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    • 专利摘要:
    METHODS AND SYSTEMS FOR IMAGING UNDERGROUND FORMATIONS WITH PRIMARY AND MULTIPLE REFLECTIONS. The present invention relates to systems and methods for imagining underground formations using primary and multiple reflections that are described. A seismological exploration vessel tows a seismic source, a receiver acquisition surface located under a free surface, and a source acquisition surface positioned at a depth below the source. The receiver acquisition surface is used to measure pressure and normal velocity wave fields and the source acquisition surface is used to measure direct descending source pressure wave fields generated by the source. The downward pressure wave fields in combination with the downward pressure wave fields and upward pressure wave fields computed from the pressure and velocity wave fields are used to compute images of the underground formation associated with primary reflections and multiple reflections. .
    公开号:BR102013013084B1
    申请号:R102013013084-2
    申请日:2013-05-27
    公开日:2021-02-17
    发明作者:Walter Söllner；Norman Daniel Whitmore, Jr.；Stian Hegna；Charles Lameloise；Rune Tonnessen；Gregory Ernest Parkes
    申请人:Pgs Geophysical As；
    IPC主号:
    专利说明:

    [0001] [0001] Since the last few decades, the oil industry has invested heavily in the development of maritime seismic survey techniques that produce knowledge of underground formations under a body of water in order to find and extract valuable mineral resources such as oil. High-resolution seismic images of an underground formation are essential for quantitative seismic interpretation and improved reservoir monitoring. For a typical marine seismic survey, a seismological exploration vessel tows one or more seismic sources and one or more seismographic cables that form a seismic data acquisition surface below the water surface and on an underground formation to be surveyed for discovery of mineral deposits. The vessel contains seismic acquisition equipment, such as navigation control, seismic source control, seismic receiver control and recording equipment. The seismic source control causes one or more seismic sources, which are typically air cannons, to produce acoustic impulses at selected times. Each impulse is a sound wave that travels down through the water and into the underground formation. At each interface between different types of rock, a part of the sound wave is refracted, a part of the sound wave is transmitted and another part is reflected back towards the body of water to propagate upwards towards the surface of the water. The floating seismographic cables towed behind the ship are elongated structures such as cables. Each floating seismographic cable includes several seismic receivers or sensors that detect pressure and / or velocity wave fields associated with the sound waves reflected back into the water by the underground formation.
    [0002] [0002] Sound waves that propagate down the subsurface and undergo a single reflection at an interface before being detected by seismic receptors are called "primary reflections", and sound waves that pass through several subsurface reflections before being detected by seismic receivers are called "multiple reflections". Multiple reflections can also be primary reflections that are subsequently reflected by the sea surface downwards on the subsurface before being detected by the receivers. In the past, conventional imaging techniques relied almost exclusively on primary reflections. As a result, significant computational effort was devoted to mitigating multiple reflections. In recent years, however, multiple reflections have been recognized as providing valuable additional information regarding underground formation. In particular, multiple reflections that include at least one reflection over the sea surface, called "sea surface multiples", are typically the strongest and most significant of the multiple reflections to use in imaging an underground formation. When an underground formation is imaged with wave fields associated with primary and multiple reflections, the field of direct incident waves that originates from the source is significant for using the primary reflections in the imaging process. However, because of the large minimum lateral distance between the source and the closest receivers and the large distance between the floating seismographic cables of a typical acquisition system, measuring the field of direct incident waves is difficult. As a result, people working in the oil industry continue to look for systems and methods that can be used to measure the field of direct incident waves. Description of Drawings
    [0003] [0003] Figure 1 shows a volume of domain of the earth's surface.
    [0004] [0004] Figure 2 shows the subsurface resources of an underground formation at the bottom of the domain volume shown in Figure 1.
    [0005] [0005] Figures 3A-3C show a method of seismological exploration by which digitally encoded data is obtained instrumentally for processing and analysis of subsequent seismological exploration in order to characterize the structures and distributions of resources and materials underlying the solid surface of the earth.
    [0006] [0006] Figures 4A-4B show top and side elevation views, respectively, of a seismology exploration vessel towing a source, a source acquisition surface and floating seismographic receiver cables.
    [0007] [0007] Figures 5A-5B show an isometric view and a side elevation view, respectively, of an exemplary seismic source.
    [0008] [0008] Figure 6A shows an example graph of hypothetical distant field gun signatures.
    [0009] [0009] Figure 6B shows an example graph of hypothetical resulting distant field signature associated with a seismic source.
    [0010] [00010] Figures 7A-7B show top and side elevation views, respectively, of an example source acquisition surface.
    [0011] [00011] Figure 7C shows a cross-sectional view of the source acquisition surface shown in Figures 7A-7B, along a line A-A, looking in the direction of a seismic exploration vessel.
    [0012] [00012] Figures 8A-8B show top and side elevation views, respectively, of an example source acquisition surface.
    [0013] [00013] Figure 9 shows a top view of a source acquisition surface such as an example.
    [0014] [00014] Figure 10 shows a side elevation view of an example source acquisition surface with paravanes.
    [0015] [00015] Figure 11A shows a side elevation view of an approximately flat source acquisition surface.
    [0016] [00016] Figure 11B shows a cross-sectional view of the flat source acquisition surface shown in Figure 11A, along a line B-B, looking in the direction of a seismic exploration vessel.
    [0017] [00017] Figures 12A-12B show top and side elevation views, respectively, of a source acquisition surface.
    [0018] [00018] Figure 13 shows a top view of a source acquisition surface with two floating source seismographic cables that cross below a seismic source.
