U.S. patent number 3,764,968 [Application Number 05/263,022] 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 Ronald A. Anderson.
United States Patent |
3,764,968 |
Anderson |
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 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 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 the member at a selected speed to develop an acoustic
signal of a desired frequency as the flow paths are momentarily
obstructed at periodic intervals. To prevent jamming of the
rotating member should debris carried in the circulating drilling
fluid become lodged between the two signal-producing members, the
rotating member is slidably mounted on the shaft to move away from
the fixed member in response to a significant increase of the
pressure differential across the two members as might occur by an
accumulation of debris or the like therebetween tending to at least
slow the rotating member. Biasing means maintain the rotating
member in its normal position as well as restore the rotating
member to its normal operating position adjacent to the fixed
member once the debris has been cleared from between the
signal-producing members by the continued flow of the drilling
fluid. Control means are also provided for alternately reversing
the motor whenever the rotational speed of the motor significantly
decreases.
Inventors: |
Anderson; Ronald A. (Seabrook,
TX) |
Assignee: |
Schlumberger Technology
Corporation (New York, NY)
|
Family
ID: |
23000056 |
Appl.
No.: |
05/263,022 |
Filed: |
June 15, 1972 |
Current U.S.
Class: |
367/84 |
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
;175/232,40 |
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;
first means including 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;
second 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; and
third means operable upon at least slowing of said second member
below said selected speed by fluid-borne solids flowing through
said fluid passage for momentarily separating said signal-producing
members to allow such solids to pass downstream of said
signal-producing members.
2. The apparatus of claim 1 wherein said second means include an
electric motor, and means cooperatively coupling said second member
to said motor for rotation thereby as well as for movement between
an operating position adjacent to said first member and a
solids-clearing position more distant therefrom; and said third
means include biasing means cooperatively arranged for yieldably
urging said second member normally toward one of its said
positions.
3. The apparatus of claim 2 wherein said one position is said
operating position of said second member.
4. The apparatus of claim 1 wherein said second means include an
electric motor, and means cooperatively coupling said second member
for rotation thereby; and said third means include means
cooperatively arranging one of said members for longitudinal
movement relative to the other of said members between an operating
position adjacent to said other member and a solids-clearing
position more distant therefrom, and biasing means cooperatively
arranged for normally urging said one member toward said other
member and yieldable in response to slowing of said second member
below said selected speed by fluid-borne solids for allowing said
one member to move longitudinally away from said other member.
5. The apparatus of claim 1 wherein said second means include an
electric motor, a rotatable shaft drivingly coupled to said motor,
means cooperatively coupling said second member to said shaft for
rotation thereby as well as for movement therealong between a
signal-producing position adjacent to said first member and a
solids-clearing position more distant therefrom; and said third
means include biasing means cooperatively arranged between said
shaft and said second member for normally biasing said second
member toward its said signal-producing position and yieldable in
response to at least one operating condition characteristic of the
rotational slowing of said second member for allowing said second
member to move at least momentarily toward its said solids-clearing
position.
6. The apparatus of claim 1 wherein said second means include a
selectively reversible electrical 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 a first position adjacent to said
first member and at least a second position more distant therefrom;
and said third means include biasing means cooperatively arranged
between said shaft and said second member normally biasing said
second member toward its said first position and yieldable in
response to slowing of said second member for allowing said second
member to move at least momentarily toward its said second
position, and circuit means responsive to the slowing of said
second member for selectively reversing the rotational direction of
said motor.
7. The apparatus of claim 1 wherein said second means include a
selectively reversible electrical motor, a rotatable shaft
drivingly coupled to said motor, means cooperatively coupling said
second member to said shaft for rotation thereby as well as for
movement therealong between a first position adjacent to said first
member and at least a second position more distant therefrom; and
said third means include biasing means cooperatively arranged
between said shaft and said second member normally biasing said
second member toward its said first position and yieldable in
response to slowing of the rotational speed of said second member
for allowing said second member to move at least momentarily toward
its said second position, and circuit means responsive to the
slowing of said second member and 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.
8. 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 to a
borehole-drilling device dependently coupled therebelow;
a flow-directing member 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 flow-obstructing member cooperatively arranged in said fluid
passage for rotation in a plane transverse to said axis 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
flow-obstructing member;
first means cooperatively coupled to said flow-obstructing member
for rotating said flow-obstructing member at at least one selected
rotational speed for cyclically producing acoustic data signals in
drilling fluids flowing through said fluid passage; and
second means operable in response to at least slowing of said
flow-obstructing member by lodging of fluid-borne debris between
said members for moving at least one of said members in relation to
the other of said members to allow such debris to be carried
downstream of said members by drilling fluids flowing through said
fluid passage.
