WO2020049362A1

WO2020049362A1 - Autonomous cleaning system and method

Info

Publication number: WO2020049362A1
Application number: PCT/IB2019/001000
Authority: WO
Inventors: Ian MCELROY; Timothée MOULINIER; Thibaut CAPPE DE BAILLON
Original assignee: Sercel
Priority date: 2018-09-04
Filing date: 2019-08-09
Publication date: 2020-03-12

Abstract

A cleaning device (200, 300) for cleaning a streamer includes a frame (202); a crawling mechanism (210) having a first clamping device (212) fixedly attached to the frame (202) and a second clamping device (214) slidably attached to the frame (202); a sensing device (220) attached to the crawling mechanism (210) and configured to determine an object (902) externally attached to the streamer (201); an actuation mechanism (240) configured to slide the second clamping device (214) relative to the first clamping device (212); and a control unit (230) configured to control the actuation mechanism (240) and the sensing device (220).

Description

AUTONOMOUS CLEANING SYSTEM AND METHOD

BACKGROUND TECHNICAL FIELD

[0001] Embodiments of the subject matter disclosed herein generally relate to cleaning devices for underwater streamers used in marine seismic surveying and, more particularly, to autonomous cleaning devices and related methods for cleaning marine growth and other contaminants deposited on marine equipment towed underwater.

DISCUSSION OF THE BACKGROUND

[0002] Marine seismic surveying investigates and maps the structure and character of geological formations under a body of water using reflection seismology. Reflection seismology is a method of geophysical exploration especially helpful in the oil and gas industry. In marine reflection seismology, the depth and the horizontal location of features causing reflections of seismic waves are evaluated by measuring the time it takes for the seismic waves to travel to receivers. These features may be associated with subterranean hydrocarbon reservoirs.

[0003] A typical marine seismic surveying system is illustrated in Figure 1. A vessel 100 tows a seismic source 102 and plural streamers 106 (only one shown for simplicity), with each streamer carrying an array of seismic receivers 104 (e.g., hydrophones, geophones, accelerometers, or a combination thereof). 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 surface 108. The seismic source 102 is configured to generate a seismic wave 1 10 that propagates downward (down, up and vertical being defined relative to gravity) toward the seafloor 120 and penetrates formations 125 under seafloor 120 until it is eventually reflected at discontinuous locations such as 122a and 122b. The reflected seismic waves 130a and 130b propagate upward and can be detected by one of receivers 104 on streamer 106. Based on the data collected by the receivers 104, an image of the subsurface formation is generated by further analyses of the collected data.

[0004] To maintain the streamers at a desired position (i.e. , such as to have predetermined cross-line distances and predetermined depths), conventionally, a head float 140 and a tail buoy 150 are attached to the streamer. Position control devices 152 (e.g., birds) may be attached to the streamer, every 300 m, to control the streamer’s position.

[0005] Significant amounts of bio-fouling settlement accumulates on the streamers’ exterior surface, which can obscure the reflected seismic wave and significantly increase streamer drag. The rate of accumulation and the impact of bio- fouling and other contaminants depend on factors, among others, such as

geographic location, water temperature, and season.

[0006] Cleaning such contaminants from the streamers’ exterior is desirable and beneficial. However, the existing cleaning devices have various limitations that prevent an efficient and autonomous cleaning of the entire streamer. For example, a cleaning device may be moved along the streamer to clean contaminants from the exterior thereof. However, it is known that the streamer has various parts and/or components, some with a larger diameter than others, e.g., the birds, and an efficient cleaning device needs to be able to cross these components while moving along the streamer. Further, the cleaning device has typically wings for propelling it along the streamer. The existing mechanisms for changing the wing positions are complicated and prone to failure, especially if marine fouling gets inside these mechanisms.

[0007] Therefore, there is a need to develop streamer cleaning devices that operate, autonomously, upstream and/or downstream over variable diameter components of the streamers, with reliable mechanical parts not prone to failure.

