METHOD FOR CONDUCTING A MARINE SURVEY OF AN UNDERGROUND FORMATION, AND METHOD FOR PRODUCING A GEOPHYSICAL DATA PRODUCT

Abstract

The present invention relates to methods for carrying out and producing geophysical data products in a marine survey of a subsurface formation using a hybrid combination of seafloor seismic receivers ("obs"), towed vast sources, and mobile serpentines. In one aspect, a separation between sail lines in a direction orthogonal to the sail lines is determined based on an average separation between serpentines and the number of serpentines. An array of obs receivers is deposited on a surface of a subsurface formation with a separation between obs receivers that is based on the separation between the sail lines. Towed vast sources and serpentines are towed above the obs receiver array behind a seismic survey vessel that moves along the sail lines separated by the separation between the sail lines.The vast towed sources can be activated above the OBS receiver array. The wave fields reflected from the subterranean formation are recorded in the OBS receivers and in the receivers located in the coils as seismic data.

Description

METHOD FOR CONDUCTING A MARINE SURVEY OF AN UNDERGROUND FORMATION, AND METHOD FOR PRODUCING A GEOPHYSICAL DATA PRODUCT CROSS-REFERENCED ON RELATED REQUEST

[001] This application claims the benefit of the Provisional Application 62 / 860.470, filed on June 12, 2019, the application for which is incorporated by reference as if presented in its entirety herein. BACKGROUND

[002] Marine seismology companies invest heavily in the development of marine seismic survey equipment and seismic data processing techniques in order to obtain accurate, high-resolution images of subsurface formations located beneath a body of water. These images can be used, for example, to determine the structure of subsurface formations, to discover oil reservoirs, and to monitor oil reservoirs during production. A marine seismic survey can be carried out with one or more seismic survey vessels towing one or more seismic sources and many cables (streamers) through the body of water. The seismic survey vessel contains seismic acquisition equipment, such as navigation control, seismic source control, seismic receiver control, and recording equipment. A seismic source control controls the activation of one or more seismic sources at selected times or locations.A seismic source comprises an array of air cannons, or one or more marine vibrators, which are activated to produce acoustic energy that spreads in all directions. A portion of the acoustic energy moves downwards through the water and into an underground formation to propagate as sound waves within the underground formation. At each interface between different types of liquid, rock, and sediment, a portion of the acoustic energy is refracted, a portion is transmitted, and another portion is reflected back into the body of water. Petition 870260062013, dated 06 / 24 / 2026, p. 11 / 76 / 31 to propagate as a reflected acoustic wave field towards the water surface. Seismic cables (seismic survey cables) are elongated, spaced cable-shaped structures towed behind a seismic survey vessel in the direction in which the seismic survey vessel is moving, which is also called the line direction. Each seismic cable contains many seismic receivers or sensors that measure the properties of the pressure wave field and / or particle motion wave field of the reflected wave field. The seismic cables collectively form a seismic data acquisition surface that records the pressure wave fields and / or particle motion as seismic data on the recording equipment.

[003] Marine surveys can also be carried out with a survey vessel towing a seismic source above seismic receivers on the ocean floor (OBS) located on ocean floor cables (OBCs) or ocean floor nodes (OBNs) deployed on the surface of the subsurface formation. OBCs include spaced receivers (e.g., geophones and / or hydrophones) that are electronically connected via transmission cables to recording equipment located elsewhere, such as aboard a seismic logging survey vessel. OBNs are positioned on the seabed using a variety of methods, e.g., remotely operated underwater vehicles. Each OBN is equipped with a battery, clock, and receiver (e.g., geophone).Since OBCs are often tethered to a seismic survey vessel, they are typically deployed in shallow water areas, such as water depths of less than one kilometer. On the other hand, since OBNs have their own power source and are not tethered to a seismic survey vessel, they can be deployed for extended periods, such as weeks or months, and at greater depths. Petition 870260062013, dated 06 / 24 / 2026, page 12 / 76 / 31 exceeding one kilometer. A line of OBNs can also be uniformly spaced along the cable, referred to as nodes in a rope. Nodes in a rope allow for the efficient deployment of uniformly spaced OBNs on the ocean floor and allow for the efficient recovery of OBNs from the ocean floor. The acoustic energy generated by the source is reflected and refracted from the seabed and interfaces between layers of different densities within the subsurface formation and is recorded by the receivers of the OBCs or OBNs as seismic data that is sent to a survey vessel for recording. DESCRIPTION OF THE DRAWINGS

[004] Figures 1A-1B show examples of seismic surveys on the ocean floor and with hybrid seismic cables (OBS) carried out using two towed sources with large lateral spacing.

[005] Figures 2A-2B show an elevated side view and a top view, respectively, of the seismic data acquisition systems shown in Figures 1A-1B.

[006] Figure 3 shows a plan view of an example of a survey vessel towing two towed sources of large lateral spacing and sixteen seismic cables along adjacent sail lines at different times in a marine survey.

[007] Figures 4A-4E show an example of a marine seismic survey carried out with two towed sources with wide lateral spacing and sixteen seismic cables to obtain uniformly spaced sublines.

[008] Figures 5A-5D show an example of a marine seismic survey carried out with two towed sources with wide lateral spacing and eighteen seismic cables to obtain uniformly spaced sublines.

[009] Figure 6 shows a plan view of a survey. Petition 870260062013, dated 06 / 24 / 2026, page 13 / 76 / 31 exemplary hybrid marine vessel in which a seismic survey vessel tows three towed sources with a large lateral offset and sixteen seismic cables above a receiver array.

[0010] Figure 7 shows a plan view of an exemplary hybrid marine survey in which a seismic survey vessel tows four towed sources with large lateral spacing and sixteen seismic cables above a series of OBS receivers.

[0011] Figure 8 shows a plan view of a hybrid marine survey in which a survey vessel tows two towed sources with large lateral offsets and sixteen seismic cables above an array of OBS receivers.

[0012] Figure 9 shows a plan view (xy plane) of a hybrid marine survey carried out with cross-shot.

[0013] Figure 10 shows a plan view (xy plane) of a hybrid marine survey carried out with parallel shooting.

[0014] Figure 11A shows a table summarizing the relationships between OBS receiver separations and source separations in the orthogonal direction for a selected candle line separation.

[0015] Figure 11B shows a table summarizing the relationships described above between candle line separation and source separations in the orthogonal direction for a selected OBS receiver separation.

[0016] Figure 12 shows a method for carrying out a marine survey of a subsurface formation located beneath a body of water.

