular movement between the shafts 34 and 50, the
signaler 32 could become inoperative. Therefore, to assure positive
angular shifting of the inner shaft 50 in relation to the outer
shaft 34 upon retraction of the cam follower 83, the lower half of
the cam follower is shaped exactly like the upper half and faced in
the opposite direction. Thus, as depicted in FIG. 2B, the cam
follower 83 is provided with a lower, enlarged-diameter cam-guiding
surface 95 which is of the same diameter as its counterpart surface
88. Similarly, separate intertwined and spiraling cam-guiding
surfaces, as at 96 and 97, are provided within the lower half of
the cam follower 83 for selectively guiding the cam rollers 79 and
80 between the uniform-diameter guiding surfaces 89 and 95.
It will be appreciated, therefore, that upon downward movement of
the cam follower 83, the lower cam rollers 79 will be positively
retracted as they are progressively moved inwardly by the
ever-decreasing diameters of their respective spiraling guide
surfaces 96 and 97. This positive action will, of course, assure
angular repositioning of the inner shaft 50 and the
port-obstructing member 36 as well as serve to return the upper cam
rollers 77 and 78 to their respective extended positions. Thus, in
the depicted preferred embodiment of the signaler 32, upon upward
shifting of the cam follower 83, it is the upper cam rollers 77 and
78 that positively shift the port-obstructing member 36 to its
port-obstructing position shown in FIG. 5A. Conversely, upon return
of the cam follower 83 to its lower operating position by
de-energization of the solenoid actuator 37, it is the lower cam
rollers 79 and 78 which positively return the port-obstructing
member 36 to its port-unblocking position shown in FIG. 3A.
Accordingly, it will be recognized that the selective operation of
the solenoid actuator 37 by the encoder 29 (FIG. 1) will be
effective for correspondingly producing data-encoded pressure
pulses in the mud stream flowing through the new and improved tool
20 of the present invention. With the port-obstructing member 36 in
its port-opening position depicted in FIG. 3a, the flowing stream
of drilling mud is uniformly divided between the several fluid
passages, as at 38 and 39, in the turbine impeller 31 for
continuously driving the generator 29 (FIG. 1). The pressure at the
surface end of the drill string 21 will be at a relatively-reduced
level corresponding to the flow conditions at that moment.
Energization of the solenoid actuator 37 by the data encoder 28
will, however, be effective for angularly repositioning the
port-obstructing member 36 to its port-blocking position as
depicted in FIG. 5A. When this occurs, the entire mud stream will
be diverted through the two remaining unblocked ports, as at 40.
Thus, since the overall flow at this point in the new and improved
tool 20 is thereby reduced to about half of its maximum-available
area, there will be a corresponding detectable increase in the
pressure of the flowing mud at the surface end of the drill string
21 (FIG. 1) so long as the flow of drilling mud is partially
obstructed. This change in pressure will, of course, be detected
and recorded on the surface apparatus 33. It will, of course, be
recognized that the turbine impeller 31 will continue to rotate and
the generator 29 will continue to provide power to the new and
improved tool 20. Experience has shown that a massive flywheel (not
shown) on the generator shaft 30 will effectively smooth out any
voltage fluctuations which might occur under even widely-varying
flow conditions.
Turning now to FIGS. 6 and 7, an alternative embodiment is shown of
a new and improved acoustic signaler 100 which also incorporates
the principles of the present invention, with FIG. 7 being
significantly enlarged in order to better illustrate certain
preferred constructional details. It will, of course, be recognized
that the alternative signaler 100 can be substituted for the
signaler 32 previously described with reference to the tool 20. In
general, the new and improved signaler 100 employs a multi-bladed
impeller 101 having a number of radially-projecting blades, as at
102 and 103, which are each rotatably journalled around an enlarged
hub 104 and cooperatively arranged for simultaneous movement about
their respective axis between selected pitch angles. To accomplish
the selective pitch adjustment of the multi-bladed impeller 101,
blade-positioning means, as shown generally at 105, are arranged
within the enlarged hub 104 and cooperatively coupled to a solenoid
actuator 106 which is respectively operated by encoded electrical
data signals such as those supplied by the encoder 28 (FIG. 1).