    [0019] [00019] Figures 14A-14B show isometric and side elevation views, respectively, of a source that includes a source acquisition surface.
    [0020] [00020] Figures 15A-15B show isometric and side elevation views, respectively, of a source that includes a source acquisition surface.
    [0021] [00021] Figure 16 shows a control flow diagram of a method for imagining an underground formation with primary and multiple reflections.
    [0022] [00022] Figure 17 shows a side elevation view of a floating seismographic cable located under a free surface.
    [0023] [00023] Figure 18 shows an example of a generalized computer system that performs an efficient method for computing three-dimensional images of an underground formation under a volume of fluid. Detailed Description
    [0024] [00024] Systems and methods for imagining underground formations using primary and multiple reflections are described. A seismological exploration vessel tows several floating seismographic cables that form a receiver acquisition surface located under an air / fluid surface referred to as a "free surface". Floating seismographic cables include receivers that measure pressure and normal velocity wave fields that are digitally encoded and stored. The ship also tows an acoustic source and a source acquisition surface positioned at a depth substantially below the source. The source acquisition surface includes several pressure sensors to measure direct descending source pressure wave fields generated by the source, which are digitally encoded and stored. The descending source pressure wave fields and ascending pressure wave fields computed from the pressure and velocity wave fields can be used to compute images of the underground formation associated with primary reflections. The pressure wave and normal velocity fields can be used to separate the pressure wave field into ascending and descending pressure wave fields at the receiving end (or predefined extrapolation level), which can be used to compute images of the underground formation associated with multiple reflections. The images associated with the primary and multiple reflections can be combined to form an image of the underground formation. Alternatively, when the full descending pressure wave field includes the descending source wave field and the descending reflected (or spread) wave field at an arbitrary extrapolation level, the images of the underground formation associated with primary and multiple reflections can be computed in a single computational operation.
    [0025] [00025] The following discussion includes three subsections: an overview of exploration seismology, examples of seismic sources and acquisition surfaces, and computational methods for imagining an underground formation with primary and multiple reflections as an example of processing methods and systems computational. Reading of the first subsection can be omitted by those already familiar with seismology of maritime exploration. An Overview of Maritime Exploration Seismology
    [0026] [00026] Figure 1 shows a volume of domain of the earth's surface. Domain volume 102 comprises a solid volume of sediment and rock 104 below the solid surface 106 of the earth, which in turn lies beneath a fluid volume of water 108 within an ocean, inlet or bay, or a large freshwater lake. The domain volume shown in figure 1 represents an example experimental domain for a class of empirical and analytical techniques and systems for exploration seismology referred to as "maritime exploration seismology".
    [0027] [00027] Figure 2 shows subsurface resources of an underground formation at the bottom of the domain volume shown in Figure 1. As shown in Figure 2, for exploration seismology purposes, fluid volume 108 is a volume of one generally homogeneous, relatively without characteristic features, overlapping the solid volume 104 of interest. However, while fluid volume 108 can be explored, analyzed and characterized with relative precision using many different types of methods and probes, including remote sensing submersibles, sonar and other such devices and methods, the underlying solid volume crust 104 the volume of fluid is comparatively much more difficult to probe and characterize. Unlike overlapping fluid volume 108, solid volume 104 is significantly heterogeneous and anisotropic, and includes many different types of resources and materials of interest to exploration seismology. For example, as shown in figure 2, solid volume 104 may include a first layer of sediment 202, a first layer of fractured and upward displaced rock 204, and a second layer of underlying rock 206 below the first layer of rock. In certain cases, the second layer of rock 206 may be porous and may contain a significant concentration of liquid hydrocarbon 208 that is less dense than the material of the second layer of rock and therefore rises within the second layer of rock 206. In the case shown in figure 2, the first layer of rock 204 is non-porous and therefore forms a cover that prevents further migration upwards of the liquid hydrocarbon, which therefore concentrates in a saturated layer of hydrocarbon 208 below the first layer of rock 204. An objective of exploration seismology is to identify the locations of porous strata saturated with hydrocarbon within volumes of the earth's crust underlying the solid surface of the earth.
    [0028] [00028] Figures 3A-3C show a seismological exploration method by which digitally encoded data is obtained instrumentally for subsequent processing and analysis of seismological exploration in order to characterize the structures and distribution of resources and materials in an underground formation. Figure 3A shows an example of a seismological exploration vessel 302 equipped to perform a continuous series of seismological exploration experiments and data collections. In particular, ship 302 tugs one or more floating seismographic cables 304-305 across a plane of approximately constant depth generally located several meters below the free surface 306. Floating seismographic cables 304-305 are long cables containing lines of transmission of energy and data to which receivers, also referred to as "sensors", are connected at regular intervals. In a type of seismological exploration, each receiver, such as the receiver represented by the darkened disc 308 in figure 3A, comprises a pair of seismic receivers including a geophone that detects vertical displacement within the fluid medium over time by detecting movement, speeds or particle accelerations, and a hydrophone that detects variations in pressure over time. Floating seismographic cables 304-305 and vessel 302 include sophisticated electronics and data processing structures that allow receiver readings to be correlated with absolute positions on the free surface and absolute three-dimensional positions with respect to an arbitrary three-dimensional coordinate system. In figure 3A, the receivers along the floating seismographic cables are shown to be below the free surface 306, with the receiver positions correlated with overlapping surface positions, such as a surface position 310 correlated with the position of the receiver 308. Ship 302 also tows one or more sources of acoustic waves 312 which produce pressure pulses at spatial and temporal intervals as ship 302 and towed seismographic cables 304-305 travel across the free surface 306.
