U.S. patent number 3,637,032 [Application Number 05/004,943] was granted by the patent office on 1972-01-25 for directional drilling apparatus.
Invention is credited to John D. Jeter.
United States Patent |
3,637,032 |
Jeter |
January 25, 1972 |
DIRECTIONAL DRILLING APPARATUS
Abstract
A pendulum is mounted in the drill pipe close to the drill bit
to assume a vertical position in the azimuthal plane of the drill
pipe. When the position of the pendulum is such that the
inclination of the drill pipe is not a preselected amount or the
azimuthal direction of the pipe is not the preselected direction, a
lateral force is imposed on the drill bit urging it to drill in a
direction that will return the drill pipe to said preselected
inclination or azimuthal direction. The pendulum and its associated
apparatus is rotated in the direction opposite the direction that
the drill pipe is rotated and at the same speed, so that the
pendulum is substantially nonrotative relative to the earth.
Inventors: |
Jeter; John D. (Cocoa, FL) |
Family
ID: |
21713320 |
Appl.
No.: |
05/004,943 |
Filed: |
January 22, 1970 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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869056 |
Oct 24, 1969 |
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Current U.S.
Class: |
175/73 |
Current CPC
Class: |
E21B
47/0236 (20200501); E21B 7/06 (20130101) |
Current International
Class: |
E21B
7/04 (20060101); E21B 7/06 (20060101); E21B
47/022 (20060101); E21B 47/02 (20060101); E21b
007/08 () |
Field of
Search: |
;175/73,74,76,75,61 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Leppink; James A.
Parent Case Text
This is a continuation in part of U.S. Pat. application Ser. No.
869,056, filed Oct. 24, 1969, and entitled "Directional Drilling
Apparatus," now abandoned.
Claims
The invention having been described, what is claimed is:
1. Apparatus for urging a drill bit connected to a drill string to
drill through the earth in a preselected azimuthal direction
comprising azimuthal direction sensing means located in the drill
string, means responsive to the azimuthal direction sensing means
when the azimuthal direction of the pipe string varies from the
preselected direction for exerting a lateral force on the drill bit
to urge the drill bit to drill in a direction that will return the
drill string to the preselected azimuthal direction, and means for
rotating the azimuthal direction sensing means relative to the
drill string at approximately the speed of rotation of the drill
string and in the opposite direction to hold the sensing means
substantially nonrotative relative to the earth.
2. The apparatus of claim 1 in which the azimuthal direction
sensing means includes a north seeking element.
3. The apparatus of claim 1 further in which the azimuthal
direction sensing means includes means for sensing the inclination
from the vertical of the drill string and means responsive to said
inclination sensing means for exerting a lateral force on the drill
bit, when the inclination of the pipe string varies from a
preselected angle to urge the drill bit to drill in a direction
that will return the drill string to the preselected angle.
4. The apparatus of claim 3 in which the inclination sensing means
includes a vertical seeking member that makes an angle with the
drill string substantially equal to the angle the drill string
makes with the vertical.
5. The apparatus of claim 4 in which the azimuth sensing means
includes a north seeking element and said inclination sensing means
include a pendulum, means providing a universal connection between
the north seeking element and the pendulum to permit the pendulum
to seek a vertical position and energize the lateral force
producing means when the inclination of the drill pipe and its
azimuthal direction vary from said preselected values.
6. The apparatus of claim 5 in which said lateral force producing
means for urging the drill bit to drill in the desired direction
includes means for providing correction signals in response to the
position of the pendulum to energize lateral force producing means
to urge the bit either upward, or downward, and to the left or to
the right as required to direct the bit through the earth at the
preselected inclination and azimuthal direction.
7. The apparatus of claim 5 in which the lateral force producing
means urges the bit to move out of axial alignment with the drill
string to cause the bit to drill in the desired direction.
8. The apparatus of claim 1 further provided with means providing a
continuous lateral force adjacent the drill bit urging the drill
bit to change its inclination as it bores through the earth.
9. Apparatus for urging a drill bit connected to a drill string to
follow a given angle from the vertical comprising, inclination
sensing means located in the drill string to sense the angle the
drill string makes with the vertical, means responsive to the
inclination of the drill string to exert a lateral force on the
drill bit, when the inclination is different from a preselected
angle, to urge the bit to drill in a direction that will return the
drill string to the preselected angle, and means for rotating the
inclination sensing means at approximately the speed of rotation of
the drill string and in the opposite direction to keep the sensing
means substantially nonrotative relative to the earth.
10. Apparatus for urging a drill bit connected to a drill string to
follow a given angle from the vertical comprising, inclination
sensing means located in the drill string having a vertical seeking
member that makes an angle with the drill string substantially
equal to the angle the drill string makes with the vertical, means
responsive to the angle the drill string makes with the vertical
seeking member for exerting a lateral force on the drill bit, when
the angle is different from a preselected angle, to urge the bit to
drill in a direction that will return the drill string to the
preselected angle, and means for rotating the inclination sensing
means at approximately the speed of rotation of the drill string
and in the opposite direction to keep the sensing means
substantially nonrotative relative to the earth.
11. The apparatus of claim 10 in which the inclination sensing
means also includes means for sensing the azimuthal direction the
well bore is taking as it is being drilled and in which said force
applying means applies a lateral force on the drill bit in response
to said azimuthal sensing means to urge the drill bit to maintain a
preselected azimuth as it drills through the earth.
12. The apparatus of claim 10 in which the means for rotating the
sensing means includes a fluid motor having a stator and a rotor,
the rotor being attached to the drill string for rotation
therewith, a source of pressure fluid for rotating the stator
relative to the rotor in a direction opposite to the direction of
rotation of the drill string, means responsive to rotation
controlling the supply of pressurized fluid to the motor to rotate
the stator at approximately the speed of rotation of the drill
string to cause the stator to be substantially nonrotative relative
to the earth, and means connecting the sensing means to the
stator.
13. The apparatus of claim 12 in which the pressure fluid
controlling means includes a gyroscope connected to the stator and
valve means responsive to forces exerted by the gyroscope, when
rotated, to control the flow of pressure fluid to the fluid
motor.
14. The apparatus of claim 13 in which the wheel of the gyroscope
is rotated by a stream of the pressure fluid directed against the
wheel.
15. The apparatus of claim 12 in which the azimuth sensing means
includes a magnetic compass having a magnetic north seeking
element.
16. The apparatus of claim 15 further provided with a second fluid
motor having a stator and a rotor, said second motor being mounted
with its rotor connected to the stator of the first motor and its
stator connected to the north seeking element of the compass, means
supplying said second motor with pressure fluid to rotate its
stator in a direction opposite the direction of rotation of its
rotor and means, responsive to relative movement between the stator
and the magnetic north seeking element, controlling the flow of
pressure fluid to said second motor to cause the stator to rotate
at approximately the same speed as the rotor is rotated by the
stator of the first motor and in the opposite direction so the
stator is substantially nonrotative relative to the earth and the
magnetic north seeking element.
