WO2015181626A1

WO2015181626A1 - System and method to optimize dynamically multi-vessel seismic operations

Info

Publication number: WO2015181626A1
Application number: PCT/IB2015/001190
Authority: WO
Inventors: Thomas Elboth; Leif Morten BY; Inger VIKAN
Original assignee: Cgg Services Sa
Priority date: 2014-05-28
Filing date: 2015-05-27
Publication date: 2015-12-03

Abstract

Controllers and methods are provided to optimize dynamically multi-vessel seismic operations. Current information on survey plans of data acquisition systems is gathered at predetermined time intervals and/or when a survey plan alteration occurs. To identify potential conflicts, an applied spatial constraint is checked to see if, according to the survey plans, it will be met throughout a foreseeable future period. If the checking reveals a conflict, at least one of the survey plans is adjusted to avoid the conflict.

Description

System and Method to Optimize Dynamically

Multi-Vessel Seismic Operations

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims the benefit of priority under 35 U.S.C. § 1 19 to U.S. Provisional Patent Application No. 62/003,558, filed on May 28, 2014, entitled "SYSTEM AND METHOD TO CONTROL SEISMIC INTERFERENCE IN

MULTI-VESSEL SEISMIC OPERATIONS", the entire disclosure of which is

incorporated herein by reference.

TECHNICAL FIELD

[0002] Embodiments of the subject matter disclosed herein generally relate to methods and systems for seismic data acquisition and, more particularly, to adjusting survey plans for a multi-vessel seismic survey to optimize dynamically operations by avoiding seismic interference and minimizing time loss.

BACKGROUND

[0003] Seismic surveys used in exploration, field development, and/or production monitoring (time lapse surveys) are employed to identify or to monitor hydrocarbon deposits under the seafloor. Reflections of energy waves from the geological structures under the seafloor carry information about the location and/or nature of features causing reflections. Time intervals from energy's emission until reflections are detected, and characteristics of the reflections, are recorded as seismic data. Seismic data

processing techniques may be used to generate images of the geological structures.

[0004] Figure 1 illustrates a marine data acquisition system. A vessel 102 tows a source 104 and streamers 106 along a sail line S. While acquiring seismic data, the source and the streamers are towed at various depths (or streamers may have a variable depth profile) and at a speed of about 5 knots. Cables 108 known as "lead-ins" connect the streamers to the vessel. Seismic sensors 1 10 (only some labeled), which are distributed along the streamers, detect reflections of the energy emitted by seismic source 104 (i.e., a pressure source including air guns, vibrators, etc.). Streamers 106 are typically several kilometers long and carry hundreds of seismic sensors. Streamers may also be equipped with compasses, acoustic pingers (e.g., 1 12), depth sensors and other auxiliary units that provide location information about heading, position and depth. Additionally, each streamer is typically equipped with position control units 1 14 (known as "birds") which are configured to adjust the lateral position and depth of the streamers.

[0005] Recordings from the seismic source and the seismic sensors together with source and sensor location information are combined into seismic data, which is then processed to generate three-dimensional (3D) maps of the geological structures under the seafloor. Chapter 1 , pages 9-79, of "Seismic Data Processing" by Ozdogan Yilmaz, Society of Exploration Geophysicists, 1987, (which is incorporated herein by reference) contains general information on "Fundamentals" of seismic data acquisition and processing. Chapter 6, pages 384-427, (which is also incorporated by reference) of the same book, focuses on obtaining 3D maps.

[0006] During seismic surveys, vessels towing seismic survey acquisition equipment sail back and forth along predetermined sail lines in order to acquire data for a survey area. A survey plan is a sequence of sail lines (simply called "lines"

hereinafter) specifying lines' coordinates (e.g., start point of data acquisition and end point thereof), turns, duration thereof, intended vessel speed, etc. A survey plan including plural lines L1 -L6 is illustrated in Figure 2. The seismic source towed by the vessel following the trajectory (L1 , turn, L2, turn, etc.) illustrated in Figure 2 is activated within the surveyed area 200, for example, between a start 210 of line L1 and an end 215 of line L1. The towing vessel turns after the end of the line to enter another line (e.g., L2). For example, for a vessel towing a streamer about 8 km long, a turn is a semi-circle with about a 4 km radius.