[0017] Figure 13 shows a method for carrying out a marine survey of a subsurface formation located beneath a body of water. DETAILED DESCRIPTION

[0018] Surveys using OBS and surveys using towed cables Petition 870260062013, dated 06 / 24 / 2026, page 14 / 76 / 31, has different advantages in the search for hydrocarbon deposits and in monitoring producing hydrocarbon deposits. For example, OBS seismic surveys have much longer source / receiver offsets and a wide range of azimuths, ranging from narrow azimuth (NAZ) seismic surveys to full azimuth (FAZ) seismic surveys. In contrast, towed cable seismic surveys have denser receiver spacing and smaller source / receiver offsets. However, combining seismic datasets obtained from a towed cable survey and an OBS survey of the same underground formation to image the underground formation is challenging due to the inherent differences in how the seismic datasets are obtained.For example, seismic datasets are typically recorded for different source symmetries and reflected wave field displacement paths, different receiver depths, and the source / receiver ghost displacement times are different for the two datasets. Furthermore, OBS seismic surveys are conducted with densely spaced source activation sites across a large seismic survey area to increase the number of chances. On the other hand, towed seismic cable surveys record seismic data over a large seismic survey area, but with sparsely spaced sail lines.

[0019] The inventors observed that many of the challenges associated with combining seismic data obtained from traditional towed seismic cable surveys and traditional OBS surveys can be attributed to non-uniform and misaligned seismic cable sublines and OBS receivers. A seismic cable subline is a line of common midpoints (CMPs) for a specific source and receivers located along a given seismic cable. A Petition 870260062013, dated 06 / 24 / 2026, p. 15 / 76 / 31. The OBS receiver subline is a line of CMPs for a specific source and the receivers located along a specific linear array of OBS receivers. Another factor that facilitates the combination of seismic data recorded in a survey by OBS receiver and hybrid towed seismic cable, as described in this document, is that the receivers on the seismic cables and the OBS receivers record the same source and reflected wave fields. In other words, the receiver located on the seismic cables and the OBS receiver located on the waterbed form a receiver space to record the same source and reflected wave fields.

[0020] The hybrid marine seismic surveys described in this document are carried out with a seismic survey vessel towing a series of wide-spacing towed sources and multiple seismic cables above an array of OBS receivers (i.e., OBC receivers or OBNs) distributed over the surface of a subsurface formation. For typical seismic surveys carried out by towed seismic cables with two or more sources, the two or more sources are towed within the separation distance of the two innermost seismic cables. In contrast, wide-spacing towed sources are towed with separations between sources that exceed the separation distances between adjacent seismic cables.The separation of sail lines, the separation between sources, and the separation between OBS receivers are selected so that seismic data are recorded with nominally uniform separations between seismic cables and OBS receiver sublines. For example, the separation of sail lines can be chosen depending on the number of cables and the average separation between cables; the separation between sources can be chosen depending on the separation of sail lines and the number of sources; and the seismic cable survey can be carried out along an array of OBS receivers that are uniformly distributed over the surface of the subsurface formation with the separation between OBS receivers. Petition 870260062013, dated 06 / 24 / 2026, p. 16 / 76 / 31 selected depending on the separation of candle lines.

[0021] Seismic data recorded by OBS receivers can be processed separately to construct a high-resolution velocity model of a subsurface formation. A velocity model is a prerequisite for seismic migration and other seismic imaging methods to map reflectors and scatterers in the subsurface using reflected or scattered waves. Techniques for constructing a velocity model of a subsurface formation from seismic data recorded by OBS receivers include full waveform inversion. The high-resolution velocity model includes contributions from all azimuths, includes anisotropic effects, and provides high-resolution velocities in subsurface formations with complex geologies.Time or depth migration can be used to generate images of the subsurface formation based on seismic data recorded by receivers on towed seismic cables and the velocity model constructed from seismic data recorded using OBS receivers. Hybrid Marine Survey with Towed Seismic Cables, Wide-Spacing Towed Sources, and OBS Receivers

[0022] In the following description, the terms uniform, equal, and aligned are used to describe the distances between adjacent sail lines, source trajectories, and separations between OBS receivers and parameters associated with configurations of sources, seismic cables, sublines, and OBS receivers. These terms imply accuracy and precision with respect to the parameters used to describe and illustrate examples of sail lines and configurations of sources, seismic cables, sublines, and OBS receivers in marine survey examples described below. However, it should be recognized that marine surveys are conducted under dynamic real-world conditions, such as changes in weather conditions and changes in water currents, which cause the shape of the cables to shift. Petition 870260062013, dated 06 / 24 / 2026, p. 17 / 76 / 31 Seismic values ​​vary, and the distances between adjacent sail lines, adjacent seismic cables, and adjacent sources deviate from intended or idealized locations. Therefore, the terms uniform, equal, and aligned in the following discussion also mean substantially or approximately uniform, approximately equal, and substantially or approximately aligned to describe the distances between adjacent sail lines, source trajectories, and separations between OBS receivers and configurations of sources, seismic cables, sublines, and OBS receivers.

[0023] Figures 1A-1B show examples of hybrid seismic cable and OBS surveying. In Figures 1A-1B, a seismic survey vessel 102 tows two sources 104 and 106 and a set of sixteen seismic cables, such as a seismic cable 108, through a body of water above an underground formation 110. The body of water may be, for example, an ocean, a sea, a lake, a river, or any part thereof. The sources 104 and 106 may be an array of air guns or one or more marine vibrators that generate source wave fields that disperse spherically outward in all directions. Ray paths 112 and 113 represent a portion of a source wave field that is reflected upward from the surface of the underground formation 110 towards the seismic cables.Ray paths 114-116 represent acoustic energy that penetrates underground formation 110, is refracted and reflected upwards from an interface of underground formation 110, and propagates towards seismic cables.

[0024] In the implementation example of Figure 1A, the shaded disks represent OBNs positioned on the surface of the subsurface formation 110. The ray path 117 represents a portion of the acoustic energy that penetrates the subsurface formation and is reflected upwards from the interface towards an OBN 118. The seismic data recorded by the OBNs can be recovered by retrieving the OBNs and transferring the data. Petition 870260062013, dated 06 / 24 / 2026, p. 18 / 76 / 31 seismic data to recording equipment located on land or aboard a vessel used to recover OBNs. Alternatively, OBNs may transmit, via a suitable means, the recorded seismic data which, in turn, are recorded by recording equipment located aboard the seismic survey vessel 102.

[0025] In the implementation example of Figure 1B, OBCs, such as OBC 120, are located on the surface of the subsurface formation 110. The triangles represent regularly spaced receivers on the OBCs. The beam path 121 represents a portion of the acoustic energy that penetrated the subsurface formation 110 and is reflected upwards towards a receiver 122. Each OBC can be electronically connected via a data transmission cable to the recording equipment located on board a logging seismic survey vessel 124. For example, a transmission cable 126 electronically transmits the seismic data generated by the receivers located along OBC 120 to the recording equipment located on board the logging seismic survey vessel 124.