17. The apparatus of claim 10 in which the vertical seeking member
of the inclination sensing means comprises a pendulum pivotally
mounted to freely seek a vertical hanging position.
18. The apparatus of claim 11 in which the azimuth and angle
sensing means includes a magnetic compass having a magnetic north
seeking element, a pendulum, means mounting the pendulum for
pivotal movement in all directions, means responsive to the
position of the pendulum to provide a corrective force when the
pendulum is not positioned in a preselected azimuth plane and to
provide a corrective force when the pendulum is not at a
preselected angle of inclination from the vertical and to provide a
zero corrective force when the pendulum is positioned in said
preselected azimuthal plane and at said preselected angle of
inclination, and means connecting the pendulum mounting means to
the north seeking element including means permitting the mounting
means to be adjusted to position the pendulum to provide said
corrective forces.
19. The apparatus of claim 10 in which the means providing said
lateral force on the drill bit includes a tubular sleeve, means
mounting the sleeve on the drill string above the drill bit for
limited lateral movement relative to the drill pipe, a plurality of
fluid-operated force transmitting members positioned
circumferentially around the drill string between the sleeve and
the drill string and means for sequentially supplying said members
with pressure fluid to cause said members to exert a lateral force
on the drill string to urge the drill bit to drill through the
earth in the desired direction.
20. The apparatus of claim 19 in which the force transmitting
members are inflatable bladders of flexible material.
21. The apparatus of claim 19 in which said force providing means
includes pressure signal passageways, valve means responsive to
inclination of said sensing means for controlling the flow of
pressure fluid to said pressure signal passageways, said
passageways having outlet ports the same radial distance from the
longitudinal axis of the drill pipe, a signal distributor member
attached to the drill pipe for rotation therewith, said member
having conduits therein with inlet ports the same radial distance
from the axis of the drill pipe as the outlet ports of the
first-mentioned passageways, said member being positioned so the
inlet ports of the conduits will move past the outlet ports each
revolution of the drill pipe to pressurize each of said conduits as
its port passes by the outlet ports of the pressure signal
passageways that are being supplied with pressure fluid by said
valve means, and means responsive to fluid pressure in said
conduits for actuating the fluid-operated force transmitting
members.
22. The apparatus of claim 18 in which said means of providing a
corrective force includes pressure signal passageways, valve means
actuated by the pendulum to pressurize the proper pressure signal
passageways, and means responsive to the pressure signal in said
passageways to exert the desired corrective lateral force on said
drill bit.
23. The apparatus of claim 22 in which said lateral force exerting
means includes a bit sub connecting the drill bit to the drill
string, means providing a universal connection between the bit sub
and the drill string and means for urging the bit sub to pivot in
one direction to move the axis of rotation of the bit out of
alignment with the axis of rotation of the drill pipe to urge the
bit to drill in a direction that will return the drill string to
the desired azimuthal direction and inclination.
24. The apparatus of claim 23 in which the lateral force exerting
means includes a plurality of orienting cylinders each connected to
one of said pressure signal passageways, a piston in each cylinder
with a rod attached thereto and extending out of said cylinder, a
shaft mounted for rotation with a swash plate attached to the shaft
at an angle and positioned to be engaged by each rod for downward
movement of a rod to cause the swash plate to rotate to position
its low side under the downwardly moving rod and thereby rotate the
shaft to the desired orientation, a power cylinder having a piston
therein slidably connected to the shaft for rotation thereby as the
swash plate orients the shaft, means supplying said cylinder with
fluid pressure to move said piston downwardly, means actuated by
the downwardly moving piston for exerting a lateral force on the
bit sub to move the drill bit out of axial alignment with the drill
string in the direction to cause the bit to tend to drill in a
direction that will return the drill string to the desired
preselected inclination and azimuthal direction.
25. The apparatus of claim 10 further provided with means providing
a continuous lateral force adjacent the drill bit urging the drill
bit to change its azimuthal direction as it bores through the
earth.
Description
This invention relates generally to directional drilling apparatus.
In one of its aspects, the invention relates to directional
drilling apparatus that urges the drill bit to drill through the
earth at a preselected inclination or angle. In another of its
aspects, the invention relates to directional drilling apparatus
that urges a drill bit to drill through the earth in a preselected
compass or azimuthal direction.
Inclinometers that are located in the drill string in the proximity
of the drill bit usually include a vertical seeking element, such
as a pendulum or plumb bob-type member. Such a member gives a
reference position from which the inclination of the drill pipe can
be measured or sensed. Also, where apparatus is provided for
measuring the compass direction a well bore is taking, a north
seeking member, such as the needle of a magnetic compass, usually
is used to provide a vertical reference plane from which the
azimuthal direction the hole is taking can be measured or sensed.
Both the inclinometers and the azimuthal direction apparatus of
this type are affected by rotation. At the normal rotating speeds
at which most drilling operations are performed, this type
apparatus will not function properly.
Therefore, it is an object of this invention to provide directional
drilling apparatus for positioning in the drill pipe that will
remain substantially stationary relative to the earth, as the drill
pipe is rotated.
It is another object of this invention to provide directional
drilling apparatus that includes an inclinometer with a vertical
seeking member and an azimuth indicating device with a magnetic
north seeking member both of which can function to seek the
vertical and the north even though the drill pipe in which they are
located is rotated at speeds normally used for drilling.
It is another object of this invention to provide directional
drilling apparatus for positioning in the drill pipe having
inclination and compass direction sensing devices that are rotated
at a speed substantially equal to the speed of rotation of the
drill pipe, but in the opposite direction, so the sensing devices
will be substantially nonrotative relative to the earth.
It is another object of this invention to provide directional
drilling apparatus that indicates the inclination of the drill pipe
adjacent the bit and the compass direction the drill pipe is taking
and, when either of these departs from a preselected angle or
direction, provides corrective signals that cause lateral forces to
be imposed on the drill bit to urge the drill bit to drill through
the earth at the preselected angle of inclination and in the
preselected compass direction.
It is another object of this invention to provide directional
drilling apparatus that will exert a lateral force to urge the
drill bit to drill through the earth in a direction that will
return the drill pipe to a preselected inclination on a preselected
azimuthal direction without interfering with the normal rotation of
the drill bit.
It is another object of this invention to provide directional
drilling apparatus that will urge the drill bit to drill either at
a preselected angle or a preselected azimuthal direction and that
can be adapted to so function both where the drill pipe rotates the
drill bit and where the drill bit is rotated by a downhole
motor.
These and other objects, advantages, and features of this invention
will be apparent to those skilled in the art from a consideration
of this specification, including the attached drawings and appended
claims.
FIGS. 1 and 2 are vertical cross-sectional views of the upper and
lower portions of an embodiment of the apparatus of this invention
located in a string of drill pipe just above the drill bit, with
the instrument housing and fluid motor portion of the apparatus
shown in elevation;
FIG. 3 is a vertical sectional view on an enlarged scale of
substantially the same portion of the apparatus that is shown in
FIG. 1 with the instrument housing shown in vertical section;
FIG. 4 is a cross-sectional view taken along line 4--4 of FIG.