9. The apparatus of claim 8 wherein said one member is said
flow-obstructing member.
10. The apparatus of claim 9 wherein said first means include motor
means; and said second means include control means coupled to said
motor means and responsive to slowing of said flow-obstructing
member below said selected speed for rotatively moving said
flow-obstructing member back and forth in relation to said
flow-directing member so long as said flow-obstructing member is
slowed below said selected speed.
11. The apparatus of claim 9 wherein said first means include a
reversible electric motor; and said second means include circuit
means operable upon slowing of said motor means for producing an
electrical signal, and control means responsive to said signal for
repetitively reversing said motor.
12. The apparatus of claim 9 wherein said first means include a
motor, and a rotatable shaft cooperatively coupled to said motor
for rotation thereby; and said second means include means
co-rotatively coupling said flow-obstructing member to said shaft
for rotation thereby as well as for movement along said shaft
between a first position adjacent to said flow-directing member and
a second more-distant position away from said flow-directing
member, and biasing means normally urging said flow-obstructing
member toward its said first position and yieldable in response to
the occurrence of an operational condition indicative of the
lodging of fluid-borne debris between said members for allowing
said flow-obstructing member to move at least momentarily toward
its said second position.
13. The apparatus of claim 12 wherein said operational condition is
an increased pressure differential across said members sufficient
to move said flow-obstructing member toward its said second
position.
14. The apparatus of claim 12 wherein said second means further
include control means coupled to said motor and responsive to
slowing of said flow-obstructing member below said selected speed
for rotatively moving said flow-obstructing member back and forth
in relation to said flow-directing member so long as said
flow-obstructing member is slowed below said selected speed.
15. The apparatus of claim 9 wherein said first means include a
motor, and a rotatable shaft cooperatively coupled to said motor
for rotation thereby; and said second means include means
co-rotatively coupling said flow-obstructing member to said shaft
for rotation thereby as well as for longitudinal movement along
said shaft between a first position adjacent to said flow-directing
member and a second more-distant position away from said
flow-directing member, and biasing means normally urging said
flow-obstructing member toward its said first position and
yieldable in response to the occurrence of an operational condition
indicative of the lodging of fluid-borne debris between said
members for allowing said flow-obstructing member to move at least
momentarily toward its said second position.
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 angularly spaced
openings cooperatively arranged for directing drilling fluids in
selected fluid paths along said fluid passage, and a rotatable
signaling 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 signaling member for producing cyclic acoustic
signals representative of said electrical signals in drilling
fluids flowing through said fluid passage;
first means cooperatively coupling said signaling member to said
motor for rotation thereby at at least one selected rotational
speed; and
second means operable upon slowing of said signaling member below
said selected rotational speed by lodging of fluid-borne materials
between said members for moving said signaling member in relation
to said flow-directing member to clear such fluid-borne materials
from therebetween.
17. The apparatus of claim 16 wherein said first means include a
rotatable shaft coupled to said motor; and
said second means include means co-rotatively coupling said
signaling member to said shaft, and control means coupled to said
motor and responsive to slowing of said signaling member below said
selected speed for alternately driving said motor back and forth in
opposite rotative directions so long as said signaling member is
slowed below said selected speed.
18. The apparatus of claim 16 wherein said signaling member is
downstream of said fluid-directing member.
19. The apparatus of claim 18 wherein said first means include a
rotatable shaft coupled to said motor; and
said second means include means co-rotatively coupling said
signaling member to said shaft, and means operable upon increased
pressure differentials across said members for shifting said
signaling member along said shaft away from said flow-directing
member and operable upon the subsequent decrease in such increased
pressure differentials for shifting said signaling member along
said shaft toward said flow-directing member.
20. The apparatus of claim 19 wherein said second means further
include means co-rotatively coupling said signaling member to said
shaft, and control means coupled to said motor and responsive to
slowing of said signaling member below said selected speed for
alternately driving said motor back and forth in opposite rotative
directions so long as said signaling 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.
22. The apparatus of claim 16 wherein said flow-directing member is
upstream of said signaling member.
23. The apparatus of claim 22 wherein said first means include a
rotatable shaft coupled to said motor; and said second means
include means co-rotatively coupling said signaling member to said
shaft for rotation thereby as well as for movement along said shaft
between a first position adjacent to said flow-directing member and
a second more-distant position away from said flow-directing
member, and biasing means normally urging said signaling member
toward its said first position and yieldable in response to the
occurrence of an operational condition indicative of the lodging of
fluid-borne debris between said members for allowing said signaling
member to move at least momentarily toward its said second
position.
24. The apparatus of claim 23 wherein said operational condition is
an increased pressure differential across said members sufficient
to move said signaling member toward its said second position.