[0007] Mega-surveys over large areas (e.g., over 10,000 km²) have recently become more frequent. If performed by a single data acquisition system (i.e., vessel, source, streamers), such surveys would take months or even years to complete. Plural independent data acquisition systems are often employed to achieve such task within environmental and/or time constraints (e.g., finishing such a mega-survey before the winter starts). A data acquisition system includes at least one vessel. The data acquisition may include more vessels, for example, if the data acquisition system is configured to acquire wide-azimuth seismic data. For the sake of simplifying the following description, a data acquisition system is assumed to include a single vessel towing both a seismic source and streamers as in Figure 1 .

[0008] A frequently encountered problem in multi-vessel marine seismic data acquisition (i.e., plural independent data acquisition systems) is data corruption due to various types of noise. Seismic interference noise is a type of noise that occurs when independently operating data acquisition systems emit energy and record reflections thereof while being too close to one another. Due to their proximity, energy emitted by a source of one data acquisition system is unintentionally detected by sensors on a streamer of another data acquisition system. Seismic interference is mostly due to the energy that propagates directly through the water-column (i.e., not emerging from the geological formation under the seafloor). The corrupting energy's amplitude mainly depends on the amount of energy emitted by the noise-causing source and the distance between this source and the other data acquisition systems' sensors. However, the water depth, the sea-surface and sea-bottom reflection coefficients may also be significant.

[0009] If the amplitude and/or moveout (i.e., apparent direction seen in the seismic record) of the seismic interference noise exceed certain thresholds, then the data acquisition systems normally have to commence time-sharing. Time-sharing means operating the data acquisition systems such that only one system is active at any given time. Time-sharing is of course inefficient and costly, and therefore operators try to avoid it. The data acquisition systems are often operated in time-sharing mode when they are at distances less than 100 km from one another. As a rough guideline, seismic interference noise becomes a problem when vessels are closer than 40 km, which is often the case in busy summer seasons in places such as offshore Northern Europe and in the Gulf of Mexico.

[0010] Even if the initial survey plans meet a predetermined spatial constraint (e.g., maintaining a distance exceeding 40 km), the plans' execution is often disrupted by weather, currents, equipment malfunction, etc. Conventionally, when such disruptions occur, navigator communications are used to coordinate vessels' operations so as to continue observing the predetermined spatial constraint. This approach leads to sub-optimal operations with expensive waiting/idling periods and/or data corruption.

[0011] Therefore, it would be desirable to provide systems and methods that better handle survey plans' disruptions. SUMMARY

[0012] In order to optimize dynamically data acquisition in multi-vessel seismic operations, methods and controllers enable exchanging survey plans periodically or whenever they are significantly altered. Up-to-date knowledge of the survey plans makes it possible to check whether a spatial constraint (such as exceeding a minimum distance and or direction between survey vessels) is met throughout a forthcoming period. If the spatial constraint is not met throughout the forthcoming period, the survey plans are adjusted.

[0013] According to an embodiment, there is a method for optimizing dynamically multi-vessel seismic operations. The method includes gathering current information on survey plans of data acquisition systems, at predetermined time intervals and/or when a survey plan alteration occurs. The method further includes checking whether, according to the survey plans, an applied spatial constraint is met throughout a foreseeable future period.

[0014] According to another embodiment, there is a controller for optimizing dynamically multi-vessel seismic operations having a communication interface and a processing unit. The communication interface is configured to receive information on survey plans at predetermined time intervals and/or when one of the survey plans is altered. The processing unit is connected to the communication interface and is configured to check whether an applied spatial constraint is met according to the survey plans, during a foreseeable future period, and to adjust the survey plans if checking reveals a conflict caused by the applied spatial constraint not being met throughout the foreseeable future period.

