GB2338972A

GB2338972A - Ultrasonic agitator

Info

Publication number: GB2338972A
Application number: GB9915412A
Authority: GB
Inventors: Anthony Yates
Original assignee: Copipe Systems Ltd
Current assignee: Copipe Systems Ltd
Priority date: 1998-07-01
Filing date: 1999-07-01
Publication date: 2000-01-12
Also published as: GB9814109D0; GB9915412D0

Description

1 2338972 1 ULTRASONIC CLAY CUTTER This invention relates to an ultrasonic

agitator 4 especially but not exclusively for use agitating and mobilising cohesive sub-sea layers.

6 7 It is highly desirable for offshore Research and 8 Development Companies to be able to disturb and move 9 different layers of the seabed. There are a number of reasons for this, including geological sampling, pipeline 11 laying, general resource exploration and subsea 12 construction.

13 14 However, certain types of layer are prone to be or may become extremely tightly packed and therefore difficult 16 to manipulate, for example layers of clay. There is also 17 the possibility that obstacles, for example large 18 boulders, may need to be dislodged.

19 It would therefore be desirable to be able to loosen such 21 layers and obstacles to allow the development of offshore 22 resources and to facilitate subsea construction works.

23 2 1 The present invention recognises that the use of high 2 energy ultrasound may provide a solution to this problem.

3 4 The effects of high energy ultrasound find a wide range of applications ranging from medical treatments to 6 chemical reaction catalysis.

7 8 High energy ultrasound works by means of the generation 9 of cavities within the liquid medium to which it is applied. Cavitation occurs as a result of the 11 rarefaction of the medium through which the energy 12 travels and leads to the formation of bubbles. These 13 bubbles subsequently collapse or implode under pressure 14 and surface tension. The resultant shock wave can be used in a number of ways, for example to dislodge 16 material for cleaning or agitation purposes, or to break 17 up particles to smaller size.

18 19 British Patent GB2 165 330A teaches the use of ultrasound to clean sub-sea structures, for example oil rigs below 21 15 metres. This cleaning system is based on directing 22 the ultrasonic energy to a common focus using either a 23 parabolic dish or a flat array in combination with a 24 focusing means. This system relies on the precise focusing of the energy.

26 27 French Patent FR2 705 198A teaches the use of ultrasound 28 in the maintenance of an aquatic equilibrium by 29 destroying algal blooms.

31 However, while it is known to use high energy ultrasound 32 for the purposes of cleaning and maintenance, its 33 application in agitating sub-sea substrates and the 3 1 seabed prior to drilling or blasting has not been prior 2 known.

3 4 It is an object of the present invention to provide a sub-sea tool to dislodge sub-sea layers based on the use 6 of high energy ultrasound.

7 8 Adcording to a first aspect of the present invention 9 there is provided apparatus for dislodging sub-sea layers and obstacles, wherein the apparatus includes an 11 ultrasound source mounted in a sub-sea tool.

12 Typically, the apparatus is in the form of an agitator.

13 14 The apparatus may be fitted with either a single ultrasound source or a plurality of ultrasound sources.

16 17 The source of the ultrasound may be, but is not limited 18 to, a sonic horn or probe, based on piezoelectric or 19 magnetostrictive effects.

21 Optionally, the apparatus is part of or associated with a 22 sub-sea excavation tool.

23 24 Preferably the apparatus is shaped in such a way that it can penetrate or contact the sub-sea layer more readily.

26 For example, the apparatus may be shaped like a corkscrew 27 or ploughblade. Alternatively, the apparatus may be 28 located at some height above the seabed, and work through 29 the water column.

31 Preferably the apparatus is provided with sensors such 32zthat sonification can commence as soon as the tool either 33 reaches the seabed or meets an obstacle.

34 4 1 Preferably the apparatus is provided with visual means to 2 allow monitoring of the operation at a remote centre.

3 4 Optionally the apparatus is provided with a self- propulsion mechanism allowing the movement of the tool to 6 be controlled from a remote centre.

7 8 According to a second aspect of the present invention 9 there is provided a method for dislodging sub-sea layers or obstacles, the method comprising the positioning of 11 one or more ultrasound sources within the seabed and the 12 emission of a controlled level of ultrasonic radiation to 13 dislodge the seabed.

14 Preferably the method further involves the removal of the 16 dislodged material. For example, a dredging or 17 vetting/flushing mechanism can be attached to the 18 agitator.

19 The method may also involve the calculation of the level 21 of ultrasonic radiation required to dislodge the required 22 amount of material.