[0026] Figures 1A-1B show a Cartesian coordinate system with three perpendicular coordinate axes denoted as x, y, and z. The coordinate system specifies orientations and coordinate locations within the water body and subsurface formation. The x-axis specifies the position of a point in a direction parallel to the length of the seismic cables or in the direction in which the seismic survey vessel is moving and is termed the line direction. The y-axis specifies the position of a point in a direction perpendicular to the x-axis and substantially parallel to the free surface of the water body and is termed the orthogonal direction. The z-axis, also termed the depth axis, specifies the position of a point perpendicular to the xy plane (i.e., perpendicular to the free surface) with the z-axis positive. Petition 870260062013, dated 06 / 24 / 2026, page 19 / 76 / 31 pointing downwards, away from the free surface.

[0027] Figures 2A-2B show an elevated side view and a top view, respectively, of the seismic data acquisition systems shown in Figures 1A-1B. As shown in Figure 2B, the seismic survey vessel 102 tows sixteen seismic cables. Each seismic cable is attached, at one end, to the survey vessel 102 via a seismic cable data transmission cable, such as a transmission cable 202 that connects seismic cable 108 to the survey vessel 102. The seismic cables are long cables containing power and data transmission lines that connect spaced receivers represented by shaded rectangles, such as receiver 204, to seismic data acquisition equipment, computers, and data storage devices located aboard the seismic survey vessel 102.Adjacent seismic cables are connected via cables, such as cable 206, to maintain equal separation between the seismic cables behind the seismic survey vessel 102, while the seismic cables are pulled in opposite orthogonal directions by the lateral paravanes 208 and 210. Buoys (not shown) may be attached to the tail ends of the seismic cables for visibility, to aid in determining GPS location, and / or to help maintain the orientation and depth of the seismic cables below the free surface of the water body.

[0028] Seismic cables can be towed to form a horizontal seismic data acquisition surface that is flat relative to the free surface. However, in practice, seismic cables may vary slightly due to active ocean currents and weather conditions. A seismic data acquisition surface is not limited to the parallel seismic cables shown in Figures 1A, 1B, and 2B. In other implementations, seismic cables can be towed with progressively greater seismic cable separation in the orthogonal direction of the surface towards the surface. Petition 870260062013, dated 06 / 24 / 2026, p. 20 / 76 / 31 longer distances from the seismic survey vessel 102 in a process called streamer fanning. Streamer fanning spreads seismic cables further, increasing the distance from the seismic survey vessel in the linear direction. Streamer fanning can improve coverage at distant source / receiver displacements without compromising seismic data resolution or quality, and can also increase acquisition efficiency by reducing seismic data fill. In still other implementations, seismic cables can be towed at a downward slope, increasing the distance from the seismic survey vessel. A seismic data acquisition surface is not limited to sixteen cables, as shown in Figures 1A, 1B, and 2B.In practice, the number of seismic cables used to form a seismic data acquisition surface can vary from just one seismic cable to as many as 20 or more seismic cables.

[0029] In Figure 2A, seismic survey vessel 102 tows the sixteen seismic cables below the free surface 212 of the water body. Curve 214 represents an upper surface of the subsurface formation 110 located in the lower part of the water body. The shaded rectangles 216a-216f are OBS receivers representing the OBN receivers positioned on the surface of formation 214, as shown in Figure 1A, or represent the OBC receivers positioned on the surface of formation 214, as shown in Figure 1B. The subsurface formation 110 may have many subsurface layers of sediments and rocks. Curves 218, 220, and 222 represent interfaces between subsurface layers of different compositions. A shaded region 224 represents an underground hydrocarbon deposit, whose depth and positional coordinates can be determined, at least in part, through processing seismic data recorded during a Petition 870260062013, dated 06 / 24 / 2026, p. 21 / 76 / 31 marine seismic survey. As the seismic survey vessel 102 moves over the subsurface formation 110, the seismic source 104 produces acoustic energy in the form of a source wave field that disperses in all directions away from the seismic source 104. For simplicity, Figure 2A shows an external field expanding from the source wave field 226 represented, in cross-section in the vertical plane, by circles of increasing radius centered on the source 104. Any part of the source wave field 226 reflected downwards from the free surface 212 is called the phantom source wave field.The wave field of origin eventually reaches the surface of formation 214, at which point the wave field may be partially reflected from the surface of formation 214 and partially refracted downwards onto subsurface formation 110, becoming elastic waves within subsurface formation 110. In the body of water, the wave field of origin 226 comprises compressive pressure waves, or P-waves, while in subsurface formation 110, the elastic waves include P-waves and transverse waves, or S-waves. Within subsurface formation 110, at each interface between different material types or at discontinuities in density or in one or more of several other physical characteristics or parameters, downward propagating elastic waves may be partially reflected and partially refracted.As a result, each point on the surface of formation 214 and each point on interfaces 218, 220, and 222 can be a reflector that becomes a potential secondary point source from which the energy of acoustic and elastic waves, respectively, can disperse upward toward receivers located on the surface of formation 214 and receivers located on seismic cables 108. As shown in Figure 2A, waves of significant amplitude can generally be reflected from points on or near the surface of formation 214, such as point 228, and points on or very near it. Petition 870260062013, dated 06 / 24 / 2026, p. 22 / 76 / 31 interfaces in the underground formation 110, such as points 230 and 232.

[0030] Waves comprising a reflected wavefield can generally be reflected at different times within a time range after the generation of an originating wavefield. A point on the surface of formation 214, such as point 228, may receive a pressure disturbance from the originating wavefield more rapidly than a point within the subsurface formation 110, such as points 230 and 232. Similarly, a point on the surface of formation 214 directly below source 104 may receive the pressure disturbance earlier than a more distant point on the surface of formation 214. Thus, the times at which waves are reflected from various points within subsurface formation 110 may be related to the distance, in three-dimensional space, of the points from the activated source.

[0031] Each receiver of the seismic cables may include a particle motion sensor and a pressure sensor. A pressure sensor detects variations in water pressure over time. The term particle motion sensor is a general term used to refer to a sensor that can be configured to detect particle displacement, particle velocity, or particle acceleration over time. The seismic cables and the seismic survey vessel 102 may include electronic sensors and data processing and / or recording capabilities that allow the seismic data generated by each receiver to be correlated with the time at which each air gun is activated, absolute positions on the free surface 212, and absolute three-dimensional positions relative to an arbitrary three-dimensional coordinate system.The pressure wave field and the particle motion wave field can be stored in the receiver and / or transmitted along seismic cables and data transmission cables to the survey vessel. Petition 870260062013, dated 06 / 24 / 2026, page 23 / 76 14 / 31 seismic 102, where data can be stored electronically, magnetically or optically on data storage devices located on board the seismic survey vessel 102 and / or transmitted ashore to data storage devices located at a seismic data processing facility.

