U.S. patent number 3,764,969 [Application Number 05/263,023] was granted by the patent office on 1973-10-09 for well bore data - transmission apparatus with debris clearing apparatus.
This patent grant is currently assigned to Schlumberger Technology Corporation. Invention is credited to Walter E. Cubberly, Jr..
United States Patent |
3,764,969 |
Cubberly, Jr. |
October 9, 1973 |
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 mounted within a drill string for directing
drilling fluids flowing through the apparatus along one or more
selected flow paths toward a second ported or grooved cylindrical
member which is coaxially mounted 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 the first 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 rotating member which would otherwise occur should debris
carried in the circulating drilling fluid become lodged between the
two signal-producing members, the rotating member is cooperatively
mounted on the motor shaft to move away from the fixed member
either in response to a significant increase of the pressure
differential across the two members or in response to a significant
increase in rotative torque as might occur by an accumulation of
debris or the like between the two members tending to at least slow
the rotating member. Biasing means are further provided to maintain
the rotating member in its normal position as well as to restore
the rotating member to its normal operating position adjacent to
the second member once the debris has been cleared from between the
signal-producing members by the continued flow of the drilling
fluid.
Inventors: |
Cubberly, Jr.; Walter E.
(Houston, TX) |
Assignee: |
Schlumberger Technology
Corporation (New York, NY)
|
Family
ID: |
23000061 |
Appl.
No.: |
05/263,023 |
Filed: |
June 15, 1972 |
Current U.S.
Class: |
367/84;
175/232 |
Current CPC
Class: |
E21B
47/18 (20130101); E21B 47/20 (20200501) |
Current International
Class: |
E21B
47/18 (20060101); E21B 47/12 (20060101); G01v
001/40 () |
Field of
Search: |
;340/18LD,18NC
;175/40,232 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Borchelt; Benjamin A.
Assistant Examiner: Birmiel; H. A.
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 flow 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; and
second means operable upon at least slowing of said second member
below said selected speed in response to either an increased
pressure differential across said signal-producing members or an
increase in driving torque on said second member for momentarily
separating said signal-producing members 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 means cooperatively coupling said second
member to said motor for rotation thereby as well as for movement
relative thereto between an operating position adjacent to said
first member and a debris-clearing position more distant therefrom;
and said second means include biasing means cooperatively arranged
for normally urging 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 said second
member for allowing said second member to move at least momentarily
toward its said debris-clearing position.
3. The apparatus of claim 1 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.
4. The apparatus of claim 1 wherein said first means include a
rotatable motor, a rotatable shaft drivingly coupled to said motor,
and 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 said second
means include first biasing means normally biasing said second
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
second member to move at least momentarily toward its said
debris-clearing position, and second 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.
5. The apparatus of claim 4 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 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; and
coupling 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 either when there is an increase in pressure differential
across said signal-producing member or when there is an increase in
driving torque on said signal-producing member to allow such debris
to be carried downstream of said flow director by drilling fluids
flowing through said fluid passage.
8. The apparatus of claim 7 wherein said flow director is fixed
within said fluid passage.
9. The apparatus of claim 7 further including control means coupled
to said 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.
10. The apparatus of claim 9 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.
11. The apparatus of claim 7 wherein said coupling means include a
rotatable shaft member cooperatively coupled to said motor means
for rotation thereby, and a coupling arranged between said shaft
member and said signal-producing member, first guide means
cooperatively arranged between said coupling and one of said
members and including a first guide and means defining a first
guide path extending between longitudinally spaced first positions,
second guide means cooperatively arranged between said coupling and
the other of said members and including a second guide and means
defining a second guide path extending between longitudinally
spaced second positions, first biasing means between said coupling
and said one member normally urging said one member toward said
flow director and yieldable in response to an increase in pressure
differential across said signal-producing member for allowing said
one member to move at least momentarily along said first guide path
away from said flow director, and second biasing means between said
coupling and said other member normally urging said other member
toward said flow director and yieldable in response to an increase
in rotative torque to drive said signal-producing member for
allowing said other member to move at least momentarily along said
second guide path away from said flow director.
12. The apparatus of claim 11 wherein one of said guide paths is
helically configured.
13. The apparatus of claim 11 wherein said one member is said shaft
member and said other member is said signal-producing member.
14. The apparatus of claim 13 wherein said coupling is a tubular
member coaxially disposed around said shaft member and within said
signal-producing member, and said second guide path is a generally
helical passage defined around said tubular coupling member so that
upon yielding of said second biasing means said signal-producing
member will move in a generally helical path along said tubular
coupling member away from said flow director.
15. The apparatus of claim 14 wherein said first guide path is a
generally longitudinal passage so that upon yielding of said first
biasing means said tubular coupling member and said
signal-producing member will move in a generally longitudinal path
along said shaft member away from said flow director.
