Method for simultaneously acquiring wide azimuth and ocean floor knot surveys

Abstract

SYSTEM AND METHOD FOR SIMULTANEOUSLY ACQUIRING WIDE AZIMUTH AND OCEAN BOTTOM NODE SURVEYS. A method may include receiving, via a processor, a first set of seismic data acquired via a Wide Azimuth (WAZ) survey. The method may also include receiving a second set of seismic data acquired via an Ocean Bottom Survey (OBS) simultaneously during a time period in which the first set of seismic data is acquired. The method may then involve processing the second set of data to obtain a seismic wave velocity model for an area that corresponds to the WAZ and OBS surveys and generating one or more seismic images of the area based on the velocity model and the first set of data.

Description

1 / 23 METHOD FOR SIMULTANEOUSLY ACQUIRING WIDE AZIMUTH AND OCEAN FLOOR NODE SURVEYS CROSS-REFERENCE TO RELATED REQUESTS

[0001] This application claims priority and the benefit of U.S. Provisional Application 62 / 975,579, entitled “SYSTEM AND METHOD FOR SIMULTANEOUSLY ACQUIRING WIDE AZIMUTH AND OCEAN BOTTOM NODE SURVEYS”, filed February 12, 2020, which is incorporated by reference herein for all purposes. FUNDAMENTALS

[0002] This disclosure generally relates to performing multiple types of seismic surveys using various azimuth distributions. More specifically, this disclosure relates to exploring complex geological structures and obtaining an accurate velocity model for them.

[0003] In hydrocarbon exploration, seismic images of subsurface layers are used to locate hydrocarbon reservoirs, such as oil fields. Thus, the accuracy of seismic images helps to more precisely determine the locations of hydrocarbon reservoirs. Several azimuth distributions can be used to acquire azimuth data that can then be used to generate seismic images. One example of such an azimuth distribution is the wide azimuth (WAZ), in which multiple vessels navigate along the same direction (e.g., parallel to each other) and acquire seismic data. In WAZ, some of the vessels emit seismic waves into the sea, while some of the vessels (e.g., the same vessels or other vessels) acquire reflections of the seismic waves through towed streamers. Hereafter, towed streamers will be referred to as streamers for simplicity.

[0004] For imaging through complex structures, such as embedded salt layers, the accuracy of a seismic wave velocity model traversing multiple areas affects the accuracy of seismic data processing. However, obtaining an accurate velocity model can be challenging in geographical areas with complex structural layers.

[0005] This section is intended to introduce the reader to various aspects of the technique that may be related to various aspects of the present disclosure, which are described. Petition 870260049611, dated 05 / 25 / 2026, p. 12 / 65 2 / 23 and / or claimed below. This discussion is considered to help provide the reader with fundamental information to facilitate a better understanding of the various aspects of this disclosure. Therefore, it is understood that these statements will be read in that light, and not as admissions of prior art. SUMMARY

[0006] A summary of certain embodiments disclosed herein is set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. In fact, this invention may encompass a variety of aspects that may not be set forth below.

[0007] In one embodiment, a system may involve a plurality of streamers having one or more streamer sensors that can acquire a first set of seismic data representative of one or more features of a subsurface region. The system may also include a plurality of seafloor modes that can acquire a second set of seismic data representative of one or more features of the subsurface region and a processing system. The processing system may receive the first set of seismic data and the second set of data, process the second set of data to obtain a seismic wave velocity model for the subsurface region, and generate one or more seismic images of the subsurface region based on the velocity model and the first set of seismic data.

[0008] In another embodiment, a method may involve receiving, via a processor, a first set of seismic data acquired via a Wide Azimuth (WAZ) survey. The method may also involve receiving a second set of seismic data acquired via an Ocean Bottom Survey (OBS) simultaneously during a time period in which the first set of seismic data is acquired. The method may then involve processing the second set of data to obtain a seismic wave velocity model for an area that corresponds to the WAZ and OBS surveys and generating one or more seismic images of the area based on the velocity model and the first set of data.

[0009] In yet another embodiment, a non-transient computer-readable medium may include computer-executable instructions which, when executed, cause at least one processor to perform one or more operations which may include receiving a Petition 870260049611, dated 05 / 25 / 2026, p. 13 / 65 3 / 23 The first set of seismic data is acquired during the first portion of a Wide Azimuth (WAZ) survey, and a second set of seismic data is received simultaneously via an Ocean Bottom Survey (OBS) during a time period in which the first set of seismic data is acquired. The operations may then involve processing the second set of data to obtain a seismic wave velocity model for an area that corresponds to both the WAZ and OBS surveys, and generating one or more seismic images of the area based on the velocity model and the first set of seismic data.

[0010] Various refinements of the above-mentioned features may exist in relation to various aspects of this disclosure. Other features may also be incorporated into these various aspects. These refinements and additional features may exist individually or in any combination. For example, several features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of this disclosure individually or in any combination. The brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of this disclosure without limitation to the subject matter claimed. BRIEF DESCRIPTION OF THE DRAWING

[0011] These and other features, aspects and advantages of the present disclosure will be better understood when the detailed description below is read with reference to the accompanying drawings, in which like characters represent like parts in all drawings, where:

[0012] FIG. 1 illustrates a schematic diagram of a seismic water survey using multiple seismic measurements according to the modalities described in this document;

[0013] FIG. 2 illustrates an example towed streamer wide azimuth configuration employed in the seismic water survey of FIG. 1 according to the modalities described herein;

[0014] FIG. 3 illustrates an example firing pattern for the wide azimuth configuration of a towed streamer of FIG. 2 according to embodiments described herein;

[0015] FIG. 4 illustrates an example layout for nodes and a wide azimuth layout for simultaneous acquisition of a wide azimuth survey and a seabed node survey according to the embodiments described herein; Petition 870260049611, dated 05 / 25 / 2026, page 14 / 65 4 / 23

[0016] FIG. 5 illustrates a flowchart of a method for processing ocean floor node (OBN) data and wide azimuth (WAZ) data acquired simultaneously to identify hydrocarbon deposits within subsurface regions of the earth according to the modalities described herein.

