US3686877A

US3686877A - Sonic method and apparatus for installing off-shore caissons for oil operations and the like

Info

Publication number: US3686877A
Application number: US116396A
Authority: US
Inventors: Albert G Bodin
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-02-18
Filing date: 1971-02-18
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29

Abstract

A relatively wide diameter caisson member is placed in the water in a desired off-shore position with the bottom end thereof being forced biased into the sediment by virtue of the weight of the caisson, and with the open opposite end thereof protruding above the surface of the water. A plurality of sonic oscillators are coupled to the portion of the caisson above the surface. These oscillators are each adapted to provide vibrational energy to the casing principally along the longitudinal axis thereof with a minimum component of transverse vibration. The oscillators, each of which is separately driven and capable of delivering only a portion of the power needed to effectively drive the caisson, are driven at a frequency such as to cause resonant elastic vibration of the caisson in a predominantly single longitudinal mode, the separate oscillators tending to adjust both in frequency and phase at this resonant frequency. The caisson is effectively driven into the bottom by virtue of the vibrational energy, the bottom sediment acting on the heavy compression column to damp out unwanted vibrational modes which would otherwise tend to wastefully dissipate sonic energy.

Description

United States Patent Bodin 1 Aug. 29, 1 972 [54] SONIC METHOD AND APPARATUS 57 ABSTRACT giggfi AND A relatively wide diameter caisson member is placed THE LIKE in the water in a desired off-shore position with the bottom end thereof being forced biased into the sedi- [72] Inventor: Albert G. Bodin, 7877 Woodley ment by virtue of the weight of the caisson, and with Ave., Van Nuys, Calif. 91406 the open opposite end thereof protruding above the surface of the water. A plurality of sonic oscillators [22] are coupled to the portion of the caisson above the [2!] Appl. No.: 116,396 surface. These oscillators are each adapted to provide vibrational energy to the casing principally along the 52 us. (:1. ...........................6l/53.5, 61134367131319, [5]] In. CI mu and 9/00 is separately driven and capable of delivering only a [58] M61 sQ rZiIIIIIIII61/s1S, 46,46.s, s2, 41, P "ceded w effectively 5m: m nantly single longitudinal mode, the separate oscilla- [56] M cm tors tending to adjust both in frequency and phase at UNTI'ED STATES PATENTS this resonant frequency. The caisson is efiectively 3,215,209 11/1965 Desvaux etal..... .....6l/53.5 x 222 m rg fi :3 22 g?! 3,101,956 8/1963 Muller ..6l/53.5 column to damp out ugwamed vibgfional FOREIGN PATENTS OR APPLICATIONS rnodes which would otherwise tend to wastefully dis- 1,120,165 7/1968 Great Britain.................l73ll emgy' 1,029,568 5/1966 Great Britain ..61/53.5

Primary Examiner-Jacob Shapiro 7 Claims, 7 Drawing Figures Atzorney-Sokolski & Wohlgemuth t ub l 50 2| m i i E 1 so i 1 a0 i 1 1 I I s 1 11 1 1 1 11 so 1 111 m d t 2 111 1 1 l i 17 1 1 1 1 1 11 14 1 L 1 1 1 1;; 1 111 PATENTEDauczs I972 3 686' 877 saw 2 or 3 INVENTOR ALBERT G. BODINE SOKOLSKI 8 WOHLGEMUTH ATTORNEYS PAYENIEDmczs i972 SHEET 3 BF 3 INVENTOR WI 5 WOHLGEMJTH AT TUiNEYS SONIC METHOD AND APPARATUS FOR INSTALLING OFF-SHORE CAISSONS FOR OIL OPERATIONS AND TIIE LIKE This invention relates to the installation of caissons for use in off-shore oil operations, and more particularly to a method and apparatus for achieving this end result utilizing sonic energy for its implementation.