    [0029] [00029] Figure 3B shows an expanding spherical acoustic wavefront, represented by semicircles of increasing rays centered on the acoustic source 312, such as semicircle 316, following an acoustic pulse emitted by the acoustic source 312. The wave fronts, in fact, they are shown in a flat vertical cross section in figure 3B. As shown in figure 3C, the field of acoustic waves expanding outward and downward, shown in figure 3B, eventually reaches the solid surface 106, at which point the acoustic waves expanding outwardly and partially reflect off the solid surface and refract partially down into the solid volume, becoming elastic waves within the solid volume. In other words, in the fluid volume, the waves are compressive pressure waves, or P waves, whose propagation can be modeled by the acoustic wave equation, whereas in a solid volume, the waves include both P waves and transverse waves, or S waves, whose propagation can be modeled by the elastic wave equation. Within the solid volume, at each interface between different types of materials or in discontinuities in density or in one or more of several other physical characteristics or parameters, waves propagating downwards are partially reflected and partially refracted, just as on the solid surface 106. As As a result, each point on the solid surface and within the underlying solid volume 104 becomes a potential secondary point source from which acoustic and elastic waves, respectively, can emanate upwards towards receivers in response to the pressure pulse emitted by the acoustic source 312. and downward elastic waves generated by the pressure impulse.
    [0030] [00030] As shown in figure 3C, secondary waves of significant amplitude are generally emitted from points on or near solid surface 106, such as point 320, and points on a discontinuity in solid volume 104, or very close to it, such as points 322 and 324. Tertiary waves can be emitted by the free surface 306 back to solid surface 106 in response to secondary waves emitted by the solid surface and subsurface resources.
    [0031] [00031] Figure 3C also shows the fact that secondary waves are generally emitted at different times within a time range following the initial pressure pulse. A point on solid surface 106, such as point 320, receives a pressure disturbance corresponding to the initial pressure pulse more quickly than a point within solid volume 104, such as points 322 and 324. Similarly, a point on the solid surface directly underlying the acoustic source it receives the pressure impulse earlier than a point further away from the solid surface. Thus, the times in which secondary and higher order waves are emitted by the various points within the solid volume are related to the distance, in three-dimensional space, from the points to the acoustic source.
    [0032] [00032] Acoustic and elastic waves, however, move at different speeds within different materials as well as within the same material under different pressures. Therefore, the displacement times of the initial pressure pulse and secondary waves emitted in response to the initial pressure pulse are complex functions of the distance from the acoustic source as well as the materials and physical characteristics of the materials through which the acoustic wave corresponding to the initial pressure impulse moves. Furthermore, as shown in figure 3C for the secondary wave emitted by point 322, the shapes of the expanding wave fronts can be changed as the wave fronts cross interfaces and as the speed of sound varies in the media. crossed by the wave. The superposition of waves emitted from within the volume of domain 102 in response to the initial pressure pulse is a wave field in a generally very complicated way that includes information regarding the shapes, sizes and material characteristics of the volume of domain 102, including information about the shapes, sizes and locations of the various resources reflecting within the underground formation of interest for seismological exploration. Examples of Seismic Sources and Source Acquisition Surfaces
    [0033] [00033] Figures 4A-4B show top and side elevation views, respectively, of a seismological exploration ship 402 towing a source 404, a source acquisition surface 406 and the eight separate floating seismographic cables 408-415 located under a free surface. In figure 4A, each floating seismographic cable is attached at one end to the ship 402 by means of a floating seismographic cable data transmission cable and at the opposite end to a buoy, such as a buoy 416 attached to the floating seismographic cable 412. For For example, the floating seismographic cables 410-413 are attached to the ship 402 by means of the data transmission cables of floating seismographic cable 418-421, respectively. The floating seismographic cables 408-415 ideally form a flat horizontal receiver acquisition surface located under the free surface. However, in practice, the receiver acquisition surface may vary slightly due to active sea currents and weather conditions. In other words, towed floating seismographic cables can wave as a result of dynamic fluid conditions. Figure 4B represents a snapshot, in a moment in time, of the free undulating surface 422 and similar to the corresponding smooth wave in the floating seismographic cable 412. Figure 4A includes an xy plane 423 and figure 4B includes an xz plane 424 of the same Cartesian coordinate system used to specify orientations and coordinate locations within the fluid volume with respect to three orthogonal spatial coordinate axes labeled x, y, and z. The x coordinate specifies exclusively the position of a point in a direction parallel to the length of the floating seismographic cables, and the y coordinate specifies exclusively the position of a point in a direction perpendicular to the x axis and substantially parallel to the free surface 422, and the z coordinate uniquely specifies the position of a point perpendicular to the xy plane with the positive z direction pointing downward away from the free surface. As shown in figure 4B, the floating seismographic cable 412 is at a depth, Zr, below the free surface, which can be estimated at various locations along the floating seismographic cables from hydrostatic pressure measurements made by depth controllers. (not shown), such as paravanes or water kites, attached to floating seismographic cables. Depth controllers are typically placed at intervals of about 300 meters along each floating seismographic cable. The estimated floating seismographic cable depths are then used to calculate a two-dimensional interpolated floating seismographic cable shape that approximates the wave-like shape of a real floating seismographic cable in an instant in time. Alternatively, the estimated floating seismographic cable depths can be used to calculate a three-dimensional interpolated surface approximation of the acquisition surface. The depth zr and the elevation of the free surface profile are estimated in relation to the geoid, which is represented in figure 4B by the dotted line 425. The geoid is the hypothetical surface of the land that coincides everywhere with average sea level and is used to define zero elevation (ie, z = 0). In figures 4A and 4B, darkened disks, such as darkened disk 426 in figure 4A, represent receivers spaced at regular intervals. The coordinates of receiver 426 are given by (xr, yr, zr), where the depth zr can be an interpolated value.