BRIEF SUMMARY OF THE INVENTION

[0008] According to an embodiment, there is a cleaning device for cleaning a streamer. The cleaning device includes a frame, a crawling mechanism having a first clamping device fixedly attached to the frame and a second clamping device slidably attached to the frame, a sensing device attached to the crawling mechanism and configured to determine an object externally attached to the streamer, an actuation mechanism configured to slide the second clamping device relative to the first clamping device, and a control unit configured to control the actuation mechanism and the sensing device.

[0009] According to another embodiment, there is a cleaning device for cleaning a streamer and the cleaning device includes a frame, a crawling

mechanism having a first clamping device fixedly attached to the frame, a second clamping device fixedly attached to the frame, and a third clamping device slidably attached to the frame, a sensing device attached to the crawling mechanism and configured to determine an object externally attached to the streamer, and an actuation mechanism configured to slide the second clamping device between the first and the second clamping devices.

[0010] According to still another embodiment, there is a method for cleaning a streamer with a cleaning device while passing an object attached to an exterior of the streamer. The method includes attaching the cleaning device with a crawling mechanism to the streamer, where the crawling mechanism has a first clamping device fixedly attached to a frame and a second clamping device slidably attached to the frame, sensing with a sensing device, which is attached to the crawling mechanism, the object attached to the streamer, opening with a motor the second clamping device to release the streamer and sliding the second clamping device, with an actuation mechanism, relative to the first clamping device, past the object, and closing the second clamping device around the streamer after passing the object. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the

accompanying drawings, in which:

[0012] Figure 1 is a schematic diagram of a conventional marine seismic surveying system;

[0013] Figure 2 is a schematic diagram of a cleaning device that is capable of passing an object attached externally to a streamer;

[0014] Figure 3 is a schematic diagram of another cleaning device that is capable of passing an object attached externally to a streamer; [0015] Figures 4A and 4B illustrates the cleaning device attached to a streamer and a power station attached to the streamer, for recharging a power source of the cleaning device;

[0016] Figures 5A to 5C illustrate a crawling mechanism used by the cleaning device for passing an object attached to the streamer;

[0017] Figures 6A and 6B illustrate brackets attached to arms of clamping devices for attaching to the streamer;

[0018] Figures 7 A and 7B illustrate a fixed clamping device used by the cleaning device for attaching to the streamer;

[0019] Figures 8A and 8B illustrate a slidable clamping device used by the cleaning device for attaching to the streamer;

[0020] Figures 9A to 9L illustrate how the cleaning devices moves past an object attached externally to the streamer;

[0021] Figure 10 is a flowchart of a method for passing the cleaning device over an object externally attached to the streamer;

[0022] Figure 1 1 is a flowchart of a method for cleaning a streamer with a cleaning device; and

[0023] Figure 12 is a flowchart of a method for cleaning a portion of a streamer that has an obstacle attached to it.

DETAILED DESCRIPTION OF THE INVENTION

[0024] The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to the terminology and structure of a streamer cleaning device used in marine seismic surveying. However, the embodiments to be discussed next are not limited to cleaning devices operating on streamers, but may be used to clean other cable-like structures.

[0025] Reference throughout the specification to“one embodiment” or“an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases“in one embodiment” or“in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more

embodiments.

[0026] A cleaning device, according to various embodiments described below, facilitate maintaining streamer portions free of bio-fouling and other contaminants between various streamer mounted units (SMUs), e.g., a bird, that have a larger diameter than the streamer. A streamer may have one or plural cleaning devices positioned to clean at least the portions of the streamer having a high rate of accumulation of bio-fouling and other contaminants. The cleaning devices may be mounted on all portions of streamers. These cleaning devices remain attached to the streamers between cleaning operations. These cleaning devices operate autonomously during the seismic survey. In one embodiment, the cleaning device does not exchange information with the streamer or the vessel towing the streamer while cleaning the streamer. The cleaning device is able to pass over various SMUs autonomous, i.e. , with no information received from the vessel or the streamer. In one embodiment, the cleaning device can dock with a given power station attached to the streamer to charge its batteries.