16. 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 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, 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;
first means cooperatively coupling said flow-obstructing member to
said motor for rotation thereby at 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 away from said flow-directing
member upon slowing of said flow-obstructing member to clear
fluid-borne debris from between said members; and
second means responsive to an increased pressure differential
across said flow-obstructing member for moving one of said members
away from the other of said members upon slowing of said
flow-obstructing member to clear such fluid-borne debris from
between said members.
17. The apparatus of claim 16 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.
18. The apparatus of claim 16 wherein said flow-obstructing member
is downstream of said flow-directing member.
19. The apparatus of claim 16 wherein said one member is said
flow-obstructing member; said first means include a rotatable shaft
coupled to said motor, and means co-rotatively coupling said
flow-obstructing member to said shaft; and said second means
include means operable upon increased pressure differentials across
said members for shifting said flow-obstructing member along said
shaft away from said flow-directing member and operable upon the
subsequent decrease in such increased pressure differentials for
shifting said flow-obstructing member along said shaft toward said
flow-directing member.
20. The apparatus of claim 19 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.
21. The apparatus of claim 16 wherein said flow-directing member is
fixed in relation to said body and is coaxially arranged in said
fluid passage upstream of said flow-obstructing member.
22. 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 thereo 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
means adapted for selectively driving said signal-producing member
including a rotatable shaft member cooperatively coupled to said
motor for rotation thereby, a coupling disposed between said shaft
member and said signal-producing member, first guide means
cooperatively arranged between said coupling and one of said
members and including a first guide and means defining a first
guide path extending between longitudinally spaced first positions,
second guide means cooperatively arranged between said coupling and
the other of said members and including a second guide and means
defining a second guide path extending between longitudinally
spaced second positions, first biasing means between said coupling
and said one member normally urging one member toward said flow
director and yieldable in response to an increase in pressure
differential across said signal-producing member for allowing said
one member to move at least momentarily along said first guide path
away from said flow director, and second biasing means between said
coupling and said other member normally urging said other member
toward said flow director and yieldable in response to an increase
in rotative torque to drive said signal-producing member for
allowing said other member to move at least momentarily along said
second guide path away from said flow director.
23. The apparatus of claim 22 wherein one of said guide paths is
helically configured.
24. The apparatus of claim 22 wherein said one member is said shaft
member and said other member is said signal-producing member.
25. The apparatus of claim 24 wherein said coupling is a tubular
member coaxially disposed around said shaft member and within said
signal-producing member, and said second guide path is a generally
helical passage defined around said tubular coupling member so that
upon yielding of said second biasing means said signal-producing
member will move in a generally helical path along said tubular
coupling member away from 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 borehold 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
arranged to the positioned immediately adjacent to another
flow-controlling member 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 slowing of the motor by solid
materials or debris between the flow-controlling members tending to
either increase the pressure differential across the
flow-controlling members or increase the torque required to drive
the rotating member for temporarily separating the members 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
either a decrease in the pressure differential to its usual
operating range or a decrease in the driving torque for restoring
the flow-controlling members to their signal-producing positions
once debris has been freed from between the two members. Means are
further provided for selectively reversing the rotational direction
of the rotating member as a further aid in clearing debris and
other solid materials from the acoustic signaling means.
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;
FIGS. 3 and 4 are cross-sectional views respectively taken along
the lines 3--3 and 4--4 in FIG. 2; and
FIG. 5 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 borehold 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 meand 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 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 in
FIGS. 2 and 3,the new and improved acoustic signaler 22 includes an
annular ported or internally grooved flow-directing member 27 which
is coaxially arranged within the flow passage 26 and secured to the
body 25 as by a set of complementary threads 28. As will
subsequently be explained in greater detail, in the preferred
embodiment of the acoustic signaling means 20 the flow-directing
member 27 is provided with a plurality of flow passages defined by
inwardly opening longitudinal grooves, as at 29, having a
substantially rectangular or square cross-sectional configuration
which are respectively cut at equal circumferentially spaced
intervals around the interior wall of the flow-directing member
parallel to and at a uniform radius from the longitudinal or
central axis 30 of the tool body 25. To minimize turbulence and
other disturbances to the flow of the downwardly flowing drilling
fluid through the tool 10, the upper face of the flow-directing
member 27 is concavely shaped as at 31.
As best seen in FIGS. 2 and 4, in its preferred embodiment the
acoustic signaler 22 further includes a rotatable ported or
externally grooved flow-obstructing member 32 which is
cooperatively arranged on the upper end of the output shaft 33 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 below the flow-directing member 27. As
illustrated in FIG. 2, the opposed lower and upper faces 34 and 35
of the flow-directing member 27 and the rotating flow-obstructing
member 32, respectively, are preferably made flat so as to
respectively lie in parallel transverse planes which are
perpendicular to the longitudinal axis 30 of the tool body 25 and
are normally spaced a very close distance apart which, in the
preferred embodiment of the present invention, is in the order of
0.020 to 0.030-inches.