3;
FIG. 5 is a vertical sectional view on an enlarged scale of the
portion of the instrument housing below the portion shown in
section in FIG. 3;
FIG. 6 is a sectional view taken along line 6--6 of FIG. 5;
FIG. 7 is a sectional view taken along line 7--7 of FIG. 5;
FIG. 8 is a view on an enlarged scale of the lateral force
producing portion of the apparatus of FIG. 2;
FIG. 9 is a view taken along line 9--9 of FIG. 8;
FIG. 10 is a sectional view taken along line 10--10 of FIG. 8;
FIG. 11 is a sectional view taken along line 11--11 of FIG. 8;
FIGS. 12A and 12B are sectional views through the four-way and
two-way control valves, respectively, employed in the embodiment
shown;
FIG. 13 is a sectional view through an averaging device employed in
the embodiment shown;
FIG. 14 is a vertical sectional view of another embodiment of
lateral force imposing apparatus;
FIG. 15 is a cross-sectional view taken along line 15--15 of FIG.
14;
FIG. 16 is a cross-sectional view taken along line 16--16 of FIG.
14;
FIG. 17A and FIG. 17B are vertical sectional views through another
embodiment of apparatus for imposing a lateral force on the drill
bit;
FIGS. 18A and 18B are another embodiment of apparatus for imposing
a lateral force on the drill bit;
FIG. 19 is a sectional view taken along line 19--19 of FIG.
17A;
FIG. 20 is an alternate arrangement of a portion of the apparatus
of FIG. 17A;
FIG. 21 is an alternate arrangement for a universal connection
between the bit sub and the drill pipe;
FIG. 22 is a sectional view taken along line 22--22 of FIG.
18A;
FIG. 23 is a sectional view taken along line 23--23 of FIG.
18A;
FIG. 24 is a vertical sectional view through the lower end of a
string of drill pipe with an alternate embodiment of the apparatus,
partly in section and partly in elevation, adopted for use with a
downhole drilling motor;
FIG. 25 is a sectional view taken along line 25--25 of FIG. 25;
FIG. 26 is a sectional view taken along line 26--26 of FIG. 24;
FIG. 27 is a cross-sectional view similar to the lower portion of
FIG. 5 of an alternate embodiment of the invention adapted to
control only the inclination of a well bore;
FIG. 28 is a sectional view taken along line 28--28 of FIG. 27;
FIG. 29 is a partial sectional view of a portion of the spool of a
two-way control valve such as shown in FIG. 12B modified to hold
the spool in a given position; and
FIG. 30 is a view similar to FIG. 29 with the spool held in another
position.
The embodiment of the apparatus shown in FIGS. 1-11 is adapted for
use in conventional drilling practice where the drill pipe string
is rotated to rotate the drill bit connected to the string at the
bottom.
Referring first to FIGS. 1 and 2, section 10 of the drill string,
with drill bit 12 attached to the lower end thereof, is positioned
in well bore 11. Section 10 is shown as one member. It is
understood, however, that the member in the actual embodiment of
the apparatus will probably comprise several tubular members
connected together with threads to facilitate the manufacturing and
assembling of the apparatus. This is also true of other members of
the apparatus. Two or three members may be shown for convenience in
the drawings as integrally connected together, but it is to be
understood that again for purposes of manufacture and assembly,
plus good engineering practice, the members in the actual
embodiment will probably comprise several separate members
connected together in any convenient manner.
Section 10 is connected to the next joint above, joint 13, with a
conventional threaded tool joint connection. As is well known, a
plurality of these joints are connected together to make up the
drill string. Joint 13 will likely be a drill collar, i.e., a
section of pipe that is used to provide weight for urging drill bit
12 to drill through the earth. "Drill pipe" and "drill string" are
used interchangeably herein when referring to the entire assembly
of pipe that is connected together to extend from the surface to
the bottom of the hole being drilled.
Means are provided to supply power to the apparatus. In the
embodiment shown, fluid motor 14 is located in the upper end of
section 10 of the drill pipe. The motor is driven by the drilling
mud that is pumped down through the drill pipe and is in the nature
of a turbine. The power produced by motor 14 is transmitted to the
apparatus located in instrument housing 15 and is used in a manner
to be described below. The drilling fluid that is discharged from
motor 14 passes through annulus 16 between instrument housing 15
and the inside of drill pipe section 10. A plurality of arms or
lift rods 17 extend out of the lower end instrument housing 15 for
purposes that will also be described below. The mud travels between
these arms back into central bore 18 of drill pipe section 10 and
is discharged through ports 19 of drill bit 12.
Extending over a portion of drill pipe section 10 is outer sleeve
20. This sleeve is connected at its upper end to section 10 by
threads 21. At its lower end, it is connected to section 10 by
annular ring 22 of resilient elastomeric material such as rubber.
Ring 22 provides a seal between the lower end of sleeve 20 and
drill pipe section 10 while allowing the lower end of sleeve 20 to
shift laterally relative to the drill pipe. Attached to and
circumferentially spaced around the outer surface of sleeve 20,
adjacent its lower end, are longitudinally extending ribs 23. The
outer surfaces of the ribs are adjacent or close to the surface of
well bore 11. Shifting the lower end of sleeve 20 laterally will
force the ribs into engagement sequentially with the well bore and
cause a lateral force to be exerted on the drill pipe just above
drill bit 12. This lateral force will tend to force the drill to
drill in the direction of the lateral force.
Sleeve 20 has inwardly curved section 20a adjacent threads 21 to
permit the desired lateral movement of the lower end of the sleeve
without producing excessively high stresses in the sleeve.
Located in instrument housing 15 are devices for sensing the
inclination and azimuthal direction being taken by the drill bit.
In accordance with this invention, means are provided for rotating
these sensing means at approximately the speed of rotation of the
drill pipe and in the opposite direction to keep the sensing means
substantially nonrotative relative to the earth. In the embodiment
shown, (FIG. 3) output shaft 14a of fluid motor 14 drives crank 25
through cylindrical member 26, which is eccentrically mounted on
the output shaft. Bearing sleeve 27 extends over the end of crank
25 and is rotatably supported by bearing 28 in member 26.
Preferably, crank 25 and member 26 rotate relative to bearing
sleeve 27 so that it will not rotate but will gyrate about the
centerline of the apparatus. This allows a mud seal to be
established between sleeve 27 and instrument housing 15 by flexible
rubber boot 29 and no rotating seals are required. Boot 29 has one
end bonded to the bearing sleeve and the other to crankshaft
bearing 25a located in the upper end of the housing.
