WO2016081579A1 - Monitoring marine seismic cables with optical fiber - Google Patents

Abstract

A marine seismic streamer cable system includes an outer streamer skin defining a longitudinally extending tube; a strength member extending longitudinally through the interior of the tube; seismic sensors located inside the tube and connected to one another electronically so as to transmit power and seismic data signals; an optical fiber extending longitudinally through the tube and configured so as to physically be coupled to the tube so that bending of the tube will directly transmit bending to the optical fiber; and an optical measurement unit that is optically connected with the optical fiber so as to measure optical transmission through the optical fiber and thereby determine various aspects of the optical fiber that are indicative of stress and strain experienced by the streamer.

Description

Monitoring Marine Seismic Cables With Optical Fiber

By

Joseph Varkey

Vladimir Hernandez Solis Maria Auxiliadora Grisanti

WG Docket No. IS14.8312

Claim to Priority / Related Applications

This application claims priority to United States Patent Application No. 62/081459 that was filed on November 18, 2014.

Technical Area

According to various embodiments, the present disclosure relates to seismic hydrocarbon exploration equipment and methods, and more particularly to marine seismic hydrocarbon exploration seismic cables, known as streamers, with optical fibers to monitor aspects of the streamers.

Background

In seismic exploration it is desirable to discover attributes of an earth formation to establish the existence and features of potential hydrocarbon or other mineral deposits. A seismic survey can do this and can be performed by actuating a source that provides a signal that travels into an earth formation, and reverberates or reflects off of various portions of the formation. The reflections or reverberations can be detected by seismic sensors, and transformed into data that is analyzed so that it shows attributes of the subsurface formation, such as the existence, location and shape of a hydrocarbon or other mineral deposit.

The surveyed formations can be on dry land, or underneath bodies of water such as oceans or lakes. They can also be in a shallow water area near the shore of a body of water or in a swamp / wetland area called a transition zone.

In the case of towed marine surveys, long seismic cables holding seismic sensors can be towed by a marine vessel. A marine seismic source WG Docket No. IS14.8312 can be actuated to provide a source signal that travels through the water and into the formation, where the signal reflects and travels upward through the water where it is detected by the sensors and turned into seismic data. The seismic data can then be used to determine attributes of the formations, such as the existence, locations and size of a hydrocarbon or other mineral deposits.

Another form of marine survey involves placing seismic cables on the ocean bottom. Those are referred to as ocean bottom cable (OBC) surveys.

In both marine towed surveys or OBC surveys, the length of cable section is on the order of 100 m. The sections can be connected together to make streamer lengths of up to 12 km. Cables of this length can use electrical power to transmit data along the length of the cables and to eventually record the same. Towed marine streamer spreads may have between 6 and 14 streamers and are seldom shorter in length than 3 km.

In a marine towed survey, the streamers can be towed by a vessel and given the length and weight of the streamers, a significant amount of tension (and resulting strain) can be placed on the streamers. Also, by way of handling activities (deployment and retrieval), and inadvertent occurrences such as tangles, or hard contact with sharp or hard objects on the vessel, the streamers can experience forces such as excessive bending stress/strain, scraping, impact, and puncturing. It is not uncommon that these lead to damage and failure of the streamer that then requires repair and leads to technical downtime.

There are other failure modes for streamers such as aging, shark bites, leaks, encounters with obstructions and other violent contacts that are not described in great detail here but are none the less failure modes for streamers. WG Docket No. IS14.8312

Marine seismic surveys are very capital intensive in that the vessels tend to be very expensive. For manned vessels, the crew is expensive. The marine seismic cables are expensive. From a business perspective any downtime because of technical failures such as streamer failures from the failure modes noted above can be very costly, and compromise profitability for a job quite quickly. It is therefore valuable to reduce technical downtime.

In the case of marine surveys in particular, reduction of technical downtime can be accomplished by determining where and to what extent damage has occurred as that can expedite repair, reduce technical downtime, improve efficiency and reduce the chances that a survey will become uneconomical and/or unprofitable due to equipment failure. Also, it is desirable to determine if failure in the future is likely, which can be determined by way of monitoring if streamer cables experience forces having a

connection to future failure modes, such as excessive levels of stress or strain.

