U.S. patent number 3,891,037 [Application Number 05/318,114] was granted by the patent office on 1975-06-24 for remotely operated seafloor coring and drilling method and system.
Invention is credited to Kenneth C. Marley, Dale E. Well.
United States Patent |
3,891,037 |
Well , et al. |
June 24, 1975 |
Remotely operated seafloor coring and drilling method and
system
Abstract
Method and apparatus for emplacing a structure such as a casing,
piling or core barrel into the floor of a body of water, hereafter
referred to as sea floor. The structure is mounted on a towable and
submersible vessel which includes a number of ballast tanks, and
means are provided to selectively vary the ballast in certain ones
of the tanks in a manner causing the vessel to have selectively
controllable negative or positive buoyancy for descent or ascent,
respectively, to or from the sea floor. A support device on the
vessel is adapted to move the structure between a horizontal
orientation for towing and descent and an upright position for
drilling. after the vessel reaches the sea floor. The vessel
descends with a positive metacenter to maintain the established
orientation until it reaches the sea floor, after which it is
anchored and leveled for commencing the drilling operation. The
structure is advanced into the floor through increments of drilling
strokes by means of rotating, through oscillatory or continuous
rotary motion, a clamping mechanism which is engaged at incremental
positions along the length of the structure. Means are provided to
control the thrust force between the drilling end of the structure
and the sea floor. An umbilical cable supplies power and control
functions from a surface ship to the submerged vessel. Water under
pressure is circulated through the interior volume of the structure
to carry cuttings material away from the cutting end. Following
completion of the drilling operation grout material is pumped into
the void spaces between the structure and sea floor. The vessel is
recovered for subsequent use by disengaging the clamping mechanism
from the structure and blowing selective ones of the ballast tanks
to cause the vessel to have positive buoyancy.
Inventors: |
Well; Dale E. (Pascagoula,
MS), Marley; Kenneth C. (Sunnyvale, CA) |
Family
ID: |
23236712 |
Appl.
No.: |
05/318,114 |
Filed: |
December 26, 1972 |
Current U.S.
Class: |
175/6; 405/202;
173/152 |
Current CPC
Class: |
B63G
8/001 (20130101); E21B 7/124 (20130101); E21B
7/20 (20130101); B63C 11/40 (20130101) |
Current International
Class: |
B63C
11/00 (20060101); B63G 8/00 (20060101); B63C
11/40 (20060101); E21B 7/12 (20060101); E21B
7/124 (20060101); E21B 007/12 () |
Field of
Search: |
;175/6,170,19,471,122,162,203 ;173/152,163 ;166/77,78 ;61/53.5 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Abbott; Frank L.
Assistant Examiner: Favreau; Richard E.
Claims
We claim:
1. An apparatus for emplacing a core barrel, casing, piling or
other type of structure having one end thereof adapted for cutting
material in the floor of a body of water, including the combination
of a support frame, ballast container means on the support frame,
means to introduce ballast into said container means to create
negative bouyancy for said apparatus, means to remove ballast from
said container means to creat-positive buoyancy for said apparatus,
means on the frame to support a length of said structure for
movement to a position with its longitudinal axis oriented along a
predetermined angle of entry with respect to said floor and with
said cutting end disposed lowermost, and means to move said one end
of the structure to cause the structure to cut into and advance
toward said floor along said angle of entry, means to cause said
core barrel, casing, piling or other type of structure of oscillate
about its longitudinal axis through a pre-determined arc, said
means to include a combination of clamping means to releasably
engage the outer periphery of said core barrel, casing, piling or
other type of structure, means to impart rotary motion to said
clamping means when the latter is in clamping engagement with said
core barrel, casing, piling, or other type of structure, means to
oscillate said clamping means, core barrel, casing, piling or other
type of structure through a pre-determined arc about the latters
longitudinal axis to include means forming a gear track on said
clamping means with said gear track extended about the longitudinal
axis of said core barrel, casing, piling or other type structure
and means to drivingly engage said gear track with one or more
sector gears engaging said gear track and means to oscillate said
sector gears through a pre-determined arc and impart rotary motion
to said gear track, said clamping means, said core barrel, casing,
piling or other type of structure.
2. Apparatus as in claim 1 in which said clamping means includes a
collar mounted about said structure, gripping means on the inner
periphery of said collar for releasably engaging said structure,
said collar being adapted to move radially to and from said
structure to respectively cause said gripping means to grip with or
release from said structure, drivable means mounted with said
collar to cause said collar to undergo said radial movement, and
actuating means mounted with said frame and including a drive
member engageable with said drivable means to actuate the latter
when said means to rotate said structure is inactivated, and means
to move said drive member into engagement with said drivable means
for gripping or release of said gripping means, or out of said
engagement whereby said clamping means is free for rotation in a
given angular direction.
3. Apparatus as in claim 2 in which said collar comprises at least
a pair of jaw members, means pivotally connecting one end of each
jaw member together, and said means to open and close the collar
includes a drive shaft, means forming two series of threads on the
shaft with opposite rotational senses, means threadably connecting
said two series of threads with respective portions of said jaw
members on ends thereof opposite said one end, and means to turn
said drive shaft whereby said collar is opened and closed.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to procedures and apparatus for
embedding casing, piling or other similar stucture into the floor
of a body of water, and for taking large core samples from the sea
floor.
Civil engineering contractors have traditionally adhered to working
offshore with conventional and cumbersome surface equipment and
techniques. Previously, harbor development and offshore
construction drilling projects have required the use large surface
work barges, or support vessels to install pier foundations, anchor
piling or terminal footings. This surface equipment demands a high
daily plant rental fee, requires a large crew, and is very
expensive to mobilize. Other significant disadvantages include
their vulnerability to surface weather and wave forces as well as
costly down time for general maintenance and rigging.
Working offshore can be much more economical and practical if the
problem is attacked from a submarine point of view. It is,
therefore, recognized that one prime factor inherent in surface
construction operations offshore which prevents these operations
from comparing more favorably with similar situations on land is
motion. If the motion caused by surface weather and wave forces is
eliminated as a factor, then a dramatic reduction in equipment,
manpower, and support services could be realized.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide a method
and apparatus for emplacing a core barrel, casing, piling or other
type of structure into the floor of a body of water.
Another object is to provide method and apparatus of the above
character for civil engineering and underwater mineral exploration
projects which include the installation of pin pile anchor arrays
for single point mooring systems, the installation of foundation
piles for fixed terminals, the utilization of various templates
together with a submersible drilling system for securing oil
storage terminals, production platforms and other types of offshore
structures with drilled-in piles, and taking core samples from the
floor of a body of water.
Another object of the invention is to provide method and apparatus
of the above character in which a mobile submersible vessel carries
a casing or other similar structure under controllable descent to a
selected site on the sea floor where the structure is moved to a
drilling position and the drilling operation is carried out under
remote control from a surface vessel. The method and apparatus
described herein thus makes it possilbe to complete the drilling
operation without the requirement of surface drilling equipment and
attendant sizeable work crew, large barges, or support vessels.
Another object of the invention is to provide a method and
apparatus of the above character in which a vessel carries a length
of a casing or other similar structure in such a manner to
facilitate towing of the vessel on the surface of the water, and
the acheive a position metacenter for the vessel during descent so
that a predetermined orientation is maintained until setdown at the
drilling site. At the drilling site, means are actuated under
remote control from the surface vessel to control a series of
functions which include leveling and anchoring the vessel with the
floor, elevating the structure to the desired drilling orientation,
oscillating or continuously rotating the structure, circulating a
stream of fluid for removing cuttings material, controlling the
rate of cutting by the control of bit thrust, drill bit speed and
circulating fluid pressure, placing grout material in the voids
between the structure and surrounding formation, and recovering the
vessel by disengaging the same from the structure and creating a
condition of positive buoyancy for ascent to the surface.