Crank 25 rotates shaft 30, which drives oil pump 31. The unoccupied
inner volume of instrument housing 15 is filled with hydraulic
fluid. Hydraulic fluid is drawn into the pump through inlet opening
31a from suction chamber 32. Annular screen 32a filters the oil
entering the pump. The oil is discharged through outlet port 31b
into chamber 33. Annular flange 35b extends upwardly from head 35a
to form chambers 32 and 33.
The oil passes through filter screen 33a and port 34 in cylinder
head 35a into cylinder 35. The hydraulic fluid can flow out of
cylinder 35 through opening 36a of tubular portion 36b of lower
cylinder head 36 to reach the apparatus below. The pump is sized so
that it will furnish more hydraulic fluid under pressure than is
required. Therefore, to let the pump run continuously while mud is
being circulated, the hydraulic fluid fills the cylinder above
piston 37 and urges the piston downward against coil spring 37a.
The cylinder, piston, and spring act as an accumulator to maintain
a supply of hydraulic fluid under pressure that is available as
needed by the apparatus. At a given pressure in the cylinder, check
valve 38 in cylinder head 35a will open and discharge excess fluid
from the pump back to suction chamber 32.
Above the hydraulic pump, drive shaft 30 passes through tubular
spool-shaped member 38. Seals 39 located at opposite ends of the
spool between the outside surface of member 38 and the inside
surface of instrument housing 15 isolate annular space 40 around
the outside of the spool and the hydraulic fluid in the housing.
Sleeve 41 of flexible material encloses the outside surface of
member 38 with each end in sealing engagement with the spool-shaped
member. The outside of the sleeve is exposed to drilling fluid that
enters housing 15 and annular space 40 through ports 42. The inside
of the sleeve is exposed to the hydraulic fluid in the housing
through ports 38a. Sleeve 41 acts as a diaphragm between the
drilling fluid and the hydraulic fluid inside instrument housing 15
to maintain the pressure of these two fluids the same and relieve
instrument housing 15 of any pressure differentials existing across
it due to the hydrostatic pressure of the drilling mud in which it
is located.
As shown in FIG. 4, instrument housing 15 is centrally positioned
inside drill pipe section 10 by radially extending ribs 43 and
annular ring 44. Ribs 43 connect ring 44 with housing 15 and the
outside diameter of ring 44 is such that it fits closely inside of
drill pipe section 10.
Referring now to FIG. 5, hydraulic fluid from the pump flows
through port or passageway 36a of tubular portion 36b and through
rotor 46b of fluid pacing motor 46. Rotor 46b and stator 46a of the
motor are shown schematically in the drawings for simplicity. Any
fluid motor can be used.
In the embodiment shown, rotor 46b is attached to or connected to
tube 36a and cylinder head 36, which connects the rotor to housing
15. The housing, as explained above, is connected to drill pipe
section 10. Therefore, the drill pipe section and rotor 46b will
rotate at the same speed.
Means are provided to control the flow of hydraulic fluid to motor
46 so that stator 46a, which is not attached to the housing, will
rotate in the opposite direction from rotor 46b at approximately
the same speed that the drill pipe is rotating. The stator then
will be substantially nonrotative relative to the earth. In the
embodiment shown, gyroscope 47 is positioned below motor 46 in
gyroscope housing 47a. The gyroscope has disc or wheel 48 mounted
for rotation on shaft 49. Shaft 49, in turn, is supported by
parallel arms 50, which are attached to annular member 51. Bearing
51a supports the gyroscope for rotation relative to the gyroscope
housing. As shown, gyroscope housing 47a is an integral part of the
stator. Thus, rotation of the gyroscope is relative to its housing
and to the stator.
In describing motor 46, the outside portion was called the "stator"
and the inside or central member the "rotor." This is conventional,
however, since the rolls of the members could be easily reversed
with the outer member becoming the "rotor." In other words the
names "stator" and "rotor" are interchangeable.
Means are provided to control the flow of hydraulic fluid to motor
46 to control the speed that the stator rotates relative to the
motor. In the embodiment shown, flow control valve 52 serves this
purpose. It is mounted in stator 46a and controls the flow of
hydraulic fluid from passageway 36a, bore 55 of the stator and
gyroscope housing 47a, passageway 54, and motor fluid inlet port
53. The pressure fluid in bore 55 also flows out nozzle 55a at an
angle and impinges on the outer surface of gyroscope wheel 48. This
surface is roughened or grooved laterally sufficiently for the
stream of fluid from the nozzle to cause the wheel to rotate. The
fluid used for this purpose is returned through ports 47c to the
fluid returning to the fluid pump along side the gyroscope
housing.
The remainder of the fluid in bore 55 flows through passageway 47d
around the cavity in the housing for the gyroscope into tubular
member 47b.
Referring now to FIG. 12A, the structure and operation of flow
valve 52 will be described. This valve is what is known as a Moog
valve. They are commercially available. Valve 56 includes valve
body 52a, which has a plurality of passageways provided therein.
The valve body is shown as an integral part of the stator and
gyroscope housing. Hydraulic fluid from bore 55 flows through
passageways 56a and 56b and is discharged in opposing streams
through orifices 57a and 57b, respectively. This fluid also flows
through upstream orifices 59a and 59b which restrict the flow of
fluid into chambers D and E between each pair of orifices. The
opposing fluid streams from orifices 57a and 57b strike valve
element 58. This element is attached to annular member 51 and will
remain substantially stationary as does the member and the
gyroscope. Movement of the stator relative to the gyroscope will
move one of orifices 57a and 57b toward the element, while moving
the other away.
If the movement of the stator is to the left as viewed in FIG. 12A,
the flat sided-valve control element will move close to orifice 57b
and retard the flow of fluid out of chamber E. By moving away from
orifice 57a, the flow of fluid through that orifice can increase
and the pressure in chamber D will decrease. Openings 56c and 56d
connect chambers D and E to chambers A and B, respectively, on
opposite sides of cylindrically shaped, valve spool 61 which slides
axially into and out of chambers A and B, both of which combine to
form one elongated cylindrical chamber C for the valve spool
61.
Passageways 60a and 60b connect passageways 56a and 56b,
respectively, to chamber C. As shown, the flow of fluid from these
passageways into the chamber is blocked by sections 61a and 61b on
spool 61, which have a diameter large enough to provide a sliding
seal with the wall of the chamber. Passageways 53a and 53b are
connected to motor 46. Fluid flowing through passageway 53a will
urge the stator to rotate relative to the rotor in one direction,
fluid flowing through passageway 53b will urge relative rotation in
the opposite direction. Passageway 53c is connected to the
reservoir of hydraulic fluid in the instrument housing.
In operation, when movement of the stator relative to the gyroscope
moves valve control element 58 to the right, as explained above,
the pressure in chamber A will drop below the pressure in chamber
B. Valve spool 61 will move to the left connecting passageways 60a
and 53a by positioning the section of the spool with the reduced
diameter adjacent the openings of these two passageways. At the
same time, this connects passageways 53b from the motor with
exhaust port 53a by moving the section of reduced diameter between
sections 61b and 61c over their openings. Fluid under pressure can
now flow to the motor to rotate the stator in a direction to move
it back toward the center or neutral position relative to orifices
57a and 57b. Movement of the stator in the other direction will
supply pressure fluid to the motor through passageways 60b and 53b
and correct relative movement of the stator and gyroscope in the
other direction and again move the valve element to the neutral
position.