    [0034] [00034] Figure 4B also shows examples of primary and multiple reflections. The dotted directional arrows 428 represent a "primary reflection" in which sound waves associated with a sound pulse generated by the source 406 pass directly from the source 406 through the source acquisition surface 406 and enter the seabed 430 to undergo a reflection in an underground interface 432 back to the fluid volume to be measured by the receivers on the receiver acquisition surface. Figure 4B also shows examples of multiple source layer and receiver side fluid layer reflections. The directional arrows of dash and dot lines 434 represent multiples of the source side fluid layer in which a sound wave generated by the source 404 crosses the source acquisition surface 406 before undergoing multiple reflections consisting of a sequence of reflections in the background of the sea 430 and reflections on the free surface 422, and followed by a reflection on the interface 432 before being measured by the receivers of the receiver acquisition surface. The dashed line directional arrows 436 represent multiples of the receiver side fluid layer in which a sound wave generated by the source 404 passes through the source acquisition surface 406 before undergoing multiple reflections consisting of a reflection at the interface 432, a sequence of reflections on the free surface 422 and reflections on the seabed 430 before being measured by the receivers on the receiver acquisition surface. Source 406 also produces sound waves that are first reflected by the free surface, as represented by directional arrow 438, before the waves travel into the underground formation to produce scattered wave fields directed backwards towards the free surface. These types of sound waves are called "source ghosts", which are delayed in time in relation to the sound waves that travel directly from the source 404 to the underground formation. Source ghosts can amplify some frequencies and attenuate other frequencies and are typically manifested as spectral indentations in the recorded seismic waveforms, making it difficult to obtain accurate high-resolution seismic images of the underground formation.
    [0035] [00035] The 404 seismic source can be implemented as a set of seismic source elements, such as air cannons, water cannons or vibrating sources, in order to overcome undesirable aspects of a signature associated with a single source element. Figures 5A-5B show an isometric view and a side elevation view, respectively, of an example seismic source 500. The source 500 includes the three separate floats 501-503 and the corresponding three separate rods 505-507 suspended by floats 501 -503. Each rod is suspended by a corresponding float by means of several cables or wires, such as cables 508 that suspend rod 505 below float 501. In the example of figure 5A, eleven cannons are suspended by each rod. For example, the eleven cannons denoted by G1-G11 are suspended by rod 505. In other words, the source 500 is composed of a set of thirty-three cannons 510. Consider, for example, air cannons. Each air gun injects a high pressure air bubble into the fluid as a source of energy to generate waves of acoustic pressure that radiate outward. In other words, when a bubble is released from a cannon there is a radial displacement of water from the center of the bubble and a pressure disturbance is propagated outwardly in the fluid. As the bubble expands, the air pressure in the bubble decreases until it falls to that of the surrounding fluid, but inertia causes the bubble to expand more so that the air pressure in the bubble is less than the hydrostatic pressure of the surrounding fluid. . Then the very expanded bubble contracts because of the hydrostatic pressure of the surrounding fluid. The expansion and contraction process continues with the bubble oscillating through many cycles. As the bubble oscillates and the bubble pressure varies, pressure waves radiate outward into the fluid. The amplitude of the bubble oscillation decreases with time, and the period of oscillation decreases from one cycle to the next. The change in pressure in the fluid as a function of time caused by the bubble is called a "cannon signature". The detailed features of a signature are determined by the subsequent movement of the bubble following its release from a cannon.
    [0036] [00036] Each cannon has a near-field signature and a distant field signature associated with it. "Near field" and "distant field" are expressions used to describe the proximity of an observation point to a cannon when the signature is measured. For a cannon that releases a pressure wave with a wavelength λ = c / f, where c is the speed of sound in the fluid and f is the frequency, the radial regions of near and far fields surrounding the cannon can be defined as : Nearby field: d ˂ λ Intermediate field: d ～ λ Distant field: λ ≪ d where d is the distance from the cannon to an observation point.
    [0037] [00037] Figure 5C represents a graph of a hypothetical near-field signature associated with a cannon. The horizontal axis 512 represents time and the vertical axis 514 represents pressure. The first peak 516 represents the initial development and release of a cannon bubble into the fluid, after which the subsequent peaks 517-519 represent a decrease in amplitude with increasing time. The near-field signature reveals that the pressure after reaching a peak drops to values below the hydrostatic pressure ph. The amplitude of the bubble oscillation decreases as time passes and the period of the bubble oscillation is not constant from one cycle to the next. In other words, the bubble movement is not a simple harmonic movement. The chamber volume of a cannon determines the associated near-field signature, which is also influenced by the pressure waves created by other cannons in the cannon set. In general, the greater the volume of the chamber, the greater the amplitude of the peaks and the greater the bubble periods of the associated nearby field signatures.
