Source: http://www.patentsencyclopedia.com/app/20120069703
Timestamp: 2017-11-19 09:01:53
Document Index: 184822341

Matched Legal Cases: ['art.\n20', 'arts 11', 'arts 11', 'art 30', 'art 35', 'art 30']

SEISMIC STREAMER - Patent application
Patent application title: SEISMIC STREAMER
Assignees: Optoplan
Patent application number: 20120069703
1. A solid seismic streamer cable: characterized by a buffer layer provided with a cut-out and a sensor element arranged in the cut-out.
2. The solid seismic streamer cable of claim 1, wherein the sensor element comprises a split-element sensor including an optical fibre sensor coil.
3. The solid seismic streamer cable of claim 2, comprising an optical fibre including the sensor coil, the optical fibre including fibre Bragg gratings (FBGs) forming optical fibre interferometers.
4. The solid seismic streamer cable of claim 3, wherein the optical fibre comprises multiple fibre Bragg gratings FBG1-FBGn arranged so that for each coil there is a corresponding pair of FBGs, one FBG on each side of the hydrophone coil.
5. The solid seismic streamer cable of claim 3, wherein the optical fibre comprises an intermediate FBG between two neighbouring sensor coils, the intermediate FBG being common to FBG pairs, each pair associated with one of the sensor coils.
6. The solid seismic streamer cable of claim 3, wherein a plurality of hydrophone coils H1-Hn are arranged on the cable between two fibre Bragg gratings FBG1-FBG.sub.2.
7. The solid seismic streamer cable of claim 3, wherein FBGs on two facing sides of two neighbouring hydrophones have the same wavelength.
8. The solid seismic streamer cable of claim 3, wherein a pair of FBGs, one FBG on each side of a hydrophone coil has the same wavelength, while another pair of FBGs on a neighbouring hydrophone coil, with one FBG on each side of the neighbouring hydrophone coil, has a different wavelength.
9. The seismic streamer cable of claim 1, comprising: a core part incorporating the buffer layer; and a protective layer for protecting the core part and the sensor element.
10. The seismic streamer cable of claim 1, wherein the at least one sensor element comprises at least one of an optical fibre hydrophone and an optical fibre accelerometer.
11. The seismic streamer cable of claim 1, comprising at least one reference element arranged in one of the slots.
12. The seismic streamer cable of claim 9, wherein the core part comprises a multilayer structure.
13. The seismic streamer cable of claim 9, wherein the core part, the sensor element and the protective layer are co-axially arranged.
14. The seismic streamer cable of claim 1, comprising optical fibre arranged loosely with an excess length in at least one groove of the buffer layer to effectively decouple the optical fibre and fibre Bragg gratings (FBGs) from strain in the seismic cable.
15. The seismic streamer cable of claim 14, wherein the groove is filled with a grease, wax or another material which can be hardened by cooling prior to coiling, such that at operating temperatures the material is softened thereby allowing the optical fibre to sink into the material, resulting in an excess fibre length.
16. The seismic streamer cable of claim 14, wherein the groove is filled with an initially hard and chemically dissolvable material which can be removed by a chemical process after fibre winding.
17. The seismic streamer cable of claim 14, wherein the optical fibre is arranged onto a shrinkable element arranged in the buffer layer groove.
18. The seismic streamer cable of claim 1, wherein optical fibre wound on the buffer layer between sensors acts as a distributed strain sensor, the strain sensor being formed by the wound optical fibre with two spaced FBGs arranged one on each side of two neighbouring sensors and produced to have the same wavelengths on facing sides.
19. An accelerometer for integration into a seismic streamer cable, the accelerometer characterized by: a split-element sensor base arranged into cut-outs in a buffer layer of a seismic cable, the sensor base including a first and a second part; the first part being provided with first attachment means for fixing to a streamer cable core part; second attachment means being arranged to movably couple the second part to the first part; and an optical fibre coiled around outer surfaces of the sensor base so as to form an accelerometer, the fibre being strained when the accelerometer is subjected to acceleration causing the second part to move in relation to the first part.