Since probably even in most systems there will be some creep of the
gyroscope resulting in some slight rotation of stator 46a relative
to the earth, second hydraulic motor 62 is provided in the
embodiment shown to reduce the effect of this creep. Motor 62
includes stator 62a and rotor 62b, here again shown more or less
schematically in FIG. 5. Rotor 62b is connected to tubular member
47b, which extends downwardly from the lower end of gyroscope
housing 47a. Therefore, the rotor will rotate at the same speed as
the stator of first pacing motor 46. The speed of rotation of
stator 62a relative to rotor 62b is controlled by valve 63, which
is a valve like valve 52 described above. Here, however, valve
control element 64 is connected to magnetic north seeking member 65
of magnetic compass 66. North seeking member 65 is mounted for
rotation relative to stator 62a and compass housing 66a by tubular
bearing sleeve 67. The member is preferably made up of a plurality
of stacked, permanently magnetized discs arranged with their north
and south poles in alignment. North seeking member 65 of the
compass will tend to remain stationary relative to the magnetic
field and will provide a feedback to the valve to control the speed
of stator 62a relative to rotor 62b, which is rotating at the speed
that gyroscope 47 and stator 46a of the first pacing motor is
rotating. This rotation will be due to inherent creep in the system
plus whatever rotation, if any, of stator 46a relative to the earth
that the first pacing motor cannot prevent. Thus, with two pacing
motors in series, stator 62a is substantially nonrotative relative
to the earth. If desired, a second gyroscope could be used for this
purpose. By using a magnetic compass, however, the magnetic north
seeking member of the compass can be used to also provide azimuth
sensing means for controlling the compass or azimuthal direction of
the well bore, along with its inclination.
In accordance with this invention, inclination sensing means are
provided for location in the drill pipe above the bit. In the
embodiment shown, the inclinometer includes a vertical seeking
member, pendulum 70, that makes an angle with the section of drill
pipe in which it is located that is substantially equal to the
angle the drill pipe section makes with the vertical. Pendulum 70
is supported by pin or shaft 71, as shown in FIG. 7. Shaft 71, in
turn, is supported by the downwardly extending arms of U-shaped
quadrant member 72. The pendulum can swing around the longitudinal
axis of pin 71. The entire assembly is supported for rotation by
second pin or shaft 73, which is perpendicular to shaft 71. It is
supported in valve and pendulum housing 74, which has central
cavity 74a in which the pendulum is located. Thus, pendulum and
U-shaped quadrant member 72 can seek a vertical position by
rotating around the longitudinal axis of both shafts.
Valve and pendulum housing 74 is connected to magnetic compass
housing 66a so that pendulum 70 can be positioned to swing in a
plane that includes the vertical axis of the drill pipe, the
longitudinal axis of shaft 73, and the azimuthal direction it is
desired for the well bore to be drilled, when the north seeking
element is pointing toward magnetic north. For example, if the well
bore is to be drilled in a due eastwardly direction, then valve and
pendulum housing 74 will be rotated until pendulum 70 will hang in
a vertical plane that includes the pendulum and the longitudinal
axis of shaft 73, and lies in a due easterly direction, when the
compass member is pointing toward magnetic north. Then if the well
bore deviates from this azimuthal direction, for example, if it
tends to head in a more northerly direction, and we are looking
east in FIG. 7, pendulum 70 will rotate around shaft 73 to the left
since shaft 73 will be held in a due east position by magnetic
north seeking element 65.
Means are provided to produce correction signals whenever the
pendulum hangs at an angle other than the preselected angle and
when the pendulum swings out of the preselected azimuthal plane. In
the embodiment shown, pivotal movement of the pendulum around the
axis of shaft 73 will move valve element 75 of control valve 76 and
cause fluid under pressure to be supplied to one of its two outlet
ports 83a and 83b of FIG. 12B. This valve operates on the same
principal as the valve in FIG. 12A, except that it is a two-way
rather than a four-way valve. As will be described below, when one
of these passageways 83a and 83b is supplied with pressure fluid, a
lateral force will be imposed on the drilling bit tending to urge
the bit to again drill in an easterly direction.
Split clamp 74b is used to releasably connect the valve and
pendulum housing to the compass housing. The clamp can be loosened
to allow the relative rotation desired, then tightened to hold the
two housings from further relative rotation.
If the well bore begins to vary from its preselected inclination,
pendulum 70 will swing either in one direction or the other around
the axis of shaft 71. The pendulum is adjustably connected to
quadrant member 72 by setscrew 77, which extends through the
pendulum and arcuate slot 78 in the quadrant. The pendulum is moved
to the desired inclination with valve member 79 of control valve 80
zeroed or centered, the lock screw is then tightened down and as
long as the inclination of the hole is at the preselected amount,
valve 80 will be in its centered or neutral position. If the
pendulum swings in one direction or the other around the axis of
shaft 71 due to an error in the inclination of the well bore,
quadrant member 72 will move valve control member 79, and valve 80
will supply pressure fluid to one of outlet ports 84a or 84b to
impose a lateral force on the drill bit to urge the bit to drill in
a direction that will return the well bore to the preselected
inclination.
Referring to FIG. 12B, valve 76 is shown in cross section.
Passageway 81a is supplied with hydraulic fluid under pressure.
Movement of pendulum 70 to the left or right around the axis of
shaft 73, as viewed in FIG. 7, will cause spool 82 to shift to the
left or right in the same manner as explained above in connection
with the valve of FIG. 12B. Movement of the spool to the right will
connect passageway 81a and passageway 83a, whereas movement of the
spool to the left will supply fluid pressure from passageway 81a to
passageway 83b. As will be explained below, one of these
passageways will carry a "right" and the other a "left" signal. In
other words, they will tend to urge the bit either to the right or
the left as required to bring it back into the desired azimuthal
plane. The same valve arrangement is used for valve 80, which will
supply passageways 84a and 84b with fluid under pressure from
passageway 81b, as shown in FIG. 7, to provide and "up" or "down"
signal. Fluid under pressure is supplied to passageways 81a and 81b
through bore 66b in the compass housing, tubular bearing sleeve 67,
and bore 74c of the valve and pendulum housing.
The four correction signal passageways carrying the "up," "down,"
"right" or "left" signals travel downwardly through valve and
pendulum housing 74 and terminate in outlet ports located in lower
flat surface 86 of the housing. Surface 86 is shown in FIG. 9, the
four ports are arranged symmetrically around the center of rotation
of surface 86. As explained above, each port may carry a pressure
signal that will produce a given desired result in the direction
taken by the drill bit. The "up" and "down" ports are opposite each
other, as are the "right" and "left" ports. Since a pressure signal
will be in only one of each of the two related ports at a time,
where a combination correction of both inclination and compass
direction is required, a combination of pressure signals will be
either "up-right," "up-left," "down-right" or "down-left." In each
combination, the two ports having fluid pressure on them will be
adjacent each other.
