U.S. patent number RE29,734 [Application Number 05/820,187] was granted by the patent office on 1978-08-15 for well bore data-transmission apparatus with debris clearing apparatus.
This patent grant is currently assigned to Schlumberger Technology Corporation. Invention is credited to Kenneth G. Manning.
United States Patent |
RE29,734 |
Manning |
August 15, 1978 |
Well bore data-transmission apparatus with debris clearing
apparatus
Abstract
In the representative embodiment of the apparatus of the present
invention disclosed herein, a first ported or grooved cylindrical
member is coaxially disposed within a drill string for directing
drilling fluids flowing through the apparatus along one or more
selected flow paths .[.through.]. .Iadd.and .Iaddend.a second
ported or grooved cylindrical member .[.which.]. is coaxially
arranged in the drill string adjacent to the first member for
rotation in a transverse plane cutting the flow paths to cyclically
obstruct these flow paths. An electric motor is cooperatively
coupled by a shaft to the rotatable member for driving this member
at a selected speed for developing an acoustic signal of a desired
frequency as the flow paths are momentarily obstructed at periodic
intervals. To prevent jamming of the flow-controlling members which
would otherwise occur should debris carried in the circulating
drilling fluid become lodged therebetween, the rotating member is
cooperatively coupled to the motor shaft to move away from the
other member in response to significant increase in the torque
required to drive the rotating member. Moreover, upon an increase
of the pressure differential across the two members as might occur
by an accumulation of debris or the like between the two members
tending to at least slow the rotating member, the other member is
arranged to move away from the rotating member. Biasing means are
respectively provided to maintain the flow-controlling members in
their normal positions as well as to restore the two members to
their normal operating positions adjacent to one another once the
debris has been cleared from between the members by the continued
flow of the drilling fluid.
Inventors: |
Manning; Kenneth G. (Houston,
TX) |
Assignee: |
Schlumberger Technology
Corporation (New York, NY)
|
Family
ID: |
23000065 |
Appl.
No.: |
05/820,187 |
Filed: |
July 29, 1977 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
263024 |
Jun 15, 1972 |
03764970 |
Oct 9, 1973 |
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Current U.S.
Class: |
367/83;
175/232 |
Current CPC
Class: |
E21B
47/18 (20130101); E21B 47/20 (20200501) |
Current International
Class: |
E21B
47/12 (20060101); E21B 47/18 (20060101); G01V
001/40 () |
Field of
Search: |
;340/18NC,18LD
;175/40,232 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Birmiel; Howard A.
Attorney, Agent or Firm: Moseley; David L. Sherman; William
R. Roney; Edward M.
Claims
What is claimed is:
1. Apparatus adapted for transmitting data signals from a well bore
to the surface and comprising:
a body adapted for connection in a pipe string and having a fluid
passage arranged to carry debris-bearing fluids between the surface
and well bore;
a first signal-producing member cooperatively arranged in said
fluid passage for directing at least a portion of a fluid flowing
therethrough along at least one selected flow path;
first means including a second signal-producing member
cooperatively arranged in said fluid passage adjacent to said first
member for rotation at a selected speed in a plane transverse to
said flow path for repetitively obstructing said flow path at
periodic intervals to cyclically produce acoustic data signals in a
fluid flowing through said fluid passage;
second means operable upon at least slowing of said second member
below said selected speed in response to an increase in driving
torque on said second member for momentarily separating one of said
signal-producing members to allow fluid-borne solids flowing
through said fluid passage to pass downstream of said
signal-producing members; and
third means operable upon at least slowing of said second member in
response to an increased pressure differential across said
signal-producing members for momentarily separating the other of
said signal-producing members from said one signal-producing member
to allow fluid-borne solids flowing through said fluid passage to
pass downstream of said signal-producing members.
2. The apparatus of claim 1 wherein said first means include a
rotatable motor, and a rotatable shaft drivingly coupled to said
motor; said second means include means cooperatively coupling said
second member to said shaft for rotation thereby as well as for
movement therealong between an operating position adjacent to said
first member and a debris-clearing position more distant therefrom,
and first biasing means normally biasing said second member toward
its said operating position and yieldable in response to an
increased driving torque for said second member characteristic of
the slowing of the rotational speed of said second member for
allowing said second member to move at least momentarily toward its
said debris-clearing position; and said third means include means
cooperatively coupling said first member to said body for movement
in said fluid passage between an operating position adjacent to
said second member and a debris-clearing position more distant
therefrom, and second biasing means normally biasing said first
member toward its said operating position and yieldable in response
to an increased pressure differential characteristic of the slowing
of the rotational speed of said second member for allowing said
first member to move at least momentarily toward its said
debris-clearing position.
3. The apparatus of claim 2 wherein said first biasing means
include spring means urging said second member toward its said
operating position, and means responsive to pressure forces on said
second member urging said second member toward its said operating
position.
4. The apparatus of claim 2 wherein said second biasing ameans
include spring means urging said first member toward its said
operating position, and means responsive to pressure forces on said
first member normally urging said first member toward its said
operating position and responsive to an increased pressure
differential across said signal-producing members for overcoming
said spring means and urging said first member toward its said
debris-clearing position.