As best seen in FIGS. 3 and 4, in the preferred embodiment of the
acoustic signaler 22, the exterior of the rotating flow-obstructing
member 32 is provided with a number of longitudinal grooves 36
which are cooperatively shaped to define a plurality of equally
spaced, outwardly directed radial projections, as at 37,
respectively having a substantially rectangular or square
configuration. Although different dimensions and shapes, relative
numbers, and relative proportions may be used for the grooves 29
and the projections 37 of the flow-controlling members, it is
preferable that the rotating member 32 be substantially
complementally shaped with respect to the interior opening of the
flow-directing member 27. In this manner, when the flow-obstructing
member 32 is angularly oriented with respect to the flow-directing
member 27 so as to align the projections 37 with the grooves 29,
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
grooves 29 and the projections 37 substantially square or
rectangular, rotation of the flow-obstructing rotor 32 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 grooves 29 and the radial
projections 37, 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 32 is slidably mounted
on a sleeve 38 arranged on the shaft 33 and co-rotatively coupled
to the sleeve for rotation relative thereto as by an inwardly
directed spline or lug 39 on the rotating member which is slidably
fitted in a helical groove 40 cooperatively arranged around the
exterior of the sleeve to permit the rotor to be turned along the
sleeve between its normal elevated position as depicted in FIG. 2
and at least one other relatively lower position where the rotor is
more distant from the flow-directing member 27. The sleeve 38 is,
in turn, co-rotatively secured to the shaft 33 by an outwardly
projecting spline 41 on the shaft which is slidably fitted within a
longitudinal groove 42 arranged in the interior bore of the
sleeve.
To define the uppermost position of the rotor 32 in relation to the
stator 27, the upper face of the sleeve 38 is counterbored, as at
43, for complementally receiving an enlarged shoulder 44 on the
uppermost end of the shaft 33 and a shoulder 45 is arranged on the
upper end of the sleeve to engage the upper face 35 of the rotor.
Biasing means, such as a compression spring 46 having a
predetermined spring force mounted in an enlarged space 47 within
the sleeve 38 around the shaft 33 between the gear-reduction unit
23 and the upper end of the sleeve, are cooperatively arranged for
normally urging the sleeve upwardly toward the flow-directing
member so as to normally maintain the opposed faces 34 and 35 of
the flow-controlling members 27 and 32 closely spaced under usual
flow conditions. As depicted, it is preferred that the lower end of
the spring 46 be supported by a fixed shoulder 48 on the shaft 33.
Additional biasing means are also provided for normally maintaining
the flow-obstructing member 32 at the upper end of the sleeve 38.
Although a torsion spring could just as well be used, it is
preferred that the additional biasing means take the form of a
compression spring 49 which is coaxially mounted on the sleeve 38
between an outwardly directed shoulder 50 on the lower end of the
sleeve and the rear face of the flow-obstructing member 32. In FIG.
2, the flow-obstructing member 32 is shown slightly below its usual
operating position (as indicated by the dashed lines at 51) to
clarify the illustration of the invention.
Accordingly, it will be appreciated that the biasing forces
provided by the spring 46 and 49 will be respectively selected to
maintain the flow-controlling members 27 and 32 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 rotating member sufficient to
overcome the upwardly directed biasing action of the spring 46, the
flow-obstructing member 32 will be carried downwardly by the sleeve
38 as the sleeve is moved downwardly along the shaft 33 until such
time that the downwardly acting forces on the rotating member are
countered by the upwardly acting force imposed by the further
compression of the spring. Similarly, should the torque required to
drive the flow-obstructing member 32 exceed the upwardly biasing
force of the spring 49, the flow-obstructing member will be shifted
downwardly along the helical path defined by the groove 40 until
the spring force counters this downward travel.
In the normal course of operation of the acoustic-signaling means
20 of the present invention, the flow-obstructing member 32 will be
rotated at a selected constant speed for producing alternating
acoustic signals having a waveform dictated by the shapes of the
openings 29 and the projections 37 and at a frequency which is
determined by the rotational speed of the rotating member as well
as the member 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 32, 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 32 to provide a given
transmission mode are not necessary for an understanding of the
principles of the present invention.