In direct rubbing contact with surface 86 is upper surface 87 of
instrument housing closure member 88. This member is rotating with
the instrument housing at the speed of the drill pipe. It is
provided with four ports 89a-89d, as shown in FIG. 10. These ports
are located so that they will rotate in the same circle as the
pressure signal ports in surface 86. Assume, for example, that
fluid pressure is on the "left" port on surface 86 then, with each
quarter of a revolution of the drill pipe, one of ports 89a-89d
will be pressurized by the fluid pressure in this port. To allow
more time for the fluid pressure to move the pistons, etc., arcuate
grooves that include the pressure signal ports can be provided as
shown in FIG. 9.
As each of ports 89a-89d is pressurized, the fluid pressure in the
ports will in turn lift its associated valve member 90a-90d (FIG.
8). The valves are opened by the upward movement of pistons 91a-91d
and their associated rods 17a-17d as each of ports 89a-89d is
supplied with pressure fluid. For example, in FIG. 2, valve 90c has
been opened by rod 17c. This allows mud pressure to flow through
passageway 94c (FIG. 8) into pressure energized, force transmitting
member 95c. In the embodiment shown, this member is an elongated
bladder made of elastomeric material, such as rubber, which will
transmit the pressure of the mud laterally between drill pipe
section 10 and sleeve 20. This will cause sleeve 20 and lateral
abutment 23 adjacent bladder 54c to push against the side of well
bore 11 and, in turn, push laterally against drill pipe 10 above
the bit to urge the bit to move to the left, as viewed in the
drawings. As soon as the first energized port 89 has passed out of
reach of the particular port or ports, "right," "up," "down," or
"left," having pressure fluid in them, valve 90c will close and the
mud in bladder 94c will bleed back into the drill pipe through
orifice 96c. This orifice is sized to allow the bladder to deflate
rapidly when the flow of mud into the bladder is stopped, but to
retard the escape of mud sufficiently to allow the bladder to be
inflated when the mud valve is open.
The return of the mud to the drill pipe is encouraged by venturi
97, which is located upstream of orifices 96. Thus, the pressure
downstream of the venturi should be somewhat less than the pressure
upstream and the mud in the bladders should readily flow back into
the drill pipe. The resilient force imposed on the bladders by
sleeve 20 attempting to return to its central position will also
help deflate each bladder after its associated inlet valve is
closed.
As each of ports 89 moves under the one or two ports in surface 86
that contain fluid pressure, each of the bladders, in turn, will be
inflated and exert their lateral forces on the drill pipe. If two
ports are provided with a pressure signal then two adjacent
bladders will be inflated at the same time and the resulting
lateral force will lie between them.
To avoid spurious pressure signals from the sensing apparatus, an
averaging device, such as shown in FIG. 13, may be used with each
pressure signal passageway. The passageway, for example passageway
83a, is connected into cylindrical space 98a in body 98. Piston 98c
in the cylindrical space must move up to uncover the continuation
of passageway 83a on the other side of the body. Spring 99 resists
this and can be selected to cut off all pressure signals except
those that last long enough to build up sufficient pressure to
compress the spring. Bleed port 98c keeps the pressure from
building up in the device due to leaks past the valve.
FIGS. 14-16 show an alternate arrangement for providing the lateral
force in response to the pressure signals produced by the apparatus
described above. In this embodiment the four fluid pressure
signals, "up," "down," "right," and "left" are transmitted directly
to the force producing apparatus through passageways 100a-100d in
cylindrical member 101. This member closes the upper end of
cylinder housing 102 and is connected to the pendulum housing of
the apparatus above (not shown). It, therefore, is earth oriented
and substantially nonrotative. Instrument housing 125 does rotate
with the drill pipe. Each of passageways 100a-100d extend into the
member and are connected to cylinders 102a-102d, respectively.
Pistons 103a-103d are located in cylinders 102a-102d, respectively.
Piston rods 104a-104d are connected to pistons 103a-103dand engage
swash plate 105. The swash plate is mounted at an angle on shaft
106. A downward force exerted by one of rods 104a will orient swash
plate 105 with its low side under that piston rod and in this
manner orient shaft 106. Thus, when a pressure signal is supplied
to one of passageways 100a-100d, this pressure will enter the
associated cylinder and exert a downward force on the piston
therein. The piston will move down and through its attached rod
exert a downward force on the swash plate causing it to rotate
shaft 106 until the swash plate is at its lowest point below this
particular piston rod. If two of the pressure ports are supplied
with a pressure signal, such as in the case of an "up-right" or
similar combination corrective signal, then two adjacent piston
rods will exert a downward force on swash plate 105 and the swash
plate's low point will be located between these two piston rods and
it will orient the shaft in the proper direction for providing the
desired lateral force to provide the combined corrections, as will
be explained below.
Connected to shaft 106 is piston 107. This piston is located in
cylinder 108 and can rotate with shaft 106 relative to the
cylinder. The space above the piston in cylinder 108 is connected
to cylinders 102a-102d through passageway 106a in shaft 106,
vertical port 101a in member 101 and lateral ports 109a-109d. The
lateral ports are located in the walls of the cylinders far enough
below the inlet ports for only the ports in the cylinders whose
piston are forced down by pressure fluid to be exposed and placed
in communication with the cylinder. Thus, as shown in FIG. 14,
piston 103a had been forced downwardly by a pressure signal
entering cylinder 102a through passageway 100a. The piston and rod
104a have caused swash plate 105 to orient shaft 106 and piston 107
connected to it in the desired position. Now port 109a is in
communication with the pressure fluid in cylinder 102a. This
pressure fluid will travel down through passageway 106a and enter
the space above piston 107 in cylinder 108.
Piston 107 has bore 109 in its lower end. The centerline of the
bore is skewed or canted from the vertical centerline of the piston
and cylinder 108. Located in skewed bore 109 is cylinder block 110
that can slide relative to bore 109. Block 110 is pivotally
connected to rod 111, which is mounted for universal pivotal
movement by ball and socket joint 112. The ball and socket joint is
supported by lateral arms 113 that extend from bit sub 114
positioned just above drill bit 115. Below the ball and socket
joint, the rod extends into annular collar 116. Ball 117 is
attached to the end of the rod and located in the collar to act as
bearing between the rod and the collar. Extending radially from
collar 116 are arms 118a-118c. These arms extend through lateral
openings 119 in bit sub 114 and are connected to rollers
120a-120c.