5. The apparatus of claim 2 wherein said motor is a
selectively-reversible electric motor; and further including
circuit means responsive to the slowing of said second member for
selectively reversing the rotational direction of said motor.
6. The apparatus of claim 5 wherein said circuit means are
selectively operable for alternately reversing the rotational
direction of said motor back and forth so long as said second
member is slowed below said selected speed.
7. Apparatus adapted for transmitting data to the surface during
the drilling of a borehole and comprising:
a body adapted for connection in a tubular drill string and having
a fluid passage arranged to conduct drilling fluids between the
surface and a borehole-drilling device dependently coupled
therebelow;
a flow director cooperatively arranged for movement in said fluid
passage and including at least one opening for directing drilling
fluids flowing through said fluid passage along a selected
axis;
a signal-producing member coaxially arranged for rotation in said
fluid passage and including a plurality of alternately-disposed
openings and obstructions angularly spaced from one another and
respectively adapted to successively cut across said axis upon
rotation of said signal-producing member for cyclically producing
acoustic data signals in a drilling fluid flowing through said
fluid passage;
motor means adapted for rotating said signal-producing member at at
least one selected rotational speed;
torque-responsive means selectively coupling said motor means to
said signal-producing member and operable in response to at least
slowing of said signal-producing member by fluid-borne debris for
momentarily moving said signal-producing member away from said flow
director when there is an increase in driving torque on said
signal-producing member to allow such debris to be carried away by
drilling fluids flowing through said fluid passage; and
pressure-responsive means normally maintaining said flow director
in an operating position adjacent to said signal-producing member
and operable in response to an increase in pressure differential
across said .[.signal-producing member causing.]. .Iadd.flow
director caused by .Iaddend.at least slowing of said
signal-producing member for momentarily moving said flow director
away from said signal-producing member to allow such debris to be
carried away by drilling fluids flowing through said fluid
passage.
8. The apparatus of claim 7 further including control means coupled
to sid motor means and responsive to slowing of said
signal-producing member below said selected speed for also
rotatively moving said signal-producing member back and forth in
relation to said flow director so long as said signal-producing
member is slowed below said selected speed.
9. The apparatus of claim 8 wherein said motor means include a
reversible electric motor; and said control means include means
operable upon slowing of said motor for producing an electric
signal, and means responsive to said electrical signal for
repetitively reversing said motor.
10. The apparatus of claim 7 wherein said torque-responsive means
include a rotatable shaft cooperatively coupled to said motor means
for rotation thereby, .[.cluth.]. .Iadd.clutch .Iaddend.means
adapted for releasably coupling said shaft to said signal-producing
member for rotation thereby upon rotation of said motor means, and
biasing means cooperatively arranged on said clutch means for
co-rotatively coupling said shaft to said signal-producing member
only so long as the torque developed by said motor means does not
exceed a predetermined magnitude.
11. The apparatus of claim 10 wherein said clutch means include
first and second axially spaced, longitudinally undulating opposed
surfaces respectively arranged around sid shaft and said
signal-producing member, and a plurality of rolling members movably
disposed between said opposed surfaces and adapted to remain
between the more widely spaced portions thereof so long as said
developed torque does not exceed said predetermined magnitude for
maintaining said signal-producing member in close proximity to said
flow director and to move between the more closely spaced portions
of said opposed surfaces when said developed torque exceeds said
predetermined torque for moving said signal-producing member away
from said flow director.
12. 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 producing
electrical signals representative of at least one downhole
condition;
acoustic-signaling means on said body and including an electric
motor coupled to said data-signaling means for selective rotation
in response to said electrical signals, a flow-directing member
operatively disposed in said fluid passage for movement between
longitudinally spaced positions therein and having a plurality of
spaced openings cooperatively arranged for directing drilling
fluids in selected fluid paths along said fluid passage, and a
rotatable flow-obstructing member in said fluid passage and having
a plurality of alternately distributed angularly spaced openings
and obstructions cooperatively arranged to successively cross said
fluid paths upon rotation of said flow-obstructing member for
producing cyclic acoustic signals representative of said electrical
signals in drilling fluids flowing through said fluid passage;
torque-responsive means cooperatively coupling said
flow-obstructing member to said motor for rotation thereby at
.Iadd.at .Iaddend.at least one selected rotational speed and
responsive to an increase in the torque required to maintain said
flow-obstructing member at said selected speed for moving said
flow-obstructing member longitudinally away from said
flow-directing member upon slowing of said flow-obstructing member
to clear fluid-borne debris from between said members; and
differential pressure-responsive means responsive to an increased
pressure differential across said .[.flow-obstructing.].
.Iadd.flow-directing .Iaddend.member for moving said flow-directing
member away from said flow-obstructing member upon slowing of said
flow-obstructing member to cler such fluid-borne debris from
between sid members.
13. The apparatus of claim 12 further including control means
coupled to said motor and responsive to slowing of said
flow-obstructing member below said selected speed for alternately
rotating said motor back and forth in opposite rotative directions
so long as said flow-obstructing member is slowed below said
selected speed.
14. The apparatus of claim 12 wherein said flow-obstructing member
is upstream of said flow-directing member.