[0032] A marine seismic survey is carried out with a seismic survey vessel towing a series of sources and numerous seismic cables in regularly spaced sail lines above an array of uniformly distributed OBS receivers positioned over the surface of a subsurface formation. The distance between adjacent sail lines, called sail line separation, can be related to the number of seismic cables towed by the seismic survey vessel and the average separation between seismic cables as follows: S&Psaii η X SepstreamX Nstream(1) where SepSaii_ is the candle line separation; Sepstream is the average separation between seismic cables in the shortest source / receiver displacements (i.e., the distance between the nearest adjacent seismic cables to the seismic survey vessel); Nstream is the number of seismic cables towed by the seismic survey vessel; en is a seismic cable spreading factor (i.e., 0 < n < D

[0033] ). The seismic cable spreading is the orthogonal distance between the outermost seismic cables towed by the seismic survey vessel and is given by [Sepstream(Nstream - 1). The seismic cable spreading factor is the fraction of overlap between the seismic cable spreadings in the region between adjacent sail lines, where a spreading factor of Petition 870260062013, dated 06 / 24 / 2026, p. 24 / 76 A seismic cable scatter factor of zero corresponds to no overlap, and a seismic cable scatter factor of one corresponds to almost total overlap. For uniform source separation in the orthogonal direction, the separation between extensive towed sources is Sepsource = Sepsan / Nsource, where Nsource is the number of sources. In other words, the separation between large towed sources with wide lateral spacing depends on the sail line separation divided by the number of sources. For two or more towed sources with wide lateral spacing, the separation between adjacent sources in the orthogonal direction is greater than the separation between seismic cables (i.e., Sepsource > Sepstream).

[0034] Figure 3 shows a plan view (xy plane) of an exemplary seismic survey vessel towing two towed sources of large lateral offset (i.e., NSource = 2) and sixteen seismic cables (i.e., Nstream = 16) along adjacent sail lines at different times during a marine seismic survey. Dashed lines 301 and 302 represent the adjacent sail lines traversed by a seismic survey vessel 304 towing two towed sources of large lateral offset 306 and 308 and sixteen seismic cables at different times during the seismic survey. In this example, the seismic cable dispersion is 15 x Sepstream and the selected seismic cable scattering factor is n = 0.5, which corresponds to a seismic cable dispersion overlap of approximately 50% and a Sepsaii sail line separation = 0.5 x Sepstream x Nstream - For a seismic cable overlap of approximately 50%, the area between sail lines 301 and 302 is covered twice by different halves of the seismic cables during the marine survey. For example, as survey vessel 304 moves along seismic line 301, half of the seismic cables cover the area between sail lines 301 and 302. As survey vessel 304 moves along seismic line 302 subsequently no. Petition 870260062013, dated 06 / 24 / 2026, p. 25 / 76 / 31 survey, the other half of the seismic cables covers the same area between sail lines 301 and 302. The separation between sources between the two widely spaced towed sources 304 and 306 in the orthogonal direction is SePsource — Sep., / 2.

[0035] An array of OBS receivers is positioned on the surface of an underground formation with a separation between OBS receivers given by SepoBs — kx Sepsail, where k is a natural number (i.e., k > 0). Since the separation of sail lines is also equal to the separation between sources in the orthogonal direction multiplied by the number of Sepsail sources (i.e., Sepsail — Nsource x Sepsource), the separation between OBS receivers in the orthogonal direction is related to the separation between sources in the orthogonal direction by [SepoBS — kx (Nsource x Sepsource)]. The separation between sources in the orthogonal direction can be chosen based on a separation between selected orthogonal direction OBS receivers given by Sepsource — SepoBS / (kx Nsource). A seismic cable subline is a line of CMPs in the orthogonal direction by a source and the receivers located along a seismic cable.An OBS receiver subline is a line of CMPs in the in-line direction of a source towed by a seismic survey vessel and the OBS receivers aligned in the in-line direction. The separation of sail lines (Sepsail), separation between sources (Sepsource), and separation between OBS receivers (SepoBS) are selected as described below with reference to the examples shown in Figures 4A-7, so that the seismic cable sublines and the OBS receiver sublines are substantially parallel and uniformly spaced and in the orthogonal direction.

[0036] Figures 4A-4E show an example of a separation between seismic lines, a separation between sources, and a separation between OBS receivers selected for a marine survey conducted with a seismic survey vessel towing two towed sources. Petition 870260062013, dated 06 / 24 / 2026, p. 26 / 76 17 / 31 large lateral spacing and sixteen cables to obtain evenly spaced parallel sublines and evenly spaced parallel sublines of OBS receivers in the orthogonal direction. The seismic cable scattering factor in the sail line separation is n = 0.5, which gives approximately 50% seismic cable scattering overlap in the area between adjacent sail lines, as described above with reference to Figure 3.

[0037] Figure 4A shows a front or rear view (yz plane) of a seismic survey vessel 401, two widely spaced towed sources 402 and 403, and sixteen seismic cables represented by a line of dots. For example, point 404 represents a view in the yz plane of a seismic cable. Line 406 represents a hypothetical horizontal reflector in the xy plane. Dashed ray paths represent the acoustic energy generated by source 402 and reflected from points on the horizontal reflector 406 with CMPs located midway between source 402 and receivers located on seismic cables. A CMP is given by xm = (¾ + xr) / 2, where xr is a receiver coordinate (xr,yr) on the free surface and xs is a source coordinate ((χΛ, yó)) on the free surface.For example, the dashed ray paths 408 and 410 represent the acoustic energy reflected from a point 412 on the horizontal reflector with a CMP located halfway between the source 402 and a receiver on the seismic cable 414. The solid ray paths represent the acoustic energy generated by the source 403 and reflected from points on the horizontal reflector 406 with CMPs located halfway between the source 403 and the receivers located on the seismic cables.

[0038] Figure 4B shows a plan view (xy plane) of seismic survey vessel 401 and the towed, wide-spacing sources 402 and 403 and the sixteen seismic cables represented by the dotted line in Figure 4A. The seismic cable sublines are represented by Petition 870260062013, dated 06 / 24 / 2026, p. 27 / 76 / 31 parallel solid lines located between the seismic cables. Each seismic cable subline represents the CMPs for one of the two sources 402 and 403 and the receivers located along a seismic cable. A seismic cable subline 420 comprises the CMPs located halfway between source 402 and receivers located along seismic cable 414. For example, a CMP 422 is located along seismic cable subline 420 halfway between the free surface coordinates of source 402 and a receiver 424 on seismic cable 414.