[0027] According to an embodiment illustrated in Figure 2, a cleaning device 200 includes a frame 202 and a crawling mechanism 210 that connects the frame

202 to the streamer 201 . The frame is made of a solid material so that it does not bend in operation. The frame’s shape can be optimized to limit the drag, which would limit the power required to move the cleaning device, and/or to add stability to the cleaning device, to avoid any turbulence on the streamer to reduce the induced noise, and/or to align the cleaning device with the streamer when passing an obstacle. The crawling mechanism 210 is configured to hold the frame 202 attached to the streamer 201 and also to move the frame along the streamer, upstream or downstream. The cleaning device 200 also includes a local control unit 230 that is attached to the frame 202 and includes the electronics necessary to control the various electrical components of the cleaning device. The control unit 230 may include a processor 234 and a memory 236 that will be discussed in detail later. The control unit may also include a power source 238, for example, a battery. The cleaning device 200 also includes a sensing device 220 that is configured to detect the presence of an SMU. The sensing device 220 may be attached to the crawling mechanism 210. If the crawling mechanism 210 has plural clamping devices, the sensing device 220 may be attached to each of the first and last clamping devices. When the control unit 230, which communicates with the sensing device 220, determines that the cleaning device has encountered an SMU, the control unit follows an established procedure, also discussed later in more detail, for passing over the SMU for continuing to clean the streamer.

[0028] The crawling mechanism 210 may include at least first and second clamping devices 212 and 214, as also shown in Figure 2. As will be discussed later, it is possible to have more than two clamping devices. A clamping device is configured to clamp and unclamp to the streamer, as instructed by the control unit 230. Also, at least one clamping device is configured to move relative to the frame 202, due to an actuation mechanism 240 while at least one clamping device is configured to be fixedly attached to the frame 202. For example, for the embodiment illustrated in Figure 2, the first or forward clamping device 212 is fixedly attached to the frame 202 and the second or aft clamping device 214 is slidably/movably attached to the frame 202. The forward and aft terms are defined relative to the vessel towing the streamer, i.e., the forward clamping device is the closest clamping device to the vessel and the aft clamping device is the most distal clamping device from the vessel. One skilled in the art would recognize that this is a convention and the label of these clamping devices may be changed without affecting the

functionality of the cleaning device. When the sensing device 220, which may be attached to the second clamping device 214, determines the presence of the SMU on the streamer 201 , the control unit 230 instructs the actuation mechanism 240 to bring the first clamping device 212 next to the second clamping device 214, then instructs the second clamping device 214 to unclamp the streamer and to move past the SMU, then instructs the second clamping device to clamp to the streamer, then instructs the first clamping device to unclamp from the streamer and to move next to the second clamping device, over the SMU, then instructs the first clamping device to clamp to the streamer and finally instructs the second clamping device to move along the streamer to a new position, away from the first clamping device. To maintain the position of the frame above the streamer while executing the above noted displacements, in one embodiment, the control unit may include a positive buoyancy chamber 232. This chamber would force the frame to stay above the streamer 201. The actuation mechanism 240 may include a leadscrew and a motor, or a pulley/chain-sprocket system, or other equivalent system for sliding one clamping device along the frame. While Figure 2 shows the sensing device 220 being attached to the second clamping device, it is possible to have a similar sensing device 220 located on the first clamping device 212. The sensing device 220 may include any sensor that can determine the presence of the SMU along the streamer, for example, an acoustic device (a sonar), a light emitting device, etc. In one application, the sensing device 220 may be configured not only to detect the SMU but also to classify it, i.e., a bird, a streamer recovery device, etc.

[0029] Figure 3 illustrates another embodiment in which a cleaning device 300 has three clamping devices 312, 314, and 316. For this embodiment, the most distal clamping devices 312 and 314 are fixedly attached to the frame 202 while the third or middle clamping device 316 can move, due to the actuation mechanism 340, between the first and second clamping devices 312 and 314. The actuation mechanism 340 in Figure 3 is shown having a leadscrew 342 and a motor 344.

However, as discussed above, other mechanisms may be used for making the middle clamping device to move between the first and second clamping devices.