15. The apparatus of claim 12 wherein said differential
pressure-responsive means include pressure-biasing means operable
upon increased pressure differentials across said members for
shifting said flow-directing member along said fluid passage away
from said flow-obstructing member and operable upon the subsequent
decrease in such increased pressure differentials for shifting said
flow-directing member along said fluid passage toward said
flow-obstructing member.
16. The apparatus of claim 15 further including control means
coupled to said motor and responsive to slowing of said
flow-obstructing member below said selected speed for alternately
rotating said motor back and forth in opposite rotative directions
so long as said flow-obstructing member is slowed below said
selected speed.
17. The apparatus of claim 12 wherein said flow-directing member is
coaxially arranged in said fluid passage downstream of said
flow-obstructing member.
18. 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 producing
electrical signals representative of at least one downhole
condition;
acoustic-signaling means on said body and including an electric
motor coupled to said data-signaling means for selective rotation
in response to said electrical signals, a flow director coaxially
arranged in said fluid passage and having a plurality of spaced
openings cooperatively arranged for directing drilling fluids in
selected fluid paths along said fluid passage, an annular
signal-producing member coaxially arranged in said fluid passage
and having a plurality of alternately distributed angularly spaced
openings and obstructions cooperatively arranged to successively
cross said fluid paths upon rotation of said signal-producing
member for producing cyclic acoustic signals representative of said
electrical signals in drilling fluids flowing through said fluid
passage; and
torque-responsive means adapted for selectively driving said
signal-producing member including a rotatable shaft coaxially
disposed in said fluid passage and cooperatively coupled to said
motor for rotation thereby, a first transversely oriented coaxial
camming surface on said .[.surface.]. .Iadd.signal
.Iaddend.producing member having a plurality of first undulations
thereon, a second transversely oriented coaxial camming surface on
said shaft opposing said first camming surface and having a
plurality of second undulations thereon substantially complementary
to said first undulations, a plurality of rolling members disposed
between said first and second camming surfaces and in rolling
engagement therewith, and first biasing means for normally urging
said first camming surface toward said second camming surface to
rotate said signal-producing member in a transverse plane adjacent
to said flow director as long as said rolling members are
respectively disposed within opposed valleys of said undulations
and for yielding in response to an increase in driving torque
required by said signal-producing member to rotate said
signal-producing member in a transverse plane more distant from
said flow director as said rolling members are respectively
disposed between opposed inclines of said undulations to clear
fluid-borne debris from between said flow director and said
signal-producing member.
19. The apparatus of claim 18 wherein said first biasing means
include spring means.
20. The apparatus of claim 18 wherein said first biasing ameans
include spring means and pressure-responsive means cooperatively
arranged for urging said signal-producing member toward said flow
director with a force related to the pressure differential across
said signal-producing member.
21. The apparatus of claim 20 wherein said signal-producing member
is upstream of said flow director.
22. The apparatus of claim 18 wherein said flow director is
cooperatively arranged for movement between longitudinally spaced
positions in said fluid passage and further including second
biasing means cooperatively arranged for normally urging said flow
director toward said signal-producing member and responsive to
increased pressure differentials across said .[.signal-producing
member.]. .Iadd.flow director .Iaddend.for yieldably shifting said
flow director away from said signal-producing member to clear
fluid-borne debris from between said flow director and said
signal-producing member.
23. The apparatus of claim 22 wherein said second biasing means
include spring means.
24. The apparatus of claim 22 wherein said second biasing means
include spring means and first pressure-responsive means
cooperatively arranged for urging said flow director toward said
signal-producing member so long as said signal-producing member is
rotating adjacent to said flow director, and second
pressure-responsive means cooperatively arranged for urging said
flow director away from said signal-producing member whenever said
obstructions on said signal-producing member are opposite said
openings on said flow director.
25. The apparatus of claim 24 wherein said first biasing means
include spring means and pressure-responsive means cooperatively
arranged for urging said signal-producing member toward said flow
director with a force related to the pressure differential across
said signal-producing member.
26. The apparatus of claim 25 further including control means
coupled to said motor and responsive to slowing of said
flow-obstructing member below said selected speed for alternately
rotating said motor back and forth in opposite rotative directions
so long as said flow-obstructing member is slowed below said
selected speed.
27. The apparatus of claim 26 wherein said signal-producing member
is upstream of said flow director.
Description
Various downhole signaling devices have been proposed heretofore
for transmitting data representative of one or more downhole
conditions to the surface during the drilling of a borehole. One of
the more-promising devices of this nature is a fluid-dynamic
transducer or a so-called "siren" (such as shown generally at "62"
in U.S. Pat. No. 3,309,656) that is selectively arranged for
developing acoustic signals which are transmitted to the surface
through the circulating mud stream in the drill string. A typical
one of these sirens includes a grooved or ported rotor which is
rotatively driven at one or more selected speeds across one or more
jets of drilling mud issuing from a fixed grooved or ported stator
for producing acoustic signals at frequencies related to the design
of the siren members, the properties of the drilling mud, and the
rotational speed of the rotor. Thus, by selectively controlling the
rotational speed of the rotor in accordance with variations in a
measured downhole condition, the siren can be selectively operated
as required for transmitting coded acoustic signals to the surface
which are representative of the measurements of the downhole
condition.