The present application describes a number of combinations of features that can help streamer monitoring to identify failure modes and attributes, and therefore help reduce technical downtime.

Brief Description of the Drawings

The following brief description of the figures is to help one skilled in the art understand the presently disclosed subject matter. It is in no way intended to unduly limit the scope of any present or subsequent patent claims.

FIG. 1 illustrates a sea vessel that may deploy one or more streamers in accordance with one or more embodiments of the present disclosure;

FIG. 2 illustrates a portion of a streamer in accordance with one or more embodiments of the present disclosure; WG Docket No. IS14.8312

FIG. 3 illustrates a marine seismic exploration configuration;

FIG. 4 illustrates how marine seismic cable having an optical fiber conductor for distributed temperature, strain and vibration measurement;

FIG. 5 illustrates a marine seismic Gun Cable can having an optical fiber conductor for distributed temperature, strain and vibration measurement techniques.

Summary

The following is a brief summary of some combinations of embodied features and is meant to assist the understanding of one skilled in the art with respect to the embodiments described herein. It is not meant in any way to be unduly limiting to any present or subsequently related claims.

According to a combination of features, the present disclosure relates to a method for use with marine seismic cables including providing at least one marine seismic cable; and monitoring distributed cable strain, and temperature and vibration data to identify and locate areas of damage in marine seismic cables during or before going into operation.

According to a combination of features, the present disclosure relates to a marine seismic streamer cable system, including an outer streamer skin defining a longitudinally extending tube; a strength member extending longitudinally through the interior of the tube; seismic sensors located inside the tube and connected to one another electronically so as to transmit power and seismic data signals; an optical fiber extending longitudinally through the tub and configured so as to physically be coupled to the tube so that bending of the tube will directly transmit bending to the optical fiber; and an optical measurement unit that is optically connected with the optical fiber so as to measure optical transmission through the optical fiber and thereby determine WG Docket No. IS14.8312 various aspects of the optical fiber that are indicative of stress and strain experienced by the streamer.

According to a combination of features, the present disclosure relates to a marine seismic streamer cable system, including an outer streamer skin defining a longitudinally extending tube; a strength member extending longitudinally through the interior of the tube; seismic sensors located inside the tube and connected to one another electronically so as to transmit power and seismic data signals; an optical fiber extending longitudinally through the tube; and an optical measurement unit that is optically connected with the optical fiber so as to measure optical transmission through the optical fiber and thereby determine aspects of the optical fiber that are indicative a physical attribute of the streamer cable.

Detailed Description

The following detailed description includes various combinations of embodied features, and is meant to assist the understanding of one skilled in the art with respect to the disclosure herein. However, it is not meant in any way to unduly limit the scope of any present or subsequent related claims.

A seismic towed marine survey includes a tow vessel that tows a series of seismic streamers, which are cables that have connected thereto seismic sensors. A seismic source is used to generate an impulse that travels through the water and into the subsurface, reflects back up through the water and is in turn detected by the seismic sensors on the streamers. The detected signals are recorded as data and through data processing are used to show and determine various aspects of the subsurface survey area.

FIG. 1 illustrates a sea vessel 100 that may include a reel or spool 104 for deploying a seismic streamer 102, which may be a cable-like structure WG Docket No. IS14.8312 having a number of sensors 103 for performing a subterranean survey of a subterranean structure 114 below a sea floor 112. A portion of streamer 102, and sensors 103, may be deployed in a body of water 108 underneath a sea surface 110. Streamer 102 may be towed by the sea vessel 100 during a seismic operation.

In an ocean bottom survey a seabed cable may be used, where the seabed cable may be deployed from a reel on the sea vessel and/or laid on a sea floor 112.

The term "streamer" as used herein is intended to cover either a streamer that is towed by a sub-sea or sea surface vessel or non-towable streamers such as a seabed cable laid on the sea floor 112 or those that may be deployed vertically in the water column, or any other configuration where a steamer is used for seismic survey.