[0015] According to yet another embodiment, there is a computer-readable recording medium non-transitorily storing executable codes which, when executed by a computer, make the computer perform a method for optimizing dynamically multi-vessel seismic operations. The method includes gathering current information on survey plans of data acquisition systems, at predetermined time intervals and/or when a survey plan alteration occurs. The method further includes checking whether, according to the survey plans, an applied spatial constraint is met throughout a foreseeable future period.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings:

[0017] Figure 1 illustrates a marine seismic data acquisition system;

[0018] Figure 2 illustrates a survey plan;

[0019] Figure 3 illustrates a survey area; [0020] Figure 4 is a diagram of a process according to an embodiment;

[0021] Figure 5 is a diagram of a process according to another embodiment;

[0022] Figure 6 is a flowchart of a method according to an embodiment; and

[0023] Figure 7 is a schematic diagram of a controller according to an

embodiment.

DETAILED DESCRIPTION

[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. Embodiments to be discussed next are not limited to the configurations described in the drawings, but may be extended to other arrangements.

[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] According to various embodiments described hereinafter, methods and controllers are configured to dynamically optimize multi-vessel seismic operations. That is, the embodiments check whether contemporaneous survey plans of data acquisition systems meet a spatial constraint during a forthcoming period. The spatial constraint may be a predetermined spatial constraint or an updated version of the predetermined spatial constraint. The term "applied spatial constraint," which is used from now on, covers both cases. For example, if online processing of seismic data yields a good separation of the seismic-reflection signal from seismic interference noise, the predetermined spatial constraint may be relaxed. Conversely, if online processing of seismic data shows an unsatisfactory separation of the signal from seismic interference noise, the predetermined spatial constraint may be strengthened. Alternatively or additionally, the predetermined constraint may be updated depending on factors like azimuth towards interfering source, relative speed and heading of the data acquisition systems, marine currents, etc. [0027] If the checking reveals a foreseeable conflict (i.e., the applied spatial constraint is not met during the forthcoming period), the survey plans are adjusted to avoid this conflict. The embodiments allow two or more data acquisition systems to operate independently and simultaneously in the same survey area (e.g., while less than 100 km from one another) without significantly compromising the quality of the acquired data (with the adjusted plans being designed to limit seismic interference, SI) and minimize time loss.

[0028] Figure 3 illustrates two adjacent rectangular survey areas 310 and 320 covering approximately 4,600 km². If two data acquisition systems operate independently and simultanoiusly in these adjacent areas, a distance of at least 40 km has to be maintained there-between to avoid unacceptable SI. Although maintaining this distance may be one prong of the applied spatial constraint, the applied spatial constraint may consist of multiple prongs and embedded conditions. For example, another prong may be: if the two data acquisition systems sail along parallel lines, they should have different speeds or opposite headings. This latest prong may be added because, if the active data acquisition systems travel at the same speed, seismic interference noise arrives at the same time from shot to shot, making it difficult to attenuate seismic interference noise during seismic data processing.

[0029] A data acquisition system includes at least one vessel, one source and streamers. However, data acquisition systems may have multiple vessels, multiple sources and/or multiple streamer spreads and may sail in parallel according to essentially same basic survey plan. The physical distances relevant for seismic interference (which becomes significant when data acquisition systems are closer than typically around 100 km from one another and acquire seismic data) are the shortest distances between a source of one data acquisition system and sensors of another data acquisition system. These distances (which may be slightly different depending on which of the two data acquisitions the source and the sensor pertain to) are referred to as "the distance or separation between vessels" in the following description, for the sake of simplicity. This terminology obscures the actual complexity of the data acquisition systems behind a model of data acquisition systems towed and represented by a single vessel. However, this simplified description does not preclude or disclaim complex data acquisition systems (i.e., multi-vessel, multi-source and/or multi-streamer spreads). In this document

"optimizing dynamically multi-vessel operations" means optimizing data acquisition resources' usage (e.g., minimizing delays), while maintaining quality of the acquired seismic data by limiting seismic interference noise. The seismic interference noise may be limited by observing a certain distance between data acquisition systems collecting seismic data.

[0030] Returning now to Figure 3, two data acquisition system survey areas 310 and 320, respectively, while moving along east-to-west and west-to-east lines with a speed of about 5 knots. Sailing a line in area 310 (i.e., about 100 km) takes about 1 1 hours and sailing a line in area 320 (i.e., 40 km) takes about 4.5 hours. During a line- change (i.e., turn), which may take around 3 hours, the data acquisition systems do not emit energy waves and do not acquire data. Therefore, while one of the systems executes a turn, the distance between the systems may become less then 40 km without a negative impact. The shapes and dimensions of areas 310 and 320 are merely exemplary and are not intended to be limiting.