As illustrated in FIG. 6, the new and improved signaler 100 is
coaxially mounted within a tubular tool body 107 (which is, of
course, similar or idential to the body 25 of the tool 20) with the
multi-bladed impeller 101 facing the downflowing mud stream. The
enlarged hub 104 is mounted on the upper end of an elongated shaft
108 which is coaxially journalled, as by one or more bearings 109
and 110, within a tubular housing 111 that is coaxially mounted
within the tool body 107 so as to define an annular passage 112 to
conduct the drilling mud on to a drill bit (not shown) dependently
coupled to the lower end of the tool body. The lower end of the
elongated shaft 108 is cooperatively coupled, as at 113, to the
upper end of the shaft 114 of a generator (not shown) mounted a
short distance therebelow in the housing 107.
To provide a suitable fluid seal around the upper end of the
elongated shaft 108, annular inserts 115 and 116 of a hardened
material are respectively mounted coaxially around the lower face
of the hub 104 and the upper end of the housing 111. Unbalanced
axial loads which are imposed on the multi-bladed impeller 101 are
carried by the bearing 109. For the same reasons as previously
discussed in relation to the signaler 32, the upper portion of the
elongated hub 104 is appropriately shaped to define an oil
reservoir 117 which has a floating piston 118 disposed therein for
maintaining the oil-filled housing 111 at borehole pressure as well
as for accommodating volumetric changes of the oil in the
system.
As best seen in FIGS. 7-9, each of the impeller blades, such as at
102, is pivotally mounted on the enlarged hub 104 and adapted for
rotation about the longitudinal axis of the blade. In the preferred
manner of accomplishing this, the central portion of the hub 104 is
shaped to define flat outwardly-facing surfaces, as at 119 and 120,
which (with four impeller blades) are uniformly distributed at
intervals of 90.degree. around the hub. Each impeller blade, as at
102 is formed with an enlarged, generally-hemispherical base, as at
121, adapted for sliding movement on its associated flat, as at
119, of the hub 104 and an inwardly-projecting tubular shank, as at
122. As best seen in FIG. 9, each of these shanks, as at 122, is
journalled in the hub, as by a bearing 123, and cooperatively
coupled to the hub by a bolt, as at 124, having its enlarged head
captured in the shank. The threaded portion of each bolt, as at
125, is in turn passed through elongated openings, as at 126 and
127, in the sides of the enlarged upper end 128 of an elongated
tubular rod 129 and threadedly coupled to a cylindrical support
block 130 that is slidably disposed within the enlarged rod end.
The tubular rod 128 is itself coaxially disposed for sliding
longitudinal movement within an elongated counterbore 131 formed in
the upper portion of the impeller shaft 108. Friction between the
heads of the bolts, as at 124, and the blade shanks, as at 122, is
minimized by a Bellville washer, as at 132. It will also be noted
that the outer ends of the hollow shanks, as at 122, are fluidly
sealed, as at 133, so that oil in the interior of the impeller
shaft 108 will lubricate the heads of the bolts and the bearings,
as at 124.
Accordingly, it will be recognized that by virtue of the bearings,
as at 123, the several impeller blades, as at 102 and 103, are each
rotatable about a radially-oriented lateral axis and that the
bolts, as at 124, simply act as axles as well as serve to retain
the blades on the hub 104. Thus, each of the impeller blades, as at
102 and 103, is capable of free rotation about its own radial axis
as necessary when the pitch angles of the blades are to be
changed.
To provide selective adjustment of the minimum and maximum pitch
angles of the several impeller blades, as at 102 and 103, the
elongated tubular rod 129 is extended on through the counterbore
131 in the impeller shaft 108 and cooperatively engaged with a
longitudinally-reciprocating tubular plunger 134 that is coaxially
disposed around the lower portion of the impeller shaft and
operatively positioned within the annular solenoid coil 135 of the
solenoid actuator 106. To couple the plunger 134 to the tubular
operating rod 129, elongated openings, as at 136, are formed in the
sides of the impeller shaft 108 and a transverse pin or screw 137
is connected between the lower end of the rod and a collar 138
slidably mounted around the impeller shaft just above the upper end
of the plunger. A compression spring 139 is cooperatively engaged
with the upper end of the elongated rod 129 for biasing the
slidable collar 138 downwardly into engagement with the upper end
of the solenoid plunger 134. This arrangement will, of course, be
effective for transferring the reciprocating movements of the
solenoid plunger 134 to the elongated operating rod 129.