20. The accelerometer of claim 19, wherein the first attachment means comprises a glue joint.
21. The accelerometer of claim 20, wherein the second attachment means comprises a flexible element comprising a blade shaped metal spring which is attached into a first longitudinal slit in the first part and into a corresponding second slit in the second part, whereby the second part is movably suspended by the flexible element.
22. The accelerometer of claim 20, wherein the second part is mounted so as to define a surrounding space whereby the second part is able to move about an axis defined by the second attachment means.
23. The accelerometer of claim 20, comprising two end sections, arranged at first and second ends of the accelerometer, the end sections serving to close the said surrounding space when the accelerometer is arranged as part of a streamer cable.
24. The accelerometer of claim 23, where the end sections are formed as semicircular sections of an annulus.
25. The accelerometer of claim 20, comprising covers which serve to protect the optical fibre of the accelerometer and the movable second cylindrical part from pressure waves and other external mechanical influences.
26. The accelerometer of claim 20, wherein the first cylindrical part is provided with a channel that extends from a space containing the fibre coil of the accelerometer and to oil or gel filled voids between the cable core part and an outer protective layer or cladding of the seismic cable so as to equalize the pressure between said space and voids.
27. The accelerometer of claim 20, wherein the first and second parts are generally shaped as halves of a cylinder in order to fit smoothly around the cut-out core part when assembled.
28. The accelerometer of claim 20, wherein at least one of the first and second parts are provided with helical grooves for allocating and guiding the fibre over a part of the accelerometer.
29. A method of producing a seismic streamer cable comprising: providing a cable core part; providing a buffer layer of the core part with cut-outs at selected locations of the cable; and arranging a split-element sensor base element in one or more of the cut-outs.
30. The method of producing a seismic streamer cable according to claim 29, wherein at least a part of an optical fibre is arranged in grooves of the buffer layer by a method which provides a larger effective coiling diameter during coiling than when the cable is completed to obtain an optical fibre excess length.
31. The method of producing a seismic streamer cable according to claim 30, wherein the depth of the groove is increased by removing material after the optical fibre is arranged in the groove.
32. The method of producing a seismic streamer cable according to claim 30, comprising filling the groove with grease, wax or another material which may be hardened by cooling, and allowing the fibre to be coiled onto the material when hard and allowing the fibre to sink into the material as it softens when brought back to an operating temperature, typically the temperature of the sea.
33. The method of producing a streamer cable according to claim 30, wherein the optical fibre is coiled onto an initially strained central structure of the cable which is subsequently relaxed, thereby providing an excess optical fibre in the grooves.
34. The method of producing a seismic streamer cable according to claim 30, wherein the effective depth of the groove is increased by softening a material under the optical fibre after it has been arranged in the groove.
35. The method according to claim 29, comprising: providing a protective cladding covering the core part and sensor element of the cable.
36. The method according to claim 29, wherein the arranging of a sensor element comprises: arranging an optical fibre on the cable core part and on the split-element sensor base so as to form the sensor element.
37. The method of claim 36, wherein the step of arranging the optical fibre forms at least one of a hydrophone and an accelerometer.
38. The method of claim 35, wherein the protective cladding is arranged so as to provide the finished cable with a longitudinally uniform outer profile.
39. The method of claim 29, wherein the cut-outs in the buffer layer are provided in a machining process which removes parts of the buffer layer.
40. The method of claim 29, wherein the cut-outs are provided in a periodic arrangement or a regularly spaced manner along the streamer cable.
41. The method of claim 29, comprising arranging a sensor reference in one of the cut-outs.
42. The method of claim 41, wherein the arranging of a sensor reference comprises combining at least two inner reference mandrel parts, at least two reference cover parts and an optical fibre reference coil between the inner reference mandrel parts and the reference cover parts.