In some embodiments, streamer 102 may have a length of 15m-100m (e.g. 30 meters or less). However, it should be noted that streamers of any length may be used without departing from the scope of the present disclosure.

FIG. 1 shows a number of signal sources 105 that may produce signals propagated into the body of water 108 and into subterranean structure 114. The signals may be reflected from layers in subterranean structure 114, including a resistive body 116 that can be any one of a hydrocarbon- containing reservoir, a fresh water aquifer, an injection zone, and so forth. Signals reflected from resistive body 116 may be propagated upwardly toward sensors 103 for detection by the sensors. Measurement data may be collected by sensors 103, and the measurement data may be stored and/or transmitted back to data storage device 106. WG Docket No. IS14.8312

Sensors 103 may be seismic sensors, which may be implemented with acoustic sensors such as hydrophones, geophones, accelerometers such as MEMS particle motion sensors, particle motion sensors, gradient sensors, and/or fiber optic based sensor systems. The signal sources 105 may be seismic sources, such as air guns, marine vibrators, electromagnetic, and/or explosives. The sensors 103 may be electromagnetic (EM) sensors 103, and signal sources 105 may be EM sources that generate EM waves that are propagated into subterranean structure 114, in the case of an EM survey.

In some embodiments, streamer 102 may include a multi-component streamer, which is a streamer 102 that may contain particle motion sensors and pressure sensors. The pressure and particle motion sensors may be part of a multi-component sensor unit. Each pressure sensor may be configured to detect a pressure wavefield, and each particle motion sensor may be configured to detect at least one component of particle motion that is associated with acoustic signals that are proximate to the sensor. Examples of particle motions include one or more components of a particle

displacement, one or more components (inline (x), crossline (y) and vertical (z) components of a particle velocity and one or more components of a particle acceleration. A more thorough discussion of particle motion sensors may be found in U.S. Patent Pub. 2012/0082001 , which is incorporated by reference herein in its entirety.

FIG. 2 shows an embodiment having a portion of streamer 102, including sections 200A, 200B, and 200C. Section 200A may include a corresponding sensor 103 (such as a seismic sensor) for detecting

subterranean features. Sensor 103 may be deployed intermittently (e.g. every other section) throughout streamer 102. In some embodiments, each section may have a corresponding sensor 103. A strength member 213 extends longitudinally through the central part of the steamer cable 102. The strength WG Docket No. IS14.8312 member can be connected to end parts (not shown) of the streamer section that are used to secure to the strength member 213 and in turn to end parts of adjacent cable sections to connect cable sections in series. The end parts can form electrical and data communication connections between cable sections 200 also. The cable sections 200 can have an outer skin 214 that extends longitudinally and forms a longitudinally extending tubular

configuration.

In the present disclosure reference is made to seismic sensors. Note, however, in other implementations, the sensors used for detecting

subterranean features may include any suitable sensors or sensing

equipment. Different arrangements may be used in other implementations. The system may also include additional equipment that is not shown in FIG. 2, for example, one or more data storage devices (e.g. data storage device 106) that are in data communication.

Section 200A may further include a second sensor 202A, which in some embodiments is a depth sensor to detect the depth of the section of the streamer 102 in the body of water 108. Each of the other sections 200B, 200C depicted in FIG. 2 also includes a corresponding second sensor 202B, 202C (e.g., depth sensors).

Section 200A may further include steering device 204 to help steer streamer 102 in the body of water. Steering device 204 may include control surfaces 206 (in the form of blades or wings) that may be rotatable to help steer streamer 102 in a desired lateral direction. Steering device 204 may be provided intermittently (e.g. every other section) throughout streamer 102.

In some implementations, steering device 204 may include a battery (or other power source) 208 that may be used to power the steering device 204. Battery 208 may also be used to power the depth sensor 202A in the WG Docket No. IS14.8312 section 200A, as well as depth sensors 202B, 202C in other sections 200B, 200C that are relatively close to the section 200A containing the steering device 204. Power from the battery 208 may be provided over electrical conductor(s) 210 to the depth sensors 202A, 202B, 202C. Battery 208 may also be configured to power a data storage device (e.g. 106, 300, etc.) and in some cases battery 208 may be included within the data storage device. Power may be provided by way of the electronics in the seismic cables.