As best seen in FIG. 8, the pitch angles of the several impeller
blades, as at 102, are preferably controlled by cooperatively
arranging camming means such as eccentrically-positioned lugs, as
at 140, on the inner ends of the shanks, as at 122, which are
respectively positioned in the elongated openings, as at 126 and
127, on the enlarged head 128 of the operating rod 129. It will be
appreciated that since the openings, as at 126 and 127, are sized
and laterally offset to accommodate both the bolt, as at 125,
carrying a blade, as at 102, as well as the lug, as at 140, on the
shank 122 of that blade, longitudinal movement of the operating rod
129 will be effective for selectively engaging either the upper
edge 141 or the lower edge 142 of each opening with the sides of
each of the eccentric lugs. Thus, as viewed in FIG. 8, upward
travel of the operating rod 129 will be effective for
simultaneously turning the several impeller blades, as at 102, in a
counter-clockwise direction (as shown by the arrow 143); and
downward travel of the operating rod will simultaneously turn the
four blades in the opposite direction (as shown by the arrow
144).
It will, of course, be appreciated that to accomplish the objects
of the present invention, two factors are involved in the selective
positioning of the impeller blades, as at 102 and 103. First of
all, the impeller blades, as at 102 and 103, must always be pitched
for producing sufficient torque to effectively drive the generator,
as at 29, of the new and improved tool 100. Secondly, to produce
detectable data-encoded pressure signals at the surface, the
impeller blades, as at 102 and 103, must be selectively arranged so
that in one operating position of the solenoid actuator 106, there
will be a significantly-increased obstruction to the flowing
drilling mud in comparison to the flow obstruction at the other
operating position of the solenoid actuator.
It will be recognized that if the impeller blades, as at 102 and
103, were successively turned from a 0.degree. pitch angle (i.e.,
where the surfaces of the blades are generally parallel to the flow
of mud) to a 90.degree. pitch angle (i.e., where the blades are
turned to present a maximum obstruction to the flow of mud), the
torque developed by the impeller 101 would progressively vary as
graphically illustrated at 145 in FIG. 10. Thus, maximum torque
output of the impeller 101 will ordinarily occur at or near a pitch
angle of 45.degree.. On the other hand, as graphically shown at 146
in FIG. 10, the pressure drop across the multi-bladed impeller 101
will progressively rise in a geometrical relationship as the
several impeller blades, as at 102 and 103, are successively turned
in unison from a 0.degree. pitch angle to a 90.degree. pitch angle.
It will, therefore, be recognized that by alternatively positioning
the several turbine blades, as at 102 and 103, at two
widely-divergent pitch angles, .THETA..sub.1 and .THETA..sub.2, the
differential, as at 147, in flow obstruction between the two pitch
angles will be sufficiently great for producing a detectable change
in pressure or an encoded pressure signal at the surface end of the
drill string, as at 21 in FIG. 1.
As indicated in FIG. 10, in the preferred manner of practicing the
present invention, it is believed best to select the two pitch
angles, .THETA..sub.1 and .THETA..sub.2, to respectively be
somewhat less and somewhat greater than 45.degree. so that the
torque developed by the impeller 101 will be substantially uniform
at each of these two blade settings. At these two pitch angles
.THETA..sub.1 and .THETA..sub.2, the differential 147 between the
corresponding pressure drops at each of these pitch angles will be
selected as required for producing encoded pressure pulses of a
desired magnitude at the surface.
Referring again to FIGS. 6 and 7, it will, of course, be
appreciated that the overall maximum travel of the solenoid plunger
134 and the operating rod 129 will be determined by the
longitudinal distance between an upwardly-facing shoulder 148 on
the impeller shaft 108 just below the plunger and a
downwardly-facing shoulder 149 as defined by the upper edges of the
lateral openings, as at 136, in the impeller shaft. Moreover, it
will be recognized that the span of longitudinal travel as
determined by the spacing between those two shoulders 148 and 149
will be directly related to the overall change in the pitch angle
that will be attained as the solenoid plunger 134 moves between its
upper and lower operating positions. Similarly, it will be
recognized that the actual minimum pitch angle, as at
.THETA..sub.1, will be determined by the actual non-energized
position of the solenoid plunger 134 and that the actual maximum
pitch angle, as at .THETA..sub.2, will be determined by the actual
energized position of the solenoid plunger.