The method of the present invention employs a submersible vessel
upon which is mounted a length of structure such as a casing,
piling or core barrel. The vessel is towed by a surface ship to a
location on the surface of the water above the desired drilling
site after which water ballast is added to make the vessel
negatively buoyant in a stable upright orientation for controlled
descent to the drilling site. Following setdown at the site the
vessel is leveled and anchored with the floor and the casing or
other structure is then elevated to the desired drilling
orientation. Water is pumped through the interior volume of the
structure through a hose connected to the top of the structure.
Drilling functions such as drill bit pressure, peripheral bit
cutting speed, water circulating pressure and the like are
monitored and controlled by both automatic controls on the vessel
and by automatic and manual controls on the surface ship through
leads extending along an umbilical cable. As drilling progresses
and the structure advance through incremental strokes into the
formation of the sea floor, the clamping mechanism is released and
moved upwardly for re-engagement with the structure for each
subsequent stroke. After drilling is completed grout material is
pumped from the surface ship through a line along the umbilical
cable to the void spaces between the structure and surrounding
formation. After the grout material sets a pull test can be applied
on the emplaced structure by exerting a vertical force on the
clamping mechanism, or by blowing water from the ballast tanks. The
vessel is retrieved by releasing the clamping mechanism and blowing
sufficient ballast to create a positive buoyancy in the vessel for
a controlled ascent.
In the apparatus the vessel is constructed with main water ballast
tanks and a plurality of pressure tanks positioned about the
periphery of the vessel whereby the degree of buoyancy and vessel
orientation during descent and ascent may be controlled. A support
device is provided to support the structure lengthwise of the
vessel for towing and descent. The support device is adapted to
elevate the structure to an upright drilling position with the
cutting end lowermost. A clamping device releasably engages the
structure and either oscillatory or continuous rotary motion is
imparted to the clamping device for drilling. The vertical thrust
force, and thereby bit pressure, is controlled by hydraulic
actuators connected with the clamping device. Ground-engaging legs
provided with helical blades are mounted about the periphery of the
vessel for leveling and anchoring the vessel with the floor. A
water pump carried on the vessel pumps water into the interior
volume of the structure for removing cuttings material, and a
three-way valve is provided to direct grout material pumped from
the surface ship into the interior volume for cementing the
structure in place.
A method of pulling the vessel down to the sea floor under positive
buoyancy and then adding one or more hydraulic winches to the
vessel and controlling these winches with separate hoses from the
surface craft.
This method would include emplacing weights or anchors on the sea
floor to which are attached cables connected to the winches on the
vessel.
The vessels ballast tanks are flooded as previously discussed until
there remains less positive buoyancy than the haul down capasity of
the winches and the negative weight of the anchors on the bottom.
The winches are then acitvated to pull the vessel down to the sea
floor. Once the vessel is on the sea floor the ballast tanks are
completely flooded to acheive the maximum gross weight on the
bottom for commencing drilling operations.
Additional objects and features of the invention will appear from
the following description in which the preferred embodiments have
been set forth in detail in conjunction with the accompanying
drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a perspective view of apparatus for carrying out the
method of the invention showing a submersible vessel and exemplary
casing structure in three sequential modes of operation.
FIG. 2 is a perspective view of an enlarged scale of the
submersible vessel of FIG. 1 showing the drilling mode thereof.
FIGS. 3A and 3B constitute a schematic diagram for the control
system of the present invention.
FIG. 4 is a top plan view, partially cut away, of the vessel of
FIG. 2 with elements thereof removed for clarity.
FIG. 5 is an end elevational view on an enlarged scale along the
line 5--5 of FIG. 4 illustrating one ground-engaging leg for the
vessel.
FIG. 6 is a view similar to FIG. 5 illustrating another embodiment
of the ground-engaging leg.
FIG. 7 is a partially broken away side elevational view of an
enlarged scale of the cutting end of the casing structure shown in
FIG. 2.
FIG. 8 is an end view taken along the line 8--8 of FIG. 7.
FIG. 9 is a side view similar to FIG. 7 illustrating another
embodiment of the cutting end for the casing structure.
FIG. 10 is an end view taken along the line 10--10 of FIG. 9.
FIG. 11 is an axial section veiw on an enlarged scale taken along
the line 11--11 of FIG. 10.
FIG. 12 is an elevational view on an enlarged scale taken along the
line 12--12 of FIG. 4 showing the clamping and rotary actuator, and
vertical thrust mechanisms.
FIG. 13 is a lateral cross sectional view taken along the line
13--13 of FIG. 12.
FIG. 14 is a partially broken away top plan view on an enlarged
scale showing details of elements of the structure of FIG. 12.
FIG. 15 is a section view taken along the line 15--15.
FIG. 16 is a schematic diagram showing the circuit for directing
fluid for cuttings removal, and for directing grout material for
cementing the illustrated casing.
FIG. 17 is partially broken away and side elevational view of
another embodiment of the invention.
FIG. 18 is a partially broken away cross sectional view taken along
the line 18--18 of FIG. 17.
FIG. 19 is a schematic diagram of the control circuit for the
elements shown in FIG. 17.
FIG. 20 is a partially broken away side elevational view of another
embodiment of the invention.
FIG. 21 is a cross sectional view taken along the line 21--21 of
FIG. 20.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG. 1 there is shown at 20 apparatus for emplacing a
structure such as an exemplary casing 21 into the floor 22 of a
body of water such as a lake, river or ocean. While the method and
apparatus of the invention will be described with particular
reference to emplacing such a casing for use as an anchor
attachment or mooring in the sea floor, for example, it is
understood that the invention will find broad application where
other similar structures are to be emplaced, e.g., in drilling core
barrels for offshore civil engineering studies and mineral
exploration, and in drilling offshore piling for bridges,
platforms, trestles and piers.
Apparatus 20 is adapted to be selectively buoyant or submersible
under influence of an automatic and manual control system to be
described hereafter. Apparatus 20 defines a vessel which, in its
buoyant mode, is adapted to be connected with a surface ship or
craft 23 by tow cable 24 and bridle 25 for transport over the
surface of the water to a location substantially above the desired
drilling site on the sea floor. Casing 21 is mounted on the vessel
in a transport orientation extending lengthwise of the vessel. For
submersion and drilling operations an umbilical cable 26 is
connected to the vessel to carry power and control circuit leads
from the surface ship, craft or station. Prior to descent, two
cable 26 is disconnected and the control circuit operated in a
manner to be described causing the vessel to submerge toward the
sea floor in the upright stable orientation illustrated at 20'.
Following setdown on the sea floor, the vessel is caused to assume
its drilling mode with casing 21 elevated, as illustrated at
20".
Referring to FIG. 2, apparatus 20 is illustrated in greater detail.
A support frame 27 of welded channel member construction is
provided to form an elongated support configuration. Ballast
container means 28 comprising a plurality of ballast and pressure
tanks are secured to the support frame, and a pair of flat walkways
or decks 29, 31 are mounted above the tanks and extend lengthwise
of the vessel. A false bow structure 32 is secured to the forward
end of the frame to facilitate towing of the vessel over the
surface of the water. Casing 21 is mounted adjacent its drilling
end 33 to the support frame by a support and drilling device 34
which is adapted to move the casing between a horizontal transport
position for transport and descent (illustrated in broken-line at
21' in FIG. 2) and an upright drilling position shown in solid
line. In the drilling position the longitudinal axis of the casing
is disposed along a predetermined angle of entry with respect to
the sea floor. The end 35 of the casing remote from the drilling
end is supported in the horizontal transport position by a pair of
semicircular support cradles 36, 37 mounted above the frame.