[0039] Figure 4C shows a plan view (xy plane) of uniformly distributed OBS receivers, uniformly spaced sail lines, uniformly spaced source paths, and uniformly spaced OBS receiver sublines in the orthogonal direction. Shaded circles, such as shaded circle 426, represent OBS receivers positioned on the surface of a subsurface formation. In certain implementations, the OBS receivers may be OBNs that have been positioned at regularly spaced grid points on the surface of the formation. In other implementations, the OBS receivers may be OBC receivers that have been positioned on the surface of the formation and are electronically connected to a record survey vessel.The dashed lines 428 and 430 represent adjacent sail lines traversed by the seismic survey vessel 401 towing the widely spaced towed sources 402 and 403 at different times during the marine seismic survey. In order to illustrate and describe sail line separation, source separation, and OBS receiver separations, the sixteen seismic cables towed by the seismic survey vessel 401 in Figure 4B have been omitted in Figure 4C. Sail lines 430 and 432 are separated by a seismic line separation Sepsaii 432. In this example, the OBS receiver separation SepoBs 434 in the orthogonal direction is equal to the sail line separation Sepsaii 432 (i.e. Petition 870260062013, dated 06 / 24 / 2026, p. 28 / 76 / 31 is, SepoBs = Sepsaii, where k = 1). Dashed lines 436a and 436b represent the source trajectories of sources 402 and 403, respectively, as seismic survey vessel 401 moves along seismic line 428. Dashed lines 436c and 436d represent the source trajectories of sources 402 and 403 when seismic survey vessel 401 moves along seismic line 430 at a different time in the marine survey. Since the sail lines are separated by Sepsaii = 2 x Sepsource, the trajectories of adjacent sources 436a-436d are uniformly spaced by the same Sepsource separation in the orthogonal direction. For example, the trajectories of sources 436a and 436b are separated by the Sepsource separation, and the trajectories of sources 436c and 436d are also separated by the Sepsource separation.Even though the trajectories of sources 436b and 436c are associated with different sail lines 428 and 430, the trajectories of sources 436b and 436c are adjacent and separated by the Sepsource source separation. The OBS receiver sublines are represented by the parallel lines 438a-438h. Each OBS receiver subline extends in the line direction and represents the CMPs for one of the two sources 402 and 403 and the OBS receivers aligned in the line direction. For example, a CMP 440 is located along the OBS receiver subline 438a halfway between the free surface coordinates of source 402 and an OBS receiver 442, and a CMP 444 is located along the OBS receiver subline 438g halfway between the free surface coordinates of source 402 and an OBS receiver 446.As seismic survey vessel 401 moves along adjacent sail lines 430 and 432, the OBS receiver sublines 438a-438h are parallel and evenly spaced in the orthogonal direction by half the separation between sources (i.e., Sepsource / 2).

[0040] As seismic survey vessel 401 moves along adjacent sail lines 428 and 430 at times Petition 870260062013, dated 06 / 24 / 2026, p. 29 / 76 / 31 different, the overlapping seismic cable sublines have twice the normal distance. In Figure 4D, seismic survey vessel 401 tows the wide-spacing towed sources 402 and 403 and the sixteen seismic cables with associated sequence cable sublines described above with reference to Figure 4B. Four seismic cable sublines associated with towing seismic survey vessel 401 along seismic line 428 are nominally aligned with the seismic cable sublines associated with towing seismic survey vessel 401 along seismic line 430 later in the marine seismic survey, as represented by directional arrows 448a-448d.

[0041] Figure 4E shows an example of evenly spaced seismic cable sublines, such as seismic cable subline 450 and evenly spaced OBS receiver sublines 438a-438h in the orthogonal direction. Overlapping seismic cable sublines on each seismic line are replicated by adjacent sail line sublines. For example, the four most central sublines are overlapping seismic cable sublines and are twice the normal distance apart. As shown in the example in Figure 4E, the evenly spaced seismic cable sublines are parallel to each other and parallel to the evenly spaced OBS receiver sublines.

[0042] A hybrid marine survey can be carried out as illustrated in Figures 4A-4E with a seismic cable separation of about 100 m (Sepstream = 100 m), a source separation of about 400 m (Sepsource = 400 m) for two towed sources with large lateral offset (Nsource = 2), resulting in a seismic cable subline separation of about 50 m (i.e., Sepst-sub = Sepstream / 2). For a source separation of 400 m, the sail line separation and the OBS receiver separation in the orthogonal direction can be equal to about 800 m (Sepsail = SepoBs = 800 m). Petition 870260062013, dated 06 / 24 / 2026, p. 30 / 76 21 / 31

[0043] Figures 5A-5D show an example of a sailline separation, source separation, and OBS receiver separation selected for a marine survey conducted with a seismic survey vessel towing two laterally far-spacing towed sources and eighteen seismic cables to obtain uniformly spaced parallel sublines and uniformly spaced parallel OBS receiver sublines in the orthogonal direction. The seismic cable scattering factor in the sailline separation is n = 0.5, which gives approximately 50% seismic cable scattering overlap in the area between adjacent saillines.

[0044] Figure 5A shows a front or rear view (yz plane) of a seismic survey vessel 501, two widely spaced towed sources 502 and 503, and eighteen seismic cables represented by a dashed line. Line 504 represents a hypothetical horizontal reflector in the xy plane. Dashed line ray paths represent the acoustic energy generated by source 502 and reflected from points on the horizontal reflector 504 with CMPs located midway between source 502 and receivers located on seismic cables. Solid line ray paths represent the acoustic energy generated by source 503 and reflected from points on the horizontal reflector 504 with CMPs located midway between source 503 and receivers located on seismic cables. In region 506, the reflection points alternate between CMPs associated with the two sources 502 and 503.Empty CMPs are free surface locations where CMPs between one of the sources and receivers located along a seismic cable are absent, creating gaps between CMPs in the orthogonal direction. The arrows identify the locations that correspond to empty CMPs. For example, arrows 508 and 510 correspond to empty CMPs.

[0045] Figure 5B shows a plan view (xy plane) of seismic survey vessel 501 and the towed sources from a great distance. Petition 870260062013, dated 06 / 24 / 2026, p. 31 / 76 / 31 lateral 502 and 503 and the eighteen seismic cables represented by the dotted line in Figure 5A. Seismic cable sublines are represented by parallel solid lines located between the seismic cables. Dashed lines, such as dashed line 512, represent nominally empty seismic cable sublines that correspond to the empty CMPs in Figure 5A. For example, the nominally empty seismic cable sublines identified by dashed lines in Figure 5B correspond to empty CMPs identified by arrows 508 and 510 in Figure 5A.