In operation, swash plate 105, shaft 106, and piston 107 are
positioned in response to pressure signals through one or two of
passageways 102a-102d. Downward movement of piston 107 due to the
pressure fluid supplied from the cylinders will impose a lateral
force on block 110 tending to move the lower end of rod 11
laterally in the opposite direction, as the rod pivots in ball and
socket joint 112. This lateral force will be transmitted
sequentially to rollers 120a-120c as the drill pipe rotates and the
rollers will in turn exert a lateral force against wall 121 of the
well bore and urge the bit to move in the desired direction. Coil
spring 122 will urge piston 107 upwardly to a neutral position with
rod 111 vertical when there is no pressure being supplied to
cylinder 108. This will be the case, when no pressure signal is
being supplied by the directional drilling apparatus of the
invention.
FIGS. 17A and 17B are vertical sections through another embodiment
of apparatus for imposing the lateral force on the bit in response
to the pressure signals produced by the apparatus. In this
embodiment, the pressure signals, "up," "down," "right," and
"left," are connected directly to four cylinders, 130a-130d,
through passageways 131a-131d. As shown in the drawings, only
cylinders 130a and 130c and their associated pressure signal
passageways are shown. It will be understood that there are two
more cylinders, all four of which are spaced radially 90.degree.
from each other, equidistant from the center of housing member
132.
In this embodiment, in the same manner as described above in
connection with the embodiment of FIGS. 14-16, pistons 133a-133d
have piston rods 134a-134d that exert downward forces on swash
plate 135 in response to pressure signals from the inclination and
azimuthal sensing apparatus located in the drill pipe above. This
orients shaft 136, which is mounted for rotation on bearing
137.
Shaft 136 extends into central opening 138 of piston 139. The
piston has an upward tubular extension 140, which is connected to
shaft 136 by a splined connection so that rotation of the shaft
will be imparted to the piston yet they can move axially relative
to each other. The piston is located in cylinder 141 and pressure
fluid from the pressure signal passageways 131a-131d is supplied to
the cylinder above piston 139 through passageway 142 in the shaft
and passageway 143 in the central position of housing member 132.
Four lateral ports connect passageway 143 with each of cylinders
130a-130d.
As shown in FIG. 17a, piston 133c has been moved downwardly by
pressure introduced into cylinder 130c through pressure signal
passageway 131c. This downward force acting on swash plate 135 has
oriented shaft 136 and piston 139 as shown. The pressure fluid is
now able to enter the space above the piston in cylinder 141. The
pressure fluid from central passageway 142 in the shaft flows
upwardly into the cylinder through ports 144 in the piston. Piston
139 then will be urged downwardly. Integrally attached to piston
139 is cam guide member 145. This member has an inclined guide slot
146 in which cam member 147 is slidably mounted. The cam member is
pivotally connected through pin 148 to swivel member 149, which is
rotatably mounted in the upper end of bit sub 150. Boot 151 is
connected to the lower end of instrument housing 152 of the
apparatus and rotates with it and the drill pipe and provides a
seal between the upper end of bit sub 150 and instrument housing
152. Inner housing 132 is maintained substantially stationary along
with the signal producing apparatus in the housing.
Bit sub 150 is connected to drill pipe 153 by a universal
connection that allows the bit sub to pivot a limited amount in any
direction relative to the drill pipe. The universal connection
shown in FIG. 17B includes annular ring 154 that is connected to
the lower end of drill pipe 153 through two circular ears 155 that
engage circular slots 156 in ring 154. Bit sub 150, in turn, is
connected by a similar arrangement of circular ears 157 and slots
158 in ring 154. This type of connection between the bit sub and
drill pipe allows the bit sub to pivot to a limited extent in any
direction relative to the drill pipe.
In operation then, as piston 139 is forced down, inclined slot 146
and cam member 147 will move upwardly along the slot and in doing
so will exert a force to the right on swivel 149, as viewed in FIG.
17a. This force will be transmitted to bit sub 150 through the
swivel member and move the bit out of axial alignment with the
drill pipe causing it to drill in the direction to return the well
bore to the desired inclination or azimuthal direction.
Drilling fluid can flow through the drill pipe and out the bit by
passing through lateral ports 161 in the bit sub located below the
swivel connection between the bit sub and swivel member 149. The
bit sub is hollow below ports 161 and the drilling fluid can flow
downwardly and out of the pipe through ports 162 in bit 160.
Pressure energized seal ring 161a keeps the drilling mud from
escaping from between the bit sub and the lower end of the drill
pipe.
FIG. 20 is an alternate connection between the lower end of the
piston and the swivel. Here link member 163 is pivotally connected
at each end to cam member 145' and to the top of the swivel member
149' by pins 165 and 166, respectively. Downward movement of the
piston and cam member 145 will exert a lateral force on the top of
swivel member 149', which is transmitted to bit sub 150' and to the
bit.
FIG. 21 is an alternate arrangement for the universal connection
between the bit sub and the drill pipe. In this embodiment bit sub
170, has central portion 171 that extends up and is connected to
the swivel (not shown). The bit sub here is integrally connected to
drill pipe 171 and is actually formed from the same piece. To
provide the required movement of the sub relative to the drill
pipe, helical groove 172 is cut through the wall of the drill pipe
to form coils 173 of a coil spring. The space between the coils and
on the outside and inside thereof is filled with sealer 174,
preferably an elastomer such as rubber that can be compressed and
stretched as the coil spring is bent due to a lateral force imposed
on the bit sub.
FIGS. 18A and 18B show another embodiment of the apparatus for
imposing a lateral force on the bit in response to fluid pressure
signals produced by corrective signals from the apparatus of this
invention. In this embodiment, the fluid pressure signals travel
through passageways 180 and exert a downward force on one of
pistons 181 in cylinders 182. (As before there are four of each if
all of the corrective signals are required. If only one of the
sensing devices is used, two of each would be sufficient.) This
embodiment in the same way as described above in connection with
the other embodiments positions swash plate 183 and shaft 184 with
the desired orientation to produce the lateral force for the
desired correction. In this embodiment, the force producing
arrangement comprises bladder 185. This bladder is made of a
flexible material and is connected to cylinders 182 so that the
particular cylinder or cylinders supplied with pressure will also
provide pressure fluid to the inside of bladder 185 after the
pistons have moved far enough down to orient the swash plate at
which time lateral ports 186 will be uncovered. These ports are
connected through check valves to passageway 187, which extends
through shaft 184 and bladder housing 184a integrally connected
thereto. At its lower end the passageway is connected to bladder
185. As the bladder is inflated with pressure fluid, it exerts a
lateral force on member 188 which is positioned on upper end 189a
of swivel member 189. Member 188 is rectangular in cross section as
is bladder cavity 184b so the member and bladder 185 will rotate
with the bladder housing and shaft and be oriented properly. Once
oriented pressure in bladder 185 exerts a lateral force on the
swivel member which in turn is transmitted to the upper end of bit
sub 190 and hence to bit 191. Movement of bit sub 190 relative to
drill pipe 192 is accomplished in the embodiment shown by using a
connection between the bit sub and the drill pipe where clearance
is provided between threads 196 with the clearance filled with
resilient material 197, such as rubber.