[0017] FIG. 6A illustrates an example triple source configuration for the layout of FIG. 4 according to the embodiments described herein; and

[0018] FIG. 6B illustrates an example triple source configuration for the layout of FIG. 4 according to embodiments described herein. DETAILED DESCRIPTION

[0019] One or more specific embodiments will be described below. In an effort to provide a concise description of these embodiments, not all features of an actual implementation are described in the descriptive report. It should be understood that in the development of any such implementation, as in any engineering project or undertaking, numerous implementation-specific decisions must be made to achieve the specific objectives of the developers, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Furthermore, it should be appreciated that such a development effort may be complex and time-consuming, but nevertheless, it would be a routine design, fabrication, and manufacturing task for those skilled in the art having the benefit of this disclosure.

[0020] When presenting elements of various modalities of this disclosure, the articles “a”, “an”, “the” and “said” are intended to mean that there is one or more of the elements. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements besides those listed. It should be noted that the terms “multimedia” and “media” may be used interchangeably in this document.

[0021] As mentioned above, in hydrocarbon exploration, seismic images of subsurface layers are used to locate hydrocarbon reservoirs, such as oil fields. Thus, the accuracy of seismic images helps to more precisely determine the locations of hydrocarbon reservoirs. Several azimuth distributions can be used to acquire azimuth data that can then be used to generate seismic images. One example of such an azimuth distribution is the Petition 870260049611, dated 05 / 25 / 2026, p. 15 / 65 5 / 23 Wide Azimuth (WAZ), in which multiple vessels navigate along the same direction (e.g., parallel to each other) and acquire seismic data. In WAZ, some of the vessels emit seismic waves to the sea, while some of the vessels (e.g., the same vessels or other vessels) acquire seismic wave reflections via towed streamers. Hereafter, towed streamers will be referred to as streamers for simplicity.

[0022] Bearing this in mind, the quality of seismic images acquired by propagating seismic waves through complex structures, such as embedded salt layers, may depend on the accuracy of a seismic wave velocity model traversing the target areas. That is, the velocity model of the target area affects the processing accuracy of the seismic data. However, obtaining an accurate velocity model can be challenging in geographic areas with complex structural layers. As such, additional data acquisition processes may be performed to determine an accurate velocity model for these geographic areas. For example, in some parts of the Gulf of Mexico, seismic data acquired using one or more azimuth distributions did not adequately image embedded salt layers because the seismic wave velocity model used in imaging lacked a threshold amount of accuracy and / or precision to reveal the salt layers.To obtain a more accurate velocity model, Ocean Bottom Surveys (OBS) can acquire seismic data that can be used to determine the velocity model. OBS can be performed before or after azimuth surveys, but these acquisitions add to the cost of seismic data acquisition by streamers and involve more time because of the additional step of acquiring seismic data using OBS Ocean Bottom Nodes (OBN) and corresponding towed sources.

[0023] With the precedent in mind, this disclosure is directed to a method for simultaneously acquiring WAZ and OBS data to obtain an accurate velocity model that can be employed in seismic data processing to generate seismic images. By implementing the methods described in this document, this disclosure can reduce the time and cost of generating these seismic images during seismic surveys using WAZ and OBS data. Further details on improving seismic data processing and analysis based on seismic surveys using WAZ and OBS data are described below. Petition 870260049611, dated 05 / 25 / 2026, p. 16 / 65 6 / 23 reference to FIGS. 1-6.

[0024] By way of introduction, FIG. 1 illustrates a schematic diagram of a marine seismic survey using multiple seismic measurements. As shown in FIG. 1, the marine seismic survey can be carried out in a body of water (e.g., ocean) having a surface 10 and a water bottom 12. Multiple subsurface layers (e.g., subsurface layers 14 and 15) may be located below the water bottom 12. Geological formations, such as subsurface formations 16 and 18 embedded in the subsurface layers, may contain hydrocarbon deposits. Seismic data acquired via marine seismic surveys can be used to image the seabed 12, subsurface layers 14 and 15, and subsurface formations 16 and 18. Images of subsurface geological structures can provide indications of hydrocarbon deposits that can later be extracted using a variety of hydrocarbon extraction processes.

[0025] In some embodiments, marine seismic surveying may include ocean bottom node (OBN) measurements employing multiple ocean bottom nodes (OBNs) 20 positioned on the waterbed 12. The OBNs may be deployed (e.g., using remotely operated vehicles (ROVs)) at selected locations and form a certain geometry (e.g., an OBN patch with a grid size of 200 meters by 200 meters). Each of the OBNs 20 may include one or more OBN sensors. The OBN sensors may include one or more geophones (e.g., single-component, two-component, and three-component geophones). In some embodiments, the OBN sensors may also include hydrophones.

[0026] Seafloor acquisition systems, including the ocean floor node (OBN) or the ocean floor cable (OBC), can be used to obtain more accurate seismic survey data in complex geological areas of water. For example, a seismic survey employing OBNs in water having complex geological structures may involve deploying an OBN patch (e.g., a 2D OBN array) and a dense grid of sources to effectively image the subsurface of the waterbed to a certain depth. The dense grid of sources can be produced by multiple seismic vessels navigating along one or more sides of the OBN patch.