In off-shore oil operations, generally a drilling platform is utilized which is supported on a series of pilings which extend from the bottom. Individual oil well casings are then utilized to complete the oil wells at the platform level. The individual oil well casings at oil well pressure are thus exposed to the elements and it is difficult to prevent their leaking, especially when faced with storms. Thus, offshore oil operations sometimes cause the spillage of oil into the ocean with disastrous results to the environment. It is a difficult task to repair a leaky oil well casing beneath the ocean surface, and thus not only the emergency task of repairing the badly leaking line but also routine maintenance thereof presents a difficult problem involving tedious and dangerous diving operations.

The method and apparatus of this invention involves means for alleviating the above enumerated problems of off-shore oil operations by enabling the sinking of a relatively large diameter caisson into the bottom sediment. This large caisson forms an enclosure providing a perimeter for individual oil well casings, with optional ocean floor completions, and a support member for a drilling and service platform at the surface. The caisson, which is embedded in the bottom sediment by means of the sonic techniques of this invention, can be pumped dry if so desired, to enable working on the oil lines without the use of divers. Further, should one of the lines spring a leak, the oil is contained within the caisson to prevent it from spilling into the surrounding sea, thus obviating past problems in this regard. The sinking of a caisson of the necessary diameter (of the order of -20 feet or more) would present formidable task with the driving techniques of the prior art, necessitating the use of extremely massive pile driving hammer equipment or the like. Further, with such prior art driving techniques, it would be difficult to simultaneously apply equal force to all portions of the top of the caisson so as to drive the caisson straight down or at a predetermined angle as may be desired. The method and technique of this invention enables the installation of the caisson by means of sonic energy which can be evenly applied so as to provide a high level vertical driving force for sinking the caisson.

It is therefore an object of this invention to facilitate off-shore oil operations.

It is another object of this invention to minimize the likelihood of oil spillage into the ocean in off-shore oil operations.

It is still another object of this invention to facilitate the servicing of off-shore wells.

It is still a further object of this invention to provide a technique and apparatus for efficiently and evenly sinking a large diameter caisson into the bottom.

Other objects of this invention will become apparent as the description proceeds in connection with the accompanying drawings of which:

FIG. 1 is a schematic drawing illustrating the utilization of the invention for sinking a caisson,

FIG. 2 is a top plan view of the apparatus illustrated in FIG. 1,

FIG. 2a is a cross-sectional view taken along the plane indicated by 20-24 in FIG. 2,

FIG. 3 is an elevational view illustrating a typical caisson which has been installed on the bottom in normal operating condition,

FIG. 4 is a side elevational view illustrating an apparatus and method for coupling the oscillators to the caisson in the device of the invention,

FIG. 5 is a side elevational view of the apparatus shown in FIG. 4, and

FIG. 6 is a schematic view illustrating the installation of a nest of caissons which are joined together to form an integral assembly.

Briefly described, the technique and apparatus of the invention comprises sonic apparatus for sinking a large diameter casing into the sediment at the bottom of a body of water. The caisson, which is made of an elastic material such as steel, and which may have a diameter of the order of 20 feet or more may be floated on its side and towed to the installation location. The caisson is then up-ended so that one end thereof is resting on the bottom with the weight of the caisson biasing this end so it penetrates slightly beneath the surface of the bottom sediment, and with the opposite end protruding above the surface of the water. A plurality of sonic oscillator units are coupled to the above-surface end of the caisson, such units usually being symmetrically arranged about the upper edge of the caisson. The oscillator units are preferably all similar so as to each provide substantially the same vibrational outputs, such vibrational outputs each being relatively small as compared with the total required driving force provided by the combined generators. The oscillator generators further are adapted and positioned on the casing so as to transfer energy thereto almost entirely along the longitudinal axis of the caisson, i.e., to provide a force such as to drive the caisson approximately straight down into the sediment. In the case of orbiting mass oscillators these are then rotatably driven at a speed such as to set up resonant elastic vibration of the caisson along the longitudinal axis thereof, with the caisson acting as a single common circuit. Another important feature is that any transverse modes of vibration which are generated in the caisson are rapidly damped out by the damping action of the sediment into which the free standing caisson is being driven, particularly from the very beginning of the penetration. The vibrational energy is applied to the caisson until it has penetrated into the bottom a sufficient depth so as to be firmly retained therein. Means are provided for readily attaching the oscillators to and removing the oscillators from the caisson so they can be used for a given installation and readily removed therefrom for use elsewhere.