    [0038] [00038] The cannons of a set of cannons are selected with different chamber volumes and arranged in a particular way in order to generate a resulting distant field seismic wave with a small and narrow signature in the vertical downward direction and with a spectrum that be uniform and broad over a frequency band of interest. Figure 6A shows an example graph of hypothetical distant field gun signatures associated with the eleven G1-G11 guns shown in figure 5. The horizontal axis 602 represents time, the vertical axis 604 represents pressure, and the oblique axis 606 represents the G1-G11 gun indexes. Each distant field signature includes a first large positive peak followed in time by a second large negative peak, which is followed by a series of smaller non-periodic oscillations. For example, the distant field signature associated with cannon G1 has a first large positive peak 608, a second large negative peak 609 and a series of non-periodic oscillations 610 associated with dampened oscillations of a bubble released from cannon G1 as measured by a pressure sensor in the distant field. The first large positive peak of each distant field signature is the initial pressure release from the cannon bubble in the distant field and is called the "primary peak". The second large negative peak from each distant field signature represents the initial pressure release reflected by the free surface and is called a "source phantom". G1-G11 guns are selected with different air chamber volumes to produce different dampened bubble oscillations following primary peaks. Figure 6A represents the signatures of distant fields associated with the G1-G11 guns when the guns are firing simultaneously. As a result, each distant field signature has a primary peak at approximately the same point in time. The signatures of distant fields associated with each of the individual cannons in a set of cannons do not match according to the principle of superposition. If interactions between pressure waves generated by cannons in a set of cannons are negligible or non-existent, the signatures of distant fields can be combined according to the principle of superposition to calculate a desirable distant field signature resulting from the set of cannons. However, interactions between the pressure waves created by the guns are not negligible, especially at low frequencies. Instead, G1-G11 cannons are selected with different chamber volumes, gun spacing and cannon positions within the gun set to amplify primary peaks and cancel dampened bubble oscillations to produce a source signature. hypothetical resulting distant field 612 from the G1-G11 cannons plotted in Figure 6B. The resulting distant field source signature 612 has an amplified primary 614 followed in time by very small amplitude oscillations. The resulting amplified primary 614 is an example of the direct downward pressure wave field used to produce the primary reflection 428 described above with reference to figure 4B.
    [0039] [00039] It should be noted that seismic sources are not intended to be limited to the set of thirty three example guns 610 shown in figure 6A. In practice, seismic sources can be configured with one or more floats and each float can have any number of cannons suspended by the float. Cannons can be arranged and selected with chamber volumes to produce a resulting distant field source signature that substantially matches the resulting distant field source signature shown in Figure 6B.
    [0040] [00040] Figure 7A shows a top view of an example source acquisition surface 702 located under the source 500 shown in figure 5. The source acquisition surface 702 includes the ten floating source seismographic cables 704-713 connected to a transverse data transmission cable 714, which is connected at a first end to a slip collar 716 and is connected at a second end to a slip collar 718. The slip collars 716 and 718, in turn, are attached to the transmission cables of floating seismographic cables 418 and 421, respectively. In other words, the source acquisition surface 702 is suspended in the fluid by the floating seismographic cable transmission cables 418 and 421. The source acquisition surface 702 is also connected to vessel 402 by means of the source data transmission cables. 720 and 722. Transmission cable 720 is connected at one end to cable 714 and is connected at a second end to ship 402, and transmission cable 722 is connected at one end to cable 714 and is connected at a second end to ship 402. As shown in the example in figure 7A, the floating source seismographic cables are shorter in length than the floating seismographic cables of the receiver acquisition surface shown in figure 4. Figure 7B shows a side elevation view of the source acquisition surface 702 located under the source 500, which is attached to the ship (not shown) via source cables, such as the source cable 726. The seismographic cables Floating source aphases 709-713 are located behind the floating seismographic cables 704-708 and are not shown in figure 7B. Floating source seismographic cables 704-713 are weighed to form a curved source acquisition surface 702 with the heavier source floating seismographic cables 708 and 709 located under source 500 and the lightest floating source seismographic cables 704 and 713 located further away from the source 500. For example, in figure 7B, the floating seismographic cable 704 is lighter than the floating seismographic cable 705, which in turn is lighter than the floating seismographic cable 706 and so on. Darkened circles, such as darkened circles 724, represent receivers (or groups of receivers) distributed at regular intervals along the columns of source elements 704-708, or receivers distributed in a mesh on a level under the sources. The receivers can be pressure sensors (or groups of pressure sensors arranged along the normal to the acquisition surface) or pressure sensors in combination with particle motion sensors. Figure 7C shows a cross-sectional view of the source acquisition surface shown in Figures 7A-7B, along a line AA, looking towards the rear of ship 402.
    [0041] [00041] The source 500 is operated as described previously with reference to figures 5-6 to generate a wave field that is measured by the receivers of the source acquisition surface 702. The wave field measured at each receiver of the surface 702 is transmitted as a signal along a corresponding source floating seismographic cable to the transmission cable 714. The signals are then transmitted from the data transmission cable 714 to the transmission cables 720 and 722, which carry the signals to the ship 402.
    [0042] [00042] In the example in figure 7, the source acquisition surface 702 is located below the level of the cannon set. In practice, the source acquisition surface may be located closest to the cannon set with floating source seismographic cables located on the outside of the source acquisition surface at approximately the same level as or above the cannon set.
    [0043] [00043] An additional cross cable can be used to secure the rear ends of the floating source seismographic cables. Figures 8A-8B show top and side elevation views, respectively, of a sample source acquisition surface 802. Surface 802 is similar to surface 702 described above with reference to figure 7, except that surface 802 includes a cable transverse 804 attached to the rear ends of floating source seismographic cables 704-713. The cross cable 804 is connected at one end to a slip collar 806 and is connected at a second end to a slip collar 808. Slip collars 806 and 808, in turn, are attached to the cable transmission cables floating seismographs 418 and 421, respectively. The transverse cable 802 adds stability and increases the depths of the rear ends of the floating seismographic cables 704-713 as shown in figure 8B. The cross cable 804 can also be a data transmission cable that carries signals from the floating seismographic cables 704-713 to the transmission cables 720 and 722.