Referring to FIG. 4 details of the ballast container means are
illustrated. A pair of elongated hollow ballast containers,
preferably cylindrical in shape, comprising main ballast tanks 38,
39 are mounted to the frame with an orientation lengthwise of the
vessel and positioned to straddle casing 21 in the latter's
transport position. A plurality of transversely extending
spaced-apart baffles 41, 42 are mounted in the interior volumes of
the two main ballast tanks 38, 39 to obviate the effects of ballast
surge which could otherwise occur when the vessel undergoes
pitching, rolling or yawing movement. Main tanks 38, 39 are flooded
with a suitable ballast, preferably water, both when the vessel is
on the surface and when submerged to contribute sufficient weight
to establish a low center of gravity and maintain a stable upright
orientation. The main ballast tanks are "soft" tanks, that is these
tanks are substantially completely flooded with water ballast while
submerged and need not be designed to withstand extreme hydrostatic
pressure while submerged.
A pair of elongate hollow ballast containers 43, 44, preferably
cylindrical in shape, are mounted on frame 27 outboard of main
tanks 38,39 and with an orientation lengthwise of the vessel. The
containers 43, 44 are "hard" pressure vessels constructed to
withstand the hydrostatic pressures encountered at the maximum
design working depth of 660 feet. The containers are positioned
about the periphery of the vessel to provide, by means of varying
the amount of ballast, control over both the vessel's buoyance and
its trim or stability during towing, descent and ascent. Each of
the containers 43, 44 is provided with a pair of internal
diaphragms or bulkheads 46, 47 and 48, 49 defining three pressure
tanks on each side of the vessel. Thus, each container is divided
into a pair of stabilizer tanks 51, 52 positioned at opposite ends
of a central variable tank 53. The control circuit of FIG. 3
provides means to flood the two variable tanks 53 with water
ballast for both descent and drilling phases, and to blow these
tanks with compressed air for ascent of for a pull test. The
control circuit further provides for independently flooding the
four stability tanks 51, 52 with variable amounts of water ballast
to maintain stability during descent and ascent, and to maintain
trim for towing on the surface. Each of the stability and variable
tanks are further provided with a plurality of transversely
extending axially spaced baffles 54, 55 which function to obviate
the effects of ballast surge when the vessel pitches, rolls or
yaws. As shown in FIG. 2, a plurality of high pressure gas tanks 56
are mounted below the decks 29, 31 to supply a source of compressed
air for blowing ballast from the main, variable and stability
tanks.
Suitable fixed ballast weight means is provided to establish, in
combination with the weight of the frame, casing, onboard equipment
and ballast in all tanks, an overall center of gravity which is
disposed below the vessel's center of buoyancy. This fixed ballast
means includes, in the illustrated embodiment as shown in FIG. 5,
longitudinally extending heavy skegs 57 filled with a ballast such
as lead and secured by suitable fastener means along the bottom
surfaces of each of the four ballast containers or tanks 38, 39, 43
and 44. Preferably the weight distribution is arranged so that the
indicated location 58 sufficiently below the resulting center of
buoyancy at the indicated location 59 to create a positive
metacenter for the vessel. This positive metacenter is maintained
while the vessel is both afloat and submerged so that any rolling
or pitching motion is counteracted by the righting moment
couple.
Means are provided for leveling and anchoring the vessel when it is
on the floor at the drilling site. This means includes a plurality
of ground-engaging legs 61,62,63,64, each of which is positioned
adjacent a respective corner of the vessel. FIG. 5 illustrates
details of the typical leg 61 mounted aft on the vessel's port side
below deck 31 and between main ballast tank 38 and stabilizing tank
52. This leg includes a shaft 66 carrying a helical blade or auger
67 and a lowermost auger drill bit 68. The shaft extends upwardly
for driving engagment through a suitable spline connection or the
like with an hydraulically powered rotary motor 69 mounted between
the two tanks. The motor is in operating connection with a suitable
linear actuator such as the hydraulic cylinder 71. Actuation of the
rotary motors and linear actuators for the four legs by the control
system following setdown drills the legs into the floor to anchor
each corner of the vessel against the forces of currents, tides,
umbilical drag, reaction forces from the drilling torque applied to
the casing, and reaction forces of the thrust acting on the cutting
end of the casing. Suitable sensors (not shown) are provided on the
vessel to provide an indication, by remote signals through the
umbilical to the surface ship, of the vessel's orientation with
respect to the horizontal. To bring the vessel to the desired
orientation selected ones of the four linear actuators 71 are
energized to extend or retract respective legs and thereby raise or
lower selected corners of the vessel. Following completion of the
drilling operation each of the rotary motors are reversely actuated
to retract the augers from the floor.
FIG. 6 illustrates another embodiment for the ground-engaging legs
of the invention. In this embodiment each of four leveling legs 72
include a length of pipe 73 provided at is lower end with a flat
leveling pad 74. Pipe 73 is adapted to be interchangeable with the
auger shaft 66 of the embodiment of FIG. 5. The upper end of pipe
73 is operatively connected with linear actuator 71 to raise and
lower a respective corner of the vessel in a manner similar to that
explained in connection with the embodiment of FIG. 5. The
embodiment of FIG. 6 especially adapted for leveling the vessel
where sea floor conditions and drilling requirements do not
necessitate anchoring, and in such case it is not necessary to
actuate rotary motors 69.
Casing 21 is of cylindrical shell configuration and is of the
selected size and wall thickness and material as determined by
particular specifications and requirements. As an example, the
casing size may be in the range of 12 to 72 inches in diameter with
11/4 inch wall thickness, and with casing length up to 50 feet.
Where it is desired to drill at greater length into the seafloor
formation, then the invention facilitates the insertion of longer
lengths of casing for deeper drilling. The upper end 35 of the
casing is closed by a circular cover 76 secured by means such as
welding. A padeye 77 may be welded to the top surface of cover 76
for attachment of an anchor chain or the like by suitable means
such as a shackle where the emplaced casing is to be used as an
offshore mooring or anchor.
As shown in FIGS. 7 and 8, cutting end 33 of the casing includes a
suitable bit shoe 78 of cylindrical configuration secured to the
casing by suitable means such as welding. The distal end of the bit
shoe is formed into a drag bit type cutter by mounting a plurality
of hard-face bits 79 by suitable means such as welding about the
bit shoe rim. As best illustrated in FIG. 8, the bits are staggered
in orientation such that alternate ones of the bits incline
radially inwardly and outwardly from the casing. As cutting
progresses the bits cut annular spaces or voids 81, 82 (FIG. 16)
into the seafloor formation on opposite sides of the casing wall.
These annular spaces provide a path for circulation of fluid for
removing cuttings material, and for circulation and deposit of
grout material where it is desired to cement the casing into the
formation. In addition, because only a narrow, circular path is
drilled into the formation, horsepower and torque requirements are
reduced as compared to conventional open hole drilling where the
entire diameter is drilled out.