43. The method of claim 29, comprising providing the streamer cable with an outer jacket, for example, by an extrusion process.
44. The method of claim 29, comprising providing grooves in the buffer layer for allocating, in a loose manner, at least sections of the optical fibre.
[0001] This application is a divisional of U.S. patent application Ser. No. 12/482,221, filed on Jun. 10, 2009, which is herein incorporated by reference in its entirety.
[0091] The tube is preferably made from steel and may be protected by a coating layer 8 to increase the strength with respect to crush and impact. Between the tube 7 and the coating layer 8 the core part may incorporate a thin conductive layer with insulation for supplying electrical power to tail buoys or bird signaling/steering.
[0139] The tube is then provided with an inner protective coating 13 for protecting the tube 7. In one alternative, the tube is provided with a conductive foil 8, for example made of copper, between the tube 7 and the inner coating 13. The conductive foil 8 may be used to provide electric power and/or signaling to a tail buoy, a bird or other components that are arranged along the streamer cable and requires electric power.
[0141] Then the addition of the buffer layer 2 will be described in some more detail. A buffer layer 2 is added, preferably by an extrusion process. The buffer layer 2 has the function of protecting the optical fibre 1 to the hydrophones, accelerometers and references and of providing buoyancy. Grooves 4 along the buffer layer 2 for allocating the optical fibre 1 and possibly also for an electric conductor may be produced during the extrusion process or in the subsequent stage.
[0143] Thirdly, the hydrophone sensor base parts (forming the hydrophone mandrels) of the optical fibre hydrophones (FIG. 5A-B) and/or optical fibre accelerometers are arranged in the cut-outs 50 to form the sensors of the seismic streamer. The two inner half cylinders 10A of the hydrophone mandrel may be bonded or glued together around the core part of the cable where the buffer layer 2 has been removed. The two inner half cylinders 10A-B, which may be produced in steel, may be glued or bonded together on the outer surface of the core part of the cable. The glue joint, which may have a defined thickness of, for example, about 0.2 mm, may be arranged in an outwardly directed manner in order that it may be inspected after the glue has cured. Thereafter the two outer cylindrical parts 11A forming the compliant or pressure sensitive parts of the hydrophone are glued to the inner cylindrical parts.
[0144] The outer cylindrical parts may be designed so as to form halves of a tube forming the pressure sensitive part. The outer cylindrical parts may also be glued with a glue joint having a defined thickness, of, for example, about 0.2 mm, with the glue joint being arranged directed inwardly between the two tube halves and directed outwardly in the contact surface with the steel cylinders. The outer cylindrical parts 11A may be made from a transparent plastic material so that most of the glue joints towards the inner cylindrical parts and the internal glue joint between the two outer cylindrical parts may be easily inspected. The process of mounting the sensor/reference mandrels and split coils for bird powering/communication may easily be automated.
[0148] Then the optical fibre accelerometer sensing coil 1 can be coiled onto the combination of the fixed part 30 and movable part 35. The optical fibre entering and exiting the accelerometer may be arranged in grooves 40A,B which may be provided in the fixed part 30 and/or the end sealing components 37A,B, as indicated on FIG. 14.
[0151] Next, the preparation of the fibre layer consists of three steps: [0152] 1. Remove/strip buffer layer to provide cut-outs, [0153] 2. Mount sensor/reference elements, and [0154] 3. Wind fibre and fibre coils. All parts that shall be under the optical fibre 1 have to be provided first. This is performed in two steps. Initially, the buffer layer 2 is removed, for example by a machining process, at desired locations along a specified length of the seismic cable. At each location where the buffer layer 2 has been removed, cut-outs 50 are created.
2009-04-09 Marine seismic streamer steering apparatus
2009-04-09 Seismic streamer platform
2011-05-05 Solid seismic streamer cable and method
2011-09-01 Gravity measurements using seismic streamers
2014-02-06 Split-element optical hydrophone