Although sirens such as these have other advantages, one of the
paramount advantages in using these signaling devices is that
acoustic signals can be efficiently produced thereby within a
frequency span of about 10 to 300-cycles/second. As noted in the
aforementioned patent, frequencies above this range are subject to
significant attenuation; and it is, therefore, preferred to operate
these sirens to produce signals at frequencies between about 10 to
60-cycles/second. Although signaling devices such as these have
shown significant promise for commercial applications, the narrow
spacing between the two siren members required to produce
satisfactory acoustic signals makes these sirens particularly
susceptible to being jammed or easily obstructed either by drilling
mud solids or by well debris and the like which is prevalent in the
circulating mud stream in a typical borehole.
Accordingly, it is an object of the present invention to provide a
new and improved well bore data-transmission system for producing
selectively-coded acoustic signals in a selected frequency range in
debris-bearing well bore fluids such as a circulating stream of
drilling mud.
This and other objects of the present invention are attained by
providing a well tool adapted to be connected in a pipe string such
as a drill string having a drill bit dependently coupled thereto
and arranged for excavating a borehole as a drilling fluid is
circulated through a fluid passage in the tool and the drill
string. To generate distinctive acoustic signals in the circulating
fluid representative of one or more downhole measurements,
acoustic-signaling means on the tool include a
selectively-controlled electric motor rotatively driving a
flow-controlling member which is normally positioned immediately
adjacent to another flow-controlling member slidably arranged
within the fluid passage so as to cyclically vary the degree of
flow obstruction presented by the two flow-controlling members in
cooperation with one another for producing an acoustic signal. The
acoustic-signaling means further include control means responsive
to operating conditions tending to slow the motor, such as either
an increased pressure differential across the flow-controlling
members or an increased requirement in driving torque, for
temporarily separating one or the other of the two members from its
companion so as to allow debris and the like to be carried free of
the two members by the flowing mud stream. The control means are
further responsive to the cessation of the operating condition
causing slowing of the motor, such as a decrease in either the
pressure differential or the driving torque to their usual
operating ranges, for restoring the flow-controlling members to
their respective signal-producing positions once debris has been
carried free of the two members.
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;
FIG. 2 depicts a preferred embodiment of the acoustic signaler
employed with the well tool shown in FIG. 1;
FIG. 3 is a cross-sectional view taken along the lines "3--3" in
FIG. 2; and
FIG. 4 schematically illustrates a representative control circuit
which may be employed in the present invention.
Turning now to FIG. 1, a new and improved well tool 10 arranged in
accordance with the present invention is depicted coupled in a
typical drill string 11 having a rotary drill bit 12 dependently
coupled thereto and adapted for excavating a borehole 13 through
various earth formations as at 14. As the drill string 11 is
rotated by a typical drilling rig (not shown) at the surface,
substantial volumes of the drilling fluid or so-called "mud" are
continuously pumped downwardly through the tubular drill string and
discharged from the drill bit 12 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 13 exterior of the drill
string. As is typical, the mud stream is circulated by employing
one or more high-pressure mud pumps (not shown) which continuously
draw the fluid from a storage pit or surface vessel (not shown) for
subsequent recirculation by the mud pumps. It will be appreciated,
therefore, that the circulating mud stream flowing through the
drill string 11 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-transmitting means 15 are arranged on the well tool 10 and
include one or more condition-responsive devices, as at 16 and 17,
respectively coupled to an appropriate measurement encoder 18
operatively arranged to produce a series of electrical coded data
signals that are representative of the measurements being obtained
by the condition-responsive devices. Although a self-contained
battery power supply could be employed, as shown at 19 it is
preferred to employ a reaction-type turbine driving a generator for
utilizing the circulating mud stream as a motivating source to
generate electric power for operation of the new and improved
data-transmitting means 15. As will subsequently be explained in
greater detail, the data-transmitting means 15 further include
acoustic signaling means 20 including an electric motor 21 coupled
to the encoder 18 and operatively arranged to respond to its coded
output signals for rotatively driving an acoustic signaler 22 by
way of a typical gear train 23 to successively interrupt or
obstruct the flow of the drilling fluid through the drill string
11. The resulting acoustic signals produced by the acoustic
signaler 22 will be transmitted to the surface through the mud
stream flowing within the drill string 11 as encoded
representations or data signals indicative of the one or more
downhole conditions respectively sensed by the condition-measuring
devices 16 and 17. As these data signals are successively
transmitted to the surface, they are detected and converted into
meaningful indications or records by suitable acoustic signal
detecting-and-recording apparatus 24 such as that disclosed in
either U.S. Pat. No. 3,309,656, U.S. Pat. No. 3,488,629, or U.S.
Pat. No. 3,555,504.