FIGS. 9-11 illustrate another embodiment of the invention in which
a modified cutting end is provided on a casing 83. In this
embodiment a bit shoe 84 formed of a plurality of annular
reinforcing members 86,87,88 is secured by welding to the distal
end of the casing. A plurality of cone-shaped roller bits 89 are
mounted in spaced-apart relationship about the periphery of the bit
shoe on suitable brackets 91 for rotation about axes inclined with
respect to lonitudinal axis of the casing. The roller bits are
dimensioned so that the inner and outer end faces thereof radially
project inwardly and outwardly of the walls of bit shoe 84 so that,
as cutting progresses, annular spaces or voids 92, 93 are formed
between the casing wall and surrounding seafloor formation for
circulation of cuttings removal fluid and grout material.
Support and drilling device 34, best shown in FIGS. 2,12, and 13,
supports the casing adjacent its cutting end in the transport mode,
elevates and lowers the casing to and from the drilling position,
and supports and inparts drilling motion to the casing in the
drilling mode. The device 34 includes a pair of extensible
actuators 94, 95, preferably hydraulic rams, pivotally mounted at
their head ends to frame 27 and pivotally mounted at their rod ends
96,97 to clevis brackets 98, 99 carried on supports 100, 101 which
in turn are secured to pivot yoke 103 on diametrically opposed
sides of the casing. A casing clamp assembly 102 is mounted on the
pivot yoke which in turn is pivotally mounted at its inboard end to
support from 27. An annular guide bearing 104 is mounted lowermost
on yoke 103 and is sized to rotatably and slidable receive and
position casing 21. Alternatively, an additional casing clamp
assembly, not shown, similar in construction and operation to that
of casing clamp 102, may be provided at the location of an in place
of guide bearing 104 to provide additional torque and vertical
control, as required, for drilling or coring operations, or such
alternate clamping mechanism may be used alone as the prime rotary
power source. Casing clamp 102 is supported uppermost on the yoke
for releasable gripping engagment with the casing 21. Both guide
bearing 104 and the casing clamp thereby provide two-point support
for the casing so that it is stabilized, when in its drilling mode,
at a predetermined angle of entry with respect to the sea
floor.
Further support for the casing both in its transport and drilling
positions is provided by a semi-cylindrical guide shoe or bearing
106 mounted on an A-frame 107 which in turn is pivotally mounted at
its lower base legs to frame 27. The A-frame and guide bearing 106
are biased by suitable means such as springs to pivot toward an
upright position, as illustrated in FIG. 2 where it supports the
casing in its drilling position. The A-frame is pivoted downwardly
with the bearing horizontally aligned with support cradles 36, 37
when the casing is in its transport position. An additional
semi-cylindrical guide shoe or bearing 108 is provided
diametrically opposite bearing 106 in the drilling position of the
casing. This guide shoe is supported by an A-frame 109 which is
pivotally mounted at is apex to the shoe and at its lower base to
false bow structure 32. An extensible actuataor 111, preferably an
hydraulic ram, is pivotally mounted at its head end to the bow
structure and at its rod end to a cross member on A-frame 109.
Extension and retraction of actuator 111 under influence of the
control system positions guide shoe 108 to the desired orientation
with respect to the vessel which will establish a predetermined
angle of entry for drilling the casing into the sea floor.
Casing clamp 102, as best illustrated in FIGS. 12-15, comprises an
annular collar defined by a pair of arcuate jaw members 112, 113
pivotally mounted together at overlapping ends by hinge pin 114 and
with radially outwardly extending arms 116, 117 formed at their
diametrically opposite ends. A series of clamping teeth 118, 119
are provided about the inner periphery of each jaw member. These
teeth preferably are of the type known in the art as tong dies. The
collar is opened and closed by actuator means 121 for disengaging
and engaging, respectively, the clamping teeth about casing 21.
This actuator means includes a reversable rotary motor 122,
preferably an hydraulic motor, connected with an annular support
123 which in turn carries the hinge pin for the two jaw members.
Motor 122 powers drive means comprising a drive shaft 124 formed
with two series of right and left hand threads disposed on opposite
sides of a central spacer flange 126. Gimbaled nuts 127, 128 are
mounted within slots 129 formed in each of the jaw arms. The nuts
127, 128 are in threadable connection with opposide threads of
shaft 124, and the nuts are pivotally carried on pins 130, 131
mounted within arms 116, 117. Rotation of the drive shaft in either
rotational sense moves the nuts apart or together along the shaft
and thereby causes the jaw members to open and close.
Means for imparting oscillatory rotary movement to the casing
clamping and casing is provided at 132.
This means includes a circular gear track or ring gear 133 formed
about the outer periphery of annular support 123. The gear track is
recessed within the support so that upper and lower annular rims
134, 135 on the support project radially outwardly of the track. A
pair of sector gears 137, 138 are mounted at diametrically opposite
positions in driving engagement with gear track 133. The upper and
lower axial end faces of each of the sector gears are slidably
fitted between the inner surfaces of the upper and lower support
rims 134, 135 for transmitting thrust forces therebetween. Drive
shafts 139, 140 coupled to the sector gears extend downwardly in
operable connection through rotary actuators 142, 143 mounted for
vertical sliding movement in slots formed on pivot yoke supports
100, 101. Rotary actuators 142, 143 preferrably comprise hydraulic
rotary actuators operated under influence of the control system to
oscillate respective drive shafts back and forth through a
predetermined circular arc. The lower most ends of the hydraulic
rotary actuators are engaged with suitable linear actuators 147,
148 which preferably comprise hydraulic rams mounted on pivot yoke
103. The linear actuators are operated under influence of the
control system to impart thrust forces to clamp 102 and casing 21
in either direction along the longitudinal axis of the casing. Thus
the actuators may be energized to exert a selectively variable
thrust force away from the sea floor to unload a portion of the
casing weight and thereby establish a predetermined axial thrust on
the cutting bits for controlling the cutting rate, as monitored by
the operator on the surface ship through remote signal leads
extending along the umbilical. As cutting progresses the two
actuators are caused to automatically retract permitting the clamp
and casing to move downwardly through a cutting stroke on the order
of 4 feet. At the end of thisstroke clamp 102 is actuated for
disengagement from the casing and the actuators 147, 148 are then
caused to extend and raise the disengaged clamp upwardly along the
casing for re-engagement in a new clamping position for initiating
the next successive cutting stroke. After the casing is drilled
into the formation to the desired depth and any injected grout
material has set, actuators 147, 148 may be energized to extend and
apply a vertical thrust force to the casing with the clamp engaged
for purposes of performing a pull test on the embedded casing.
The present invention also faciliates the drilling of casing,
piling or core barrels of various diameters through utilization of
a single casing clamp and a plurality of paired semi-cylindrical
adapter members, not shown, fitted with inwardly facing clamping
teeth. The adapter members would be mounted about the inner
circumference of the two jaw members where it is desired to drill a
smaller diameter casing. At the same time, an adapter ring of the
appropriate diameter would be mounted within guide bearing 104 for
supporting the lower end of the casing structure.
In the schematic of FIG. 16 there is shown a system for circulating
in either direct or reverse flow directions a fluid for cuttings
material removal. The system further provides for the injection of
a flowable grout material where it is desired to cement the casing
or other structure into the formation. A water pump 149 is mounted
within a suitable protective enclosure 151 mounted on the
submersible vessel and is driven by a suitable prime mover,
preferably the electric motor 152, although other prime movers such
as hydraulic or pneumatic motors may also be utilized. Electrical
power to drive motor 152 is supplied from the surface ship by means
of a cable extending along umbilical 26. During drilling, fordirect
circulation of the fluid (as illustrated by the arrows), pump 149
receives water from the sea surrounding the vessel through valve 54
and conduit 156 and discharges it under pressure through valve 157
and conduit 158 leading to a three-way valve 159. This three-way
valve directs the water through a branch conduit or flexible hose
160 leading to an elbow fitting 161 which opens into the casing
through casing cover 76. Sea water is thereby pumped into the
interior volume 162 of the casing where it circulates downwardly
along the void space of inner annulus 82 and discharges outwardly
between the cutting bits 79 to carry the cuttings material upwardly
along the void space of outer annulus 81 for deposit on the sea
floor. Water pump pressure and volume is controlled by automatic
and manual controls as a means of controlling both the rate of
cuttings removal.
