GB2094852A

GB2094852A - Submarine core drilling unit

Info

Publication number: GB2094852A
Application number: GB8107344A
Authority: GB
Original assignee: ELMGERN KJELL INGVAR
Current assignee: ELMGERN KJELL INGVAR
Priority date: 1981-03-09
Filing date: 1981-03-09
Publication date: 1982-09-22
Also published as: GB2094852B

Abstract

In drilling units 1 for submarine prospecting and surveying operations, e.g. on the bottom (4) of the sea, a device is provided for transmitting to the drilling unit 1 the energy required e.g. for deep-drilling operations in the sea bottom strata. In accordance with the invention the drilling unit (1) is equipped with a body, e.g. winch 16, which is arranged to be displaced in a first direction against the action of a reset force, e.g. spring 22, by means of a wire (13) operated from a ship (7) which is anchored above the drilling unit and to drive a generator 20, and then to be returned to the original position by said reset force. This arrangement makes it possible to transfer with the aid of one single wire the energy required to operate and drive said drilling unit and all its functions. <IMAGE>

Description

SPECIFICATION A device in drilling units for submarine prospecting work Drilling units are already known which are designed for obtaining samples from the bottom of the sea. Such units are controlled from a ship positioned above the prospecting area and are capable of operating at depths of 200 meters or more below the water level. Divers are not required either to install the equipment or to perform the test drilling proper. Drilling units of this kind are suitable for surveying the bottom of the sea to establish its economical and geological potentialities as well as to examine the sea bottom geologically prior to installation of drilling towers, and also for prospecting work of submarine channels. Hydraulic pumps and electric motors operate in the interior of the drilling unit.The drilling -- usually diamond drilling, that is drilling with diamond cutter heads - is performed using boring tubes which are about three meters long and which are mounted in a reservoir holding e.g.

twenty tubes. Together with their associated core barrel the boring tubes are interconnected in succession in response to an impulse emitted from the ship. When a boring tube has been completely drilled into the sea bottom, its barrel tube with the core sample therein is conveyed to the surface with the aid of a special hoisting mechanism and the sample is taken onboard for examination.

Considerable energy is consumed to operate and work the drilling unit. The energy is supplied via an electric cable from the ship. In addition, the drilling unit is connected to the ship with the aid of steel wires, making it possible to displace the drilling unit from one position to another on the bottom of the sea. This flexible interconnection between the ship and the drilling unit allows some leeway and consequently drilling work is possible also when the weather is not favourable.

The drilling unit rests on the sea bottom on three hydraulically operated and vertically movable legs, the movements of which are controlled from a control panel onboard the ship as are all other functions of the drilling unit. This makes it possible to align the drilling machine in the favourable drilling direction which may be ascertained from instruments, the sensors of which are positioned in the unit and the signals of which are transmitted to a receiving instrument onboard the ship.

The large number of lines and cables used have proved to cause certain inconveniences.

Particularly when the sea is rough, the electric cable is liable to break and cause damage and injury to the personnel. The steel wires easily cross one another below sea level and form uncontrolled tangles.

The primary purpose of the subject invention is to remedy these inconveniences and drawbacks.

The invention is characterised in that the drilling unit comprises a body which is arranged to be displaced in one direction against the action of a reset force with the aid of a wire which is operated from a ship anchored above the drilling unit and, in response to said reset force, to be returned to the original position while generating electrical, mechanical or hydraulic energy. By means of this wire it is possible to trensmit from the ship to the drilling unit all energy required to perform the prospecting operations. Transmission and reception of the required control impulses from the ship to the drilling unit and vice versa are effected with the aid of (ultra) sonic waves of a kind similar to those used in echo sounding.

In accordance with one embodiment of the invention the lower end of the wire is attached to a winch drum which is connected to an electric generator or to a rotating hydraulic pump.

In accordance with yet another embodiment the lower end of the wire is connected to a piston which performs a reciprocating vertical movement in an hydraulic piston-and-cylinder unit and which pumps pressurized fluid to a pressure container from which an hydraulic motor is driven.

The invention will be described in closer detail in the following with reference to the accompanying partly diagrammatical drawings, wherein Fig. 1 is a lateral view of a drilling unit in accordance with the invention as positioned on the bottom of a sea or lake and also showing the service ship anchored above, Fig. 2 shows the drilling unit proper on an enlarged scale, Fig. 3 is a cross-sectional view of a winch associated with the unit with the lower end of the traction chain wound about the winch drum, Fig. 4 is a similar cross-sectional view showing the chain in position for lifting the entire drilling unit, Fig. 5 is a longitudinal section through the lower end of a boring tube, and Fig. 6 is a coupling diagram relative to a hydraulic driving aggregate in the drillig unit in accordance with one embodiment of the invention.

Fig. 1 illustrates the position of a diamond drill head drilling unit 1 resting with its hydraulically operable, vertically movable legs 2 on the bottom 4 of the sea, which consists of a sediment layer 3.

Anchor wires 5, 6 anchor a service ship 7 in position above the drilling unit. The ship is equipped with machinery 8 including a rotatably driven flywheel 9 at the periphery of which is a pin 10 on which is mounted a sleeve 1 One end 12 of a wire 13 is secured to the sleeve 11 and the wire 13 travels over a deflector roll 14 mounted on an outrigger 1 5. The opposite end of the wire 1 3 is wound about a winch drum 1 6 (Figs. 2, 3), which is secured on a shaft 1 7 mounted in the drilling unit 1.The lower end 1 8 of the wire 13 (Fig. 4) is secured to the winch drum 1 6. One end of the shaft 1 7 is via a frictional clutch 1 9 connected to an electric generator 20 supplying the energy required to operate the drilling unit.