Turning now to FIG. 2, a partially cross-sectioned elevational view
is shown of a preferred embodiment of the new and improved acoustic
signaler 22. As seen there, the tool 10 includes a tubular body 25
which is cooperatively arranged in a typical manner with
appropriate end connections (not shown) to allow the body to be
tandemly coupled in the drill string 11. The tubular body 25
includes an axial fluid passage 26 for conducting the drilling
fluid flowing through the drill string 11 to the drill bit 12
therebelow. As illustrated, the new and improved acoustic signaler
22 includes an annular ported or internally grooved flow-directing
member 27 which is coaxially mounted for limited longitudinal
movement around an annular support 28 which is, in turn, arranged
within the flow passage 26 and secured to the body 25 in some
convenient manner. A plurality of flow passages, as at 29, are
arranged in the support 28 below the flow-directing member to
conduct drilling fluids on past the support. As will subsequently
be explained in greater detail, in the preferred embodiment of the
acoustic-signaling means 2:0 the flow-directing member 27 is
provided with a plurality of radially directed teeth or
projections, as at 30, having a substantially rectangular or square
cross-sectional configuration which are respectively distributed
equally around the flow-directing member for defining a plurality
of circumferentially spaced flow passages, as at 31, parallel to
the longitudinal or central axis 32 of the tool body 25.
In its preferred embodiment, the acoustic signaler 22 further
includes a rotatable ported or externally grooved flow-obstructing
member 33 which is cooperatively coupled by torque-responsive means
34 to the upper end of the output shaft 35 of the gear train 23 and
coaxially disposed within the central fluid passage 26 for rotation
in a transverse plane of rotation normally lying immediately above
the flow-directing member 27. The exterior of the rotating
flow-obstructing member 33 is provided with a number of equally
spaced, outwardly directed radial projections, as at 36,
respectively having a substantially rectangular or square
configuration which are cooperatively shaped to define a plurality
of circumferentially spaced longitudinal flow passages 37.
Although different dimensions and shapes, relative numbers, and
relative proportions may be used for the flow passages and the
radial projections of the flow-controlling members, it is
preferable that the projections 36 on the rotating member 33 either
be slightly wider or substantially complemental with respect to the
flow passages 31 of the flow-directing member 27. In the preferred
embodiment of the present invention, the flow-controlling member 27
and 33 are arranged with their respective projections 30 and 36 of
about the same diameter and are closely spaced so that the opposed
flat faces of the projections will be normally separated a distance
in the order of 0.020 to 0.030-inches.
In this manner, when the flow-obstructing member 33 is angularly
oriented with respect to the flow-directing member 27 so as to
align the projections 36 with the passages 31, there will be a
substantial momentary obstruction to the flow of the circulating
mud stream through the tool 10. As pointed out in the
aforementioned U.S. Pat. No. 3,309,656, by making the several
passages 31 and the projections 36 substantially square or
rectangular, rotation of the flow-obstructing rotor 33 in relation
to the flow-directing stator 27 will repetitively obstruct the
fluid passage 26 to a substantial degree and then re-open the
passage as the radial projections are progressively moved into
registration and then out of alignment with the grooves for
producing cyclically-varying sinusoidal pressure signals in the
flowing drilling mud of significant amplitude at the design
fundamental frequency. In other words, by virtue of the rectangular
or square configurations of the flow passages 31 and the radial
projections 36, the effective flow area for the drilling mud
passing through the tool 10 will vary continuously in a linear
fashion so as to minimize the unwanted generation of acoustic
signals of significant amplitudes at high-order harmonic
frequencies.
Of particular significance to the present invention, it will be
appreciated that instead of being fixed to its driving shaft as is
the case for the siren disclosed in the aforementioned U.S. Pat.
No. 3,309,656, the flow-obstructing member 33 is co-rotatively
coupled to the shaft 35 by only the torque-responsive means 34 for
permitting the rotor to also move longitudinally in relation to the
shaft between its normal position as depicted in FIG. 2 and at
least one other relatively-higher position where the rotor is more
distant from the flow-directing member 27. To provide the
torque-responsive means 34, the rotating member 33 is provided with
an inwardly-enlarged portion 38 having a downwardly facing annular
surface 39 which is longitudinally spaced above an upwardly facing
annular surface 40 defined by an enlarged shoulder 41 on the shaft
35. As illustrated, the opposed surfaces 39 and 40 are shaped to
define vertically undulating camming surfaces which extend
completely around the circumference of the shoulders 38 and 41,
respectively, and are maintained apart by a plurality of cam
members such as three balls as at 42. Biasing means, such as a
compression spring 43 have a predetermined spring force mounted
around the shaft 35 between a shoulder 44 thereon and the upper
face of the enlarged portion 38 on the rotating member 33, are
cooperatively arranged for normally urging the rotating member
downwardly toward the flow-directing member 27 so as to normally
maintain the opposed faces of the projections 30 and 36 on the two
members closely spaced under usual flow conditions. As depicted, in
this situation, the balls 42 are respectively retained in enlarged
spaces defined by the opposed undulated surfaces 39 and 40 so as to
maintain the opposed faces of the projections 30 and 36 at their
selected minimum spacing. It will, of course, be recognized that
this close spacing will be maintained only so long as the balls 42
remain in the enlarged spaces defined by the low spots or valleys
of the undulating surfaces 39 and 40. On the other hand, when
rotation of the shaft 35 in relation to the flow-obstructing member
occurs, this slippage will carry the balls 42 between the high
spots or peaks of the undulating surfaces 39 and 40 to elevate the
flow-obstructing member in relation to the shaft and thereby widen
the gap between the flow-controlling members 27 and 33.