Depending upon veriables such as the type and hardness of the sea
floor formation, as determined from pre-drilling coring or
exploration surveys, the cuttings removal flow circuit may be set
up for reverse flow during the drilling operation, e.g. where
formation cave-in could otherwise impede direct flow. To establish
the reverse flow circuit a branch conduit 163 and valve 164 are
provided between conduit 158 and the downstream side of valve 154,
while a discharge conduit 167 and valve 166 are connected with the
outlet of pump 149 downstream of valve 157. The two valves 164, 166
which are both closed for direct flow operation, are opened for
reverse flow with valves 154 and 157 then closed. Operation of pump
149 acts to draw sea water downwardly along annulus 81 to carry
cutting material from the bits upwardly along annulus 82 and
through the casing into conduits 160, 158 and 163 for discharge
into the sea through conduit 167.
While the schematic of FIG. 16 illustrtes the direct mounting of
motor 152 and water pump 149 on the vessel, the invention also
contemplates a system in which a water pump provided on the surface
ship pumps the water to the casing through a suitable flexible hose
or conduit extending along umbilical 26.
Three-way valve 159 is adapted for actuation by suitable means such
as the hydraulic actuator 168 under influence of the control system
to disconnect conduit 158 from branch conduit 160 and connect the
latter with grout supply conduit 169 where it is desired to cement
the casing in place. A suitable grout material such as neat cement
is then pumped from the surface ship into supply conduit 169 from a
suitable flexible hose extending along umbilical 26. The grout
material is directed into branch conduit 160 into the interior
volume of casing 21 where it circulates downwardly along annulus
82, outwardly between the cutting bits and upwardly into annulus 81
to fill the voids in the formation. The grout material cures or
sets after a time interval typically 4 hours after which a pull
test may be conducted either by applying a predeterminee vertical
thrust force on the casing with actuators 147, 148, by blowing the
ballast tanks with the casing clamp engaged, or by attaching a
calbe or chain to padeye 77 and applying a pull force from a
surface ship. For reocvery of the vessel branch line 160 is
disconnected from elbow 161 by remotely actuated means or by a
diver.
FIGS. 17-19 illustrate another embodiment of the invention showing
an alternate system for applying drilling motion to an exemplary
casing structure 170. The casing is supported in its drilling mode
with an orientation along the desired angle of entry by means of
two semi-cylindrical guide shoes 171, 172 Guide shoe 171 is
pivotally mounted to support frame 173 by means of A-frame 174.
This A-frame is biased by suitable spring means to pivot in a
counterclockwise direction, as seen in FIG. 17. As the casing is
brought to the drilling position, the guide shoe 172 is pivotally
mounted the support frame by an A-frame 176 which is moved to a
selected position by means of extensible hydraulic actuator 177 to
establish the desired angle of entry. The casing 21 is supported
and positioned at its lower end by means of an annular guide
bearing 181 together with a support and drilling device 179 which
is carried on a pivot yoke 182. As illustrated in the schematic of
FIG. 19, pivot yoke 182 is mounted by suitable pin means 183 for
pivotal movement on support frame 173. A pair of extensible
actuators, 175 preferrably hydraulic rams, are pivotally mounted at
their head ends to frame 173 and at their rod ends to support 188
on the drilling device 179. Hydraulic fluid is directed through
conduits 186, 187 into the rams under the influence of the control
system to move the casing between its transport and drilling
positions.
A rack and gear type oscillator motor 189 is carried by support 188
which in turn is mounted for vertical movement above yoke 182 by
means of a pair of diametrically opposed linear actuators 191,
which preferrably comprise hydraulic rams. Hydraulic fluid under
pressure is directed into the rams through conduits 192, 193 under
influence of the control system for controlling the thrust force on
drilling device 179 when the same is engaged with the casing to
control bit pressure during cutting, to move the casing back and
forth for successive strokes, and to conduct the pull test after
the casing is embedded in the formation. A casing clamp 194 similar
to that described in connection with the embodiment of FIGS. 12-15
is mounted about the casing. This clamp includes a pair of arcuate
jaw members 196, 197 pivotally mounted together at pin 198 and with
a plurality of clamping teeth or tong dies mounted about their
inner periphery. The jaw members are closed and opened to engage
with and disengage from the casing by actuator means comprising a
reversible rotary hydraulic motor 199 secured to the oscillator
motor housing. Hydraulic fluid is supplied through flexible
conduits 201, 202 into the motor for turning threaded drive shaft
203 in the selected direction for moving, through suitable gimbaled
nuts, arms on the two jaw members.
Oscillator motor 189 includes means forming a circular gear track
or ring gear 204 upon which casing clamp 194 is mounted.
Diametrically opposed sides of motor housing 206 are formed into a
pair of hollow cylinders adapted to slidably received respective
gear racks 207 each of which is formed at opposite ends with a
piston 208, 209 fitted within and slidably mounted in the
cylinders. The two gear racks tangentially engage gear track 204
which is oscillated through a predetermined circular arc within an
arc of up to substantially 90.degree., although a back and forth
oscillating arc of 35.degree. is preferred. As shown in the
schematic of FIG. 19 the racks are reciprocated by hydraulic fluid
directed altermatively through respective conduit pairs 211, 212
and 213, 214 into opposite ends of the cylinder. As cutting
progresses hydraulic rams 191 are retracted through a cutting
stroke on the order of four feet, after which clamp 194 is opened,
rams 191 extended upwardly, and the clamp closed for re-engagement
and initiation of the next successive cutting stroke.
FIGS. 20 and 21 illustrate another embodiment of the invention
providing a modified form of the clamping mechanism specially
adapted to provide continuous rotary drilling motion to the
exemplary casing 215. In this embodiment a support and drilling
device 216 is carried by a pivot yoke 217 which in turn is mounted
on the vessel's frame in a manner similar to that described in
connection with the foregoing embodiments whereby the casing may be
pivoted between its transport and drilling positions. An annular
guide bearing 218 is mounted below the pivot yoke to rotatably
support and position the lower end of the casing.
Support and drilling device 216 includes a casing clamp 218 having
a pair of arcuate jaw members 219, 220 pivotally mounted together
at pin 222. A plurality of clamping teeth or tong dies 223, 224 are
mounted about the inner periphery of the jaw members. A pair of
arms 226, 227 are provided at the open ends of the jaw members, and
a drive shaft 228 formed with two series of right and left hand
threads is in threadable connection with gimbaled nuts mounted with
in slots in the arms in a manner similar to that described in
connection with FIGS. 14 and 15. One end of the drive shaft is
provided with an enlarged socket head 229 formed with a recessed
drive socket 231. Clamp actuating means 232 is mounted on a bracket
233 connected by a suitable bracket 234 for conjoint movement with
the casing clamp lengthwise of the casing. This actuating means
includes a drive member 235 formed with a pointed end 236 having a
configuration (e.g. square in cross section) adapted to move into
and out of driving engagement with a corresponding configuration
for the recess of drive socket 231. Drive member 235 projects
through a reversable motor 237, preferably an hydraulic motor, and
this hydraulic motor is mounted on a bracket 238 which slides
through a slot formed in bracket 233 lengthwise of the drive
member. The end of drive member 237 remote from end 236 is
connected with a suitable linear actuator 239, preferably an
hydraulic ram operated under influence of the control system.