    [0044] [00044] A source acquisition surface may include several cross cables to form a source acquisition surface such as a network. Figure 9 shows a top view of an example source acquisition surface 902. Surface 902 is similar to surface 802, except that surface 902 includes the three additional cross cables 904-906 attached to the floating seismographic source cables 704- 713. Like the transverse cables 714 and 804 described earlier, cables 904-906 are connected to the transmission cables of floating seismographic cables 418 and 421 by means of sliding collars. One, two or all three cross cables 904-906 can be data transmission cables that carry signals from the floating seismographic cables 704-713 to the transmission cables 720 and 722.
    [0045] [00045] Floating source seismographic cables can also be equipped with depth controllers, such as paravanes or water pipes, to control the position and maintain the depths of floating source seismographic cables. Figure 10 shows a side elevation view of an example source acquisition surface 1002. In the example in figure 10, surface 1002 is similar to surface 702 described above, except that each of the floating seismographic cables is equipped with two parapets , such as paraffins 1004 and 1006 attached to the floating seismographic cable 708. Paravanes include wings can include depth sensors, and can be controlled remotely to control the shapes, positions and depths of floating seismographic cables to create the acquisition surface. font with a desired shape. In other embodiments, the floating source seismographic cables can have approximately the same weight and the paravanes can be weighted and / or operated to control the shapes, positions and depths of the floating source seismographic cables.
    [0046] [00046] Source acquisition surfaces are also not limited to curved surfaces. Font acquisition surfaces can also have an approximately flat configuration. Figure 11A shows a side elevation view of an approximately flat source acquisition surface of example 1102, and figure 11B shows a cross-sectional view of surface 1102 along a line BB, shown in figure 11A, looking in the direction of the back of the ship 402. The surface 1102 is similar to the source acquisition surface 702 except that the surface 1102 is composed of the floating seismographic cables of source 1104-1113 that have approximately the same weight in order to position them at approximately the same depth below of the free surface. Floating seismographic cables 1104-1113 are connected to a data transmission cable 1116 that carries signals for transmission cables 720 and 722. Surface 1102 can also include several cross cables as described previously with reference to figures 8-9 for forming a substantially flat source acquisition surface with a structure such as a network.
    [0047] [00047] A source acquisition surface may include floating source seismographic cables located below and on opposite sides of the source. Figures 12A-12B show top and side elevation views, respectively, of an example source acquisition surface 1202 composed of the five floating source seismographic cables 1204-1208. Floating seismographic cables 1204-1208 are attached to data transmission cables 1210 represented by dashed lines. The data transmission cables attached to the floating seismographic cables 1204 and 1205 are connected to the source cable 1212 by means of the slip collar 1214; the data transmission cable attached to the floating seismographic cable 1206 is connected to the source cable 1216 by means of the slip collar 1218; and the transmission cables attached to the floating seismographic cables 1207 and 1208 are connected to the source cable 1220 by means of the slip collar 1222. As shown in the example in figure 12, the floating seismographic cables 1205-1207 are positioned below the columns of source elements of source 500 and floating seismographic cables 1204 and 1208 are positioned at shallower depths and on the sides of source 500. floating seismographic cables 1205-1207 measure the descending source wave fields, and shallower floating seismographic cables 1204 and 1208 measure fields of source waves spreading horizontally. Floating seismographic cables 1205-1207 can be heavier than floating seismographic cables 1204 and 1208 in order to position floating seismographic cables 1205-1207 deeper than floating seismographic cables 1204 and 1208. Floating seismographic cables 1204-1208 can include paravanes and / or passive controllers laterally, such as paravane 1224 shown in figure 12B, which position the floating seismographic cables 1205-1207 below the source 500 and / or position the floating seismographic cables 1204 and 1208 on opposite sides of the source 500. Floating seismographic cables 1204-1208 may also include buoyancy elements that position the rear ends of the floating seismographic cables 1204-1208 at the desired depth. In other embodiments, a source acquisition system may consist of a single floating source seismographic cable located under the source and have two or more floating source seismographic cables located at different depths on opposite sides of the source.
    [0048] [00048] In other embodiments, the source acquisition surface may include only a single floating source seismographic cable positioned below a source, or the source acquisition surface may have two or more floating source seismographic cables that cross below of the source. Figure 13 shows a top view of an example source acquisition surface 1302 composed of the two floating source seismographic cables 1304 and 1306 that intersect below the source 500. As shown in the example in figure 13, the floating seismographic cable of source 1304 is connected at one end to the floating seismographic cable of receivers 418 by means of a slip collar 1308 and at a second end to the floating seismographic cable by receivers 421 by means of a slip collar 1310. The source floating seismographic cable 1306 is connected at one end to the floating seismographic cable of receivers 421 by means of a slip collar 1312 and at a second end to the floating seismographic cable by receivers 418 by means of a slip collar 1314. Floating seismographic cables 1304 and 1306 are connected to the transmission cables 720 and 722, respectively.