The motor 344 is powered by the power source 238 and controlled by the processor 234 illustrated in Figure 2. [0030] Figure 4A shows another embodiment in which a cleaning device 400, which is similar to the cleaning device 300, has an inductive coupling unit 420 implemented into the first or second clamping device 312 or 314, and in electrical contact with the power source 238. For this embodiment, the streamer 201 is provided with a corresponding inductive coupling unit 410, that is in electrical contact with a power source located on the towing vessel. Although the inductive coupling unit 410 is shown in Figure 4A having at least a part being located around an exterior of the streamer, as illustrated in Figure 4B, it is possible that the entire inductive coupling unit 410 is located inside the streamer. When the first or second clamping device reaches the inductive coupling unit 410, a corresponding current is induced into the inductive coupling unit 420. The control unit 230 is configured to detect this signal and stop the advancement of the cleaning device 400 when the two inductive coupling units 410 and 420 overlap, so that electrical power is transferred, in a wireless manner, from the streamer 201 to the power source 238 of the control unit 230. In this way, the power source of the cleaning device can be recharged as the cleaning device is attached to the streamer. As the seismic survey can continue for days, there is no need to stop the seismic survey acquisition process for charging the cleaning device when its power source runs out of energy.

[0031] A configuration of the clamping device 212 is now discussed in more detail with regard to Figures 5A to 5C. Note that all the distal clamping devices may have an identical configuration (i.e., devices 212, 214, 312, and 314) while the middle clamping device 316 may differ slightly as discussed later. Figure 5A shows the clamping device 212 having a frame 500 that is fixedly attached to the frame 202 of the cleaning device. The frame 500 has a hole 502 for receiving an end of the actuation mechanism 240, for example, an end of the leadscrew 342 shown in Figure 3. Two rotating arms 510 and 520 are attached to the frame 500 with rotatable connectors 512 and 522, respectively. Rotatable connectors 512 and 522 may be connected to a motor 530, that is configured to rotate the rotatable

connectors with a desired angle, for example, between 1 and 275 degrees. The motor may be powered by the power source 238 and controlled by processor 234, which is shown, for example, in Figure 2. The motor 530 is attached to the frame 500 and is connected to the rotatable connectors 512 and 522 with corresponding links 532.

[0032] Arms 510 and 520 have corresponding brackets 514 and 524, respectively, attached to their distal ends as illustrated in Figure 5A. The brackets 514 and 524 are shaped to closely (snugly) fit an outer diameter of the streamer 201 , as also shown in Figure 5A (i.e., they have a curvature that fits the curvature of the streamer). This means that there is no gap between the brackets 514 and 524 and the streamer 201. In this way, when the two arms 510 and 520 are in a closed position, as illustrated in Figure 5A, the two brackets 514 and 524 grip tightly the streamer so that the clamping device 212 does not move (slide axially or rotate around the circumference) relative to the streamer. This means that when the arms of at least on clamping device are closed, the entire cleaning device is fixed relative to the streamer. In addition, due to the positive buoyancy of the chamber 232, when the arms 510 and 520 are closed around the streamer 201 , the cleaning device 200 is an upright position, as shown in Figures 2 and 3. In other words, due to the positive buoyancy chamber 232, the cleaning device always clamps in an upright position relative to the streamer. [0033] One skilled in the art would understand that this embodiment may be modified to transform the positive buoyancy chamber 232 into a negative buoyancy chamber, so that the cleaning device will always clamp in a downright position relative to the streamer. The operation of the cleaning device, which is discussed in the next paragraphs, would work the same way for an upright or downright cleaning device.

[0034] Figure 5B illustrates an open position of the clamping device 212. In this position, the arms 510 and 520 are fully open so that the rotatable connectors 512 and 522 have been rotated about 180 degrees. In one application, the rotatable connectors 512 and 522 can be rotated with a smaller or larger angle. For this position, the brackets 514 and 524 have been fully moved away from the streamer, for example, above the frame 500 of the clamping device. In one embodiment, the brackets 514 and 524 are moved above the frame 202 of the cleaning device so that the clamping device can move past the SMU attached to the streamer (not shown).