Accordingly, in the usual situation, the flow-obstructing member 32
is steadily rotated at a speed governed by the operation of the
driving motor 21 with the flow-obstructing member being at its
usual operating position as shown at 51. So long as the
flow-obstructing member 32 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 detection 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 29 in the
flow-directing member 27 and must be carried past the rotating
member 32 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 32 at any
given moment. Thus, when this situation arises with a signaling
device such as that shown in the aforementioned U.S. 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 cooperatively arranged for
operation in 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 29 and 37, which are then aligned and thereby halt the
flow-obstructing member 32 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 sleeve 38 downwardly along its
cooperative spline 41 on the shaft 33 to open an increased flow
area for the passage of debris past the acoustic signaler 22. It
will be recognized that as the sleeve 38 carries the
flow-obstructing member 32 away from the flow-directing member 27,
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 32 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 32 will be
freed and the upwardly directed biasing action of the spring 46
will be effective for returning the sleeve 38 and the rotating
member to their normal positions immediately below the
flow-directing member 27. Thus, the operation of acoustic-signaling
means 20 will continue as before until the acoustic signaler 22
again become temporarily jammed by additional debris.
It should be recognized, however, that downward movement of the
sleeve 38 caused by an increased pressure differential across the
flow-controlling members 27 and 32 is contingent upon the
projections 37 remaining in substantial registration with the
openings 29 such as will be the case when the debris jamming the
signaler 22 is a piece of wire or the like. Thus, should the piece
of debris jamming the flow-controlling members 27 and 32 be a stick
or something of larger diameter, the openings 36 in the rotating
member could well be retained in substantial alignment with the
openings 29 in the fixed member. This would, of course, result in
little or no increase in pressure differential across the
flow-controlling members 27 and 32 so that there would be no
significant force tending to overcome the biasing action of the
spring 46. Accordingly, by virtue of the helical groove 40, should
a piece of larger debris become lodged in the openings 29 and 36,
the continued rotational torque applied to the flow-obstructing
member will be sufficient to carry the rotating member downwardly
along the helical groove and thereby open up the spacing between
the flow-controlling members 27 and 32 sufficiently to hopefully
dislodge the debris.
It should be further noted at this point that there may well be
debris when cannot be dislodge by simply shifting the
flow-obstructing member 32 downwardly in relation to the
flow-directing member 27. 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 32 will simply maintain the debris
in a jamming position. However, by virtue of the ability of the
flow-controlling members 27 and 32 to separate, it will be
appreciated that by reversing the rotation of the motor 21, the
respective openings, as at 29 and 36, 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 30 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 32 will pull the
debris in a different direction and hopefully dislodge the
debris.
In any event, once the piece of jamming debris has been cleared
from the acoustic signaler 22, the flow-obstructing member 32 will
be quickly returned by the springs 46 and 49 to its usual position
at 51 immediately below the flow-directing member 27. 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 32 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 52 such as depicted in FIG. 5 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 53
coupled to typical driver circuits 54 connected to the two windings
of the motor. To accomplish the alternate reversals of the motor
21, a typical reversing switch 55, 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 55, a typical tachometer 56 is
coupled to the shaft 57 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 58, and supplied to one input of a
comparator 59 having a reference voltage, as at 60, supplied to its
other input. The output of the comparator 59 is connected to one
input of a gate, such as NAND gate 61, having its output connected
to the input of a counter 62. The other input of the gate 61 is
connected to one of the outputs of the power supply 53 to provide a
source of pulses. Any selected one of the outputs of the counter 62
is connected to the reversing switch 55. The output of the
comparator 59 is also connected by way of an inverter 63 to one
input of a second gate, such as a NAND gate 64, having its output
connected to the reset input of the counter 62. The other input of
the gate 64 is also connected to the selected output of the power
supply 53.
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 56 of such a magnitude that there will be no output
signal from the comparator 59. This will correspondingly disable
the gate 61 and enable the gate 64 so that there will be no output
pulses supplied to the counter 62 and the counter will remain in a
reset state. Once, however, the motor 21 slows such as when the
acoustic signaler 22 first jams, the output voltage of the
tachometer 56 will drop so as to produce an output signal from the
comparator 59 which, in turn, enables the gate 61 and disables the
gate 64. Once the gate 61 is enabled, the pulses from the power
supply 53 will be supplied to the counter 62. Thus, each time the
number of pulses supplied to the counter 62 reach a number capable
of producing an output signal at the connected output of the
counter, the reversing switch 55 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 62 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 62 which again energizes or
activates the reversing switch 55. Thus, reversal of the motor 21
will be repeated at frequent intervals such as every few seconds or
so as long as the tachometer 56 indicates that the speed of the
motor is below its normal operating speed and accordingly maintains
the gate 61 in an enabled state. Once the speed of the motor 21
again increases, the gate 61 will again be disabled and the gate 64
will again be enabled to reset the counter 62 so that the reversing
switch 55 will again be positioned to return the motor 21 to its
original direction of rotation.
Accordingly, it will be appreciated 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 sliding movement in
relation to its supporting shaft to permit the flow-controlling
members to be separated either in response to increased torque or
increased pressure differential caused by jamming 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 rotating member to its normal position 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.
* * * * *