    [0049] [00049] In other modalities, the source acquisition surface can be incorporated into the source in order to obtain near field measurements in the cannons. Near-field measurements are used to calculate theoretical source signatures associated with each of the cannons. A theoretical source signature is a measurement of a near-field pressure sensor without the influence of pressure waves from neighboring guns. Pressure sensors can also be designed to perform direct pressure measurements while suppressing ghosts from a smaller amplitude source. Figures 14A-14B show isometric and side elevation views, respectively, of an example seismic source 1400 that includes a source acquisition surface composed of pressure sensing rods 1401-1403. The 1400 source is similar to the 500 source except that a set of pressure sensing rods 1401-1403 is suspended between the floats and the rods by which the cannons are suspended. For example, pressure sensing rod 1401 is suspended between float 501 and rod 505 by which cannons G1-G11 are suspended. Each stem 1401-1403 includes seven pressure sensors. Each pressure sensor is positioned and designed to directly measure the pressure wave generated by the one or two cannons suspended below the pressure sensor, while suppressing the ghosts of smaller amplitude. For example, stem 1401 includes pressure sensors 1404-1410 with each of these pressure sensors located above one or two of the G1-G11 guns. Pressure sensors 1404-1410 measure the signatures of fields close to the corresponding G1-G11 guns. In other embodiments, the pressure sensing rods can be suspended below the cannons. Figures 15A15B show isometric and side elevation views, respectively, of a source 1500 that includes a source acquisition surface composed of pressure detection rods 1401-1403. The 1400 source is similar to the seismic source 1500 except that the pressure detection rods 1401-1403 are at depths below the cannons. For example, pressure sensing rod 1401 is suspended by rod 505 with cables 1502. In the examples in Figures 14 and 15, pressure sensing rods 1401-1403 form a source acquisition surface that is incorporated into a source . Methods for Imaging with Primary and Multiple Reflections as an Example of Computational Processing Methods and Systems
    [0050] [00050] Computational methods and systems for computing images of an underground formation using primary and multiple reflections are now described. Figure 16 shows a control flow diagram of a method for imagining an underground formation with primary and multiple reflections. In figure 16, blocks 1601 and 1603-1605 are displayed in parallel to blocks 1602, 1606 and 1607, and in the description below the operations associated with blocks 1603-1605 are described before the operations associated with blocks 1606 and 1607. However, blocks 1601-1607 are not intended to be limited to the particular ordering of operations. Alternatively, the computational processes associated with blocks 1603-1605 can be run after the computational processes associated with blocks 1606 and 1607. Alternatively, the computational processes associated with blocks 1603-1605 can be run in parallel with the computational processes associated with blocks 1606 and 1607.
    [0051] [00051] In block 1601, descending source wave fields are measured in source acquisition surface pressure sensors, and in block 1602 pressure wave fields and normal speed wave fields are measured in acquisition surface receivers. of receivers. Figure 17 shows a side elevation view of the floating seismographic cable 412 located under the free surface 422. As shown in figure 17, and in figure 4B, the source acquisition surface 406 and the receiver acquisition surface composed of the cables floating seismographs 408-415 form a closed acquisition surface. Receivers on the receiver acquisition surface are dual sensors that include a pressure sensor, such as a hydrophone, and a motion sensor, such as a geophone. For example, a receiver 1702 includes a pressure sensor that measures a pressure wave field, p (⃗xr, t) 1704, and includes a motion sensor that measures a normal speed wave field, v ⃗n (⃗xr, t ) 1706, where ⃗xr = (xr, yr, zr) et represents time. Motion sensors can be mounted on a joint to guide motion sensors to detect particle movement in a direction normal to the receiver acquisition surface. In other words, the receiver's motion sensor 1702 detects a velocity wave field v normaln normal to the floating seismographic cable 412 with the subscript vector ⃗n representing a normal unit vector pointing downwards in the xz plane. As previously described, the source acquisition surface 406 includes pressure sensors that measure the wave field of the descending source Sdesc (⃗xps, t) 1708 generated by the source 404, where ⃗xps = (xs, ys, zr) represents the coordinates of a pressure sensor on the source acquisition surface at the zr depth level. This wave field can be extrapolated (that is, provided with new data) to a given reference from which the imaging can start.
    [0052] [00052] Returning to figure 16, in block 1603, the theoretical source signatures s (⃗xm, t) are calculated from the wave field measured in the near field pressure sensors, where ⃗xm represents the coordinates ⃗xm = (xm, ym, zm) from an elementary source (for example, air or water cannon) in source 404, shown in figure 14 (see, for example, "The signature of an air gun array: Computation from near– field measurements including interactions ", by A. Ziolkowski et al., Geophysics, Vol. 47, No. 10, October 1982;" The signature of an air gun array: Computation from near-field measurements including interactions-Practical considerations ", by GE Parkes and others , Geophysics, Vol. 48, No. 2, February 1984). Theoretical source signatures s (⃗xm, t) are transformed from the time domain to the frequency domain, and assuming a homogeneous acoustic medium and a free flat surface at z = 0, the wave field of descending source can be calculated in the domain of the frequency-wave number in a flat reference data by:
    [0053] [00053] When the assumptions indicated above are satisfied, the source wave field calculated from the theoretical source signatures and the measured source wave field must be equivalent. On the other hand, any differences can be used to precondition the inversion of theoretical signatures.
    [0054] [00054] In block 1606, the pressure wave field p (⃗xr, t) and the normal speed wave field v ⃗n (⃗xr, t) obtained in block 1602 can be transformed from the space-time domain to the domain of frequency-number of waves using Fourier transformations given by:
    [0055] [00055] In practice, the transformation from the space-time domain to the frequency-wave number domain can also be performed with fast discrete Fourier transformations. In block 1607, wave field decomposition is performed to calculate upward and downward pressure wave fields of the pressure and velocity wave fields in the frequency-wave number domain:
    [0056] [00056] Standardized flow decomposition is an alternative procedure for separating wave fields that satisfies the reciprocity of wave fields at the intersection of interfaces with impedance contrast (see, for example, "Review of elastic and electromagnetic wave propagation in horizontally layered media ", B. Ursin, Geofísica, 48,1063-1081, 1983; and" Reciprocity properties of oneway propagators ", by K. Wapenaar, Geofísica, 63, 1795-1798, 1998).