[0046] Figure 5C shows a plan view (xy plane) of uniformly distributed OBS receivers, uniformly spaced sail lines, uniformly spaced source paths, and uniformly spaced OBS receiver sublines in the orthogonal direction. Shaded circles, such as shaded circle 514, represent OBS receivers positioned on the surface of a subsurface formation. In certain implementations, the OBS receivers may be OBNs that have been positioned at regularly spaced grid points on the surface of the formation. In other implementations, the OBS receivers may be OBC receivers that have been positioned on the surface of the formation and are electronically connected to a record survey vessel.Dashed lines 516 and 518 represent the adjacent sail lines traveled by seismic survey vessel 501 towing large towed sources with wide lateral spacing 502 and 503 and eighteen seismic cables at different times in the marine seismic survey. Sail lines 516 and 518 are separated by a sail line separation Sepsaii 520. In this example, the separation between receivers SepoBs 522 in the orthogonal direction is equal to the sail line separation Sepsaii 520 (i.e., SepoBs = Sepsaii, where k = 1). Dashed lines 520a and 520b represent the source trajectories of sources 502 and 503, respectively, as survey vessel 501 moves along seismic line 516. Petition 870260062013, dated 06 / 24 / 2026, p. 32 / 76 / 31 Dashed lines 520c and 520d represent the source trajectories of sources 502 and 503 as survey vessel 501 moves along seismic line 518 at a different time in the marine survey. Because sail lines are separated by Sepsail = 2 x Sepsource, adjacent source trajectories 520a-520d are evenly spaced by the same Sepsource separation in the orthogonal direction. Although the trajectories of sources 520b and 520c are associated with different sail lines 516 and 518, the trajectories of sources 520b and 520c are separated by the Sepsource separation. OBS receiver sublines are represented by parallel lines 522a-522h. Each subline of OBS receivers extends in the linear direction and represents the CMPs for one of the two sources 502 and 503 and the OBS receivers aligned in the linear direction.The OBS 438a-438h receiver sublines are parallel and evenly spaced in the orthogonal direction by half the separation between sources (i.e., Sepsource / 21). As the seismic survey vessel 501 moves along the adjacent sail lines 516 and 518 at different times, the nominally empty seismic cable sublines located between the sail lines are filled in by non-empty seismic cable sublines to create parallel and evenly spaced seismic cable sublines. In Figure 5C, the nominally empty seismic cable sublines associated with towing the seismic survey vessel 501 along seismic line 516 are aligned with the non-empty seismic cable sublines associated with towing the seismic survey vessel 501 along seismic line 518. For example, the directional arrow 524 identifies the alignment of an empty seismic cable subline 526 with a non-empty seismic cable subline 528.For the Sepsail sail line separation, the empty seismic cable sublines located within the area between sail lines 516 and 518 are filled in by seismic cable sublines associated with seismic survey vessel 501. Petition 870260062013, dated 06 / 24 / 2026, p. 33 / 76 / 31 moves along the adjacent seismic line 518, resulting in parallel and evenly spaced seismic cable sublines in the orthogonal direction.

[0047] Figure 5D shows an example of uniformly spaced seismic cable sublines, such as seismic cable subline 452, and uniformly spaced OBS receiver sublines 520a-520h in the orthogonal direction. As shown in the example in Figure 4E, the uniformly spaced seismic cable sublines are parallel to each other and parallel to the uniformly spaced OBS receiver sublines.

[0048] A hybrid marine survey can be carried out, as illustrated in Figures 5A-5D, with a seismic cable separation of about 100 m (Sepstream = 100 m), a source separation of about 450 m (Sepsource = 450 m) for two towed sources with large lateral offset (Sepsource = 2), resulting in a seismic cable subline separation of about 25 m (i.e., Sepst-sub = Sepstream / 4). For a source separation of 450 m, the sail line separation and the OBS receiver separation in the orthogonal direction can both be equal to about 900 m (Sepsail = SepoBS = 900 m).

[0049] Marine surveys conducted according to the methods described in this document are not limited to two widely spaced towed sources and OBS receiver separation equal to sail line separation, as described above. A seismic survey vessel may tow two or more widely spaced towed sources, and the OBS receiver separation in the orthogonal direction may be increased by two, three, four, or more times the sail line separation. Exemplary hybrid marine surveys shown in Figures 6-8 below illustrate examples of different sail lines and OBS receiver separations, and variations in the number of towed sources that produce separations between seismic cables (seismic gauge cables) and OBS receiver sublines in the direction Petition 870260062013, dated 06 / 24 / 2026, p. 34 / 76 25 / 31 orthogonal uniforms.

[0050] Figure 6 shows a plan view (xy plane) of an example of seismic survey vessel 501 towing three large lateral offset towed sources 602, 603 and 604 and sixteen seismic cables above an array of OBS receivers positioned on the surface of a subsurface formation. Shaded circles, such as shaded circle 605, represent OBS receivers of the OBS receiver array. The dashed-dotted lines 606 and 608 represent adjacent sail lines. Seismic survey vessel 601 tows sources 602, 604 and seismic cables along the two sail lines 606 and 608 at different times in a marine survey. Dashed lines 610a, 610b, 610c, and 610d represent the source paths of sources 602 and 604, respectively, with the source path to the middle source 603 overlapping candle lines 606 and 608.In this example, the Sepsau sail line separation is equal to the Sepoes OBS receiver separation in the orthogonal direction. For the three towed sources with large lateral offsets 602, 603, and 604, the source separations in the orthogonal direction are Sepsource = SepSaii / 3, and the OBS receiver separation in the orthogonal direction is Sepoes = Sep sail — 3 x 5' ep source.

[0051] Figure 7 shows a plan view (xy plane) of an example of seismic survey vessel 701 towing four large lateral offset towed sources 702, 703, 704 and 705 and sixteen seismic cables above an array of OBS receivers positioned over the surface of a subsurface formation. Shaded circles, such as shaded circle 705, represent OBS receivers of the OBS receiver array. The dashed-dotted lines 706 and 708 represent adjacent sail lines. Seismic survey vessel 701 tows sources 702, 705 and seismic cables along the two sail lines 706 and 708 at different times in a marine seismic survey. The lines Petition 870260062013, dated 06 / 24 / 2026, p. 35 / 76 / 31. Dashed lines 712a-712d represent the source paths of the four sources 702-705 as the seismic survey vessel 701 moves along seismic line 706. Dashed lines 712e-712h represent the source paths of the four sources 702-705 as the seismic survey vessel 701 moves along seismic line 708. In this example, the sail line separation is equal to the OBS receiver separation in the orthogonal direction. For the four towed sources with large lateral spacing 702-705, the separations between sources in the orthogonal direction are Sepsource = Sepsaii / 4 and the separation between OBS receivers in the orthogonal direction is SepoBS = Sepsail = 4 x Sepsource.

[0052] Figure 8 shows a plan view (xy plane) of a seismic survey vessel 801 towing two large lateral offset towed sources 802 and 804 and sixteen seismic cables above an array of OBS receivers positioned on the surface of a subsurface formation. Shaded circles, such as shaded circle 805, represent OBS receivers of the OBS receiver array. Dashed-dotted lines 806a-806f represent adjacent sail lines traversed by the seismic survey vessel 801 at different times in a marine seismic survey. The dashed lines 808a808l represent the source trajectories of the two towed sources with large lateral offsets 802 and 804. In this example, the separation between receivers OBS is twice the separation of sail lines in the orthogonal direction (i.e., SepoBS = 2 x Sep a).For the two towed sources with large lateral distances 802 and 804, the separations between sources in the orthogonal direction are Sepsource = Sepsaii / 2 and the separation between receivers OBS in the orthogonal direction is SepoBS = 2 x SepoBS = 4 x Sepsource.