A large diameter caisson would normally be expected to break into many distortional modes of wall flexure if an attempt were made to excite it in a single mode such as longitudinal. It is not obvious to expect that even a small amount of initial penetration into the sediment will dampen and prevent distortional modes. The reason for success is that apparently these flopping modes are of low impedance. The procedure here is to resonate the caisson in a high impedance mode such as longitudinal, while causing the caisson to stand in heavy compression right from the beginning. The second important discovery is that completely separate oscillators, even though each driven by its own prime mover, and also even though separated from each other with substantial distance of floppy caisson wall means therebetween, will not necessarily vibrate randomly and independently as would be expected. The interesting fact here is that these oscillators, if their frequency is first guided near to that of a high impedance mode of the properly damped caisson, will all lock in to this single frequency mode, in a cooperative manner so that their power inputs are in additive phase to the basic frequency. This all results in a uniquely manageable system wherein the power elements can be brought into place in convenient sizes, and with power capabilities increased as needed by simply adding more of these oscillators.

in resonant sonic driving of conventionally proportioned pipe piles, such as pipes typically one or two feet in diameter, the sonic driver has crane support; and there are usually no appreciable wall flexing modes in the relatively small diameter pipe to cause problems. When caissons are normally constructed it is conventional to use interlocking sheet pile elements which are individually driven by pile hammers so as to form the caisson like a group of barrel staves. On the other hand now, this invention makes possible the resonant driving of a large tank type caisson which is driven as a single prefabricated water tight unit. These directly driven caissons can for the first time be typically of the order to twenty to fifty feet in diameter, providing the requirements of this invention are met. For oil wells, such a caisson makes it possible that a large number of directionally drilled wells can have their well heads grouped together safely on the ocean floor at the bottom of the caisson. The well heads can be serviced by pumping the caisson out. In addition to being a large oil trap preventing oil spills into the ocean environment, the one piece caisson provides a rugged base for a platform above the ocean surface, to withstand storms, collisions from ships, etc. Furthermore, such an open caisson also provides the rig function, such as for racking and assembling pipe during drilling and servicing, etc.

It has been found most helpful in analyzing the method and device of this invention to analogize the acoustically vibrating circuit utilized to an equivalent electrical circuit. This sort of approach to analysis is well known to those skilled in the art. In making such an analogy, force F is equated with electrical voltage E, velocity of vibration u is equated with electrical current i, mechanical compliance C,, is equated with electrical capacitance C,, mass M is equated with electrical inductance L, mechanical resistance (friction) R is equated with electrical resistance R and mechanical impedance Z, is equated with electrical impedance 2,.

Thus, it can be shown that if a member is elastically vibrated by means of an acoustical sinusoidal force F,sinw (is being equal to 21r times the frequency of vibration), that F sin mt u) mass is no longer a blocking effect and velocity of vibration at is at a maximum, power factor is unity, and energy is more efficiently delivered to a load to which the resonant system may be coupled.

It is important to note the significance of the attainment of high acoustical "Q" in the resonant system being driven, to increase the efficiency of the vibration thereof and to provide a maximum amount of power. As for an equivalent electrical circuit, the "Q" of an acoustically vibrating system is defined as the sharpness of resonance thereof and is indicative of the ratio of the energy stored in each vibration cycle to the energy used in each such cycle. "0" is mathematically equated to the ratio between wM and R,,,. Thus, the effective 0 of the vibrating system can be maximized to make for highly efficient, high-amplitude vibration by minimizing the effect of friction in the system and/or maximizing the effect of mass in such system. Massive caissons thus can be an advantage with this system.

In considering the significance of the parameters described in connection with Equation 1, it should be kept in mind that the total effective resistance, mass, and compliance in the acoustically vibrating system are represented in the equation and that these parameters may be distributed throughout the system rather than being lumped in any one component or portion thereof.