[0035] Figure 5C shows a third position of the clamping device 212, which is used when the clamping device crawls along the streamer while also cleaning the streamer. This position is called herein the cleaning position or sliding/rolling position or mode. Note that the closed position illustrated in Figure 5A does not allow the cleaning device to move along the streamer, while the open position illustrated in Figure 5B is used to pass an SMU on the streamer. The cleaning position shown in Figure 5C has the brackets 514 and 524 slightly removed from the streamer 201 , so that a gap G is formed between the outside surface of the streamer and the brackets. The size of the gap G may be in the order of millimeters or centimeters, depending on the size of the marine growth on the streamer. The brackets of the clamping device are considered herein to be loosely attached to the streamer for the cleaning position, which means that the G is formed and has a size not larger than 3 cm. The cleaning position illustrated in Figure 5C promotes a cleaning of the streamer due to the interaction between the outside surface of the streamer and the moving brackets 514 and 524.

[0036] This cleaning action is promoted as the brackets 514 and 524 are provided with a cleaning element 516 and 526, respectively, as illustrated in Figures 5B and 5C. The cleaning element 516 and 526 may be a soft element 614 (see Figure 6A) as a soft scraper, a bristle, a flexible rod, a wire, or any other element that may be used to remove marine life from the exterior of the streamer. Note that the cleaning elements 516 and 526 need to be flexible (i.e., easily bendable) so that for the closed position of Figure 5A, the cleaning elements do not interfere with gripping the streamer with the brackets 514 and 524. However, it is possible to have the cleaning elements 516 and 526 implemented as a solid element 616 (see Figure 6B), for example, a wheel, a solid scraper, or similar devices. If the cleaning element is implemented as a solid element, then the clamping device would still close around the streamer but would also be able to slide or crawl along the streamer while being closed. In other words, the clamping device can be configured to be static (i.e., it does not move relative to the streamer) when closed around the streamer or it can be configured to slide along the streamer when the arms are fully closed, for example, if rollers are present inside the brackets. The rollers may include a breaking mechanism to stop them from rolling, if so desired. Further, the rollers can include a motor to roll along the streamers both ways, like a tire on a road. The clamping device can also slide along the streamer without rollers, when in the cleaning position, i.e., the arms are slightly open relative to the streamer.

[0037] A possible implementation of the clamping device 212 is illustrated in Figures 7A and 7B. Figure 7A shows the clamping device being closed while Figure 7B shows the clamping device being open. Both figures show a nut 742 that is attached to an end of the leadscrew 342, and the nut 742 is located in the hole 502 of the frame 500. Further, both figures show that support pads 710 are fixedly attached to the frame 500 and these support pads are configured to be attached to the frame 202 of the cleaning device. The figures further show a specific

implementation of the links 532 between the drive motor 530 and the arms 510 and 520. In this embodiment, the links 532 are implemented as a motor wheel 734, which is connected to the motor drive 530, and a tie rod 736, which is connected between the motor wheel 734 and a corresponding arm 510 or 520. The rotatable connectors 512 and 522 are implemented as pins that enter the frame 500 in this embodiment.

[0038] While Figures 7A and 7B show the end of the leadscrew 342 being attached to the nut 742, Figures 8A and 8B shows that for a middle clamping device 316 there is no nut 742, but the leadscrew 342 extends all the way through the frame 500 so that the middle clamping device 316 can travel along the leadscrew 342, between the first and second clamping devices 312 and 314. For this reason, the support pads 710 of the middle clamping device are slidably attached to the frame 202 while the support pads 710 of the first and second clamping devices are fixedly attached to the frame 202. Note that the first and second clamping devices, also called the forward and aft clamping devices, cannot travel relative to the leadscrew 342 of the frame 202 of the cleaning device.

[0039] A method for cleaning a streamer with the cleaning devices introduced above is now discussed with regard to Figures 9A to 9L. The method includes a step 1000 (see Figure 10) of attaching the cleaning device 300 to the streamer 201. Then, in step 1002, the cleaning device 300 starts moving downstream along the streamer for cleaning the streamer. Figures 9A to 9L indicate the presence of a marine current 900. The cleaning device 300 autonomously performs the cleaning operation and an operation of passing the SMU 902 (in this case a bird having wings) as now discussed.