[0031] The initial survey plans (one for each system) may be designed to meet the applied spatial constraint (e.g., maintain minimum vessel separation while the systems acquire data). However, in practice, technical problems, bad weather or other unexpected events inevitably and frequently cause the data acquisition systems to depart from initial survey plans. Conventional tools are not able to deal efficiently with such inevitable changes. Some of the improved tools according to various embodiments are flexible and able to handle various acquisition features and situations. In the following description, the term "tool" is used for method, controller and system embodiments in order to make the description more compact and clear by skipping repetitions of features present in more than one type of embodiments.

[0032] According to one embodiment, a tool gathers survey plans of independently operating data acquisition systems (two or more) in a survey area. A plan may include characterization of the area intended to be surveyed (e.g., shape, dimensions and actual physical location), the sail lines and turns there-between. The tool may correlate a current position of the vessel, with the survey plan. After the tool has acquired an initial plan, later gatherings may only include contemporaneous position and status of the vessel, if the lines have not changed. However, later updates may provide a completely new sequence of lines for the surveyed area or may signal that the data acquisition system has suspended its survey plan execution.

[0033] The tool may passively receive contemporaneous information related to the survey plans from the vessels. However, the tool may also (alternatively or additionally) actively inquire about the contemporaneous survey plans. Yet alternatively or additionally, the system may receive initial survey plans and be informed when significant departures from the initial plans occur, or when a data acquisition system restarts acquiring data after a planned (e.g., turn) or unplanned interruption. A combination of the above-described alternative manners of acquiring information about the survey plans may be employed.

[0034] The tool then uses this information to identify potential conflicts between simultaneously operating data acquisition systems. When a conflict is foreseen based on frequent information exchange (near real-time updates), the tool may propose, require and/or signal the need to adjust at least one of the survey plans and/or the vessels speed. That is, the tool may illustrate the conflict, may provide a solution to the conflict, may order the change of a specific survey plan (e.g., issue a command), and/or may merely signal the spatio-temporal coordinates of the potential conflict. It is also possible for the tool's action relative to plan adjustment to differ from one vessel to the other in an analyzed pair of vessels. An analyzed pair of vessels means that data acquisition systems acquire data close enough from one another (e.g., vessels whose current distance is less than 100 km) so that seismic interference noise is a concern.

[0035] According to one embodiment, conflicts may be avoided if a tool generates a graphical view of the scheduled lines according to current survey plans. This graphical view may also be extended to encompass planned activities of other vessels (such as tankers docking at offshore loading buoys, rig moves, installation vessels, cable-laying vessels, dredging operations, hydrographic survey vessels, etc.). This tool enables an operator to identify potential conflicts during an ongoing survey. Information about the planned activities (e.g., a survey plan) can be received automatically from a navigation system onboard a vessel and/or via a Web application or other standalone software.

[0036] Such a tool is thus configured (1 ) to gather survey plans of data acquisition systems (i.e., vessels) operating in a survey area; (2) to check for potential conflicts (e.g., if vessels may get closer than a minimum required separation while they are active); and (3) to enable navigators to control which one(s) of the survey plans and how to adjust it/them to avoid potential conflicts.

[0037] Figure 4 is a diagram of a process according to an embodiment. Vessels 410 and 420 are configured to inform all vessels in the same area (e.g., at less than 100 km from one another) when they update their survey plan(s). This information exchange may occur via a survey controller or by broadcasting the information at 430. If no potential conflict is identified at 440 and 450, respectively, the vessels 410 and 420 continue their surveys according to their most recent survey plans as suggested by boxes 460 and 470, respectively. The tool may be a controller configured to perform steps 430 and at least one of steps 440 and 450 onboard one of the ships. However, the tool may also be configured to perform steps 430 and one of 440 onboard one of the vessels and step 450 onboard the other one of the vessels.

[0038] Since a conflict affects two data acquisition systems simultaneously, adjusting both survey plans may not achieve conflict avoidance. In one embodiment, vessels may be assigned priorities and, the higher the priority, the longer the delay in changing the survey plan (i.e., waiting for the lower priority vessel's plan to be altered and overcome the conflict). In another embodiment, vessels may be assigned random delays before proceeding to adjust their plans, thus "breaking" the potentially destructive simultaneity of plan changes.