The opposite end of the shaft 1 7 is connected to the shaft 21 in a spring housing 22 the steel spring 23 of which is compressed upon rotation of the winch drum 1 6 in the electric generator 20 driving direction.

Reference numeral 24 designates the machinery designed to drive down boring tubes 26a together with an associated core barrel 27 (Fig. 5) supplied from the reservoir 25 of boring tubes 26.

When the flywheel 9 rotates it pulls the wire 13 upwards over half of each revolution, whereby upon unwinding of the wire 1 3 the winch drum 1 6 is forced to turn a corresponding number of revolutions while driving the generator 20 and at the same time compressing the spring 23. Over the subsequent half revolution of the flywheel 9 the wire 13 is allowed to siacken since the resiliency force of the spring 23 returns the winch drum 1 6 to the original position while the frictional clutch 1 9 permits the rotor of the generator 20 to continue turning as a result of the speed (flywheel mass). Simply by alternatingly pulling the wire 13 upwards with the aid of a machine and then allowing it to slacken it is thus possible to transfer energy from the service ship 7 down to the drilling unit 1.

When the drilling unit 1 is to be transferred from one place to another the upper end of the wire is wound e.g. onto a second winch drum, since winch drum 1 6 must rotate until it assumes the position shown in Fig. 4. Upon continued hauling-in of the wire 13, the latter lifts the entire drilling unit 1 off the bottom 2 and the unit 1 may then be transported by the ship 7 to the intended location and again be deposited on the bottom of the sea.

In accordance with the embodiment illustrated in Fig. 6 the electric generator 20 (Fig. 2) is replaced by a piston 29 which is arranged for reciprocating movement in a hydraulic cylinder 28 and the rod of which 30 is connected to the lower end of the wire 13. The piston 29 which is urged to its lower end position by a steel spring 31 is provided with a non-return valve 32 inserted in a through-flow passageway 33. The lower end 34 of the cylinder 28 is via a line 35 connected to a reservoir 36 holding pressurized fluid, preferably oil. The upper end 37 of the cylinder 28 communicates via a line 38 with the lower part of a pressure-fluid reservoir 39 having an air cushion 40 at its upper end. Via a line 41 the pressurefluid reservoir 39 is connected to a hydraulic motor 42 driving the machinery 24 of the drilling unit 1.Another line 43 connects the pressure-fluid reservoir 30 to a hydraulic motor 44 driving an electric generator 43 which generates the electric energy required by the various electric sensors 46 (Fig. 2) of the drilling unit 1. In order to ensure that the pressure in the reservoir 39 does not exceed the maximum allowable pressure, a line 47 communicates this reservoir with reservoir 36 via an adjustable over-flow valve 48.

Upon each pulling action on the wire 13 pressurized fluid is pumped into the reservoir 39 against the action of the reset-spring 31 while compressing the air 40 at the upper end of the reservoir 39. The pressurized fluid is used to drive the machinery 24 as well as the electric generator 45.

The embodiments as shown and described are to be regarded as examples only and a variety of modifications are possible within the scope of the appended claims. For instance, the line 13 may be arranged to drive the armature of a linear electric generator instead of the electric generator 20 or the hydraulic piston 29. The rest force may be obtained through other means than with the aid of the steel springs 23 or 31. In addition, the reset force can be used also to provide additional energy generation. The unit may be used also in geotechnical pressure probing operations, in which case a rod which is provided at its lower end with a pressure probing tip is pressed into the sea bottom layer 3. Information regarding the magnitude of resistance experienced by the probe tip is transferred through wireless transmission to the service ship 7 via the sensor 46 in the unit 1.

The pulling force on the wire 13 may be obtained otherwise than by means of a rotating flywheel 9 on the ship 7. The heaving motions of the ship may also be made use of to provide the pull on the line. The latter is preferably equipped with instruments measuring the pulling force thereon.

In order to make it possible to lift and transport the drilling unit 1 with the aid of the wire 13, the latter may be formed with a thicker part which abuts against a stationary shoulder on the drilling unit when the wire has been pulled upwards sufficiently far.

Claims

1. A device in drilling units designed for submarine prospecting operations, such as surveying the bottom (4) of lakes and the sea, wherein energy is required e.g. for deep-drilling of the sea bottom, characterised by a body (16, 29) which is arranged in the drilling unit (1) and which is arranged to be displaced in one direction against the action of a reset force with the aid of a wire (13) which is operated from a ship (7) anchored above the drilling unit, and to be returned to the original position in response to said reset force while generating electrical, mechanical or hydraulic energy.

2. A device as claimed in claim 1, characterised in that the lower end of the wire (13) is secured to a winch drum (16) about which is wound a part of said wire, a means such as a frictional clutch (19) connecting said drum with an electric generator (20), a rotating hydraulic pump or the like.

3. A device as claimed in claim 1, characterised in that the lower end of the wire (13) is secured to a piston (29), said piston arranged for reciprocating vertical movements inside a hydraulic cylinder (28), in that the pressure side (37) of said cylinder is connected to a pressure medium reservoir (39) and in that the reservoir is connected also to a hydraulic motor (44) driving an electric generator (45).

4. A device as claimed in claim 1, characterised in that the lower end of the wire (13) is connected to one end of an armature of a linear electric generator.