23 24 In order to provide a better understanding of the invention, embodiments of the invention will now be 26 described by way of example only, with reference to the 27 accompanying Figures in which:

28 29 Figure 1 illustrates an ultrasonic agitator in 30 accordance with the present invention; 31 32 Figure 2 illustrates an ultrasonic agitator in its 33 position of operation; and 34 1 Figure 3 illustrates an alternative agitator in 2 accordance with the present invention.

3 4 Referring firstly to Figure 1 an ultrasonic agitator is generally depicted at 1 comprising a probe 2, a casing 3, 6 a control panel 4, a cable 5 and a spindle 6. The probe 7 2 contains a plurality of sources of ultrasound 7.

8 9 In Figure 2 the ultrasonic agitator 1 is illustrated in its position of operation in a sub-sea layer 8.

11 12 In Figure 3 an alternative agitator is generally depicted 13 at 9 comprising a control panel 10, a casing 11 and a 14 tapered nozzle 12. A control cable 13 is attached to the casing 10. A plurality of ultrasonic sources 14 are 16 housed within the casing 11. The tapered nozzle 12 also 17 contains an ultrasonic probe 14 and a sensor 15. The 18 sensor 15 detects the presence of any obstacles.

19 Referring again to Figures 1 and 2, the agitator 1 is 21 used in the following way. The agitator 1 is lowered 22 such that the tip of the probe 2 is on the seabed 8.

23 Rotation of the spindle 6 is commenced and the probe 2 24 enters the seabed 8. The spindle 6 is rotated until the probe 2 is completely buried and the casing 3 is now on 26 the seabed 8. The controls of the spindle 6 are housed 27 in the casing 4. Ultrasound is then emitted from the 28 sources 7 until the desired effect has been achieved.

29 The agitator 9 of Figure 3 can be used in a similar way 31 to the agitator 1 of Figures 1 and 2.

32 33 Both the agitators 1 and 9 can be used at a number of 34 different depths and in different layers.

6 2 The advantage of the present invention is that it 3 provides a simple method for the agitation of tightly 4 packed sub-sea layers allowing further offshore research 5 and development. 6 7 An alternative embodiment provides for the agitator to be 8 equipped with ultrasonic probes that can be extended from 9 the agitator when in use and stored within its casing 10 when not in use. The probes could thus be protected from 11 their harsh operational environment when not in use. 12 13 Further modifications and improvements may be made 14!without departing from the scope of the invention herein 15 intended.

Claims

7 1 CLAIMS:

2 3 1. Apparatus for dislodging sub-sea layers and 4 obstacles, wherein the apparatus includes an ultrasound source mounted in a sub-sea tool.

6 7
2. Apparatus as claimed in Claim 1 in the form of an 8 agitator.

9
3. Apparatus as claimed in Claims 1 or 2 wherein the 11 apparatus is fitted with a plurality of ultrasound 12 sources.

13 14
4. Apparatus as claimed in any of the preceding Claims wherein the source of the ultrasound includes a sonic 16 horn or probe, based on piezoelectric or 17 magnetostrictive effects.

18 19
5. Apparatus as claimed in any of the preceding Claims wherein the apparatus is part of or associated with a 21 sub-sea excavation tool.

22 23
6. Apparatus as claimed in any of the preceding Claims 24 wherein the apparatus is shaped to physically penetrate the sub-sea layer.

26 27
7. Apparatus as claimed in any of Claims 1-5 wherein the 28 apparatus is elevated above the seabed, and works 29 through the water column.

31
8. Apparatus as claimed in any of the preceding Claims 32 wherein the apparatus is provided with sensors such 33 that sonification can commence as soon as the tool 34 either reaches the seabed or meets an obstacle.

I 8 2
9. Apparatus as claimed in any of the preceding Claims 3 provided with visual means to allow monitoring of the 4 operation at a remote centre.

6
10. Apparatus as claimed in any of the preceding Claims 7 provided with a self-propulsion mechanism allowing 8 the movement of the tool to be controlled from a 9 remote centre.

11
11. A method for dislodging sub-sea layers or obstacles 12 comprising the positioning of one or more ultrasound 13 sources within the seabed and the emission of a 14 controlled level of ultrasonic radiation to dislodge 15 the seabed. 16 17
12. A method as claimed in Claim 11 wherein the method 18 further involves the removal of the dislodged 19 material.

21
13. A method as claimed in Claims 11 or 12 wherein the 22 method also involves the calculation of the level of 23 ultrasonic radiation required to dislodge the 24 required amount of material.