[0039] The plan exchange (i.e., 430) may occur regularly at predetermined time intervals (e.g., every hour) and may be executed via electronic data transfers.

Alternatively, information exchange/replication can take place in near real time after a survey plan alteration occurs. This information exchange may occur automatically, without human intervention. If a navigator manually alters a survey plan of a vessel (e.g., by changing the sail lines' pre-plot line(s), selected start and end time(s) or selected speed(s)), the new plan may be announced by specifying the changes. An automatic update may also occur if the vessel gets significantly ahead of or behind schedule according to the initial plan (e.g., due to variations in the speed of the vessel).

[0040] Checking for potential conflicts may cover only a forthcoming period (such as the next 48-72 hours) or the next few lines. Referring back to Figure 3, two

simultaneously operating vessels are usually separated by much more than 40 km.

Therefore, direct radio communication between the vessels may be difficult to maintain. Satellite communication may then be used instead of radio communication. For example, information may be sent through VSAT (Very Small Aperture Terminal)/Ethernet/Web) or similar systems that already exist on nearly all vessels. The survey plans may then be imported into the INS (Integrated Navigation System) used by seismic vessels.

[0041] In one embodiment in which time correlation is performed at the vessel, the minimum amount of information that a vessel needs to provide for exchange is: identifiers of the next few lines to be sailed according to the plan, and planned start/end time of shooting for these lines. One or more of the following additional pieces of information may be provided: speed (on line, in turn and other planned speeds), bottom speed, water speed and vessel's current information (such as a timestamp for the information, shot- point, currents, vessel's position), etc. [0042] According to another embodiment, a tool may be characterized by the following features: (1 ) survey plans are regularly exchanged between vessels operating in a survey area; (2) the plans are graphically jointly displayed, and checks are performed to identify potential conflicts within a predetermined period of time; and (3) a solution is provided (i.e., which and how one of the survey plans is to be adjusted, e.g., by scheduling alternative sail lines) to avoid the conflict. These alternative lines may be chosen so that extending data acquisition time is minimized. The adjustments may be performed such that vessel(s) preferably do not have to go on standby and/or according to solutions which make the vessels to become further apart. When jointly displaying the plans, a few lines of two or more survey plans are illustrated on the same display. Such images enable an operator to visually identify potential conflicts and find alternatives to avoid a potential conflict. The complexity of the graphical techniques employed may vary from simply using 2D displays of the next few lines, to animations of the planned vessel motions showing evolution of vessel separation. Each vessel may be displayed within an envelope, which might be circular, elliptical or have any other shape. An envelope means a graphical object larger than a target (e.g., the vessel) because the envelope represents plural possible locations of the target. Various types of color-coding may also be used to provide additional visual clues to an observer.

[0043] According to yet another embodiment, a tool may be characterized by the following features: (1 ) survey plans are regularly exchanged between vessels operating in a survey area, (2) potential conflicts (e.g., vessels get closer than a minimum required separation when they are shooting) are identified, and (3) based on a priority list, a lower priority vessel among the vessels involved in the potential conflict must adjust its survey plan to avoid conflict with a higher priority vessel.

[0044] A diagram of such a process is illustrated in Figure 5. Vessels 510 and 520 are at a distance less than typically around 100 km. The tool starts gathering the survey plans at 530. The tool then time-correlates the plans; that is, based on the vessels' current positions, the tool calculates projected positions and separation for a predetermined upcoming period of time (e.g., 48-72 hours or a few lines of vessel 510). Based on this time correlation, the tool checks whether the applied spatial condition (e.g., separation remaining larger than a predetermined threshold while the vessels actively acquire data) is met for the predetermined upcoming period of time. In other words, potential conflicts are identified. [0045] Vessels 510 and 520 have Priority 1 and Priority 2, respectively. Vessel 510's priority is higher than vessel 520's priority and, therefore, if a potential conflict is identified at 540, the tool prompts vessel 520 to modify its survey plan at 545. If no potential conflict is identified at 540, the vessels continue to sail according to the current survey plans as suggested by boxes 550 and 560. The tool may be physically located and executed on vessel 510, vessel 520 or another ship in the area.