As previously mentioned, the flow-directing member 27 is
cooperatively arranged for limited longitudinal movement in
relation to the annular support 28. To accomplish this, the
flow-directing member 27 is preferably shaped as illustrated to
provide an inwardly enlarged upper portion 45 which is disposed
around a reduced-diameter portion 46 of the support 28 and a lower
portion 47 which is disposed around an enlarged-diameter portion 48
of the annular support. One or more inwardly opening, elongated
longitudinal slots, as at 49, are provided around the interior bore
of the flow-directing member 27 for receiving outwardly-projecting
lugs, as at 50, on the annular support 28 so as to correspondingly
limit the longitudinal travel of the flow-directing member in
relation to the support and the body 25. Biasing means are provided
such as a compression spring 51 having a predetermined spring rate
which is arranged between the lower portion 47 of the
flow-directing member 27 and the enlarged portion 48 of the support
28 for normally urging the flow-directing member upwardly against
the lugs 50.
Accordingly, it will be appreciated that the biasing forces
provided by the springs 43 and 51 will be selected to maintain the
flow-controlling members 27 and 33 at their desired longitudinal
spacing in relation to one another for producing acoustic signals
of a desired characteristic during the normal operation of the
acoustic signaler 22. However, should there be a downwardly acting
force on the flow-directing member 27 sufficient to overcome the
upwardly directed biasing action of the spring 51, the
flow-directing member will be moved downwardly along the support 28
until such time that the downwardly acting forces on the
flow-controlling member are countered by the upwardly acting force
imposed by the further compression of the spring. Similarly, should
the rotating member 33 become slowed or halted with a sufficient
force to overcome the biasing force of the spring 43, rotation of
the shaft 35 in relation to the flow-obstructing member will be
effective for carrying the inclined portions of the camming
surfaces 39 and 40 along the balls 42 to elevate the
flow-obstructing member in relation to the shaft 35 as well as the
flow-directing member 27.
Although the springs 43 and 51 could be sized to respectively
provide sufficient biasing forces, it is preferred to augment these
spring forces with pressure-biasing arrangements so as to minimize
the physical sizes of the springs as well as to make the acoustic
signaler 22 more responsive to varying borehole conditions. To
accomplish this, an inverted cylindrical dome, as at 52, is secured
to the upper end of the flow-obstructing member 33 and extended
upwardly well above the upper end of the shaft 35. The dome 52 is
perforated and its interior is lined with an elastomeric bag 53.
Thus, by filling the interior of the bag 53 with a suitable oil or
the like, the oil therein will be maintained at the pressure of the
drilling fluid at that point in the fluid passage 26. It will, of
course, be recognized by those skilled in the art that this
entrapped oil can be directed through suitable passages and
clearance spaces, as at 54 for example, to the other parts of the
acoustic-signaling means 20 for lubrication as well as maintaining
the internal portions of other parts of the system at elevated
pressures to at least minimize the entrance of the drilling
mud.
To provide a pressure-derived downward biasing force on the
flow-obstructing member 33, sealing means, such as an O-ring 55,
are arranged between the flow-obstructing member and the shoulder
41 and the lower end of the shoulder 41 is arranged to maintain a
sliding seal with the upper end 56 of the annular shoulder 28.
Similarly, seals, as at 57 and 58, are arranged between the upper
and lower ends of the flow-directing member 27 and the adjacent
portions 46 and 48 of the support 28 to isolate the oil-filled
slots 49 and the space enclosing the spring 51. A passage 59 is
provided in the flow-directing member to normally maintain the
space between the opposed faces of the flow-controlling members 27
and 33 at the lower downstream pressure of the drilling fluids.
Thus, by virtue of the lower downstream pressure normally existing
in the space between the flow-controlling members 27 and 33, the
higher upstream pressure will be effective for urging the
flow-obstructing member downwardly against the balls 42.
Conversely, the higher pressure of the oil in the enclosed spaces
49 will urge the flow-directing member 27 upwardly with a force
proportional to the difference in the areas sealed by the O-rings
57 and 58. The total upward biasing force is arranged, however, to
be effective only so long as the pressure between the
flow-controlling members 27 and 33 is lower than the upstream
pressure while the acoustic signaler 22 is running without
interruption.
In the normal course of operation of the acoustic-signaling means
20 of the present invention, the flow-obstructing member 33 will be
rotated at a selected constant speed for producing alternating
acoustic signals having a waveform dictated by the shapes of the
openings 31 and the projections 36 and at a frequency which is
determined by the rotational speed of the rotating member as well
as the number of the openings and projections. As various borehole
conditions being measured by the measuring devices 16 and 17 change
during the course of the drilling operation, the data encoder 18
will be effective for controlling the motor 21 so as to produce,
for example, signals of different frequencies such as described in
detail in the aforementioned U.S. Pat. No. 3,309,656. It will, of
course, be appreciated that other signal-transmission modes may
also be employed with the data-transmitting means 15. For example,
by momentarily operating the motor 21 so as to either retard or
advance the rotation of the flow-obstructing member 33, the phase
relationship of the resulting output acoustic signal may be
selectively varied sufficiently either in relation to previous
output signals or in relation to a constant reference signal for
producing other forms of distinctive acoustic signals which are
also representative of the borehole conditions being monitored by
the measuring devices 16 and 17. It will, of course, be appreciated
that the details of such selective regulation of the motor 21 for
driving the flow-obstructing member 33 to obtain different modes of
signal transmission are not necessary for an understanding of the
principles of the present invention.