It is also to be noted that orbiting-mass oscillators may be utilized in the implementation of the invention that automatically adjust their output frequency and phase to maintain resonance with changes in the characteristics of the load. Thus, in the face of changes in the effective mass and compliance presented by the load with changes in the conditions of the work material as it is sonically excited, the system automatically is maintained in optimum resonant operation by virtue of the lock-in characteristic of applicant's unique orbiting-mass oscillators. A further very important feature is having the oscillators all lock with each other at the resonant vibration frequency. Furthermore, in this connection the orbiting-mass oscillator automatically changes not only its frequency but its phase angle and therefore its power factor with changes in the resistive impedance load, to assure optimum efficiency of operation at all times. The vibrational output from such orbiting-mass oscillators also tends to be constrained by the resonator to be generated along a controlled predetermined coherent path to provide maximum output along a desired axis.

Referring now to FIGS. 1, 2 and 20, one embodiment of the invention is illustrated. Caisson l l, which is of an elastic material such as steel, is floated out to the desired installation location and then is filled with water and up-ended as indicated in FIG. 1, with the bottom end lla thereof resting in the sediment 14 at the bottom of body of water 15. Caisson 11 has a manhole 17 formed near the final ground line thereof which is sealed off by manhole cover 18, to enable access by a diver when the caisson is partially or fully filled with water. Additional holes 20 which are appropriately sealed off by removable covers 21, are provided in the upper portion of the caisson to facilitate the rapid filling of the caisson with water in the event of a storm so as to act as damping orifices and to minimize the buffeting to which it is subjected.

Connected to the top edge portion of the caisson 11b are a plurality of orbiting mass oscillator units 25 which, as can be seen in FIG. 2, are symmetrically arranged around the rim of the caisson. As can be seen in FIG. 2a, each oscillator assembly has a pair of

rotor members

25a and 25b which may be in the form of cylindrical masses and which are rotatably driven in opposite directions around

raeeways

25c and 25d formed in the oscillator housing. With the rotors oppositely driven and positionally phased as indicated in FIG. 2a, traverse vibrational components generated thereby will be substantially cancelled out, while the longitudinal vibrational components developed by the two rotors will be added together, thus providing longitudinal vibrational energy for driving the caisson. The oscillators may be of the type described in my US. Pat. No.

3,217,551. Rotatable drive for the

rotors

25a and 25b is provided by means of motors 30 whose drive shafts ar coupled to the rotors.

The oscillator assemblies 25 are removably attached to the casing by means of clevis units 35, such clevis units being fixedly attached to the oscillator assemblies to form a base support therefor. As can be best seen in FIGS. 4 and 5, each clevis unit 35 has a long arm portion 350 with a pair of windows 35b and 350 formed therein. A ledge member 354 and 35: extends outwardly from the arm portion at the bottom of each of

windows

35b and 35c respectively. Clevis 35 also has finger portion 35) which extends angularly away from arm portion 35a. Bars 40 are welded to the side of caisson ll, when things are in position, so as to fit through

apertures

35b and 35c in abutment against

ledge portions

35d and 35e. The ledge portions are held to the cars by means of bolts 43 which fit therethrough. To facilitate installation, the oscillator assembly is weighted so that its center of gravity is above the right side of the clevis (as viewed in FIG. 4), thus tending to bias the long arm portion 350 against the wall of the caisson.

The motors 30 and oscillator assembly 25 are joined together by yoke 45. The oscillator assemblies are placed in position on top angularly the caisson by means of a hoist mechanism 47, the hook 47a of which fits through hole 45a in yoke 45. The oscillator assembly can readily be lifted off the caisson by first removing bolt 43 and then using hoist 47 with its hook 47a engaged in hole 450 to lift upwardly on the yoke. In view of the off-center position of hole 45a, the clevis will be tilted to the right with finger 35f resting against the caisson. With the clevis in this position,

apertures

35b and 35c move away from cars 40 so that the clevis can be drawn upwardly without interference from these ears.