[0046] The applied spatial constraint may include not having the vessels travel on parallel lines with exactly the same speed. In this embodiment, one of the vessels might have to change its speed or shot point interval (temporal or spatial) slightly to avoid recording seismic interference noise at the same time after a shot. A minimum δ-range, where δ is the difference in shot-point interval between the two vessels, may be

monitored.

[0047] The minimum separation may depend on the vessels' azimuth determined by their relative positions and traveling directions. Azimuth means the direction (vector) from one vessel to the other vessel. Some noise removal algorithms can better remove seismic interference noise that comes from certain azimuths. Therefore, if these algorithms are used, more seismic interference noise arriving from certain azimuths may be tolerated. For example, more seismic interference noise arriving from astern may be tolerated than from the front or sides. Allowing more seismic interference noise translates into allowing the vessels to be closer. On a graphical display, this feature may be illustrated by having an envelope asymmetric relative to the vessel's location or more envelopes around a vessel.

[0048] The minimum separation may also depend on source volumes. A vessel with a smaller source volume may be allowed be get closer than if the source had a larger volume.

[0049] In one embodiment, other activities in the survey area are taken into consideration. For example, drilling operations on a platform cause a lot of noise. When drilling is ongoing, preferably the distance between the vessels acquiring data is larger than when drilling stops. In this case, the tool gathers not only the survey plans, but also the platform's current and planned schedule. Plural platforms or other conditions may be taken into consideration.

[0050] After modifying a survey plan, re-checking the applied spatial condition may reveal another conflict that has occurred for the vessel whose plan has been modified and another vessel. The plan of the other vessel may then be modified. The chain of plan changes may continue until either the spatial separation condition has been satisfied or until a predetermined number of changes have occurred. When the predetermined number of changes has occurred, the tool may generate an operator alarm, prompting the operator to propose a solution to overcome the current situation.

[0051] Figure 6 is a flowchart of a method 600 according to an embodiment.

Method 600 includes gathering current information on survey plans at predetermined time intervals or when a survey plan alteration is signaled, at 610, and checking whether the applied spatial constraint is met throughout a foreseeable future based on the survey plans, at 620. Method 600 then includes adjusting at least one of the survey plans to avoid a conflict (i.e., the applied spatial constraint is not met throughout the forthcoming period) identified during the checking, at 630. Various embodiments including method 600's operations may also include one or more of the features described above using the generic term of "tool."

[0052] Figure 7 is a block diagram of a controller 700 for optimizing dynamically multi-vessel seismic operations. Controller 700 includes a communication interface 710 configured to receive contemporaneous survey plans at predetermined time intervals and/or when a survey plan alteration is signaled. The controller further includes a processing unit 720 connected to interface 710. Communication unit 720 is configured to check whether an applied spatial constraint is met throughout a survey according to the contemporaneous survey plans, and to adjust the survey plans if a conflict caused by the applied spatial constraint is not met throughout the foreseeable future period. Various embodiments including controller 700's basic structure may also include other components enabling the features described above using the generic term of "tool." In one

embodiment, the processing unit is configured to update the applied constraint based on current survey conditions (e.g., azimuth towards interfering source, relative speed and heading of the data acquisition systems, marine currents, etc.) and/or results of online (i.e., shortly after being acquired) seismic data processing.

[0053] The controller may further include a memory 730 to store historical data related to the survey, or executable codes implementing method 600 or other

embodiments. The controller may also include a display 740 connected to the processing unit and configured to display current positions of at least a subset of the vessels.

[0054] The controller may also include an operator command interface (not shown) connected to the processing unit and configured to receive and transmit operator commands to the processing unit. The operator command interface may be part of the interface 710. In the embodiments in which the operator command interface is present, the processing unit is configured to adjust one or more survey plans according to the operator commands.

[0055] The disclosed exemplary embodiments provide tools for dynamically optimizing operations during multi-vessel data acquisition. 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. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

[0056] Although the features and elements of the present exemplary

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. The methods or flow charts provided in the present application may be implemented in a computer program, software, or firmware tangibly embodied in a computer-readable storage medium for execution by a general purpose computer or a processor.