Accordingly, in the usual situation, the flow-obstructing member 33
is steadily rotated at a speed governed by the operation of the
driving motor 21. So long as the flow-obstructing member 33 is free
to rotate with relation to the flow-directing member 27, the
acoustic signals produced by the acoustic signaler 22 will be
transmitted to the surface by way of the drilling fluid within the
drill string 11 for detecting and recording by the surface
apparatus 24. However, as it is not at all uncommon, debris and the
like which is commonly found in a borehole, such as at 13, during a
typical drilling operation will be swept to the surface along with
the returning drilling mud where significant portions of such
debris will be picked up by the mud pumps and discharged into the
drill string 11. As a result, those skilled in the art will
appreciate that it is quite likely that pieces of wire, sticks, and
other solid foreign materials will, from time to time, enter one or
more of the grooves 37 in the flow-obstructing member 33 and must
be carried past the flow-directing member 27 if rotation of the
rotor is to continue. However, all too frequently, it has been
found that the torque applied to the flow-obstructing member is
insufficient to cut or break debris which is spanning the
flow-controlling members 27 and 33 at any given moment. Thus, when
this situation arises with a signaling device such as that shown in
the aforementioned Pat. No. 3,309,656, the rotor described there
will be easily jammed to halt the further operation of that
signaling device.
In keeping with the objects of the present invention, however, the
new and improved acoustic signaler 22 is co-operatively arranged
for operation of a debris-laden drilling mud. Thus, with the
acoustic-signaling means 20 of the present invention, should debris
such as a piece of wire or a stick become lodged in two openings,
as at 31 and 37, which are then aligned and thereby halt the
flow-obstructing member 33 in a slightly advanced angular position
where these two openings are then substantially out of
registration, the resulting increased pressure differential in the
flowing stream of drilling fluid will be effective for
longitudinally shifting the .[.flow-directiong.].
.Iadd.flow-directing .Iaddend.member 27 downwardly along the
support 28 to open an increased flow area for the passage of
drilling mud past the acoustic signaler 22. When this occurs, the
upstream pressure will be imposed on the upper face of the
projections 30 to develop a sufficient force to momentarily
overcome the spring 51 and the upward pressure-biasing force on the
flow-directing member 27.
It will be recognized that as the flow-directing member 27 moves
downwardly in relation to the flow-obstructing member 33, the motor
21 will correspondingly turn the rotating member slightly as
permitted by the length and rigidity of the piece of debris that is
then lodged in the acoustic signaler 22. In some instances,
separation of the flow-controlling members 27 and 33 will be
sufficient for pulling the piece of jamming debris free of the
flow-directing member so that the continuing flow of the drilling
mud will be effective for washing the debris out of the
flow-obstructing member to restore the rotational freedom of the
rotating member. Thus, once a piece of debris has been cleared from
the acoustic signaler 22, the flow-obstructing member 33 will be
freed and the upwardly directed biasing action of the spring 51
will be effective for returning the flow-directing member 27 to its
normal position immediately below the flow-obstructing member.
Thus, the operation of acoustic-signaling means 20 will continue as
before until the acoustic signaler 22 again becomes temporarily
jammed by additional debris.
It should be recognized, however, that downward movement of the
flow-directing member 27 caused by an increased pressure
differential across the flow-controlling members 27 and 33 is
contingent upon the projections 36 remaining in substantial
registration with the openings 31 such as will be the case when the
debris jamming the signaler 22 is a piece of small-diameter wire or
the like. Thus, should the piece of debris jamming the
flow-controlling members 27 and 33 be a stick or something of
larger diameter, the openings 37 in the rotating member could well
be retained in substantial alignment with the openings 31 in the
flow-directing member. This would, of course, result in little or
no increase in pressure differential across the flow-controlling
members 27 and 33 so that there would be no significant force
tending to overcome the biasing action of the spring 51 and the
pressure-biasing action on the flow-directing member. Accordingly,
by virtue of the torque-responsive means 34, should a piece of
large debris become lodged in the openings 31 and 37, the continued
rotational torque applied to the flow-obstructing member will be
sufficient to carry the rotating member upwardly in relation to the
flow-directing member and thereby momentarily open up the spacing
between the flow-controlling members 27 and 33 sufficiently to
hopefully dislodge the debris.
It should be further noted at this point that there may well be
debris which cannot be dislodged by simply shifting the
flow-controlling members 27 and 33 downwardly or upwardly in
relation to one another as the case may be. Ordinarily, this would
result in a permanent jamming of the acoustic signaler 22 since the
continued torque applied by the motor 21 on the piece of debris
linking the flow-controlling members 27 and 33 will simply maintain
the debris in a jamming position. However, by virtue of the
respective abilities of the flow-controlling members 27 and 33 to
separate, it will be appreciated that by reversing the rotation of
the motor 21, the respective openings, as at 31 and 37, into which
the piece of debris has been lodged can be returned into
registration with one another for momentarily positioning a piece
of jamming debris in a generally parallel relation to the
longitudinal axis 32 so as to hopefully permit the correspondingly
increased flow of drilling mud to dislodge the debris. On the other
hand, should this fail, reverse rotation of the flow-obstructing
member 33 will pull the debris in a different direction and
hopefully dislodge the debris. Repeated back and forth reversal of
the rotating member 33 will also be likely to cut through many
types of debris for ultimately freeing the flow-obstructing
member.
