GB2132961A

GB2132961A - Streamer weights

Info

Publication number: GB2132961A
Application number: GB08236458A
Authority: GB
Inventors: Roy Wyatt; Derek Geoffrey Finch
Original assignee: GEOPHYSICAL SYSTEMS Ltd
Current assignee: GEOPHYSICAL SYSTEMS Ltd
Priority date: 1982-12-22
Filing date: 1982-12-22
Publication date: 1984-07-18

Abstract

A streamer weight (1) can be attached to a streamer (not shown) that is trailed from a marine vessel, e.g. for measuring geological parameters of the seabed. The weight (1) comprises a sleeve member (1a) that has a longitudinal split (4) so that the sleeve member can be opened outwardly along the split and placed on the streamer, after which closure of the split will cause the sleeve member to encircle and grip the streamer. The sleeve member (1a) can be formed from an elastically flexible material such that, after opening of the split (4), the split tends to close on releasing the sleeve member so that the sleeve member will encircle and grip the streamer. Additionally, or alternatively, closure means such as straps (5) may be provided for holding the split (4) closed. Weight members (3), supported by the sleeve member (1a), add to the weight of the sleeve member. The weight members (3) may be in the form of longitudinally-extending metal rods embedded in the sleeve member (1a). <IMAGE>

Description

SPECIFICATION Streamer weights This invention relates to streamer weights.

A method of measuring geological parameters of the seabed makes use of measuring apparatus disposed inside and at intervals along the length of a streamer, which may for example be 3km long and have a diameter of 7cm. The streamer is trailed from behind a marine vessel. The marine vessel receives data from the measuring apparatus inside the streamer and the data can be analysed on board the vessel.

It is desirable that such streamers remain submerged below the surface of the sea when in use, and that their susceptibility to being swayed by underwater currents be low. Previously proposed methods of attaining these ends have involved constructing the streamers in sections so that the weight of the streamer can be varied along its length by adjusting the weight of each section independently. This is carried out by draining and then refilling appropriate sections with sufficient oil and kerosene to bring the section to the required weight. This weight adjustment technique involves the use of sophisticated equipment and is time-consuming.

According to the present invention there is provided a streamer weight comprising: a sleeve member which is split longitudinally so that the sleeve member can be opened outwardly along the split and placed on a streamer, after which closure of the split will cause the sleeve member to encircle and grip the streamer; and weight members for adding to the weight of the sleeve member, the weight members being supported by the sleeve member.

Embodiments of this invention described hereinbelow may be used to add weight to points along the length of the streamer without the need to drain and then refill sections of the streamer with oil and kerosene.

The sleeve member may be formed from an elastically flexible material such as rubber or a flexible plastics material, the flexibility being such that the split closes on releasing the sleeve member so that, when placed on a streamer, the sleeve member encircles and grips the streamer. Additionally or alternatively, means such as straps may be provided to hold the split closed. The straps, which may be made from a plastics material, can be riveted on the outer surface of the sleeve member or, alternatively, they can be moulded integrally therewith. In order that the weight of a given volume of the rubber or plastics material of the sleeve member may be increased, the material may be mixed with a granular metal such as zinc.

The weight members supported by the sleeve member may be embedded therein and formed, for example, as longitudinally extending metal rods.

The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a side elevational view of a streamer weight embodying this invention; Figure 2 is a plan view from above of the streamer weight of Figure 1; Figure 3 is a view of part of the streamer weight in an opened out position; Figure 4 is a side elevational view of a streamer weight embodying this invention having a pair of straps mounted thereon; and Figure 5 is a plan view from above of the streamer weight of Figure 4.

Figures 1 to 3 show a hollow cylindrically shaped streamer weight 1 comprising a sleeve member la made from a rubber or plastics material, e.g. marine grade polyurethane. The polyurethane may have granular zinc mixed therewith in order to add to the weight of the streamer weight 1. The streamer weight 1 has a tapered end 2 for reducing turbulence when it is fastened to a streamer (not shown) and towed through the sea. If a group of the streamer weights 1 are attached to a streamer, it is only necessary for the sake of turbulence reduction for the leading streamer weight 1 to have such a tapered end.