Extension and retraction of ram 239 reciporcates the drive member,
together with hydraulic motor 237, so that pointed end 236 moves
into and out of engagement with drive socket 231. With the pointed
end engaged in the drive socket hydraulic motor 237 is actuated to
turn the drive member in the desired direction and thereby open and
close the jaw members. With the pointed end retracted, the drive
member clears the socket sufficiently to permit the jaw members and
casing to undergo continuous rotary motion in either directional
sense.
A gear track or ring gear 241 is formed between spaced rims 242,
243 of annular support 244 upon which the casing clamp is mounted.
This gear track is recessed radially within the two rims and a pair
of diametrically opposed pinion gear 246, 247 are mounted between
the rims in rotary driving engagement with the gear track. The
pinion gears are adapted to transmit axial thrust forces to the
casing clamp and casing. A pair of drive shafts 248, 249 extend
downwardly from the two pinion gears and are connected at their
lower ends with suitable linear actuators 251, 252, preferably
hydraulic rams, mounted to pivot yoke 217. Suitable rotary
actuators 253, 254, preferably hydraulic motors, are mounted in
driving connection with the two shafts 248, 249, with the housings
for each motor mounted on brackets 256, 257 for sliding movement in
slots formed along upright frame members 258, 259 of the pivot
yoke. Operation of the two rotary actuators 253, 254 under
influence of the control system drives the pinion gears for turning
the engaged clamp and casing, while at the same time the hydraulic
pressure within the linear actuators 251, 252 is controlled to
provide the desired axial thrust force on the clamp, and thereby
control bit pressure. As drilling progresses the rams are caused to
retract downwardly through a drilling stroke on the order of four
feet, with rotary actuators 253, 254 and clamp actuating means 232
moving downwardly with the drive shafts through the bracket and
slot connection on the frame members. As the extremity of each
stroke is reached, the rotary actuators are stopped with the jaw
members and drive socket positioned as shown in FIG. 21. Linear
actuator 239 is then energized to extend drive member 235 until
pointed end 236 is in driving engagement with socket 231. Hydraulic
motor 237 is then energized to turn the drive member in a direction
moving arms 226, 227 apart, thereby opening the jaw members for
disengagement from the casing. Rams 251, 252 are then extended to
move clamp 216 together with clamp actuator 232, upwardly along the
casing for a return stroke a distance on the order of 4 feet. Motor
237 is then energized to turn drive member 235 in a reverse
directional sense moving arms 226, 227 together so that the jaw
members re-engage about the casing. Linear actuator 239 is then
retracted to disengage the pointed end from the drive socket, and
rotary actuators 253, 254 are then energized to resume the drilling
operation.
The casing, piling or core barrel structure may also be oscillated
about its longitudinal axis for drilling by suitable structure, not
shown, in which extensible hydraulic elevating and drilling rams of
the type shown at 94 and 95 in FIG. 2 for moving the casing between
its transport and drilling positions are reicprocated in opposite
directions. In such an arrangement the rod ends of these rams would
be attached through suitable swivel connections for movement with
the casing clamp. Axial thrust control rams of the type shown at
147, 148 in FIG. 12 would be connected at their one end in annular
slots formed around the casing clamp and at their other end with a
yoke structure pivotally mounted to the vessel's frame. The control
system in this arrangement would be effective to direct hydraulic
fluid to the elevating and drilling rams in parallel connection for
simultaneous extension and retraction to raise and lower the
casing, and in series connection so that the same rams impart
oscillatory drilling movement to the clamp, and thereby to the
casing.
FIGS. 3A and 3B schematically illustrate a preferred control system
for the invention. A suitable oil-filled enclosure 261 is mounted
on the vessel to protect the component elements indicated as within
the enclosure from sea water. A power cable 262 extending along the
umbilical connects with a source of electrical power 263 on surface
ship 23 for operating electric motor 264 through lead 266, for
operating water pump motor 152 (FIG. 16) through lead 153, and for
operating leak detector device 267 through lead 268. A control
cable 269 carrying a plurality of signal leads for control
functions to be hereafter described also extends to enclosure 261
from the surface ship along the umbilical. While the operation of
the various control and operating elements will be explained as
activated or controlled by hydraulic or pneumatic power, the
invention contemplates that any suitable medium could be utilized
for each function, such as electrical, hydraulic, or pneumatic
media, or any combination thereof.
The electric motor 264 drives a suitable hydraulic power pump 271
adapted to deliver approximately 30 GPM of fluid at 3,000 psi. Pump
271 draws supply fluid through inlet 272 from the reservoir of
hydraulic fluid or oil which fills enclosure 261. The pressurized
fluid is directed into a supply conduit 273 and branch conduit 274
to establish a high pressure circuit, and into a pressure reducer
276 which reduces the fluid pressure to substantially 500 psi for
delivery into manifold 277 to establish a low pressure circuit. A
branch conduit 278 feeds into a suitable hydraulic accumulator tank
279 adapted to contain a pressurized supply to fluid. An automatic
control valve 281 provided in branch conduit 278 operates to direct
fluid from the accumulator tank into the supply conduit should pump
operation fail or cease for any reason to insure continued
operation of the control elements for a number of cycles.
Alternatively, the hydraulic fluid for the high and low pressure
circuits may be supplied from suitable pumping equipment on the
surface ship connected with a flexible conduit in the
umbilical.
Low pressure manifold 277 feeds a plurality of solenoid-operated
hydraulic valves 282-290 which are actuated under remote control by
electrical signals received through the plurality of leads 292
contained in branch cables 293, 294. The branch cables extend into
control cable 269 and along the umbilical to suitable electrical
signal generating means incorporated into control console 296 on
the surface ship. Branch cable 293 supplies leads to the five
valves 282-286 controlling circulation of fluid for cuttings
removal and grout injection, and for flooding the ballast tanks.
Branch cable 294 supplies the leads to the four valves 287-290
controlling venting and blowing of the ballast tanks. The nine
valves 282-292 direct return fluid into exhaust manifold 295 which
emptys into the interior of enclosure 261 through filter 296.
Activation of the valves 282-290 under influence of electrical
signals received through their associated leads directs pressurized
hydraulic fluid from manifold 277 into the associated pairs of
conduits 297-305 leading outwardly from enclosure 261 to the
hydraulically activated control valves 159 and 308-315. Valve 282
is connected through the conduits 297 with the three-way valve 159
for selecting either direct or reverse water circulation for
cuttings removal, or for grout material injection.
Valve 283 is connected through the conduits 298 with four flood
valves 308 (one of which is shown), with each valve 308 being
mounted in a lower portion of a respective one of the four
stability tanks 51, 52. Upon activation of valve 283, the four
flood valves are simulteneously opened for flooding the stability
tanks.
Valve 284 is connected through the conduits 299 with flood valve
309 which is mounted in a lower portion of the starboard variable
ballast tank 53 for selective remote control flooding of this
tank.
The valve 285 directs hydraulic fluid through conduits 300 into
flood valve 310 in the lower portion of the port ballast tank 53
for remote control flooding of this tank.
The valve 286 directs hydraulic fluid through conduits 301 into
four flood valves 311 (one of which is shown) provided in the lower
portions of the main ballast tanks 38, 39 for remote control
simultaneous flooding of these tanks.