[0027] One or more seismic source vessels may be used in marine seismic surveying. For example, a source vessel 22 towing a Petition 870260049611, dated 05 / 25 / 2026, page 17 / 65 7 / 23 seismic source 25 and another source vessel 32 towing another seismic source 35 can be used to create seismic waves propagating downwards into subterranean geological structures. Each of the seismic sources 25 and 35 may include one or more source arrays and each source array may include a certain number of air guns or other seismic wave generating device.

[0028] Marine seismic surveying may also include multiple streamers traversing the body of water to obtain streamer measurement data. For example, source vessel 22 may tow multiple (e.g., two, four, six, eight, or ten) streamers 23 along one navigation line, and source vessel 32 may tow multiple streamers 33 along another navigation line. Streamer measurement data may be acquired simultaneously with OBN measurement using shots detonated by seismic sources 25 and 35. That is, each streamer may include multiple streamer sensors. For example, each of the 23 streamers may include sensors from streamers 24, and each of the 33 streamers may include sensors from streamer 34. The sensors from streamers 24 and 34 may include hydrophones that create electrical signals in response to detected water pressure changes caused by reflected seismic waves reaching the hydrophones.In this way, the seismic waves generated by sources 25 and 35 can be reflected out of the underground regions in or under the water bottom 12 and the reflected seismic waves can be detected by streamer sensors 24 and 34.

[0029] In addition to source vessels 22 and 32, the marine seismic survey may also include additional source vessels 26 and 28 with seismic sources 27 and 29. Furthermore, although not shown, source vessels 26 and 28 may include streamers and other equipment as described as being part of source vessels 22 and 32. Although the following description of the modalities described in this document is detailed with four source vessels, it should be noted that the techniques described in this document may be performed using any suitable number of source vessels and are not limited to the description in FIG. 1.

[0030] In some embodiments, marine seismic surveying may include vertical seismic profile (VSP) measurement employing seismic sensors (e.g., fiber optic sensors, geophones, or hybrid sensors) in one or more wells. For example, an array of hybrid sensors including fiber optic sensors and geophones may be laid along a steel cable deployed in a wellbore, which may be Petition 870260049611, dated 05 / 25 / 2026, p. 18 / 65 8 / 23 drilled for subsurface formation 16. Fiber optic sensors can measure deformations caused by seismic waves reflected or refracted traveling along the hybrid sensor array. The geophone can measure ground movements (e.g., particle movements such as velocity and acceleration) caused by seismic waves traveling along the hybrid sensor array.

[0031] During marine seismic surveying, seismic source 25 can be activated to generate seismic waves 40 traveling downwards to subsurface geological structures. When seismic waves 40 reach the waterbed 12, a portion of seismic energy contained in the seismic waves 40 is reflected by the waterbed 12. Reflected waves 42 travel upwards and reach different sensors, such as streamer sensors 24 and 34, where they are measured by corresponding sensors. Another portion of the seismic energy contained in the transmitted seismic waves 44 propagated through the waterbed 12 to the subsurface layer 14. A portion of the seismic energy contained in the transmitted waves 44 is reflected by the subsurface formation 16. Reflected waves 46 travel upwards and arrive at different sensors, whereupon they are measured by the corresponding sensors.

[0032] It should be noted that the elements described above in relation to marine seismic surveying are exemplary elements. For example, some modalities of marine seismic surveying may include additional or fewer elements than those shown. For example, as mentioned above, marine seismic surveying may include a different number of source vessels. In some modalities, separate receiving vessels may be used to tow the streamers. In some modalities, streamer measurement may be acquired independently of OBN measurement for operational or logistical reasons.

[0033] Seismic data acquired simultaneously from different sensors can be collected and processed by a processing system 60. The processing system 60 may include one or more seismic recorders 62, a processor 66, a memory 68, a storage 70, one or more displays 72, and the like. The one or more seismic recorders 62 may receive ocean bottom node (OBN) data from OBNs 20, streamer data from streamer sensors 24 and 34, or other suitable seismic sensors. Collected data may be processed by the processor 66 using processor-executable code stored in memory 68 and storage 70. The processed data may be stored in storage 70 for later use. Results Petition 870260049611, dated 05 / 25 / 2026, page 19 / 65 9 / 23 of processing can be displayed via one or more displays 72. Data processing based on multiple measurements will be discussed in detail below with reference to FIG. 6.

[0034] Processor 66 may be any type of computer processor or microprocessor capable of executing computer executable code. Processors 66 may include single-threaded processor(s), multi-threaded processor(s), or both. Processors 66 may also include hardware-based processor(s), each including one or more cores. Processors 66 may include general-purpose processor(s), special-purpose processor(s), or both. Processors 66 may be communicatively coupled to other components (such as one or more seismic registers 62, memory 68, storage 70, and one or more displays 72).

[0035] Memory 68 and storage 70 may be any suitable articles of manufacture that can serve as means for storing processor-executable code, data, or the like. These articles of manufacture may represent computer-readable media (e.g., any suitable form of memory or storage) that can store processor-executable code used by processor 66 to execute the techniques presently disclosed. Memory 68 and storage 70 may also be used to store described data (e.g., fiber sensor data, geophone data), various other software applications for seismic data analysis and data processing.Memory 68 and storage 70 may represent non-transient computer-readable media (e.g., any suitable form of memory or storage) that can store processor-executable code used by processor 66 to execute various techniques described in this document. It should be noted that non-transient only indicates that the medium is tangible and not a signal.

[0036] One or more displays 72 may operate to represent visualizations associated with software or executable code being processed by processor 66. Display 72 may be any suitable type of display, such as a liquid crystal display (LCD), plasma display, or an organic light-emitting diode (OLED) display.

[0037] It should be noted that the components described above in relation to the system Petition 870260049611, dated 05 / 25 / 2026, page 20 / 65 10 / 23 of processing 60 are exemplary components and the processing system 60 may include additional or fewer components than shown. For example, the processing system 60 may include one or more communication interfaces to send commands to different seismic acquisition systems and receive measurements from different seismic acquisition systems.