25. The apparatus of claim 24 wherein said second means further
include control means coupled to said motor and responsive to
slowing of said signaling member below said selected speed for
alternately driving said motor back and forth in opposite rotative
directions so long as said signaling member is slowed below said
selected speed.
26. The apparatus of claim 23 wherein said means corotatively
coupling said signaling member to said shaft include
spline-and-groove means between said signaling member and said
shaft for allowing said signaling member to move along said shaft
between its said first and second positions.
27. The apparatus of claim 23 wherein said means corotatively
coupling said signaling member to said shaft include
spline-and-groove means between said signaling member and said
shaft for allowing said signaling member to move longitudinally
along said shaft between its said first and second positions.
28. The apparatus of claim 27 wherein said operational condition is
an increased pressure differential across said members sufficient
to move said signaling member toward its said second position; and
said second means further include control means coupled to said
motor and responsive to slowing of said signaling member below said
selected speed for alternately driving said motor back and forth in
opposite rotative directions so long as said signaling member is
slowed below said selected speed.
29. The apparatus of claim 28 wherein said motor is a reversible
motor; and said control means include means operable upon slowing
of said motor for producing an electrical signal, and means
responsive to said signal for repetitively reversing said motor.
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 groove 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
arranged to be 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 an operating condition, such as
an increased pressure drop across the two members, which is
indicative of slowing of the motor for temporarily separating the
flow-controlling 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 the cessation of the
operating condition causing slowing of the motor, such as a
decrease in the pressure differential to its usual operating range,
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) as 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 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 the shaft 33 and co-rotatively coupled thereto as by one or more
complementary longitudinal splines and grooves, as at 38, which are
cooperatively arranged to permit the rotor to also slide
longitudinally along the shaft 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. To define the uppermost position of the rotor 32 in
relation to the stator 27, the upper face 35 of the rotor is
counterbored, as at 39, for complementally receiving an enlarged
shoulder 40 on the uppermost end of the shaft 33. Biasing means,
such as a compression spring 41 having a predetermined spring force
mounted around the shaft 33 between the gear-reduction unit 23 and
the lower face of the flow-obstructing member 32, are cooperatively
arranged for normally urging the rotating member upwardly toward
the flow-directing member 27 so as to normally maintain the opposed
faces 34 and 35 of the two members closely spaced under usual flow
conditions. As depicted, it is preferred that the lower end of the
spring 41 be supported by a fixed shoulder 42 on the shaft 33 and
having its lower face slidably engaged with the upper end of the
gear-reduction unit 23.
Accordingly, it will be appreciated that the biasing force provided
by the spring 41 will be 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 41, the flow-obstructing member 32
will be 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.
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 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 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. 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 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 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 rotating member downwardly along its
cooperative spline and groove arrangement 38 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
flow-obstructing member 32 moves further 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 acoustic signaler 22 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 41 will be effective for returning the
rotating member to its normal position 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 becomes temporarily jammed by additional debris.
It should be further noted at this point that there may well be
debris which cannot be dislodged 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 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 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 spring 41 to its usual position
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 43 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 operational level. 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 44 coupled to typical driver circuits 45 connected to the
two windings of the motor. To accomplish the alternate reversals of
the motor 21, a typical reversing switch 46, 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 46, a typical tachometer 47 is
coupled to the shaft 48 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 49, and supplied to one input of a
comparator 50 having a reference voltage, as at 51, supplied to its
other input. The output of the comparator 50 is connected to one
input of a gate, such as a NAND gate 52, having its output
connected to the input of a counter 53. The other input of the gate
52 is connected to one of the outputs of the power supply 44 to
provide a source of pulses. Any selected one of the outputs of the
counter 53 is connected to the reversing switch 46.
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 47 of such a magnitude that there will be no output
signal from the comparator 50. This will correspondingly disable
the gate 52 so that there will be no output pulses supplied to the
counter 53. Once, however, the motor 21 slows such as when the
acoustic signaler 22 first jams, the output voltage of the
tachometer 47 will drop so as to produce an output signal from the
comparator 50 which, in turn, enables the gate 52. Once the gate 52
is enabled, the pulses from the power supply 44 will be supplied to
the counter 53. Thus, each time the number of pulses supplied to
the counter 53 reach a number capable of producing an output signal
at the connected output of the counter, the reversing switch 46
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 53 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 53
which again energizes or activates the reversing switch 46. Thus,
reversal of the motor 21 will be repeated at frequent intervals
such as every few seconds or so as long as the tachometer 47
indicates that the speed of the motor is below its normal operating
speed and accordingly maintains the gate 52 in an enabled
state.
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 flor sliding movement in
relation to its supporting shaft to for the flow-controlling
members to be 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 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.
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