Venting and blowing of the ballast tanks is accomplished in the
control circuit by remote control of the four valves 287-290. Valve
287 directs hydraulic fluid through conduits 302 into four
vent-blow valves 312, (one valve is shown) each of which is mounted
uppermost in a respective one of the four stability tanks 51, 52
for simultaneous venting of the contained air for flooding, and for
simultaneously blowing ballast from these tanks by establishing
communication with a high pressure air manifold 317 connected
through high pressure valve 318 with the air supply tanks 56.
Valve 288 directs fluid through conduits 303 into valve 313 mounted
uppermost on the starboard variable ballast tank 53 to vent this
tank during flooding, and to establish communication with high
pressure air manifold 317 for blowing a selected amount of
contained ballast for purposes of maintaining the vessel's
stability and trim.
Valve 289 directs fluid through conduits 304 into the valve 314
mounted uppermost on the port variable ballast tank 53 to vent this
tank during flooding, and to establish communication with high
pressure air manifold 317 for blowing a selected amount of
ballast.
Valve 290 directs fluid through conduits 305 into two valves 315
(one valve is shown), each of which is mounted uppermost in a
respective one of the main ballast tanks 38, 39 to either vent
these tanks during flooding, or to establish communication with the
high pressure air manifold for blowing selected amounts of ballast
from the tanks.
A solenoid operated hydraulic valve 319 is provided to direct
hydraulic fluid from low pressure manifold 277 into conduit 321
leading to an hydraulically operated main exhaust valve 322 which
is adapted to vent air manifold 317, and thereby each of the tanks
associated with the valves 312-315. When one or more of the valves
312-315 is opened for venting, a signal is directed through lead
323 to energize valve 319 and open this main exhaust valve thereby
venting conduit 317 into the sea through outlet 324.
A solenoid operated hydraulic valve 326 is provided to direct
hydraulic fluid from low pressure manifold 277 through conduit 327
into the high pressure valve 318. Actuation of valve 326 by means
of a signal received through lead 328 controls this high pressure
valve to establish communication from the air supply tanks 56 into
manifold 317 for blowing ballast from the tanks associated with
whichever of the valves 312-315 are opened by the control
system.
A pressure transducer 329 is provided in the low pressure manifold
conduit 277. This transducer senses fluid pressure in the conduit
and directs an electrical signal through lead 331 extending along
branch cable 332 and the umbilical to a suitable indicator gauge on
the surface ship for purposes of monitoring the pressure level in
the low pressure circuit.
Conduit 274 in the high pressure circuit supplies fluid to solenoid
operated hydraulic valves 333-336 controlling leveling of the
vessel. Selected ones of the valves 333-336 are energized by remote
signals through four leads 337 extending along branch cable 338 and
the umbilical to the surface ship. Selective energization of the
valve 333-336 directs high pressure hydraulic fluid into conduit
pairs 339-342 for operating the hydraulic actuators 71 for raising
and lowering the ground-engaging legs 61-64. Return fluid from the
valves is directed through return conduits 343 into exhaust
manifold 295.
The clamping and drilling functions are remotely controlled by
means of four solenoid operated hydraulic valves 344-347 each of
which is operated under remote control by electrical signals
supplied through leads 348 extending along branch cable 338 and the
umbilical to the surface ship. Return fluid from the valves is
directed through return conduits 349 into the filter 296 for return
to the reservoir.
Clamping motor 122 is activated for engaging and disengaging the
clamp with the casing by means of valve 344. This valve directs
supply fluid from high pressure manifold 274 into a pair of
conduits 350 for forward and reverse operation of the clamping
motor. A flow control regulator 351 is provided upstream of valve
344, and this regulator is adapted to be manually set, either prior
to descent or by diver assistance while submerged, the desired flow
rate, e.g. up to 10 GPM, for controlling the operating speed of the
clamping motor.
Valve 345 controls the pair of elevating rams 94, 95 to raise and
lower the casing between its transport and drilling positions.
Hydraulic fluid supplied to this valve from high pressure manifold
274 is directed to the rams in parallel connection through conduits
352. A flow regulator 353 is provided in this branch conduit for
manually setting, either prior to descent or by diver assistance
while submerged, the fluid flow rate, e.g. up to 10 GPM, to the
elevating rams for controlling the rate of casing elevation.
Valve 346 is provided to control the linear actuators 147, 148
which in turn control the axial thrust force on the clamp and
casing, and provide for downward advance of the casing through its
drilling stroke and upward movement through its return stroke.
Hydraulic fluid is supplied to the valve 346 from high pressure
manifold 274, and the fluid is directed to the actuators in
parallel connection through a pair of conduits 354. A remotely
controled pressure regulator 356 is provided upstream of valve 346
to control the pressure of fluid supplied to the linear actuators,
and thereby control the thrust forces produced by the actuators.
The regulator 356 is controlled by electrical signals received
through a lead 357 extending along branch cable 338 and the
umbilical to the surface ship. A pressure transducer 358 is also
provided upstream of valve 346 to generate electrical signals
through lead 359 extending along branch cable 338 and the umbilical
to a suitable indicated gauge on the surface ship for purposes of
monitoring the working pressure of the actuators. This permits the
drilling operator to calculate the axial thrust force on the casing
to determine and control drilling bit forces, and thereby control
drilling rate. Valve 347 controls the operation of the two casing
oscillator rotary motors 142, 143. Hydraulic fluid is supplied to
this valve from high pressure manifold 274 and the fluid is
directed to the motors in parallel connection through a pair of
conduits 361 and an automatic flow reversing valve 362. A flow
regulator 363 is provided upstream of valve 347, and this regulator
is remotely controlled by electrical signals received through lead
364 extending along branch cable 338 and the umbilical. The
drilling operator on the surface ship may thereby control regulator
363 to establish the desired flow rate into the oscillator or
rotary motors and thereby control the casing oscillating rate or
rotary speed, perferrably up to a maximum of 10 cycles per minute
or 20 rpm which inturn controls the peripheral cutting speed of the
bits. The flow reversing valve 362 automatically reverses flow to
the motors 142, 143 responsive to these motors reaching opposite
ends of their respective strokes. In the case of rotary motors the
functions of 362 are not required. A pressure transducer 366 is
provided in communication with high pressure manifold 274 to
generate a remote electrical signal through lead 367 extending
along branch cable 339 and the umbilical to a suitable pressure
indicator on the surface ship.
Leak detector 267 is provided within enclosure 261 to provide a
remote alarm signal indicating any salt water leakage into the
enclosure. A suitable open circuit switch 339 is provided and is
adapted to short out responsive to the leakage of sea water into
the enclosure and close a circuit through lead 341 extending along
the umbilical to the surface ship.
An example of the use and operation of the invention is as follows.
A submersible vessel is constructed in accordance with the
embodiment of FIGS. 1-5, 12-16. It will be assumed that a casing
having a drilling end constructed in accordance with FIGS. 7, 8 is
to be embedded into the sea floor. The diameter, length and wall
thickness of the casing is selected depending upon the desired
application, e.g. as an offshore mooring attachment, and upon the
type of formation material as determined from studies of geological
core samples taken at the drilling site. In this example a casing
size 4' diameter 50' length and 1 1/2 inches wall thickness is
selected. All ballast tanks on the vessel are blown until the
desired drim is attained for stability while afloat. The tow cable
24 is attached and the vessel is towed by surface ship 23 to a
location above the drilling site. The casing is loaded at this time
from an adjacent barge or ship with the casing cutting end
supported by support and drilling device 34 and with its opposite
end supported by the two cradles 36, 37. Umbilical 26 with its
control and power leads and cables is them connected with the
vessel and the two cable may be detached. The stability tanks are
first flooded to achieve the desired trim. The control circuit is
activated to initiate flooding of the main ballast tanks 38, 39
until they are substantially full. The control circuit is them
activated to control the flooding of variable tanks 53. Variable
flooding into the tanks continues until just after a conditon of
negative buoyancy is achieved. At this point the flooding and vent
valves for all tanks are closed and the vessel begins its descent.