[0038] With the precedent in mind, a wide azimuth (WAZ) survey of an area of ​​interest can be carried out using streamer sensors 24 and 34. For example, during a first portion of the WAZ survey, Obs data can be acquired via OBNs 20. Using the data acquired from the first portion of the WAZ survey and the OBS data, the processing system 60 or any suitable computing device can determine a velocity model for the seismic waves using a full waveform inversion (FWI) technique. The processing system 60 can then use the velocity model to generate a representative seismic image of the area of ​​interest that corresponds to the WAZ and OBS data. By acquiring the OBS data simultaneously with the WAZ survey data, the present embodiments described in this document can reduce the amount of processing time and energy used by the processing system 60 to generate a seismic image.That is, by conducting the WAZ and OBS surveys simultaneously, as opposed to conducting these surveys at different times, the processing system 60 can process the acquired seismic data in relation to each other to process the acquired seismic data more efficiently.

[0039] As an example, the WAZ survey may first involve the use of streamers to scan a continuous surface area via navigation lines that do not overlap each other. Seismic data (e.g., reflections) can be acquired via receivers placed on the streamers during a portion of the WAZ survey. In some embodiments, the area of ​​interest for the WAZ survey is laterally divided into multiple sub-areas (e.g., first area portions) arranged close to each other so that the navigation lines of the sub-areas do not overlap. In each of the sub-areas, the streamers can navigate in a first direction and a second opposite direction along their respective navigation lines to acquire the WAZ data during the first portion of the WAZ survey. In this way, the streamers can scan the entire area while none of the navigation lines can overlap. In some Petition 870260049611, dated 05 / 25 / 2026, p. 21 / 65 11 / 23 modes, none of the discharges from the vessels' firing sources may overlap each other in a lateral direction. The lateral direction may correspond to a direction along the sea surface and perpendicular to the navigation lines.

[0040] Depending on one or more methods, a single source per firing point may be sufficient to obtain the velocity model using full waveform inversion (FWI) of the OBN data. Thus, the velocity model can be determined during the first portion of the WAZ survey using a single firing. When acquiring WAZ data during the first portion of the WAZ survey, OBS data can be acquired simultaneously. Since WAZ data are acquired simultaneously with OBS data, the receivers (e.g., nodes) for the OBS can be positioned further apart or more sparsely than the receivers of an OBS conducted without streamers recording data for the WAZ survey. For example, in an OBS without a simultaneous WAZ survey being conducted, each receiver can be positioned approximately 400 meters (m) away from adjacent receivers to allow the OBS data to include sufficient detail to generate a velocity model.However, by conducting OBS simultaneously with the WAZ survey, this distance can exceed 400 m, for example, approximately 1,000 m or 1,200 m, thus reducing the cost of conducting the OBS.

[0041] In addition to performing WAZ surveys using a single source array per vessel or streamer, in some modes, multiple source arrays can be used per vessel or streamer. The use of multiple source arrays per vessel can increase the resolution of seismic images, can allow receivers (e.g., nodes) for the OBS to be more sparsely spaced than receivers of an OBS using a single source, and similarly. Furthermore, the use of multiple source arrays on a vessel or streamer can increase the signal-to-noise ratio by increasing the shot intensities. That is, source arrays providing a single shot can be installed with a step distance less than half a wavelength of the seismic waves (e.g., in seawater into which the seismic waves are emitted) that the source arrays generate.For example, assuming the wavelength of seismic waves is about 150 m, the step distance between adjacent source arrays can be less than 75 m, such as 50 m, which may be a function of streamer separation.

[0042] Keeping this in mind, Petition 870260049611, dated 05 / 25 / 2026, p. 22 / 65 12 / 23

[0043] By way of introduction, accurate imaging of hydrocarbon reservoirs located beneath complex salt bodies or structurally complex overburden can be achieved using: (1) seismic data with good deviation and azimuth distribution; and (2) an accurate velocity model that can be used to image the seismic data. However, these two conditions may not be available in many areas. For example, in some parts of the Gulf of Mexico, seismic data acquired with towed streamers using Narrow Azimuth, Wide Azimuth, and Full Azimuth acquisition geometries did not provide sufficient data to adequately image subsalt structures because a velocity model used in imaging was not accurate enough to fully reveal the subsalt structures.

[0044] As such, in some embodiments, acquiring an Ocean Bottom Survey (Obs) in addition to existing data can help obtain an accurate velocity model that can be used with other seismic data processing techniques to obtain accurate images of subsurface structures. Full azimuth and long offset OBN data (e.g., offset of more than 40 km) can allow deriving an accurate velocity model using Full Waveform Inversion (FWI). The resulting velocity model can be used to image existing data and OBN data. Images from the two acquisitions can then be combined to obtain an enhanced subsurface image. As such, one or more embodiments disclosed in this document may be applicable to areas where seismic data with good offset and azimuth distribution, such as Wide Azimuth and Full Azimuth, are not available.To reduce the cost of seismic exploration and exploration cycle time, Wide Azimuth towed streamer seismic data and OBN data for velocity model building can be acquired simultaneously.

[0045] With the precedent in mind, FIG. 2 presents an example configuration for a WAZ 80 towed streamer acquisition survey with reference to navigation lines employed when acquiring seismic data. In the embodiment illustrated in the WAZ 80 acquisition survey of FIG. 2, source vessels 26 and 32 may be present along with streamers 23 and 33. In addition to source vessels 26 and 32, source vessels 26 and 28 may also be part of the WAZ 80 acquisition survey with corresponding streamers 30 and 31 (e.g., having respective streamer sensors). In certain embodiments, the distance between the source vessels may be a Petition 870260049611, dated 05 / 25 / 2026, p. 23 / 65 13 / 23 function of the number of streamers and streamer separation distances. For example, a navigation line interval can be defined as: Navigation line interval = number of streamers x streamer separation (1) Therefore, assuming there are 12 streamers 23 following the source vessel 22 and each streamer is separated by 100 meters (m) from each other, the navigation line range is 1,200 m.

