|Publication number||US3891037 A|
|Publication date||Jun 24, 1975|
|Filing date||Dec 26, 1972|
|Priority date||Dec 26, 1972|
|Publication number||US 3891037 A, US 3891037A, US-A-3891037, US3891037 A, US3891037A|
|Inventors||Marley Kenneth C, Well Dale E|
|Original Assignee||Marley Kenneth C, Well Dale E|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (13), Referenced by (19), Classifications (14)|
|External Links: USPTO, USPTO Assignment, Espacenet|
United States Patent [191 Well et al.
[ 1 June 24, 1975 I 1 REMOTELY OPERATED SEAFLOOR CORING AND DRILLING METHOD AND SYSTEM  Inventors: Dale E. Well, 3902 Lincolnshire St..
Pascagoula, Miss. 39567; Kenneth C. Marley, 1074 Valley Forge Dr., Sunnyvale, Calif. 94087  Filed: Dec. 26, 1972  Appl. N0.: 318,114
 U.S. CI. 175/6; 61/535; 61/46; 61/465; 173/152  Int. Cl. E2113 7/12  Field of Search 175/6, 170, 19, 471, 122, 175/162, 203; 173/152, 163; 166/77, 78; 61/535  References Cited UNITED STATES PATENTS 1,706,002 3/1929 Sipe 61/50 2,488,074 11/1949 Thornley 61/50 2,766,011 10/1956 Winder 173/163 X 3,054,285 9/1962 Roosen 175/19 X 3,095,048 6/1963 ONeill et a1. 175/6 3,282,339 11/1966 Hasha 166/78 X 3,438,452 4/1964 Bernard et a1... 175/6 3,442,339 5/1969 Williamson... 175/6 3,491,842 l/l970 Delacour 175/171 X 3,595,322 7/1971 Reimann.... 173/163 X 3,666,026 5/1972 Allard 173/152 3,763,654 10/1973 Matsushita. 61/535 3,779,322 12/1973 Stevens 175/171 FOREIGN PATENTS OR APPLICATIONS 1,085,775 10/1967 United Kingdom 175/203 Primary Examiner-Frank L. Abbott Assistant Examiner-Richard E. Favreau 5 7 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.
3 Claims, 22 Drawing Figures SHEET PATENTEDJUN 24 ms PATENTED JUN 2 4 I975 SHEET .l -'ig.lO.
PATENTEDJUN 24 I975 SHEET Fig.|5
PATENTEDJUN24 I975 3,891,037
SHEET 9 Fig.l6
REMOTELY OPERATED SEAFLOOR CORING AND DRILLING METHOD AND SYSTEM BACKGROUND OF THE INVENTION This invention relates generally to procedures and apparatus for embedding casing, piling or other similar stucture into the floor ofa body of water, and for taking large core samples from the sea floor.
Civil engineering contractors have traditionally ad hered 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. Groundengaging 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 groundengaging 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 ofa 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 latters transport position. A plurality of transversely extending spacedapart 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 vessels 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 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 vessels 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 easing. 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 vessels 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 l% 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 hardface 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 easing 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 easing 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 easing 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 to- 7 Ward 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 semicylindrical 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 easing 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 meansof controlling both the rate of cuttings removal.
Depending upon veriables such as the type and hardness of the sea floor formation, as determined from predrilling 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 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 up wardly 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, 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 con trol 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 easing. 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 are within an arc of up to substantially 90, although a back and forth oscillating arc of 35 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 vessels 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 easing. 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 reengage 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 vessels 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 apressurized 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 inthe 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 mounteduppermost 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 vessels 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 groundengaging 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 easing 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. l-S, 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 diame- .ter 50' length and l /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 vessels 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. lf 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 predetermined 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 rewater 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 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 overburden, 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 deenergized. 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 re-
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|U.S. Classification||175/6, 405/202, 173/152|
|International Classification||B63C11/00, E21B7/12, B63C11/40, E21B7/124, B63G8/00|
|Cooperative Classification||E21B7/124, B63C11/40, B63G8/001|
|European Classification||B63G8/00B, B63C11/40, E21B7/124|