[0053] In other implementations, the OBS receivers of an OBS receiver array can be deployed on the surface of an underground formation with a separation between OBS receivers in the direction Petition 870260062013, dated 06 / 24 / 2026, p. 36 / 76 / 31 orthogonal given by SepoBs = 0.5 x (k + 1) x Sepsail to obtain uniform seismic cable and OBS receiver sublines, as described above. For example, OBS receivers can be separated in the orthogonal direction by 1.5 x Sepsail, 2.5 x Sepsail, and 3.5 x Sepsail.

[0054] In certain implementations, a hybrid marine seismic survey can be performed by cross-shooting, where a seismic survey vessel tows large laterally offset towed sources and seismic cables nominally perpendicular to a parallel arrangement of OBCs or nodes on a string deployed in a subsurface formation. Figure 9 shows a plan view (xy plane) of a hybrid marine survey performed by cross-shooting. Lines 901-905 represent five OBCs or represent cables connecting OBNs to form five sets of nodes on a string. The OBS receivers distributed along the cables are represented by shaded circles, as is shaded circle 906. Each cable is configured with the same separation between OBS receivers SepoBS 908. In this example, the cables are deployed nominally parallel to each other in the orthogonal direction and with OBS receivers aligned in the line direction.As a result, the OBS receivers are deployed in a regular, uniform grid. The dashed arrow 910 represents a seismic line traversed by a seismic survey vessel 912. The seismic sources and cables towed by the seismic survey vessel 912 are not shown for illustrative purposes. A hybrid marine survey conducted with the OBCs or knots on a rope and a survey vessel towing large lateral offset towed sources and seismic cables, as shown in Figure 9, provides uniform sublines of seismic cables and OBS receivers, as described above.

[0055] In other implementations, a hybrid marine survey can be carried out with parallel firing, where a seismic survey vessel tows large lateral spacing towed sources and cables. Petition 870260062013, dated 06 / 24 / 2026, p. 37 / 76 / 31 seismic nominally parallel to a parallel arrangement of OBCs or nodes on a string deployed in a subsurface formation. Figure 10 shows a plan view (xy plane) of a hybrid marine survey conducted with parallel shooting. Lines 1001-1003 represent three OBCs or represent cables connecting OBNs to form three sets of nodes on a string. The OBS receivers distributed along the cables are represented by shaded circles, as is shaded circle 1004. Cables 1001-1003 are deployed nominally parallel to each other in the linear direction and with the same separation between OBS receivers SepoBs 1006 in the orthogonal direction. The dashed arrow 1008 represents an ideal seismic line oriented parallel to cables 1001-1003.With parallel firing, a seismic survey vessel can move along the ideal seismic line 1008 towing large laterally offset towed sources and seismic cables oriented parallel to cables 1001-1003. However, with parallel firing, such an arrangement is not necessary. If a seismic survey vessel 1010 towing large laterally offset towed sources (not shown) and seismic cables (not shown) moves along a seismic line 1012 oriented at a skewed angle θ 1014 relative to the ideal seismic line 1008, then, to ensure uniform geometries of seismic cable lines and receiver lines OBS, the sail lines are oriented parallel to the seismic line 1012, with a sail line separation between adjacent sail lines given by Sepcrooked = SepoBs cos θ.

[0056] Figure 11A shows a table summarizing the relationships described above between OBS receiver separations and source separations in the orthogonal direction for a selected sailline separation. Each entry in the table contains an OBS receiver separation and a source separation that can be used in a marine survey and are determined based on the selected sailline separation. The Petition 870260062013, dated 06 / 24 / 2026, page 38 / 76 / 31 entries in each row represent separations between different OBS receivers as multiples of the candle line separation for a fixed number of sources and a fixed separation between sources in the orthogonal direction. The entries in each column represent separations between different sources for different numbers of sources in the orthogonal direction and a fixed separation between OBS receivers.

[0057] Figure 11B shows a table summarizing the relationships described above between sail line separation and source separations in the orthogonal direction for a selected orthogonal OBS receiver separation. Each entry in the table contains a sail line separation and a source separation that can be used in a marine survey and are determined based on a selected orthogonal OBS receiver separation. The entries in each row represent different sail line separations and source separations in the orthogonal direction for a fixed number of sources and a selected orthogonal OBS receiver separation. The entries in each column represent different source separations and a sail line separation for a fixed orthogonal OBS receiver separation.

[0058] Figure 12 shows a method for conducting a marine survey of a subsurface formation. In block 1201, a sailline separation in an orthogonal direction is determined for the marine survey based on an average separation between seismic cables and a selected number of seismic cables for the marine survey. In block 1202, an array of OBS receivers is deployed over a surface of the subsurface formation. The OBS receivers are spaced in the orthogonal direction by an OBS receiver separation that is based on the sailline separation. In block 1203, two or more towed sources with wide lateral spacing and multiple seismic cables are towed above the array. Petition 870260062013, dated 06 / 24 / 2026, p. 39 / 76 / 31 of OBS receivers in sail lines in the line direction. The sail lines are spaced in the orthogonal direction with a sail line separation that is based on the separation between OBS receivers. In block 1204, towed sources with wide lateral spacing are activated as towed sources with wide lateral spacing and seismic cables are towed above the OBS receiver array. In block 1205, wave fields reflected from the subsurface formation are recorded in the OBS receivers and the receivers located on the seismic cables as seismic data.

[0059] Figure 13 shows a method for conducting a marine survey of a subsurface formation. In block 1301, a sailline separation in an orthogonal direction is determined for saillines of a marine survey based on an average separation between seismic cables and the selected number of seismic cables for the marine survey. In block 1302, a separation between sources on the directed seismic line is determined for two or more laterally far-sparse towed sources based on the sailline separation and a selected number of laterally far-sparse towed sources. In block 1303, an array of OBS receivers is deposited on a surface of the subsurface formation. The OBS receivers are spaced in the orthogonal direction by an OBS receiver separation that is based on the sailline separation.In block 1304, two or more laterally spaced towed sources and seismic cables are towed above the OBS receiver array in the in-line direction and in separate sail lines in the orthogonal direction by sail line separation. In block 1305, laterally spaced towed sources are activated as laterally spaced towed sources and seismic cables are towed above the OBS receiver array. In block 1306, wave fields reflected from the subsurface formation are recorded on the OBS receivers and receivers located on the seismic cables as seismic data. Petition 870260062013, dated 06 / 24 / 2026, p. 40 / 76 / 31

[0060] The methods and systems described in this document can be used to produce a geophysical data product indicative of certain properties of a subsurface formation. A geophysical data product can be produced using the methods and systems described in this document to generate geophysical data and store the geophysical data on a computer-readable medium. The geophysical data can be pressure data, vertical velocity data, hydrophone data, or geophone data, and any image of a subsurface formation calculated from the seismic data recorded using the methods and systems described in this document. The geophysical data product can be produced offshore (i.e., by equipment on the seismic survey vessel 102) or onshore (i.e., at an onshore computing facility), or both.

