Device for low contact cable cleaning

A method and cable cleaning device that includes a housing and at least one cleaning element attached to the housing. The cleaning element is configured to clean marine fouling from a cable. The cleaning element is at least partially rolled around the cable and its tautness is adjustable.

TECHNICAL FIELD

Embodiments of the subject matter disclosed herein generally relate to cleaning devices for cables and other structures used in marine seismic surveying.

BACKGROUND

During the past years, offshore drilling has continually increased. Given high costs and risks associated with offshore drilling, to avoid a dry well, marine seismic surveys are used to generate a profile (image) of the geophysical structure under the seafloor. While this profile does not necessarily provide an accurate location for the oil and gas, it suggests, to those trained in the field, the presence or absence of oil and/or gas.

A typical marine seismic surveying system is illustrated inFIG. 1. A vessel100tows a seismic source102and plural streamers106, each streamer carrying an array of seismic receivers104(e.g., hydrophones). It is desirable to maintain the streamers at predetermined horizontal cross-line distances (i.e., along an axis perpendicular to the towing direction T), and at predetermined depths (e.g., 10 m) relative to the water surface108. The seismic source102is configured to generate a seismic wave110that propagates downward (down, up and vertical being defined relative to gravity) toward the seafloor120and penetrates formations125under seafloor120until it is eventually reflected at discontinuity locations such as122aand122b. The reflected seismic waves130aand130bpropagate upwardly and can be detected by one of receivers104on streamer106. Based on the data collected by receivers104, an image of the subsurface formation is generated by further analyses of the collected data.

To maintain the streamers at a desired position (i.e., such as to have predetermined cross-line distances and predetermined depths), conventionally, a head float140and a tail buoy150are attached to the ends of the streamer. Position control devices160(e.g., birds) may be attached to streamer, every 300 m, to control a position of the streamer.

Marine surveys often last for weeks or months, which is more than enough time for the survey cables to attract barnacles and other unwanted wildlife or debris. Such materials, when attached to the streamer, tend to increase drag on the cables, thereby requiring a greater amount of towing energy and placing increased strain on the ship, the cables, and the positioning devices. Such materials can also induce additional turbulence, which may impair the quality of the data acquired from the sensors distributed along the cable. Current methods of cleaning survey streamer cables tend to be time consuming, labor intensive, and generate premature worn to the streamer cables and its measuring instruments, as now discussed.

A conventional tool and method for cleaning survey cables is described in U.S. Patent Publication No. 2013/0098394 A1 (herein, '394 application), the entire content of which is incorporated herein by reference. The '394 application discloses, as illustrated inFIG. 2(which corresponds to FIG. 3A in '394 application), a cleaning tool for cleaning a survey cable202. This cleaning tool employs a cable guide205with a roller mechanism206that lifts the survey cable clear of the water and guides it through a scraper mechanism211. As the cable guide205lifts and passes along underneath the survey cable, the cable exerts a frictional pull on the roller mechanism206, causing it to turn at a rate that matches the speed of the cable relative to the workboat. The roller mechanism206is coupled via a belt drive system204to rotate a set of scraper wheels210. The scraper wheels210have short bristles of plastic, wire, or some other material selected for its effectiveness at removing barnacles. These scraper wheels cause wear to the survey cable's surface due to their abrasive manner of removing the barnacles.

Due to the scraper wheels' abrasive approach in removing marine fouling, the streamer jacket becomes rough with the premature wear, which enables barnacles to settle more easily and at a quicker rate. This then creates an undesirable situation where the more one cleans the streamer, the faster the barnacles can return.

Further, due to the nature of the cleaning tool employed inFIG. 2, the belt drive system204is susceptible to erroneous behavior due to excess barnacle build-up. Any debris or marine contaminant that may enter inside the belt drive system, the roller mechanism206, or the springs216, used in this embodiment, would render the device inoperable.

There is, therefore, a need to develop non-destructive methods of cleaning to eliminate premature wear and mechanical parts that are prone to failure.

SUMMARY

According to an embodiment, there is a cable cleaning device that includes a housing and at least one cleaning element attached to the housing and configured to clean marine fouling from a cable. The cleaning element is at least partially rolled around the cable and its tautness is adjustable.

According to another embodiment, there is a marine seismic acquisition system that includes a cable and a cable cleaning device. The cable cleaning device includes a housing and at least one cleaning element attached to the housing and it is configured to clean marine fouling from the cable. The cleaning element is at least partially rolled around the cable and its tautness is adjustable, and at least one pair of high pressure nozzles configured in opposite directions to clean the cable.