The vessel's level orientation during descent is maintained by
monitoring suitable level indicators and a depth guage carried on
the vessel, with controlled adjustments being made in the ballast
as required. The vessel may be guided to the drilling site either
by free descent, or by the use of small anchors or templates placed
on the sea floor with guide lines running to a surface buoy through
a suitable bridle on the vessel. Descent is controlled at a rate
preferably within the range of 25-30 f.p.m. through remote control
from the surface ship by varying the ballast in the variable and
stabilizer tanks. After the vessel achieves setdown at the drilling
site, the control circuit is activated to flood all tanks
completely to establish a maximum vessel weight on the seafloor for
stability during drilling. The control circuit is then activated
either by the surface driller or by diver attending the vessel to
anchor it into the seafloor for the drilling operation. The rotary
motors 69 and linear actuator 71 are energized to drill the ground
engaging legs 61-64 into the sea floor. A determination is then
made from observation of signals from the level indicators carried
on the vessel as to whether adjustment is required to bring the
vessel into the desired level orientation for the drilling
operation. If so, selected ones of the linear actuators 71 are
energized to raise or lower corresponding corners of the vessel to
bring the vessel to the desired orientation. The casing 21 is then
elevated to the desired drilling position with its longitudinal
axis disposed at a pre-determined angle of entry with respect to
the sea floor, e.g. a perpendicular angle of entry where the casing
is to be used as a mooring attachment. To accomplish this, the
control system is operated to first activate ram 111 and pivot
guide shoe 108 to the orientation required to establish this angle
of entry. Elevating rams 94, 95 are then extended to elevate the
casing by pivoting casing clamp 102 and yoke 103 until the casing
bears against guide shoe 108, with the opposite guide show 106
moving upwardly with the casing by spring bias. The drilling
operation is initiated by first operating the control system so
that the three-way valve 159 is placed in its direct circulation
mode, as shown on FIG. 16, afterwhich motor 152 is energized to
drive water pump 149 and pump sea water into interior cavity 162 of
the casing. Alternatively, a stream of air may be injected into the
stream of circulating water so that an air-water mixture is created
to assist in lifting the cuttings from about the drill bits. Casing
clamp 102 is locked in engagement about the casing and oscillator
motors 142, 143 are activated by the control circuit to commence
oscillation through an angle of 35.degree. at a rate of thirty
oscillations per minute by imparting 600,000 foot pounds of torque
from the oscillating motors. At the same time, linear actuators
147, 148 are operated by the control circuit to establish a
pre-determined axial thrust force on the clamp, e.g. 157 tons of
thrust force, to maintain the desired bit thrust force. Rotary
drilling speed is initially calculated from bottom conditions such
as type and hardness of formation, and over-burden, and the like.
As drilling progresses the surface driller or attending diver
monitors the control gauges and indicators signalling bit thrust
force as a function of axial thrust, cutting bit speed as a
function of oscillating rate, and water pressure within the casing
as a function of discharge pressure from pump 149. As the casing
penetrates different formations, the control circuit is activated
to adjust the bit thrust force, drilling speed and pump pressure to
maintain the desired drilling rate. Furthermore, the control system
automatically retracts the linear actuators 147, 148 through the
cutting stroke by maintaining the required fluid pressure into
these actuators.
After the casing moves to the end of its 4 foot cutting stroke
oscillator motors 142, 143 are stopped and clamp actuator 122
energized to disengage jaw members 112, 113 from the casing. Linear
actuators 147, 148 are then energized to extend and raise casing
clamp 102 for a 4 foot return stroke, afterwhich clamp actuator 122
is reversed to re-engage the jaw members about the casing. The
foregoing drilling steps are then repeated for a successive number
of strokes until the casing is drilled to the desired depth into
the formation. The drilling operator monitors the drilling depth by
counting the number of drilling strokes.
After the desired drilling depth is reached, oscillator motors 142,
143 and linear actuators 147, 148 are de-energized. Water
circulation is continued for a number of minutes after drilling
ceases to flush clean the annuli 81, 82 surrounding the casing.
Three-way valve 159 is then actuated into its grout circulation
mode and a suitable grout material such as neat cement is pumped
from the surface ship along supply line 169 into the interior
volume of the casing for deposit in the voids between the casing
and formation. After grout injection is completed line 169 is
disconnected by a diver.
Following injection of the grout material, the vessel 20 may either
be immediately returned to the surface or utilized to perform a
pull test on the emplaced casing. For immediate return, the control
system is operated to disengage casing clamp 102 from the casing
and back-off, through reverse rotation of motors 69 and retraction
of actuators 71, the ground engaging legs 61-64 from the sea floor.
Water ballast is then blown from the main, variable and stability
tanks until the indicator gauges show initial lift off from the sea
floor. At this point ballast blowing is terminated to maintain a
fixed positive buoyancy for controlled ascent. During ascent the
flood valves for the main ballast tanks are opened to accomodate
for air expansion. The operator on the surface ship can monitor and
vary the vessel's orientation and rate of ascent by blowing or
flooding selected ones of the stability and variable tanks. Where
it is desired to conduct a pull test then the grout material is
allowed to cure for a time on the order of 4 hours. With the casing
clamp engaged linear actuators 147, 148 are extended to apply a
vertical force on the clamp and casing. The applied force is
determined from monitoring fluid pressure supplied to the
actuators, and from this the pullout resisting capabilities of the
emplaced casing are calculated. After completion of the test, the
casing clamp is disengaged, the ground engaging legs are backed off
and the ballast tanks blown for ascent of the vessel.
With the vessel on the surface, it may be reloaded with additional
casing for drilling in another site by either horizontal or
vertical loading procedures. For horizontal loading, support and
drilling device 34 is moved to its horizontal orientation and a
cable is payed out between the jaw members and attached to a length
of casing which is carried on an adjacent barge. The cable is then
reeled in to draw the casing from the barge and onto the vessel
with the cutting end drawn between the jaw mambers. For vertical
loading, support and drilling device 34 is moved to its vertical
orientation. The casing is then lifted by a suitable overhead crane
from an adjacent barge and dropped cutting end first downwardly
between the jaw members. The jaw members are engaged with the
casing and drilling device then 34 pivoted downwardly to bring the
casing to its horizontal position.
Where it is desired to drill additional casing in one area on the
sea floor, then following emplacement of one length of casing the
casing clamp is first disengaged. The vessel is then caused to have
slightly positive buoyancy so that it can be lifted off the casing
and moved sideways a short distance to the next drilling site. The
additional length of casing is flooded until it is made slightly
buoyant, and then pulled down by a cable extending upwardly from a
winch on the submerged vessel. This casing is then inserted through
the clamp and the drilling procedures outlined above are undertaken
for emplacing it in the sea floor.
While the embodiments herein are at present considered to be
preferred, it will be understood that numerous variations and
modifications may be made therein by those skilled in the art, and
it is intended to cover in the appended claims all such variations
and modifications as fall within the true spirit
* * * * *