[0061] It should be recognized that the foregoing description of the embodiments described is provided to enable any person skilled in the art to make or use the present invention. Various modifications to the embodiments will be apparent to those skilled in the art, and the generic principles set forth herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be strictly limited to the embodiments shown herein, but should be granted the broadest scope consistent with the innovative principles and features described herein.

Claims

CLAIMS 1. Method for carrying out a marine survey of a subterranean formation, the method comprising: determining (1201) a separation between sail lines in a direction orthogonal to the marine survey; towing (1203) two or more widely spaced towed sources and seismic cables in the direction in line behind a seismic survey vessel; activating (1204) the widely spaced towed sources; and recording (1205) wave fields reflected from the subterranean formation on receivers located on the seismic cables as seismic data;characterized in that determining (1201) the separation between sail lines in the orthogonal direction comprises multiplying an average separation between seismic cables by the selected number of seismic cables and a seismic cable spreading factor corresponding to a percentage of overlap of the seismic cables in a region between adjacent sail lines separated by the sail line separation; the method further comprising: depositing (1202) a seafloor seismic receiver array, OBS, on a surface of the subsurface formation with an OBS receiver separation in the orthogonal direction based on the sail line separation; wherein two or more towed sources of wide lateral spacing and seismic cables are towed above the OBS receiver array in the direction in line behind the seismic survey vessel;and the method also includes recording (1205) wave fields Petition 870260062013, dated 06 / 24 / 2026, page 42 / 76 2 / 6 reflected from the underground formation at the OBS receivers as seismic data.; 2. Method, according to claim 1, characterized in that depositing the set of OBS receptors on the surface of the underground formation with separation between the OBS receptors in the orthogonal direction comprises determining a separation between the OBS receptors in the orthogonal direction based on the separation of candle lines multiplied by a selected natural number value.

3. A method according to claim 1 or 2, characterized in that towing two or more laterally far-spar towed sources and seismic cables above the OBS receiver array in the in-line direction comprises: determining a source separation between adjacent laterally far-spar towed sources based on the sail line separation divided by the number of sources; and towing the laterally far-spar towed sources in the in-line direction along the trajectories of the sources separated by the source separation.

4. A method according to any one of claims 1 to 3, characterized in that towing two or more laterally far-spar towed sources and seismic cables above the OBS receiver array in the in-line direction comprises: determining a source separation between adjacent laterally far-spar towed sources based on the separation between the OBS receivers and the number of sources; and towing laterally far-spar towed sources in the in-line direction along the source paths separated by the source separation.

5. Method, according to any one of claims 1 to 4, Petition 870260062013, dated 06 / 24 / 2026, p. 43 / 76 3 / 6 characterized in that towing two or more towed sources of wide lateral spacing and seismic cables behind the seismic survey vessel along the sail lines comprises: towing the two or more towed sources of wide lateral spacing and seismic cables behind the seismic survey vessel along a first sail line between the sail lines; and towing the two or more towed sources of wide lateral spacing and seismic cables behind the seismic survey vessel along a second sail line adjacent to the first line, such that seismic cable sublines are aligned with empty seismic cable sublines.

6. A method according to any one of claims 1 to 5, characterized in that towing the two or more laterally far-spacing towed sources and seismic cables above the OBS receiver array comprises towing the two or more laterally far-spacing towed sources such that seismic cable sublines are uniformly spaced in the orthogonal direction and OBS receiver sublines are uniformly spaced in the orthogonal direction.

7. A method according to any one of claims 1 to 6, characterized in that it further comprises: determining a separation between sources in the orthogonal direction for two or more towed sources of great lateral spacing based on the separation between the sail lines and a selected number of towed sources of great lateral spacing; wherein the two or more towed sources of great lateral spacing are spaced in the orthogonal direction by the separation between sources.

8. Method, according to claim 7, characterized in that determining the separation between sources in the orthogonal direction Petition 870260062013, dated 06 / 24 / 2026, page 44 / 76 4 / 6 comprises determining the separation between sources between adjacent towed sources of large lateral spacing based on the separation between sail lines divided by the number of sources.

9. Method according to claim 7, characterized in that towing the seismic cables and the two or more towed sources of great lateral spacing behind the seismic survey vessel comprises the seismic survey vessel traveling on sail lines separated in the orthogonal direction by the separation between the sail lines.

10. Method for carrying out a marine survey of a subsurface formation, comprising: determining (1201, 1301) a separation between sail lines in an orthogonal direction; towing (1203, 1304) two or more towed sources of wide lateral spacing and seismic cables in the direction in line behind a seismic survey vessel moving along the sail lines separated in the orthogonal direction by the separation between the sail lines; activating (1204, 1305) the towed sources of wide lateral spacing; and recording (1205, 1306) wave fields reflected from the subsurface formation on receivers located on the seismic cables as seismic data; characterized in that the separation between sail lines is determined as the separation between seismic receivers on the ocean floor, OBS, in the orthogonal direction, divided by a natural number for an array of OBS receivers deployed on the subsurface formation;wherein two or more towed sources with wide lateral spacing and seismic cables are towed above the OBS receiver array in the direction in line behind the seismic survey vessel Petition 870260062013, dated 24 / 06 / 2026, p. 45 / 76 5 / 6; and the method further comprises recording (1205) wave fields reflected from the subsurface formation on the OBS receivers as seismic data.; 11. A method according to claim 10, characterized in that towing two or more laterally far-spar towed sources and seismic cables above the OBS receiver array in the in-line direction comprises: determining a source separation between adjacent laterally far-spar towed sources based on the sail line separation divided by the number of sources; and towing laterally far-spar towed sources in the in-line direction along the trajectories of the sources separated by the source separation.

12. A method according to any one of claims 10 or 11, characterized in that towing two or more laterally far-spar towed sources and seismic cables above the OBS receiver array in the in-line direction comprises: determining a source separation between adjacent laterally far-spar towed sources based on the separation between the OBS receivers and the number of sources; and towing laterally far-spar towed sources in the in-line direction along the source paths separated by the source separation.

13. Method, according to any one of claims 10 to 12, characterized in that towing two or more towed sources of large lateral spacing and seismic cables behind the seismic survey vessel along the sail lines comprises: towing the two or more towed sources of large lateral spacing and seismic cables behind the seismic survey vessel along a first seismic line of the sail lines; and tow the two or more widely spaced towed sources and seismic cables behind the seismic survey vessel along a second seismic line adjacent to the first line, so that seismic cable sublines are aligned with empty seismic cable sublines.

14. A method according to any one of claims 10 to 13, characterized in that towing the two or more laterally far-spacing towed sources and seismic cables above the OBS receiver array comprises towing two or more laterally far-spacing towed sources such that the seismic cable sublines are uniformly spaced in the orthogonal direction and the OBS receiver sublines are uniformly spaced in the orthogonal direction.

15. Method for producing a geophysical data product, characterized in that it comprises carrying out the method as defined in any one of claims 1 to 14, and storing the recorded seismic data on a non-transient, computer-readable medium.

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