Power may be provided from an alternative source, such as from the sea vessel 100, solar charger associated with a buoy, over an electrical cable 212 (or fiber optic cable) that may be routed through the streamer 102. To derive power from a fiber optic cable, each sensor 202 would include a conversion circuit to convert optical waves into electrical power. One source of power may include a wave powered generator. A more thorough discussion of wave generated power may be found in U.S. Patent Pub. 2009/0147619, which is incorporated by reference herein in its entirety. Accordingly, the data storage device described herein may include a battery to store such wave motion generated power.

In accordance with some embodiments, depth sensors 202 (202A, 202B, 202C shown) may be used to detect which sections 200 of streamer 102 are deployed in the body of water 108. Depth sensors 202 may provide data regarding whether corresponding sections are in the body of water 108 by communicating the data over a communications link (e.g., electrical or fiber optic cable) 212 that is run along the length of the streamer 102 to the reel 104 on the sea vessel 100 and/or to data storage device 106. The data provided from depth sensors 202 may be received at and stored within data storage device 106.

It should be appreciated that during a seismic survey significant forces may be experienced by the streamers. Also, various damages to the WG Docket No. IS14.8312 streamers can take place. With that in mind, it is beneficial to determine what stresses and strains are experienced by the streamers, so as to determine if the streamers have or will be experiencing loads that are beyond the streamer capacity. This can be used to determine a damage situation, or to help avoid a situation where damage may take place by monitoring various failure modes.

Streamers face a number of other failure modes, such as impact with hard objects that can cut or scrape the streamer and/or puncture the streamer. This can happen during deployment or retrieval. It can also happen by way of marine animal attack such as a shark attack. It can also happen if the streamer is taken into a ships propeller or other marine hardware encounter.

In the case of the streamer becoming punctured, the seawater can damage the inner electronics of the streamer, as well as other inner hardware. Water intrusion from damaged cable jacket materials can migrate along the cable's conductors and damage connectors. Water intrusion can be determined by detecting a temperature drop inside the streamer, with the optical fiber 215, since seawater is generally cold.

It should be appreciated that if damage of this sort can be quickly identified, that a remedy can often be applied in a timely manner, thus reducing the overall negative impact both operationally and financially for a job. Much of this damage can be mitigated if the presence vibration measurements or strained points in the cable or leaks in the jacketing material are determined in a timely manner and cable maintenance is performed before the damage worsens to the point of cable failure.

An optical fiber 215 extends through the seismic cable section 102 and can be connected within the seismic cable section 102 so that stress and WG Docket No. IS14.8312 strain forces experiences by the seismic cable are transmitted to the optical fiber 215 and can thus be detected. The optical fiber 215 can be connected with an optical measurement unit 216 that uses light transmitted through the optical fiber 215 to determine attributes experienced by the optical fiber 215 and in turn to determine aspects being experienced by the seismic cable 102 such as stress, strain, temperature and vibration.

According to various embodiments described herein, the optical fiber is located inside a seismic streamer cable, lengthwise along the inside part of the streamer cable, and connected with a sensing system so that the optical fiber serves as a monitoring device for the streamer cable to measure aspects of the cable such as stress, strain, temperature, and the position of those aspects on the streamer. The optical fiber can extend substantially the entire length of the seismic cable 102. Based on those measured aspects, according to various embodied features described herein, many of the aforementioned damage modes can be identified and/or predicted and addressed quickly.

According to an aspect of the present disclosure, in the optical fiber sensors as described herein, light signals in optical fibers are subject to three main scattering mechanisms: Rayleigh, Raman and Brillouin. Rayleigh scattering occurs when the light signal encounters bubbles or defects within the optical fiber. Raman scattering is observed as backscatter as a result of temperature differences in the optical fiber. Brillouin scattering fluctuates in reaction to a combination of temperature changes and strain placed on the optical fiber.