[0040] In step 1004, the sensing device 220 has reached the SMU 902 and is sending a signal to the control unit 230 (not illustrated in Figures 9A to 9L for simplicity) about the presence of the SMU 902. Note that in this embodiment, the sensing device 220 has been attached to the aft clamping device 314. The control unit instructs in step 1006 the motor 344 of the actuation mechanism 340 to move the middle clamping device 316 next to the aft clamping device 314, as illustrated in Figure 9A. Note that when a clamping device is moving along the streamer, that clamping device may be instructed by the control unit to enter the cleaning position, i.e., to slightly open its arms as illustrated in Figure 5C, to promote the sliding of the brackets along the streamer and also the cleaning of the streamer. Note that the cleaning device 200 or 300 needs to have a cleaning element 516 or 526 present on only one of the clamping devices to achieve the streamer cleaning. However, in one application, two or more of the clamping devices may be fit with the cleaning elements. In another application, all the clamping devices may be fit with corresponding cleaning elements. Thus, by simply moving one clamping device along the streamer, that specific clamping device automatically cleans the streamer.

[0041] In step 1008, the control unit instructs the aft clamping device 314 to open its arms, as illustrated in Figure 9B (see also Figures 5B and 7B), so that the aft clamping device 314 can pass over the SMU 902. In step 1010, the control unit instructs the middle clamping device 316 to be in the closed position and the forward clamping device to be in cleaning position so that when the motor 344 turns the leadscrew 342, as illustrated in Figure 9C, the middle clamping device 316 is fixed relative to the streamer and the forward clamping device 312 moves along the streamer, towards the middle clamping device 316, while also cleaning the streamer. At the same time, the aft clamping device 314 is moving together with the frame 202 past the SMU 902. This movement continues until the forward clamping device 312 reaches the middle clamping device 316. At this instant, two of the clamping devices are upstream the SMU 902, fixedly attached to the streamer, and the aft clamping device is past the SMU 902, not yet attached to the streamer. In step 1012, the control unit instructs the aft clamping device 314 to close to become fixedly attached to the streamer, as illustrated in Figure 9D, and instructs the middle clamping device to open its arms to be able to pass over the SMU 902, as illustrated in Figure 9E.

The forward clamping device remains fixedly attached to the streamer during this step. In step 1014, the control unit instructs the middle clamping device 316 to move across the SMU 902, as illustrated in Figure 9F. When the middle clamping device 316 has reached the other end of the leadscrew 342, as illustrated in Figure 9F, the control unit instructs in step 1016 the closure of the arms of the middle clamping device 316 as illustrated in Figure 9G. Then, in optional step 1018, the control unit instructs the aft clamping device 314 and the middle clamping device 316 to move further downstream, in this order, to make space for the forward clamping device, as illustrated in Figures 9H an 9I. Note that if the frame 202 is long enough, step 1018 is not necessary. Then, in step 1020, the control unit instructs the forward clamping device 312 to open its arms as illustrated in Figure 9J, and in step 1022 the control unit instructs the middle clamping device to be in the closed position, the aft clamping device to be in the cleaning position, and the motor 344 to rotate the leadscrew 342, so that the frame 202 of the cleaning device and the aft clamping device 314 move downstream, and the forward clamping device 312 passes the SMU 902 as illustrated in Figure 9K. Then, in step 1024, the control unit instructs the forward clamping device to close its arms around the streamer, as shown in Figure 9L, and the cleaning device moves in step 1026 downstream to continue to clean the streamer.