[0057] 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 method (600) for optimizing dynamically multi-vessel seismic

operations, the method comprising:

gathering (610) current information on survey plans of data acquisition systems, at predetermined time intervals and/or when a survey plan alteration occurs;

checking (620) whether, according to the survey plans, an applied spatial constraint is met throughout a foreseeable future period; and

if the checking reveals a conflict as the applied spatial constraint is not met throughout the foreseeable future period, adjusting (630) at least one of the survey plans to avoid the conflict.

2. The method of claim 1 , wherein the applied constraint is checked for at least a pair among the data acquisition systems, the data acquisition systems in the pair being closer than a separation threshold from one another.

3. The method of claim 1 , wherein the applied spatial constraint includes maintaining a distance exceeding a threshold value between a pair among the data acquisition systems moving according to the survey plans, while the data acquisition systems in the pair actively acquire data.

4. The method of claim 3, wherein the threshold value depends on a relative position and traveling directions of the data acquisition systems in the pair.

5. The method of claim 3, wherein the threshold value depends on an amount of energy emitted by sources of the data acquisition systems in the pair.

6. The method of claim 1 , wherein the adjusting of the survey plans is performed in an order depending on priorities associated to the data acquisition systems, respectively.

7. The method of claim 1 , wherein the adjusting comprises:

modifying one of the survey plans;

re-checking whether the applied spatial constraint is met throughout the foreseeable future period; and modifying another one of the survey plans, if the re-checking indicates that the applied spatial constraint is not yet satisfied throughout the foreseeable future period.

8. The method of claim 7 wherein the re-checking and the modifying of another one of the survey plans are performed repeatedly until the applied spatial constraint is met or a predetermined number of survey plans have been modified.

9. The method of claim 8, further comprising:

generating an operator alarm signal if the applied spatial constraint is not met after modifying the predetermined number of survey plans.

10. A controller (700) for optimizing dynamically multi-vessel seismic operations, the system comprising:

a communication interface (710) configured to receive information on survey plans at predetermined time intervals and/or when one of the survey plans is altered; and

a processing unit (720) connected to the communication interface and configured to check whether an applied spatial constraint is met according to the survey plans, during a foreseeable future period, and

to adjust the survey plans if checking reveals a conflict caused by the applied spatial constraint not being met throughout the foreseeable future period.

1 1 . The control system of claim 10, wherein the processing unit is configured to check whether the applied constraint is met for at least a pair among the data acquisition systems, the data acquisition systems in the pair being closer than a separation threshold from one another.

12. The control system of claim 10, wherein the applied spatial constraint includes maintaining a distance exceeding a threshold value between a pair among the data acquisition systems moving according to the survey plans, while the data acquisition systems in the pair actively acquire data.

13. The control system of claim 12, wherein the threshold value depends on a relative position and traveling directions of the data acquisition systems in the pair, and/or on an amount of energy emitted by sources of the data acquisition systems in the pair.

14. The control system of claim 10, further comprising:

a display connected to the processing unit and configured to display current positions and/or survey plans of at least two of the data acquisition systems.

15. The control system of claim 14, wherein the display is further configured to display survey plans of data acquisition systems involved in the conflict.

16. The control system of claim 10, further comprising:

an operator command interface connected to the processing unit and configured to receive and transmit operator commands to the processing unit,

wherein the processing unit is further configured to adjust the survey plans according to the operator commands.

17. The control system of claim 10, wherein the processing unit is further configured to update the applied constraint based on current survey conditions and/or result of online seismic data processing.

18. The control system of claim 10, wherein the applied spatial constraint includes different conditions to be met by different pairs among the data acquisition systems.

19. The control system of claim 10, wherein the processing unit is configured to adjust one or more of the survey plans in an order depending on priorities associated to the data acquisition systems, respectively.

20. A computer-readable recording medium (730) non-transitorily storing executable codes which, when executed by a computer, make the computer perform a method for optimizing dynamically multi-vessel seismic operations, the method (600) comprising:

gathering (610) current information on survey plans of data acquisition systems, at predetermined time intervals and/or when a survey plan alteration occurs; checking (620) whether, according to the survey plans, an applied spatial constraint is met throughout a foreseeable future period; and