Embodiments of the present disclosure include the use of strain, stress, temperature and vibration measurement by way of optical fiber sensors for marine cables to forecast potential and detect issues with the cables in the field. WG Docket No. IS14.8312

According to a combination of embodied features, methods can use Brillouin scattering of light signals transmitted on a single-mode optical fiber, which also allows measurement of fluctuations in temperature and strain along the cable's length. Also, single optical fibers by means of the coherent Rayleigh noise, coherent OTDR and acoustic sensing also allow the use of distributed vibration measurements along the length of the cable.

Embodiments of the present disclosure describe the application of techniques that can be used to monitor marine seismic cables containing optical fiber conductors for damage due to cable strain, water incursion, or leaks of oil from optical fiber conductors and as predictive and monitoring tools using the cable vibration. These techniques can determine items such as the length of the cable lowered deployed overboard, distance reference temperature readings, and distance reference strain placed on the cable. Optical fibers may be used to obtain distributed measurements of strain and temperature by using Optical Time Domain Reflectometry (OTDR) technology to measure Brillouin scattering along the optical fiber. The optical fibers can also be used to measure vibration.

Embodiments of the present disclosure apply concepts for use in monitoring distributed cable strain, temperature and vibration data to identify and accurately locate areas of damage in marine seismic cables during or before going into operation. Strain and temperature readings can be acquired using Brillouin scattering data from optical fibers using Optical Time Domain Reflectometry (B-OTDR). Vibration readings can be acquired by using data from optical fibers using Coherent Rayleigh Noise (CRN), Coherent ODTR and Distributed Acoustic Sensing (DAS). Further details for each system and how they can be used in marine seismic applications are described herein.

When using Brillouin-Optical Time Domain Reflectometry (B-OTDR), measurements can be based on the distance the light signal travels; accurate WG Docket No. IS14.8312 cable length measurement is unaffected by cable stretch; the only

requirements are knowing the overall length of the cable, plus the location of a reference point from which to measure the length of cable overboard. This reference point can be created by inducing a high scattering point

recognizable by the B-OTDR at a known distance before the top of the well. Different configurations might be used to measure strain: one single mode fiber, two looped single mode fiber or one single mode fiber with reflector.

By way of measuring strain and temperature a number of issues and failure modes for the streamers and the spread can be determined. Under rough weather, the strain measurements obtained from the optical fibers can be used to know whether or not the cables are being subjected to forces so large that it may be harmful for the cables and thus stop operations when needed. Through strain measurements, one can detect entanglement of cables. Through temperature measurements and correlation of strain measurements and depth in the water, once can detect malfunction of floats, wings, or any other device that keeps the cables at certain depth and in certain orientation. Measurement of forces at termination Y points or any other devices that are used for an over and under seismic configuration can be used to determine failure modes. One can use the monitoring to help regulate the strain caused by tow chains, ropes or any other devices that exert forces on cables during seismic operations. One can determine the portions of the cable that have lost fairing during operations, and monitor the noise produced because of the lost fairing.

Many of the embodied features described in connection with a seismic streamer equally apply to gun cables. Gun cables provide pressurized air to the seismic source guns, and also take up tension forces. Some applications in that regard can be detection hose air leakage, determination of hose extension and contraction during gun firing, monitoring conductors health WG Docket No. IS14.8312 during gun firing, detection of gun cable "football shape" phenomena due to hose air leakage, jacket damage, or armor opening, and detection of kidney bean collapse of high pressure plastic hoses reinforced with Kevlar. In connection therewith, fiber optics may be embedded in the hose or above Kevlar reinforcement in the jacket. This is shown in FIG. 5.

It can also be desirable to use a distributed optical line to measure vibration. Distributed vibration sensing measurements can use amplitude based coherent or heterodyne C-OTDR techniques, which is phase measurement of backscattered light. Pulses of laser light are launch into the fiber optics, where the scattering process returns a fraction of the light to the end of the fiber where it originated, and the returning light is analyzed in very short intervals of time. The backscatter light is affected by variations in vibrations along the sensor length and the data is continuously analyzed to provide vibration data along the whole length of the sensor, such as the marine cable. Vibration techniques that can be used are DVS and hDVS. hDVS techniques has an optical configuration and signal processing as well. A single mode fiber with no reflection or loop is needed to measure vibration.