[0046] In the particular embodiment represented in FIG. 2, each source vessel 22, 26, 28, 32 can be fitted with a source array. The four vessels shown in FIG. 2 can navigate in one direction (e.g., forward) and in the opposite direction (e.g., backward) in an interleaved manner with an interval that is half the navigation line interval. That is, referring to FIG. 2, the navigation line interval is 1,200 m for each source vessel 22, 26, 28, 32 and the interval between adjacent navigation lines (i.e., navigation line interval) is 600 m, which is the distance between a forward navigation line and an adjacent backward navigation line. In this way, the forward navigation line can overlap more than half of the adjacent backward navigation line.

[0047] With this in mind, FIG. 3 illustrates an example of a WAZ 100 firing configuration in which some of the navigation lines overlap. Referring briefly back to FIG. 2, each of the streamers 23, 30, 31, 33 following the source vessels 22, 26, 28, 32 can correspond to a particular navigation number in the WAZ 100 firing configuration of FIG. 3. For example, when navigating in a forward or first direction, a first streamer of a set of streamers following each of the source vessels 22, 26, 28, 32 is represented by a number with a prime symbol (e.g., 1'). Therefore, the four 1' values ​​represented in the WAZ 100 firing configuration correspond to one streamer from each set of streamers (e.g., 23, 30, 31, 33) followed by a respective source vessel 22, 26, 28, 32. Thus, the number represented in FIG.3 corresponds to a navigation line number for the seismic survey using the four source vessels 22, 26, 28, 32 and their respective streamers 23, 30, 31, 33.

[0048] In addition, backward navigation lines in which streamers 23, 30, 31, 33 travel in a second direction opposite to the first direction during the seismic survey. Petition 870260049611, dated 05 / 25 / 2026, page 24 / 65 14 / 23 are represented without a prime symbol next to the navigation line number (e.g., 1). That is, after streamers 23, 30, 31, 33 acquire seismic data while traveling via a first navigation line (e.g., 1') in the forward direction, streamers 23, 30, 31, 33 can again acquire seismic data via the first navigation line (e.g., 1) while traveling in the backward direction.

[0049] As shown in FIG. 3, streamers 22, 26, 28, 32 can be separated by approximately 1,200 meters (+ / - 5%). As such, the navigation line interval between streamers 23, 30, 31, 33 is 1,200 meters. Referring again to FIG. 3, the intercalated navigation line where the streamers overlap the navigation lines crossing each other corresponds to half the navigation line interval or 600 meters. In FIG. 3, the horizontal axis is along a lateral direction, which is perpendicular to the navigation lines.

[0050] According to the WAZ 100 firing configuration, each source line is repeated 4 times, or each firing point in the WAZ seismic survey is repeated 4 times at 1,200-meter intervals. For example, as mentioned above, forward navigation lines annotated with “1” may correspond to streamers 23, 30, 31, 33 navigating in the forward direction, and backward navigation lines annotated with “1” may correspond to streamers 23, 30, 31, 33 navigating in the backward direction. Similar configurations can be applied to navigation lines with other annotation numbers. For example, navigation lines annotated with “2’ or 2” may correspond to streamers 23, 30, 31, 33 that are laterally displaced by the navigation line interval (e.g., 1,200 m).

[0051] In some embodiments, WAZ seismic surveying can be performed with fewer than four shots per firing station to obtain a velocity model using a full wave inversion (FWI) method. That is, WAZ seismic surveying can be performed using a single source per firing point and the acquired seismic data can then be used with the FWI process. For example, WAZ seismic data can be acquired in two passes (e.g., steps) as described below.

[0052] On the first pass, a first set of seismic data used for FWI can be acquired via streamers 23, 30, 31, 33. The first set of seismic data can be acquired so that the navigation lines traversed by the source vessels 22, 26, 28, 32 can provide continuous subsurface coverage. Petition 870260049611, dated 05 / 25 / 2026, page 25 / 65 15 / 23 without overlapping firings (i.e., without overlapping navigation lines). As such, seismic data acquired by streamers 23, 30, 31, 33 can receive reflected seismic data from a corresponding seismic source on a respective source vessel 22, 26, 28, 32. For example, during a first pass, WAZ seismic data can be acquired by streamers 23, 30, 31, 33 via navigation line 1. That is, for example, source vessel 22 can activate source 25 while crossing sail line 1 and streamers 23, 30, 31, 33 can receive the resulting reflected seismic data.

[0053] In subsequent passes, WAZ seismic data for the rest of the navigation lines are acquired. For example, in the WAZ 100 trigger configuration of FIG. 3, WAZ seismic data can be acquired via navigation lines 2, 3 and 4 by activating sources associated with source vessels 26, 28 and 32, respectively, and recording the resulting reflected seismic data via streamers 23, 30, 31, 33.

[0054] With the precedent in mind, ocean bottom survey (Obs) data can also be acquired simultaneously with reflected seismic data acquired via streamers 23, 30, 31, 33 to perform modalities described in this document. That is, OBS data (hereinafter also referred to as OBN survey) can also be acquired during the first pass. In this way, OBN data acquired via OBN 20 during the first pass of the WAZ 100 firing configuration described above can be used to calculate a velocity model for subsurface layers 14 and 15. The velocity model can represent one or more rates at which one or more waves travel through a medium (e.g., a scalar) or one or more rates at which a body (e.g., water, subsurface regions) is displaced in a given direction (a vector).