According to still another embodiment, there is a method for cleaning a marine cable while being towed. The method includes a step of mounting a cleaning device on the cable and a step of cleaning the cable using an adjustable cleaning element located in the cleaning device. The adjustable cleaning element is made taut when in contact with the cable.

DETAILED DESCRIPTION

According to embodiments, among other things, it is desirable to address the fouling problem related to cables used in marine seismic exploration as discussed in the Background. The following embodiments describe devices and methods which can use a soft element or high pressure nozzles or a combination of both soft element and high pressure nozzles to clean marine fouling on marine seismic streamers. Note, as used herein, soft element is intended to include one or more soft elements.

According to an embodiment illustrated inFIG. 3, a cleaning device300is deployed around a streamer302, located or not in a body of water, and soft element304, e.g., fibrous material, ropes, strings, fibers, etc., is used to clean marine fouling from the streamer. Soft element304is adjustable so that when it comes in contact with streamer302, it becomes taut.FIG. 3shows soft element304A and304B which are rolled around the streamer one or more times so that marine fouling material is removed. Soft element304is attached to a housing306of the cleaning device300. In one embodiment, the soft element304is attached to the housing306using springs between at least one end of the soft element304and the housing306. In another embodiment, part310of the soft element304is kept parallel relative to the housing306with e.g., springs, clamps312, hooks, rails, etc., before making contact with the streamer302, as illustrated inFIG. 3.FIG. 4Aillustrates housing306having plural soft elements304, one of which304A is shown having a spring312attached to one of its ends304A-1. Note that soft element304A extends then to a pulley type element (i.e., a pulley or simply a hook)314, enters through a hole316inside housing306and then extends to another hook318and the other end304A-2of the soft element is finally connected to a clamp320inside housing306. Those skilled in the art would appreciate that more or less pulley type elements may be located inside the housing for any given soft element304. Although a single stage of soft element304is illustrated inFIG. 3, more stages may be used, if desired, and their location relative to the housing306may be chosen depending on the application. For example, in one embodiment, the soft elements304can be attached to the ends of the housing306. The number of soft element304in each stage may be more or fewer depending on the application and their configuration modified for the desired application. In one embodiment, the soft element304completely turns around the exterior of the streamer302. In another embodiment, none of the individual soft element304fully wraps around the streamer, but the soft element304A and304B collectively fully wrap around the streamer.FIG. 4Billustrates a cross-sectional view of cleaning device400with streamer402being cleaned by soft element404located in housing406. Note that an obstacle410attached to streamer402and having a larger exterior diameter than the streamer can easily pass through the cleaning device because soft element304's elastic properties. Also note that in one application, both ends of the soft element are attached to an inside of housing406.

According to another embodiment illustrated inFIG. 5, a cleaning device500is positioned over the streamer502. Soft element504(only part of it is shown in the figure) is connected to contra-turning ends506A and506B which are configured to turn in opposite directions about the streamer502, as illustrated by arrows A and B. By this action, turning ends506A and506B tauten soft element504to adjust fit around streamer502to clean marine fouling. The contra-turning ends506A and506B slide in corresponding rails or along some tracks510and ball-bearings512may be used to allow ends506A and506B to rotate relative to the tracks. Soft element504is contained within a housing508of the cleaning device500. In one application, only a single turning end is provided for changing a stress induced in the soft element. One or more handles514may be attached to the turning end for facilitating the turning. In another application, a stop mechanism516is connected to handle514for fixing it in place relative to track510. For example, stop mechanism516may include a nut and washer that attach to an end of handle514, which end is configured as a screw. Other stop mechanisms may be conceived by those skilled in the art that will achieve the same functionality.

According to another embodiment illustrated inFIG. 6, a cleaning device600is deployed around a streamer601. Soft element604, contained within housing602, is connected to at least one of contra-turning ends606A and606B which are configured to turn in opposite directions about the streamer601in order to tauten soft element604to adjust fit around streamer601to clean marine fouling. High pressure nozzles608are located on the housing and configured to eject a pressurized fluid (e.g., water) in opposite directions to be able to clean around hidden corners (e.g., weights, connections, etc.) of streamer601. The high pressure nozzles608may be oriented at a 45° angle. However, the high pressure nozzles may be oriented at other angles between 1 and 90°.

According to another embodiment illustrated inFIG. 7, a cleaning device700is fitted over a streamer. Soft element704is connected to a central turning element706which tautens or loosens soft element704to adjust fit around a streamer to clean marine fouling. Soft element704is contained within a housing702of the cleaning device700and attached to the central turning element706. The central turning element706slides in corresponding rails or along some tracks708and it may use ball-bearings for rotation.