Apart from measuring the vibration, other application in vibration sensing in seismic cables are possible. It can be used to determine the amount of cable deployed or the depth of the cable from the sea surface. It can be used to monitor cable during operation to detect entanglement of cables, or source firing sequences. It can be used to determine if there are any malfunctions during firing or the locations of the cable that has lost fairing.

FIG 4 shows an embodiment of a seismic survey spread using towed seismic cables. A tow vessel 300 is connected to lead-ins 305 that in turn connect to the front portion of streamer cables 303. At the front portion of the steamer cables are deflectors 306 that are commercially available. WG Docket No. IS14.8312

Connected to the tow vessel 300 are seismic sources 304 that are connected to the tow vessel 300 by way of gun cables.

According to various embodiments, marine seismic cables can have single-mode fiber-optic conductors. A single-mode optical fiber can be sufficient to measure temperature, strain or vibration. Marine seismic cable designs having optical fibers are shown in FIG. 4. FIG. 4 shows a marine seismic cable 400 having optical fiber 401 conductors for distributed temperature, strain and vibration measurement techniques. A central strength member 402 is shown and supports tensile loads on the streamer cable 400. The streamer cable 400 has an outer skin 403 that extends longitudinally and forms a longitudinally extending tubular shaped enclosure.

FIG. 5 shows a cross section of an embodiment of a marine seismic air gun cable 500 having optical fiber conductors 501 for distributed temperature, strain and vibration measurement techniques. The cable 500 has a central annulus 502 for pressurized air to flow.

In order to accurately determine the location of a given temperature measurement, the total length of the cable and the length of the cable deployed overboard can be determined. A Brillouin optical time-domain reflectometer (B-OTDR) can be used first to determine the cable's total length. The B-OTDR can be used to determine the length of cable on the drum, the cable can be temperature-marked at an on-board location. At three points near this onboard location, the cable can be alternately cooled (for example using chilled water) and heated (for example, using steam or infrared radiation) to create a reference point. The process may consist of: Cooling the cable significantly below ambient temperature at point A, Heating the cable significantly above ambient temperature at point B, Then cooling the cable significantly below ambient temperature at Point C. WG Docket No. IS14.8312

Heating and cooling a cable can be used to determine length of cable on reel/overboard. A series of temperature changes is reflected by a characteristic reading on the B-OTDR from which the cable length between the B-OTDR and a designated "on-board" location is determined. Subtracting the length of cable on the reel from the overall length gives the length of cable deployed overboard.

When marine seismic cable jackets are damaged during operations, water leaks can develop that allow water to travel along conductors the cable's conductors until they reach the terminations and cause serious damage to the cable. Given the temperature of the sea water where marine seismic operations occur, the water can be detected by using a B-OTDR to monitor for Brillouin scattering evidence of lower temperatures. Because B- OTDR readings are distributed, the location of the damage can be located with great accuracy. This allows the cable to be retrieved for repairs before the cable is damaged to the point that it must be discarded.

Cable strain can also result in characteristic wave forms on the B- OTDR readout. On-board distance-reference point marking may be performed using the method described above, or by inducing a localized high strain point. Because strain measurements can be affected to some extent by temperature fluctuations along the cable, it may be necessary to consider temperature readings along the cable and adjust the locations of detected areas of high-strain accordingly.

Cables can be damaged through cable handling both in deployment, take in, during operations, and through other onboard or off board operational hazards. When a cable damaged by cable strain would otherwise be deployed, that damage can be detected through B-OTDR allowing for avoidance of this deployment. WG Docket No. IS14.8312

It should be noted that the embodiments shown in any of the figures may be used in conjunction with any or all of the components discussed in other figures included herein and may be implemented in systems consistent with and/or similar to those shown in the figures, as well as numerous others.

Monitoring source firing sequences by pressure sensing using optical fibers is possible. Monitoring of bubbles propagating in the water using optical fibers in the case of air guns being used as sources.