[0055] By obtaining the OBS data after the first pass, the processing system 60 or other suitable computing device can determine a corresponding velocity model based on the OBS data before completing the WAZ survey using the WAZ trigger setting 100. In this way, the total amount of processing time for performing the combined WAZ and OBN surveys can be reduced. That is, by simultaneously performing the WAZ and OBN surveys together, the need to perform additional WAZ surveys to determine the velocity model can be avoided because the OBS data can be used to determine the velocity model. Petition 870260049611, dated 05 / 25 / 2026, page 26 / 65 16 / 23

[0056] Bearing this in mind, it should be noted that sparse OBN data acquired during the WAZ survey may not include data with a sufficient amount of detail to construct an accurate velocity model using FWI. However, according to one or more modalities, when sampling OBN data, the receiver (node) sampling can be more sparse than for regular OBS, which is typically 400 m x 400 m. In fact, employing the modalities described in this document, receiver sampling can be performed at 1,000 m x 1,000 m or 1,200 m x 1,200 m spacing.

[0057] The firing sampling for OBNs 20 can be a function of the navigation line interval (e.g., according to the interleaved space). According to one or more embodiments, the firing sampling in the transverse direction (i.e., lateral direction) can be 600 m. The firing sampling in the line direction can be a function of a series of source arrays that are installed on each source vessel 22, 26, 28, 32. For example, in the case where each of the source vessels 22, 26, 28, 32 shown in FIG. 2 includes a single source array and a nominal firing interval between source vessels 22, 26, 28, 32 is 25 m, and firing is sequential, the firing interval along the source line is 4 x 25 m = 100 m. Thus, the OBN source sampling for the described configuration can be 100 m x 600 m.In other words, the sampling in the lateral direction is 600 m, which corresponds to the distance between adjacent navigation lines, and the sampling along the navigation line direction is 100 m, which corresponds to the source firing cycle of the four source vessels 22, 26, 28, 32 in FIG. 2.

[0058] With this in mind, FIG. 4 illustrates an example deployment configuration 120 for OBNs 20 (e.g., receivers) for simultaneous acquisition of OBN and WAZ surveys according to one or more modalities. The deployment configuration 120 illustrates the presence of a firing halo around the OBNs 20 which may be 20 km or less, depending on a specified maximum deviation in the surveyed area. In some modalities, the firing line interval or the distance between firing lines 122 corresponding to the WAZ seismic survey may be 600 m with firing spacing between 50 and 100 m during the WAZ seismic survey.

[0059] FIG. 5 illustrates a flowchart of a method 130 for processing OBN data and WAZ data acquired simultaneously to identify potential hydrocarbon deposits in subsurface regions of the earth. Although the following method 130 is Petition 870260049611, dated 05 / 25 / 2026, p. 27 / 65 While method 130 is described as being performed in a particular order, it should be understood that method 130 can be performed in any suitable order. Furthermore, although method 130 is described as being performed by processing system 60, it should be understood that method 130 can be performed by any suitable computing device. Additionally, while the following description of method 130 refers to data acquired using the configurations and acquisition methodologies described above, it should be noted that the seismic data used to perform method 130 may not be limited to the specific number of streamers, seismic sources, OBNs, and other details mentioned above. Instead, method 130 can be performed using seismic data acquired via a variety of suitable configurations.

[0060] With reference now to FIG. 5, in block 132, processing system 60 can receive a first set of seismic data which corresponds to reflected seismic data acquired during a first pass of the WAZ seismic survey described above with reference to FIG. 3. As such, the first set of seismic data can correspond to reflected seismic waves acquired by sensors of streamers 23, 30, 31, 33 in response to seismic waves produced by one or more seismic sources while streamers 23, 30, 31, 33 cross navigation line 1 of FIG. 3.

[0061] In block 134, processing system 60 can receive OBS data acquired via OBNs 20. The OBS data may correspond to reflected seismic waves acquired by the sensors of streamers 23, 30, 31, 33 in response to one or more seismic sources while streamers 23, 30, 31, 33 cross navigation line 1 of FIG. 3. As such, the OBS data may have been acquired simultaneously while the sensors of streamers 23, 30, 31, 33 collected reflected seismic waves. In this way, the seismic data acquired by the sensors of streamers 23, 30, 31, 33 and the OBS data may represent the same geological features of the same subsurface region of the earth.

[0062] After receiving the first seismic dataset and the OBS data, processing system 60 can, in block 136, generate a velocity model using a full waveform inversion (FWI) process based on the first seismic dataset and the OBS data. The FWI process can iteratively minimize differences between the first seismic dataset and the OBS data and generate a velocity model representative of the subsurface region that reflected seismic waves originally produced by one or more seismic sources while streamers 23, 30, 31, Petition 870260049611, dated 05 / 25 / 2026, p. 28 / 65 18 / 23 were crossing navigation line 1. Using the OBS data and the first dataset to generate the velocity model, the two datasets can be used to confirm properties and characteristics in each respective dataset. As a result, the velocity model generated based on these two simultaneously acquired seismic datasets can be more accurate compared to a velocity model determined based on the use of any seismic dataset alone, using multiple seismic datasets acquired using the same receivers (e.g., OBNs or streamer sensors) representative of different and similar seismic firings.