According to another embodiment illustrated inFIG. 8, a cleaning device800has contra-turning ends806A and806B to tauten or loosen soft element804. Guiding elements810(e.g., wheels, rings, etc.) guide and keep streamer801oriented relative to housing802. High pressure nozzles808A and808B are located on the housing and configured to eject a pressurized fluid (e.g., water) in opposite directions to be able to clean around hidden corners (e.g., weights, connections, etc.) of streamer801. A hydraulic motor812is connected to a hydraulic pump814to provide high pressure to high pressure nozzles808A and808B. The hydraulic motor812and the hydraulic pump814may be located, for example, on the workboat. Although multiple high pressure nozzles808A and808B are illustrated, above and below streamer801, the location of the high pressure nozzles808A and808B need not be restricted to the ends of cleaning device800and may be positioned anywhere along the housing802and in as many stages as desired and in as many pairs as needed. The location of high pressure nozzles808A and808B need not be limited to above or below the streamer801, as illustrated, and the configuration can be changed according to the desired application. Guiding elements810may be located at various points and in various stages throughout cleaning device800according to the desired application.

According to another embodiment illustrated inFIG. 9, a cleaning device900has a central turning element906to tauten or loosen soft element904contained within housing902. Guiding elements910guide and keep streamer901oriented relative to high pressure nozzles908A and908B which are configured in opposite directions to be able to clean around hidden corners (e.g., weights, connections, etc.) of streamer901. A hydraulic motor912is connected to a hydraulic pump914to provide high pressure to high pressure nozzles908A and908B. In one embodiment, high pressure nozzles908A and908B are distributed on a bar920contained within the housing902and surrounding streamer901. One or more bars may be positioned within the housing. The high pressure nozzles may be oriented so that the water jets922A and922B make a predetermined angle α. In one application, angle α is about 90°.

According to an embodiment illustrated inFIG. 10, a vessel1004tows a streamer1002. A cleaning device1000is attached to a workboat1006via a connector1008(e.g., straps, railing, crane, etc.). Workboat1006communicates with vessel1004to raise one or more sections of streamer1002out of the water using position control devices1010(e.g., birds). Workboat1006then connects cleaning device1000to streamer1002and moves parallel to streamer to allow cleaning device1000to remove marine fouling. Cleaning device1000may be attached anywhere along workboat1006via connector1008that would allow for cleaning of streamer1002. Cleaning device1000may be any one described above.

According to an embodiment illustrated inFIG. 11, a cleaning device1100is located on the back deck1108of a vessel1104. During the recovery process of streamer1102, the cleaning device1100is positioned around streamer to clean it of marine fouling as it is stored in storage device1106(e.g., spool, container, etc.).

According to an embodiment illustrated inFIG. 12, a vessel1204tows a streamer1202. A workboat1206has attached a cleaning device1200with cleaning stages1210A,1210B, and1210C via a connector1208. One possible configuration of the cleaning stages1210A,1210B, and1210C is that stage1210A contains a soft cleaning stage. The soft cleaning stage can include, for example, one of the soft elements discussed above. In addition, the soft cleaning stage may include abrasive elements (e.g., scraper wheels, brushes, wires). Stage1210B may contain a high pressure and/or ultrasound cleaning causing cavitation with sufficient power to overcome the particle-to-substrate adhesion forces, loosening contaminants, and stage1210C may contain an application of an antifouling wax to prevent future growth. Application of the antifouling wax may be selected according to which barnacle species would be most affected by the antifouling wax. Cleaning device1200's cleaning stages1210A,1210B, and1210C need not necessarily be located in 3 separate housings, as illustrated inFIG. 12, but are shown in this configuration to illustrate one possible configuration. The order of the stages1210A,1210B, and1210C may also be changed.

According to an embodiment illustrated inFIG. 13, there is a method for cleaning a streamer. The method includes a step1300during which a workboat communicates with a towing vessel to partially raise streamer, a step1302of workboat making visual confirmation of streamer, a step1304of workboat lifting a section of streamer, a step1306of workboat clamping on the raised portion of the streamer the cleaning device, a step1308of workboat driving from the tail to the head of streamer section while actuating the cleaning device, and a step1310of workboat unclamping and re-clamping of cleaning device for passing small obstacles (e.g., birds).

The disclosed embodiments provide an apparatus and a method for removing marine growth on marine seismic streamers. It should be understood that this description is not intended to limit the invention. On the contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items.