In any event, once the piece of jamming debris has been cleared
from the acoustic signaler 22, the flow-obstructing member 33 will
be quickly returned by its pressure biasing and the spring 43 to
its usual position immediately above the flow-directing member 27
and the balls 42 will again assume their usual position. Similarly,
the flow-directing member 27 will also be returned upwardly by its
pressure biasing and the spring 51. Once this happens, the acoustic
signal will of course, be restored to continue the transmission of
data or information signals to the surface. It should be noted that
clearing of the debris will also flush away any accumulation of
drilling mud solids on the jammed flow-controlling members 27 and
33 which will occur when the two members are halted in a misaligned
position.
It will, of course, be appreciated that various circuits can be
provided to selectively reverse the driving motor 21 for attaining
the objects of the present invention. However, in the preferred
embodiment of the data-transmitting means 15 of the present
invention, motor control circuitry 60 such as depicted in FIG. 4 is
cooperatively arranged for alternately reversing the rotation of
the motor 21 back and forth so long as the speed of the motor is
below a desired speed. As shown there, the motor 21 is a two-phase
induction motor which is selectively driven in either rotational
direction by a conventional two-phase square wave power supply 61
coupled to typical driver circuits 62 connected to the two windings
of the motor. To accomplish the alternate reversals of the motor
21, a typical reversing switch 63, such as a relay or suitable
logic gates, is arranged to selectively reverse the leads to one of
the motor windings.
To control the reversing switch 63, a typical tachometer 64 is
coupled to the shaft 65 of the motor 21 and cooperatively arranged
for producing an output voltage which is proportional to the
rotational speed of the motor. This output voltage is preferably
rectified and filtered as at 66, and supplied to one input of a
comparator 67 having a reference voltage, as at 68, supplied to its
other input. The output of the comparator 67 is connected to one
input of a gate, such as NAND gate 69, having its output connected
to the input of a counter 70. The other input of the gate 69 is
connected to one of the outputs of the power supply 61 to provide a
source of pulses. Any selected one of the outputs of the counter 70
is connected to the reversing switch 63.
Accordingly, in normal operation of the signaler 22, the speed of
the motor 21 will be sufficient to maintain the output voltage of
the tachometer 64 of such a magnitude that there will be no output
signal from the comparator 67. This will correspondingly disable
the gate 69 so that there will be no output pulses supplied to the
counter 70. Once, however, the motor 21 slows such as when the
acoustic signaler 22 first jams, the output voltage of the
tachometer 64 will drop so as to produce an output signal from the
comparator 67 which, in turn, enables the gate 69. Once the gate 69
is enabled, the pulses from the power supply 61 will be supplied to
the counter 70. Thus, each time the number of pulses supplied to
the counter 70 reach a number capable of producing an output signal
at the connected output of the counter, the reversing switch 63
will be energized or activated to reverse the rotation of the motor
21. The pulses will, of course, continue to be supplied to the
counter 70 so long as the speed of the motor 21 is below its normal
range. This will, therefore, accomplish a second reversal of the
motor 21 once there is a subsequent output from the counter 70
which again energizes or activates the reversing switch 63. Thus,
reversal of the motor 21 will be repeated at frequent intervals
such as every few seconds or so as long as the tachometer 64
indicates that the speed of the motor is below its normal operating
speed and accordingly maintains the gate 69 in an enabled state. It
should be noted that rotation of the motor 21 back and forth will
successively raise and lower the flow-obstructing member 33 as the
balls 42 move back and forth along the camming surfaces 39 and
40.
Accordingly, it will be .[.aprpreciated.]. .Iadd.appreciated
.Iaddend.that the present invention has provided new and improved
well bore apparatus for transmitting information or data signals
representative of one or more downhole conditions to the surface
during the course of a drilling operation. By arranging the
acoustic signaling means of the present invention to include a
rotating flow-obstructing member which is cyclically rotated in the
proximity of the flow-directing member as the drilling fluid is
circulated past these members, an acoustic signal of a frequency
related to the design of these members and the rotational speed of
the rotating member is produced. To prevent debris and the like
which is typically carried in a circulating stream of drilling mud
from jamming the signaling means, the rotating member is
cooperatively arranged for rotational and longitudinal movement in
relation to its supporting shaft and the flow-directing member is
slidably mounted in relation to the tool body to permit the
flow-controlling members to be respectively separated thereby
opening the normal close spacing between the two members a
sufficient amount to allow the drilling fluid to wash the debris
free of the acoustic-signaling means. Biasing means are
cooperatively arranged for restoring the flow-controlling members
to their normal positions once the piece of jamming debris has been
cleared from the acoustic-signaling means.
While only a particular embodiment of the present invention has
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.
* * * * *