Metal rods 3 are encapsulated in the sleeve member la and extend parallel to the longitudinal axis of the streamer weight. The rods 3 are of a material (e.g. steel) that is denser than the material of the sleeve member la to provide additional weight thereto.

A longitudinal slit 4 runs along the length of, and radially through, the periphery of the sleeve member 1a, the slit 4 running parallel to the metal rods 3. The material of the sleeve member la is flexible, the flexibility being such that the longitudinal slit 4 may be opened outwardly in the directions of arrows A in Figure 2 so that the streamer weight 1 may be disposed on a streamer. The flexibility and resilience of the material is such that, after the streamer weight 1 has been placed over the streamer, the longitudinal slit 4 closes in the direction of arrow B so that the streamer weight encircles and grips the streamer.

Figures 4 and 5 show the streamer weight 1 when provided with a pair of straps 5 which may be formed from a plastics material. The straps 5 provide an additional means for securing the streamer weight 1 to the streamer. Each of the straps 5 comprises a fastening portion 6, a lace portion 7, and a buckle 8. The fastening portion 6 and the lace portion 7 are attached to the streamer weight 1 by rivets 9. Once the streamer weight 1 has been placed around the streamer, respective lace portions 7 are threaded through respective buckles 8 of the respective straps 5. The lace portions 7 are then fastened to the fastening portions 6 by means of projections 10 projecting from the fastening portions 6, which projections engage with corresponding apertures (not shown) in the lace portion 7. The straps 5 are examples only of straps which may be provided on a streamer weight 1 embodying this invention. Other types of strapping systems or tying systems may be employed.

CLAIMS (Filed on 28/9/83) 1. A streamer weight comprising: a sleeve member which is split longitudinally so