As used in any embodiment described herein, the term "circuitry" may comprise, for example, singly or in any combination, hardwired circuitry, programmable circuitry, state machine circuitry, and/or firmware that stores instructions executed by programmable circuitry. It should be understood at the outset that any of the operations and/or operative components described in any embodiment or embodiment herein may be implemented in software, firmware, hardwired circuitry and/or any combination thereof.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in

combination with other claimed elements as specifically claimed. The WG Docket No. IS14.8312 description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosure in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the disclosure. The embodiment was chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.

Although a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing from the Seismic Streamer System described herein. Accordingly, such

modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. § 112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words 'means for' together with an associated function.

Having thus described the disclosure in detail and by reference to embodiments thereof, it will be apparent that modifications and variations are WG Docket No. IS14.8312 possible without departing from the scope of the disclosure defined in the appended claims.

Claims

WG Docket No. IS14.8312 What Is Claimed Is:

1. A method for use with marine seismic cables comprising: providing at least one marine seismic cable; and monitoring an aspects of a marine seismic cable during or before going into operation by way of an optical fiber that extends longitudinally within the seismic cable.

2. The method of claim 1 , wherein strain and temperature readings are acquired using Brillouin scattering data from the optical fiber using Optical Time Domain Reflectometry (B-OTDR).

3. The method of claim 1 , wherein vibration readings are acquired by using data from the optical fiber using Coherent Rayleigh Noise (CRN), Coherent ODTR and Distributed Acoustic Sensing (DAS).

4. The method of claim 1 , wherein the at least one marine seismic cable includes the optical fiber conductor extending longitudinally inside substantially the full length of the marine seismic cable.

5. The method of claim 1 , further comprising: marking an on-board reference point associated with the at least one seismic cable.

6. The method of claim 1 , further comprising: WG Docket No. IS14.8312 detecting cable damage through distributed temperature readings.

7. The method of claim 1 , further comprising: measuring distance-referenced cable-strain.

8. A marine seismic streamer cable system, comprising: a seismic streamer cable having an outer streamer skin defining a longitudinally extending tube; a strength member extending longitudinally through the interior of the tube; seismic sensors located inside the tube and connected to one another electronically so as to transmit power and seismic data signals; an optical fiber extending longitudinally through the tube and configured so as to physically be coupled to the tube so that bending of the tube will transmit bending motion to the optical fiber; and an optical measurement unit that is optically connected with the optical fiber so as to measure optical transmission through the optical fiber and thereby determine various aspects of the optical fiber that are indicative of stress and strain experienced by the streamer.

9. The marine seismic streamer cable system of claim 8, wherein the optical measurement unit uses Optical Time Domain Reflectometry to measure stress or strain in the seismic cable. WG Docket No. IS14.8312

10. The marine seismic streamer cable system of claim 9, wherein the optical measurement unit uses Brillouin scattering data from optical fibers using Optical Time Domain Reflectometry (B-OTDR).

11. A marine seismic streamer cable system, comprising: a seismic streamer cable having an outer streamer skin defining a longitudinally extending tube; a strength member extending longitudinally through the interior of the tube; seismic sensors located inside the tube and connected to one another electronically so as to transmit power and seismic data signals; an optical fiber extending longitudinally through the tube; and an optical measurement unit that is optically connected with the optical fiber so as to measure optical transmission through the optical fiber and thereby determine aspects of the optical fiber that are indicative of a physical attribute of the streamer cable.

12. The marine seismic streamer cable of claim 11 , wherein the optical measurement unit uses Optical Time Domain Reflectometry to measure stress or strain in the seismic cable.

13. The marine seismic streamer cable system of claim 11 , wherein the optical measurement unit measures vibration of the streamer and the location along the streamer where the vibration occurs. WG Docket No. IS14.8312

14. The marine seismic streamer cable system of claim 11 , wherein the optical measurement unit measures temperature of the streamer and the location along the streamer where the temperature measurement occurs.

15. The marine seismic streamer cable system of claim 11 , wherein the optical measurement unit measures vibration and where the vibration occurs.