[0042] A method for cleaning the streamer between two consecutive SMUs is now discussed with regard to Figure 11. In step 1 100, the cleaning device 200 is attached to the streamer so that at least one clamping device is in a closed position. In step 1 102, the control unit instructs the aft clamping device to be in the closed position and the forward clamping device to be in the cleaning position. In step 1 104, the control unit activates the actuation mechanism 240 so that the forward clamping device moves toward the aft clamping device while also cleaning the streamer. When the forward clamping device arrives next to the aft clamping device, the control unit instructs in step 1106 the forward clamping device to enter the closed position and the aft clamping device to enter the cleaning position. In step 1 108, the control unit instructs the actuation mechanism to move the aft clamping device downstream and in step 11 10 checks whether an SMU has been detected. If no SMU has been detected, the method returns to step 1 102 and continues to move the clamping devices along the streamer. If an SMU has been detected, then the control unit initiates the passing method discussed with regard to Figure 10. Note that for this embodiment, one clamping device is fixed to the streamer while the other clamping device is moving along the streamer. If the cleaning device 300 is used instead of the cleaning device 200, then when the middle clamping device is moving along the streamer in the cleaning position, the forward and aft clamping devices are fixed to the streamer and then the middle clamping device is fixed to the streamer and the forward and aft clamping devices are moving along the streamer in the cleaning positions. While the methods above have been described for a cleaning device that moves downstream along the streamer, the same steps may be used to move the cleaning device upstream the streamer, i.e., to start the cleaning process from the tail of the streamer and move toward its head as each of the forward and aft clamping devices may have a corresponding sensing device 220 for detecting the presence of the SMU. Also, the cleaning device may be configured to continuously clean the streamer during the seismic survey, so that when the cleaning device arrives at the end of the streamer (either tail or head), it may automatically reverse its cleaning direction. Note that at the tail and head ends of the streamers, a corresponding acoustic signal may be transmitted to the control unit to inform the cleaning device that it needs to change direction. The control unit may have an acoustic modem (i.e., receiver and transmitter) for the purpose of communicating with the streamer. Alternatively, the ends of the streamer may be provided with a specific SMU, which when recognized by the cleaning device, automatically changes its cleaning direction. In still another embodiment, the cleaning device may be programmed to change the cleaning direction after passing a given number of SMUs.

[0043] In one application, the control unit may be configured, with commands stored in the memory 236, so that after a given number (e.g., three) of failed attempts to pass an SMU, to reverse direction and move in the opposite direction for continuing the cleaning procedure. In another application, the cleaning device may be configured to stop during seismic data acquisition to reduce noise generation, which may interfere with the collected seismic data. In yet another application, the cleaning device may have a recharging device installed on its frame, so that the water current 900 may generate electrical power, which may be used to recharge the power source 348.

[0044] A method for cleaning a streamer with a cleaning device while passing an object attached to an exterior of the streamer is now discussed with regard to Figure 12. The method includes a step 1200 of attaching the cleaning device with a crawling mechanism to the streamer, where the crawling mechanism has a first clamping device fixedly attached to a frame and a second clamping device slidably attached to the frame, a step 1202 of sensing with a sensing device, which is attached to the crawling mechanism, the object attached to the streamer, a step 1204 of opening with an actuation mechanism the second clamping device to release the streamer and sliding the second clamping device relative to the first clamping device, past the object, and a step of closing the second clamping device around the streamer after passing the object. [0045] The method may further includes opening the first clamping device to release the streamer, and sliding the frame with the first clamping device toward the second clamping device, past the object. In one application, the method may further include closing the first clamping device around the streamer; releasing a grip of the second clamping device from around the streamer; and sliding the second clamping device away from the first clamping device to clean the streamer.

[0046] The method may also include closing the second clamping device tightly around the streamer; releasing a grip of the first clamping device from around the streamer; and sliding the first clamping device toward the second clamping device. The crawling mechanism may also include a third clamping device that is fixedly attached to the frame, and the second clamping device slides between the first and third clamping devices.

[0047] The disclosed embodiments provide a cleaning device for cleaning ,_¾ portions of a streamer while being able to pass over an object externally attached to the streamer during a seismic survey. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary 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 exemplary 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.

[0048] Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.

[0049] 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.

Claims

WHAT IS CLAIMED IS:

1. A cleaning device (200, 300) for cleaning a streamer, the cleaning device comprising:

a frame (202);

a crawling mechanism (210) having a first clamping device (212) fixedly attached to the frame (202) and a second clamping device (214) slidably attached to the frame (202);

a sensing device (220) attached to the crawling mechanism (210) and configured to determine an object (902) externally attached to the streamer (201 ); an actuation mechanism (240) configured to slide the second clamping device

(214) relative to the first clamping device (212); and

a control unit (230) configured to control the actuation mechanism (240) and the sensing device (220). 2. The cleaning device of Claim 1 , wherein the cleaning device is autonomous and is configured to clean the streamer without exchanging data with the streamer and a towing vessel.