In installing the caisson in position, it is first placed as shown in FIG. 1, with end 11a resting on the bottom. Then oscillators 25 are installed on the caisson as shown and simultaneously driven with their associated rotors rotating in opposite directions so as to cause resonant elastic vibration of the caisson in a longitudinal vibration mode. The power of each of the oscillators is kept at a point such that it will not unilaterally control the vibration but rather all of the oscillators will lock in at a resonant vibration frequency of the caisson as a single resonant circuit once such resonant vibration has been established by any one of the oscillators.

This important phase and frequency cooperation of the group of applicants orbiting mass oscillators is explained in the discussion earlier in the application.

The bias force of the weight of the caisson initially causes end 11a thereof to penetrate slightly beneath the surface of the bottom sediment 14. This initial penetration of the sediment affords a damping of lateral or wall flexing vibration modes, and thus minimizes the dissipation of energy in such flapping type of vibration. As already noted, the oscillators are adapted to provide substantially all of their vibrational energy in a longitudinal vibration mode which operates to drive the caisson downwardly into the sediment. Vibrational energy is applied until the caisson has reached the desired depth whereat it is firmly lodged in the sediment, such as, for example, shown in FIG. 3, and then the oscillators are removed from the caisson as already described. It is to be noted that it is contemplated that with the technique and apparatus of this invention it is possible to install caissons having a diameter of the order of 20 feet or substantially more, the use of vibrational energy from plural sources in the manner described enabling the performance of such a task that would be very difficult or impossible to achieve with prior art driving techniques. It is still further to be noted that when relatively long caissons are required, these elongated units can be formed from several sections which are welded together in situ, as indicated by weld joints 50 in FIG. 1. Also, in situations where the caisson is to be driven very deeply into the sediment, it may be possible to add sections at the top above the water surface as the driving operation proceeds, placing the oscillators on top of each newly added unit.

Referring now to FIG. 3, a typical caisson with the technique of this invention is illustrated under normal operating conditions. A plurality of oil well casings 52 are contained within caisson ll, remotely controlled solenoid valves 520 at the ocean floor, being used to control the flow of oil through the production lines in the various casings. A pump 55 is provided to enable the pumping of water out of the inside of the caisson. Under normal operating conditions, the inside of the caisson would be pumped dry to enable ready access to the well casings from the surface without the use of divers. In the event of a storm, the ports 20 (FIG. 1) could be opened to permit the caisson to fill so as to make it less vulnerable to the storm. As already noted, in the event of oil leakage, the oil will be contained within the caisson so that it is not spilled into the surrounding water.

Referring now to FIG. 6, an installation of a deep water cluster of caissons which are joined together is illustrated. The caissons are installed so that they lean slightly towards each other, in the nature of a tripod, and are joined together by means of braces 59 which are attached to the sides thereof. The three caissons 11 support a single platform 58 from which the various necessary operations are performed. In this manner, the group of caissons can be used to reinforce each other structurally to provide for an assembly having higher structural integrity, particularly for greater vertical dimensions. Of course, this is only one example of how groups of caissons can be used cooperatively.

Thus, the technique and apparatus of this invention enables the installation of large diameter caissons in off-shore oil operations wherein the caissons are driven by multiple source sonic energy into the bottom. These caissons can be used to contain a plurality of oil well casings, and can be pumped so that they are free of water to enable work on the casings. Moreover, in those situations where it is preferable to fill the caisson with water, and use divers for maintenance, the caisson permits first pumping out silty mud which obscures vision, so that the diver can work in a well lighted, sharkfree environment.

While the invention has been described and illustrated in detail it is to be clearly understood that this is intended by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the invention being limited only by the terms of the following claims.

l claim:

1. A method for installing a caisson in the bottom below a body of water comprising the steps of:

placing the caisson in an upright position with one end thereof resting on the bottom and being force biased thereagainst by the weight of the caisson, the opposite end of said caisson being above the surface of the water,

removably attaching a plurality of orbiting mass oscillator units to said opposite end of the caisson, said oscillator units each having substantially the same power capacity and being arranged symmetrically about said caisson, and

driving said oscillator units at a speed such as to cause resonant elastic vibration of said caisson in a longitudinal vibration mode, said oscillator units being adapted to lock in frequency and phase to the resonant frequency,

whereby said caisson is driven into the bottom by the vibrational energy imparted thereto with non-longitudinal vibrational energy being damped out by the earthen material of the bottom.