Accordingly, to provide sufficient latitude for selectively
establishing the overall pressure differential between the maximum
and minimum pitch angles of the impeller 101 as well as for
pre-setting the actual pitch angle at each end of this differential
scale, the new and improved signaler 100 is arranged so that one or
more selected stop members or sets of shims, as at 150 and 151, can
be respectively mounted on the signaler. For example, one or more
shims, as at 150, can be mounted on the impeller shaft 108 on top
of the shoulder 148 for selectively increasing the lower pitch
angle as well as reducing the overall differential between the
lower and upper pitch angles, .THETA..sub.1 and .THETA..sub.2, of
the impeller 101. Similarly, one or more shims, as at 151, can be
coaxially mounted on the impeller shaft 108 between the collar 138
and the upper end of the solenoid plunger 134 for reducing the
maximum-available upper pitch angle as well as reducing the overall
differential between the pitch angles .THETA..sub.1 and
.THETA..sub.2. Thus, it will be recognized that the new and
improved signaler 100 can be pre-adjusted at the surface to
establish both the amplitude of its output pressure signals as well
as the torque output for driving an electrical generator, as at 29,
in the previously-discussed tool 20.
In the practice of the present invention, it will, of course, be
recognized that with either the signaler 32 or the signaler 100,
the down-flowing mud stream will be effective for continuously
driving the electrical generator, as at 29, in FIG. 1; and, as
either of these signalers is operated, the mud stream will be
selectively obstructed in accordance with successive changes in the
one or more downhole conditions measured by the measuring devices
26 and 27 for producing corresponding data-encoded pressure signals
in the mud stream. These signals are, of course, respectively
detected and decoded at the surface by the equipment 33.
It should be appreciated that with the preferred embodiment of the
signaler 32, the mud stream is alternately divided into either two
or four individual streams depending upon the angular position of
the port-obstructing member 36. This alternate division of the mud
streams will, of course, determine whether or not the overall mud
flow is being substantially obstructed; and by selectively
controlling the degree of this flow obstruction in accordance with
the downhole conditions or formation characteristics being measured
by the measuring devices 26 and 27, corresponding encoded pressure
signals will be produced in the flowing mud stream without
significantly impairing the continued generation of sufficient
electrical power for the downhole electrical components in the tool
20.
In a similar fashion, the operation of the alternative embodiment
of the apparatus of the present invention as exemplified by the
signaler 100 will result in the mud stream always being divided
into four streams (assuming, of course, the use of the depicted
four-bladed impeller 101), with each of these four streams being
simultaneously obstructed further as the solenoid actuator 106 is
operated. Thus, hereagain, a data-encoded pressure signal will be
produced in the flowing mud stream in accordance with the one or
more borehole conditions for formation properties being measured by
the one or more measuring devices, as at 26 and 27, included with
the tool 20. There is, of course, no reduction in the
power-generating capacity of the signaler 100 as these signals are
produced.
Accordingly, it will be appreciated that the present invention has
provided new and improved apparatus for reliably producing coded
acoustic signals which are representative of one or more measured
borehole or formation characteristics while simultaneously
providing sufficient downhole electrical power. In contrast to the
prior-art, the new and improved apparatus of the present invention
have also uniquely reduced the overall power requirements of the
downhole components of the signal transmission system by a
significant amount since, for example, these new and improved tools
do not require a motor for driving a downhole signaler. It should
also be recognized that the principles of the present invention are
not limited to so-called "measuring-while-drilling" applications.
Thus, it should be understood that either of the two disclosed
embodiments of the invention could alternatively be installed in a
stationary pipe string such as a string of production tubing for
transmitting signals representative of one or more downhole
conditions by way of the up-flowing connate fluids.
While only particular embodiments of the present invention have
been shown and described, it is apparent that changes and
modifications may be made without departing from this invention in
its broader aspects; and, therefore, the aim in the appended claims
is to cover all such changes and modifications as fall within the
true spirit and scope of this invention.
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