Vertical guide ribs 194 and sleeve 195 support apparatus housing
198 in the center of the drill pipe for rotation with the drill
pipe. The pistons, bladders, etc., are connected to the pendulum
housing through connecting member 199 and is nonrotative relative
to the earth or earth oriented. Here as in the previous embodiment,
the lateral force causes the bit sub and bit to move out of
alignment with the drill pipe into a preferred axis in the
direction it is desired for the hole to take. This is in effect
"slewing" the bit to cause it to drill in the desired
direction.
In the above-described embodiments, the drill pipe rotated the
drill bit and therefore rotated at the same speed as the bit. When
the downhole motor, such as a turbodrill, rotates the bit the drill
pipe need not rotate. Usually, however, it is deemed desirable to
rotate the drill pipe, even though not required, to reduce the
danger of the pipe becoming stuck by a pressure differential
between the hydrostatic pressure of the drilling fluid and a
formation pressure. Even if the drill pipe is not rotated at the
surface the reaction torque imposed on the drill pipe by the
drilling motor will cause a varying amount of windup of the pipe,
particularly with long strings of drill pipe. Therefore, the means
for rotating the inclinometer and azimuth sensing means at the
speed of rotation of the drill pipe and in the opposite direction
is still important to the proper functioning of the directional
drilling apparatus of this invention. In FIGS. 24-26, the apparatus
is adapted for use with a downhole motor. The apparatus is located
in housing 200, which is positioned in the drill pipe above
downhole motor 201. This motor rotates drill bit 202. In the
embodiment shown, the apparatus in housing 200 includes means for
orienting a shaft in response to the signals from the apparatus. An
arrangement such as shown in FIGS. 17A and 17B or FIGS. 18A and
18B, could be used, for example. The apparatus then orients shaft
203 in response to the signals from the inclination and azimuthal
sensing means. This shaft is eccentrically mounted with respect to
the longitudinal axis of drill pipe 204. Valve rods 205a-205d
extend radially through the wall of housing 200. They are spaced
90.degree. apart. Attached to the outer end of each rod are valve
elements 206a-206d. The valve elements close lateral ports
207a-207d, respectively, when they are in engagement with the inner
wall of the drill pipe. Coil springs 208 are located on each rod,
between the inside of housing 200 and the enlarged ends of the rods
to urge the rods away from the drill pipe and toward eccentric
shaft 203. With the shaft positioned off center, as the housing and
drill pipe rotate relative to the shaft, each rod will move its
valve element away from the drill pipe and allow drilling fluid in
annulus 209 to flow into the opened port. For example, in FIG. 25,
port 207b is open and receiving drilling fluid. As the drill pipe
rotates another 90.degree. in a clockwise direction, port 207a will
be opened and 207b will be closed. Rotation in the other direction
would next open port 207c.
Each port connects to a pressure energized force transmitting
device located between the drill pipe and the wall of the well bore
to exert a lateral force on the drill pipe adjacent the bit. In the
embodiment shown, four inflatable bladders 210a-210d of resilient
material, such as rubber, are positioned circumferentially around
the drill pipe. As shown the bladders are integrally connected
together, each bladder consisting of an opening in annular body 211
of resilient material.
Annular body 211 is located between drill pipe 204 and outer
tubular member 212, which is made of a relatively rigid material
such as steel, and bonded to the annular body of resilient
material. Drilling fluid flows into each of bladders 210
sequentially as the drill pipe is rotated and ports 207 are opened
successively. The pressure of the drilling fluid in the bladder
exerts a lateral force on housing 215 of the downhole motor and on
the well bore through spaced vertical ribs 213. The force on the
downhole motor housing is transmitted directly to the bit. This
lateral force is oriented by the position of eccentric shaft 203 to
direct the force in the desired direction. As each port is closed,
the drilling fluid in the bladder to which the port is connected
drains out of the bladder through openings 214a-214d. These
openings are sized so they are small enough to allow fluid out at a
lower rate than it enters the bladder so it will be enlarged by the
drilling fluid; but they are large enough to allow the fluid to
exhaust from the bladder fast enough not to interfere with the
proper location of the lateral force. The drilling fluid is
exhausted on the outside of the drill pipe, which is at a lower
pressure than the fluid in annulus 209.
As stated above, it is one of the objects of this invention to
provide directional drilling apparatus that will urge the drill bit
to drill either at a preselected angle or a preselected azimuthal
direction. In addition, the apparatus can be adjusted to provide a
continuous corrective signal of a given type.
For example, in FIG. 27 the apparatus has been adapted to control
inclination only. All of the parts remain the same as in the
embodiment shown in FIG. 5 with one exception, so they have been
assigned the same numbers in this figure. The new part of the
combination is member 220, which replaces north seeking member 65.
This member is not needed for inclination only, however, means are
needed to keep the pendulum positioned to swing toward the low side
of the hole. In the embodiment shown, member 220 has mass 220a
positioned on one side of its axis of rotation around bearing
sleeve 67. Instead of seeking the north, it will rotate to position
mass 220a on the low side of the hole. This will cause valve 63 to
hold stator 62a in position for the longitudinal axis of shaft 73
to point toward the low side of the hole, which will position
pendulum 70 in the proper plane to control the inclination of the
hole.
If pacing motor 62 holds the pendulum shaft in the proper
orientation, no signals will be produced by control valve 76. Since
it is unlikely that the pacing motor can hold the shaft that still,
the azimuthal signal producing members are preferably deactivated.
This can be done simply by plugging their associated output ports
with, for example, a removable pipe plug.
It may be desirable to provide a continuous control signal. For
example, it may be desired to cause a well bore to continuously
increase its inclination in a given direction. This can be done in
several ways. For example, shaft 71 or shaft 73 could be locked in
position to give the desired corrective signal continuously.
Setscrews could be used for this purpose. Also, this can be done by
locking the spool of the control valve concerned, such as spool 80,
for inclination. FIGS. 29 and 30 illustrate apparatus for doing
this. In FIG. 29, setscrew 222 is positioned in tapped hole 224 in
the wall of the valve body. It can be positioned to hold the spool
to provide a continuous corrective signal. It can hold the spool
only from moving to the right, however. So for the other signal,
the spool has tapped hole 226 which is engaged by threaded member
or bolt 228. The diameter of the threaded portion of member 228 is
small enough to extend through tapped hole 224. Rotation of member
228, as by an Allen wrench, will pull the spool to the right, as
viewed in FIG. 30, and hold it in position to provide a continuous
corrective signal. Enlarged heads 230 and 232 of setscrew 222 and
bolt 228, respectively, carry seal rings 234 to isolate the inside
of the valve body from the outside.
From the foregoing description of one embodiment of this invention
by way of example, it will be seen that this invention is one well
adapted to attain all of the ends and objects hereinabove set
forth, together with other advantages which are obvious and which
are inherent to the apparatus and structure.
* * * * *