[0063] In block 138, processing system 60 may receive a subsequent set of seismic data acquired during additional passes of the WAZ seismic survey. That is, for example, the second or subsequent set of seismic data may be acquired after streamers 23, 30, 31, 33 cross navigation line 1. In some embodiments, processing system 60 may receive a series of seismic data sets acquired during additional passes of the WAZ seismic survey. In any case, using the second (or additional) set(s) of seismic data, processing system 60 may, in block 140, generate a third set of seismic data based on the velocity model and the second set (or additional sets) of seismic data received in block 138.As such, the 60 processing system can process the second seismic dataset using the velocity model to more accurately characterize the reflected seismic waves recorded in the second seismic dataset. The velocity model can allow the 60 processing system to filter and shift the second seismic dataset so that the recorded seismic reflections more accurately represent features within the subsurface region of the earth from which the seismic waves generated by a respective seismic source reflected.

[0064] In block 142, processing system 60 can generate seismic image data representative of the corresponding subsurface region of the earth based on the third seismic data set generated in block 140. That is, processing system 60 can convert the seismic or sound waves present in the third seismic data set into image data that represent features that may be present in a corresponding subsurface region of the earth. The seismic image data may represent the presence of complex geological structures, hydrocarbon deposits, and Petition 870260049611, dated 05 / 25 / 2026, p. 29 / 65 19 / 23 similar. In block 144, processing system 60 can identify hydrocarbon deposits present in the subsurface region that corresponds to the third set of seismic data and display the results on display 72 or similar.

[0065] In some embodiments, the 60 processing system can use the OBS data to generate the velocity model and process the first seismic dataset based on the velocity mode to generate another seismic dataset. The new seismic dataset can then be used to generate the seismic image data as discussed above.

[0066] As mentioned above, a FWI that can be used for velocity modeling in complex geological areas (e.g., embedded salt layers) can utilize seismic data acquired via a long offset and a full azimuth distribution. Furthermore, the FWI can use seismic data with good signal-to-noise ratios for very low frequencies (e.g., 1.5–2 Hz) to obtain accurate images. As such, OBN acquisition according to one or more modalities described in this document could provide the offsets and azimuths that can allow the FWI to effectively generate seismic images. That is, very low frequency generation may involve a seismic source capable of generating these low-frequency source waves. However, since the signal strength of such low-frequency seismic waves generated by certain seismic sources can be weak, the signal-to-noise ratio of such low-frequency seismic waves can also be weak or low.As such, the present embodiments described below include a source geometry for WAZ acquisition that can be used to improve the signal-to-noise ratio for low-frequency seismic waves.

[0067] With this in mind, in some embodiments, two source matrices or three source matrices may be employed for the WAZ survey, as shown in FIGS. 6A and 6B. That is, referring to FIG. 6A, source vessels 22, 26, 28, 32 may be separated by 1,200 m, as described above, and may each include three seismic sources 25. Similarly, in FIG. 6B, source vessels 22, 26, 28, 32 may be separated by 1,200 m, as described above, and may each include two seismic sources 25. Using multiple source matrices or seismic sources 25 per vessel, the resolutions of the acquired WAZ survey data and OBN survey data may increase by decreasing the bin size in the lateral direction. That is, each bin is a subdivision of the seismic survey, and bins (cells) are acquired by recording the data. Petition 870260049611, dated 05 / 25 / 2026, page 30 / 65 20 / 23 Seismic clusters with a common midpoint. A common midpoint can be defined as a point on a surface halfway between a source and a receiver, such that the point is shared by numerous source-receiver pairs. The bin size is a function of the streamer separation. When each vessel includes a source array, the bin size is half the streamer separation. For example, referring again to FIG. 2, if each vessel includes a source array and considering a streamer separation of 100 m, the bin size could be 50 m. Depending on one or more embodiments, for dual-source array and triple-source array configurations, the bin size can be decreased by a factor of 2 and 3, respectively. For example, if each vessel shown in FIG. 2 includes dual-source arrays, the bin size would be 25 m.Furthermore, if each of the vessels includes triple source arrays, the bin size would be 16.6 m.

[0068] In addition to employing multiple source arrays, different source firing schemes can be used, as shown in Table 1 for triple source arrays and in Table 2 for double source arrays below. Sources Firing sequence Oscillation type Nominal firing interval Firing interval along the line Source matrix depth Triple source matrix: Source Matrix 1 to Source Matrix 12 1+4+7+10 (simultaneous) 2+5+8+11 (simultaneous) 3+6+9+12 (simultaneous) random 25 m 75 S1 7 m S2 10 m S3 13 m S4 16 m Triple source matrix: 1+2+3 (simultaneous) 4+5+6 (simultaneous) deterministic 25 100 m S1 7 m S2 10 m S3 13 m Petition 870260049611, dated 05 / 25 / 2026, p. 31 / 65 21 / 23 Source 1 to Matrix of Source 12 7+8+9 (simultaneous) 10+11+12 (simultaneous) Table 1: Tri-source potential source firing sequence for WAZ and Sparse OBN acquisition Sources Firing Sequence Oscillation Type Nominal Firing Interval Firing Interval Along the Line Source Matrix Depth Dual Source Matrix: Source Matrix 1 to Source Matrix 12 1+3+5+7 (simultaneous) 2+4+6+8 (simultaneous) random 25 m 50 m S1, S2 7 m S3, S4 10 m S5, S6 13 m S7, S8 16 m Dual Source Matrix: Source Matrix 1 to Source Matrix 12 1+2 (simultaneous) 3+4 (simultaneous) 5+6 (simultaneous) 7+8 (simultaneous) deterministic 25 100 m S1 7 m S2 11 m S3 7 m S4 11 m S5 7 m S6 11 m S7 7 m S8 11 m Table 2: Dual-source potential source firing sequence for WAZ and Sparse OBN acquisition

[0069] According to one or more modes, multiple source arrays can trigger seismic waves simultaneously. For example, as shown in Table 1, for Petition 870260049611, dated 05 / 25 / 2026, p. 32 / 65 22 / 23 triple source arrays S1-S12, source arrays 1, 4, 7, and 10 can be fired simultaneously. Source arrays 2, 5, 8, and 11, which are located 25 m away, can be fired simultaneously. Similarly, source arrays 3, 6, 9, and 12, located 25 m further on, can be fired simultaneously. In this way, the firing interval along the navigation line would be 75 m. This simultaneous firing (i.e., source firing) can allow for more efficient data acquisition with higher resolutions.