2. The method of claim 1 wherein said oscillators each comprises a pair of rotor members, said rotor members being driven in opposite directions and positioned in phase opposition relationship.

3. The method of claim 1 wherein said oscillator units are removably attached to said caisson by being lowered over the edge portion thereof, a clevis unit extending from each of the oscillator units to engage said edge portion.

4. The method of claim 3 wherein said clevis units each includes a straight arm portion and a finger portion extending angularly away from said arm portion, said arm portion abutting against the side of said caisson.

5. The method of claim 4 and further including the step of lifting said oscillator units from said caisson when the caisson has been driven to the desired depth, said clevis units being tilted with said lifting whereby the arm portion moves away from the caisson side and the finger portion moves thereagainst.

6. In combination, a caisson member fabricated of an elastic material having a relatively large diameter, said caisson member being placed in an upright position with one end thereof resting on the bottom beneath a body of water;

luralit of orbi' m oscillt u i r n ans fo remova attzi hing e ll ops id oscillator units to the opposite end of said caisson which extends above the surface of the water, said oscillator units being arranged symmetrically about said caisson, said oscillator units each including a pair of oppositely phased rotor members,

means for rotatably driving said rotor members in opposite directions such as to generate resonant elastic vibration in said caisson along the longitudinal axis thereof,

whereby said caisson is driven into the bottom by the vibrational energy with non-longitudinal vibrational modes of said caisson being damped out by the bottom material.

'7. The device of claim 6 wherein said means for removably attaching said oscillator units to said caisson comprises a clevis unit attached to the bottom of each of said oscillator units, each of said clevis units having an arm portion with apertures formed therein, and a finger portion extending angularly away from said arm portion, ear members extending out from the side of the caisson, said ear members extending through the apertures in the arm portion, and means for securing the clevis to said ear members with said arm portion in abutment against the end of said caisson.

Claims

1. A method for installing a caisson in the bottom below a body of water comprising the steps of: placing the caisson in an upright position with one end thereof resting on the bottom and being force biased thereagainst by the weight of the caisson, the opposite end of said caisson being above the surface of the water, removably attaching a plurality of orbiting mass oscillator units to said opposite end of the caisson, said oscillator units each having substantiAlly the same power capacity and being arranged symmetrically about said caisson, and driving said oscillator units at a speed such as to cause resonant elastic vibration of said caisson in a longitudinal vibration mode, said oscillator units being adapted to lock in frequency and phase to the resonant frequency, whereby said caisson is driven into the bottom by the vibrational energy imparted thereto with non-longitudinal vibrational energy being damped out by the earthen material of the bottom.

6. In combination, a caisson member fabricated of an elastic material having a relatively large diameter, said caisson member being placed in an upright position with one end thereof resting on the bottom beneath a body of water; a plurality of orbiting mass oscillator units, means for removably attaching each of said oscillator units to the opposite end of said caisson which extends above the surface of the water, said oscillator units being arranged symmetrically about said caisson, said oscillator units each including a pair of oppositely phased rotor members, means for rotatably driving said rotor members in opposite directions such as to generate resonant elastic vibration in said caisson along the longitudinal axis thereof, whereby said caisson is driven into the bottom by the vibrational energy with non-longitudinal vibrational modes of said caisson being damped out by the bottom material.

7. The device of claim 6 wherein said means for removably attaching said oscillator units to said caisson comprises a clevis unit attached to the bottom of each of said oscillator units, each of said clevis units having an arm portion with apertures formed therein, and a finger portion extending angularly away from said arm portion, ear members extending out from the side of the caisson, said ear members extending through the apertures in the arm portion, and means for securing the clevis to said ear members with said arm portion in abutment against the end of said caisson.