3. The cleaning device of Claim 1 , wherein the first and second clamping devices have arms that are configured to fixedly attached to the streamer for a closed position, make a gap with the streamer for a cleaning position, and move away from the streamer for an open position.

4. The cleaning device of Claim 3, wherein each arm has a bracket at a distal end and the bracket is shaped to mate a curvature of the streamer.

5. The cleaning device of Claim 4, wherein the bracket has a cleaning element that is configured to slide along an exterior surface of the streamer to clean the streamer.

6. The cleaning device of Claim 1 , wherein each of the first and second clamping devices has two arms, and the two arms are configured to close around the streamer for cleaning and open up to release the streamer when passing the object.

7. The cleaning device of Claim 6, wherein the object is a bird.

8. The cleaning device of Claim 1 , wherein the actuation mechanism includes a motor and a leadscrew.

9. The cleaning device of Claim 8, wherein the leadscrew is fixedly attached to the first clamping device and movable attached to the second clamping device. 10. The cleaning device of Claim 1 , further comprising:

a third clamping device fixedly attached to the frame and the second clamping device is sandwiched between the first and third clamping devices.

1 1. The cleaning device of Claim 10, wherein the second clamping device is configured to slide along the streamer between the first and third clamping devices.

12. The cleaning device of Claim 1 , wherein the control unit comprises:

a processor;

a memory; and

a power source,

wherein the power source is electrically connected to an inductive contact attached to the crawling mechanism, and the inductive contact is configured to receive electrical energy from the streamer to recharge the power source.

13. A cleaning device (300) for cleaning a streamer, the cleaning device comprising:

a frame (202);

a crawling mechanism (210) having a first clamping device (312) fixedly attached to the frame (202), a second clamping device (314) fixedly attached to the frame (202), and a third clamping device (316) slidably attached to the frame (202); a sensing device (220) attached to the crawling mechanism (210) and configured to determine an object (902) externally attached to the streamer (201 ); and

an actuation mechanism (240) configured to slide the second clamping device (316) between the first and the second clamping devices (312, 314).

14. The cleaning device of Claim 13, wherein each of the first to third clamping device comprises:

a . clamping device frame;

first and second arms rotatably attached to the clamping device frame;

first and second brackets attached to the first and second arms, respectively; and

a drive motor attached to the clamping device frame and configured to open and close the first and second arms so that the first and second brackets fixedly attach to the streamer for a closed position, loosely attach to the streamer for a cleaning position, and are far from the streamer for an open position.

15. The cleaning device of Claim 14, wherein each bracket has a cleaning element. 16. A method for cleaning a streamer (201 ) with a cleaning device (200, 300) while passing an object (902) attached to an exterior of the streamer, the method comprising:

attaching (1200) the cleaning device (200, 300) with a crawling mechanism (210) to the streamer (201 ), wherein the crawling mechanism (210) has a first clamping device (212) fixedly attached to a frame (202) and a second clamping device (214) slidably attached to the frame (202);

sensing (1202) with a sensing device (220), which is attached to the crawling mechanism (210), the object (902) attached to the streamer (201 ); opening (1204) with a motor (530) the second clamping device (214) to release the streamer and sliding the second clamping device (214), with an actuation mechanism (240), relative to the first clamping device (212), past the object (902); and

closing (1206) the second clamping device (214) around the streamer after passing the object (902).

17. The method of Claim 16, further comprising:

opening the first clamping device to release the streamer; and

sliding simultaneously the frame with the first clamping device toward the second clamping device, past the object.

18. The method of Claim 17, further comprising:

closing the first clamping device around the streamer;

releasing a grip of the second clamping device from around the streamer; and sliding the second clamping device away from the first clamping device to clean the streamer.

19. The method of Claim 18, further comprising:

closing the second clamping device tightly around the streamer;

releasing a grip of the first clamping device from around the streamer; and sliding the first clamping device toward the second clamping device.

20. The method of Claim 16, wherein the crawling mechanism (210) includes a third clamping device that is fixedly attached to the frame, and the second clamping device slides between the first and third clamping devices.