[0070] In some modalities, when multiple source arrays fire simultaneously, it can be beneficial to differentiate between the firings of the source arrays to obtain higher resolution images. As such, the source arrays can be arranged at different depths to differentiate between the wavelets associated with each source array having different source ghosts. Having different depths for the source arrays can allow for better source separation (e.g., demixing) during seismic data processing. Examples of arranging the source arrays at different depths are shown below in Table 1 and Table 2.Depending on one or more modes, even if the source matrices are not fired simultaneously, the source matrices can be arranged at different depths to take advantage of the differentiation between the wavelets associated with the source matrices and also to intensify the signal for noise at low frequencies.

[0071] Furthermore, for sources that are close to each other, the signal-to-noise ratio can be enhanced based on the concept of “shared low frequency”. That is, for very low frequencies (e.g., below 15 Hz), two sources that are separated by less than half the seismic wavelength can be considered as a point source. As such, two sources, with a source separation of 50 m in the cross-line direction, could be considered a point source for frequencies below 15 Hz.

[0072] Bearing the above in mind, the benefits of using multiple source arrays that are close to each other may include improving seismic imaging resolution by reducing the cross-line bin interval to half the source array separation, so that the streamer separation is greater than the source array separation. Another benefit may include increasing the signal-to-noise ratio for the final migrated image because more source points are acquired and the subsurface Petition 870260049611, dated 05 / 25 / 2026, p. 33 / 65 23 / 23 could be better sampled.

[0073] In some modes, an oscillation (e.g., a slight time delay) may be introduced into the simultaneous shots to differentiate between the seismic data associated with the shots. The oscillations may be random or predetermined (i.e., deterministic oscillations).

[0074] Although only certain features of disclosed embodiments have been illustrated and described herein, many modifications and changes will occur for those skilled in the art. Therefore, it should be understood that the appended claims are intended to encompass all such modifications and changes that fall within the true spirit of the present disclosure.

[0075] The techniques presented and claimed herein are referenced and applied to material objects and concrete examples of a practical nature that demonstrably improve the present technical field and, as such, are not abstract, intangible, or purely theoretical. Furthermore, if any claims appended to the end of this descriptive report contain one or more elements designated as “means for [performing] [a function]…” or “step for [performing] [a function]…”, it is intended that such elements should be interpreted in accordance with 35 USC 112(f). However, for any claims containing elements designated in any other way, it is intended that such elements should not be interpreted in accordance with 35 USC 112(f). Petition 870260049611, dated 05 / 25 / 2026, p. 34 / 65

Claims

1 / 2 CLAIMS 1. Method, characterized in that it comprises: acquiring a first set of seismic data via a Wide Azimuth, WAZ, survey, representative of one or more features of an underground region (16, 18) with a plurality of streamers (23, 30, 31, 33) comprising one or more streamer sensors (24, 34), wherein the WAZ survey comprises a first portion corresponding to a time period and a second portion corresponding to an additional time period subsequent to said time period; acquire a second seismic dataset with a plurality of ocean floor modes, OBNS, simultaneously during a time period in which the first seismic dataset is acquired, where the first portion of the first seismic dataset is acquired while the plurality of streamers (23, 30, 31, 33) traverses a first navigation line;and the second portion of the first seismic dataset, representative of one or more features of the subsurface region (16, 18), is acquired while the plurality of streamers (23, 30, 31, 33) traverse a second navigation line in a direction opposite to that of the first navigation line; wherein a trigger sampling for the OBNs is a function of a first navigation line interval; receive (132), by a processor (66), the first portion of the first seismic dataset and the second dataset and receive (134) the second seismic dataset acquired via the OBS simultaneously during a time period in which the first seismic dataset is acquired; process (136), by the processor (66), the first portion of the first seismic dataset and the second seismic dataset to obtain a seismic wave velocity model for an area corresponding to the WAZ and OBS survey;receive (138), by processor (66), the second portion of the first seismic data set; process (140), by processor (66), the second portion of the second seismic data set and the velocity model for the subsurface region (16, 18) to generate a third seismic data set; and Petition 870260049611, dated 05 / 25 / 2026, p. 35 / 65 2 / 2 generate (142), by processor (66), one or more seismic images of the area based on the third seismic data set.; 2. Method, according to claim 1, characterized in that the WAZ survey is carried out using a plurality of vessels (22, 26, 28, 32) configured to acquire the first set of seismic data in a continuous data acquisition across the entire area, by navigating in two directions through a plurality of non-overlapping navigation lines.

3. System according to claim 2, characterized in that at least one of the pluralities of vessels (22, 26, 28, 32) comprises a plurality of source arrays (25, 35) arranged at different depths.

4. Method according to claim 2, characterized in that at least one vessel of the plurality of vessels (22, 26, 28, 32) comprises a plurality of source matrices (25, 35) configured to generate one or more seismic waves having a frequency lower than a threshold determined based on a separation between each source matrix of the plurality of source matrices, a depth of each source matrix of the plurality of source matrices and a firing time of each source matrix of the plurality of source matrices.

5. Method according to claim 1, characterized in that the first portion of the first seismic dataset and the second portion of the first seismic dataset are acquired based on one or more seismic waves produced by a plurality of (25, 35) source arrays arranged at a plurality of depths. Petition 870260049611, dated 05 / 25 / 2026, p. 36 / 65

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