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Streamer weights This invention relates to streamer weights. A method of measuring geological parameters of the seabed makes use of measuring apparatus disposed inside and at intervals along the length of a streamer, which may for example be 3km long and have a diameter of 7cm. The streamer is trailed from behind a marine vessel. The marine vessel receives data from the measuring apparatus inside the streamer and the data can be analysed on board the vessel. It is desirable that such streamers remain submerged below the surface of the sea when in use, and that their susceptibility to being swayed by underwater currents be low. Previously proposed methods of attaining these ends have involved constructing the streamers in sections so that the weight of the streamer can be varied along its length by adjusting the weight of each section independently. This is carried out by draining and then refilling appropriate sections with sufficient oil and kerosene to bring the section to the required weight. This weight adjustment technique involves the use of sophisticated equipment and is time-consuming. According to the present invention there is provided a streamer weight comprising: a sleeve member which is split longitudinally so that the sleeve member can be opened outwardly along the split and placed on a streamer, after which closure of the split will cause the sleeve member to encircle and grip the streamer; and weight members for adding to the weight of the sleeve member, the weight members being supported by the sleeve member. Embodiments of this invention described hereinbelow may be used to add weight to points along the length of the streamer without the need to drain and then refill sections of the streamer with oil and kerosene. The sleeve member may be formed from an elastically flexible material such as rubber or a flexible plastics material, the flexibility being such that the split closes on releasing the sleeve member so that, when placed on a streamer, the sleeve member encircles and grips the streamer. Additionally or alternatively, means such as straps may be provided to hold the split closed. The straps, which may be made from a plastics material, can be riveted on the outer surface of the sleeve member or, alternatively, they can be moulded integrally therewith. In order that the weight of a given volume of the rubber or plastics material of the sleeve member may be increased, the material may be mixed with a granular metal such as zinc. The weight members supported by the sleeve member may be embedded therein and formed, for example, as longitudinally extending metal rods. The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a side elevational view of a streamer weight embodying this invention; Figure 2 is a plan view from above of the streamer weight of Figure 1; Figure 3 is a view of part of the streamer weight in an opened out position; Figure 4 is a side elevational view of a streamer weight embodying this invention having a pair of straps mounted thereon; and Figure 5 is a plan view from above of the streamer weight of Figure 4. Figures 1 to 3 show a hollow cylindrically shaped streamer weight 1 comprising a sleeve member la made from a rubber or plastics material, e.g. marine grade polyurethane. The polyurethane may have granular zinc mixed therewith in order to add to the weight of the streamer weight 1. The streamer weight 1 has a tapered end 2 for reducing turbulence when it is fastened to a streamer (not shown) and towed through the sea. If a group of the streamer weights 1 are attached to a streamer, it is only necessary for the sake of turbulence reduction for the leading streamer weight 1 to have such a tapered end. Metal rods 3 are encapsulated in the sleeve member la and extend parallel to the longitudinal axis of the streamer weight. The rods 3 are of a material (e.g. steel) that is denser than the material of the sleeve member la to provide additional weight thereto. A longitudinal slit 4 runs along the length of, and radially through, the periphery of the sleeve member 1a, the slit 4 running parallel to the metal rods 3. The material of the sleeve member la is flexible, the flexibility being such that the longitudinal slit 4 may be opened outwardly in the directions of arrows A in Figure 2 so that the streamer weight 1 may be disposed on a streamer. The flexibility and resilience of the material is such that, after the streamer weight 1 has been placed over the streamer, the longitudinal slit 4 closes in the direction of arrow B so that the streamer weight encircles and grips the streamer. Figures 4 and 5 show the streamer weight 1 when provided with a pair of straps 5 which may be formed from a plastics material. The straps 5 provide an additional means for securing the streamer weight 1 to the streamer. Each of the straps 5 comprises a fastening portion 6, a lace portion 7, and a buckle 8. The fastening portion 6 and the lace portion 7 are attached to the streamer weight 1 by rivets 9. Once the streamer weight 1 has been placed around the streamer, respective lace portions 7 are threaded through respective buckles 8 of the respective straps 5. The lace portions 7 are then fastened to the fastening portions 6 by means of projections 10 projecting from the fastening portions 6, which projections engage with corresponding apertures (not shown) in the lace portion 7.The straps 5 are examples only of straps which may be provided on a streamer weight 1 embodying this invention. Other types of strapping systems or tying systems may be employed. CLAIMS (Filed on 28/9/83)

1. A streamer weight comprising: a sleeve member which is split longitudinally so that the sleeve member can be opened outwardly along the split and placed on a streamer, after which closure of the split will cause the sleeve member to encircle and grip the streamer; and weight members for adding to the weight of the sleeve member, the weight members being supported by the sleeve member.

2. A streamer weight according to claim 1, wherein the sleeve member is formed from an elastically flexible material such that, after opening of the split, the split tends to close on releasing the sleeve member so that, when placed on a streamer, the sleeve member will encircle and grip the streamer.

3. A streamer weight according to claim 1 or claim 2, including closure means for holding the split closed.

4. Astreamer weight according to claim 3, wherein the closure means comprise straps.

5. A streamer weight according to claim 4, wherein the straps are made from a plastics material.

6. A streamer weight according to claim 4 or claim 5, wherein the straps are rivetted to an outer surface of the sleeve member.

7. A streamer weight according to claim 4 or claim 5, wherein the straps are moulded integrally with the sleeve member.

8. A streamer weight according to any one of the preceding claims, wherein the sleeve member is formed from a rubber or plastics material that has granular metal admixed therewith to increase its density.

9. A streamer weight according to claim 8, wherein the granular metal is zinc.

10. A streamer weight according to any one of the preceding claims, wherein the weight members are embedded in the sleeve member.

11. A streamer weight according to any one of the preceding claims, wherein the weight members are longitudinally extending metal rods.

12. A streamer weight substantially as herein described with reference to Figures 1 to 3 or Figures 1 to 5 of the accompanying drawings.

13. A streamer having fitted thereto at least one streamer weight according to any one of the preceding claims.