    [0057] [00057] In block 1608, a depth level z0 greater than zr is selected, as represented by the dashed line 1710 in figure 17. In block 1609, the upward pressure wave field calculated in block 1607 is extrapolated to the level of depth z0 as follows: Pasc (Kx, Ky, Z0, ω) = Pasc (Kx, Ky, Zr, ω) eikz (z0-zr) (6)
    [0058] [00058] In block 1610, the downward wave field calculated in block 1605 is extrapolated to the depth level z0 as follows: Sdesc (Kx, Ky, Z0, ω) = Sdesc (Kx, Ky, Zr, ω) e-ikz (z0-zr) (7) and the downward pressure wave field calculated in block 1607 is also extrapolated to the depth level z0 as follows: Pdesc (Kx, Ky, Z0, ω) = Pdesc (Kx, Ky, Zr, ω) e-ikz (z0-zr) (8)
    [0059] [00059] In block 1611, the Pasc rising wave field (kx, ky, z0, ω) and the descending wave field Sdesc (Kx, Ky, Z0, ω) and Pdesc (Kx, Ky, Z0, ω) suffer inverse transformation of the frequency-wave number domain to the space-frequency domain:
    [0060] [00060] Next, in blocks 1612 and 1613, an imaging condition at the selected depth level is applied. In one embodiment, the imaging condition can be a cross-correlation function given by:
    [0061] [00061] In other modalities, the imaging condition can be a function of deconvolution given by:
    [0062] [00062] The integrals in Equations (10) and (11) can be evaluated using numerical integration. Imaging conditions generate image pixel values. In other words, I (⃗x, z) is a pixel in a digital image of an underground formation. In block 1612, when the cross correlation function given by Equation (10) is used, primary image values at the z0 depth level are calculated by:
    [0063] [00063] In block 1612, when the deconvolution function given by Equation (11) is used, values of primary images at the depth level z0 are calculated by:
    [0064] [00064] It should be noted that, in imaging with primary reflections, the deconvolution imaging condition given by Equation (11) is often used instead of the cross correlation function given by Equation (10) in order to remove an impression of source signature of the final image of an underground formation. Use of the deconvolution imaging condition, however, is important for imaging with multiple reflections because of complex source signatures, including secondary sources.
    [0065] [00065] In block 1614, when another depth level greater than zr is selected, the operations associated with blocks 1608-1613 are repeated to obtain primary image values and multiple image values for the depth level. The operations of blocks 1608 and 1609 are repeated for a series of depth levels to obtain a primary image of the underground formation and a multiple image of the underground formation. In block 1615, the primary image and the multiples image are added to obtain a resulting three-dimensional image of the underground formation given by: Result (x, y, z) = Primary (x, y, z) + Multiple (x, y, z) (16)
    [0066] [00066] It should be noted that, when the deconvolution function given by Equations (11) and (14) is selected as the imaging condition, elimination of ghosts from the Sdesc descending source wave field is not necessary. On the other hand, when the cross correlation function given by Equations (10) and (12) is selected, the descending source wave field Sdesc has the elimination of ghosts in a separate operation.
    [0067] [00067] The computation methods described previously with reference to figure 16 can be applied to imagine an underground formation when the source acquisition surface used to measure the downward wave field is one of several types of source acquisition surfaces. previously described with reference to figures 7-13. On the other hand, when the source acquisition surface is incorporated into the source, as previously described with reference to figures 14 and 15, hydrophones measure the source wave field directly from the cannons and suppress the lower amplitude source phantom. As a result, the downward wave field in block 1605 can be calculated using:
    [0068] [00068] Equation (17) is equal to Equation (1) except that the reflection coefficient r0 is assigned the value zero. As a result, the descending source wave field does not need to have source ghosting eliminated during imaging and the descending source wave field can be used when eliminating source ghosting is not necessary, which is when multiple reflections have been removed from the seismic data. .
    [0069] [00069] Figure 18 shows an illustrative example of a generalized computer system that performs an efficient method for computing images of an underground formation using primary and multiple reflections and, therefore, represents a seismic analysis data processing system for which the description is targeted. The internal components of many small, medium and large computer systems as well as storage systems based on specialized processors can be described with respect to this generalized architecture, although each particular system can feature many additional components, subsystems and similar parallel systems with architectures similar to this generalized architecture. The computer system contains one or multiple central processing units ("CPUs") 1802-1805, one or more electronic memories 1808 interconnected with the CPUs via an 1810 CPU / memory subsystem bus or multiple buses, a first bridge 1812 that interconnects the CPU / memory subsystem bus 1810 to the additional buses 1814 and 1816, or other types of high-speed interconnection media, including multiple high-speed serial interconnections. These serial buses or interconnections, in turn, connect CPUs and memory to specialized processors, such as an 1818 graphics processor, and to one or more additional 1820 bridges, which are interconnected to high-speed serial links or to multiple controllers 1822-1827, such as the 1827 controller, which provide access to several different types of computer-readable media, such as 1828 computer-readable media, electronic displays, input devices, and other such components, subcomponents and computational resources. Electronic displays, including display screens, speakers and other output interfaces, and input devices, including mice, keyboards, touch screens and other such input interfaces, together constitute input and output interfaces that allow the computer system interact with human users. 1828 computer-readable media is a data storage device, including electronic memory, optical or magnetic disk drive, USB drive, flash memory and other such data storage devices. 1828 computer-readable media can be used to store machine-readable instructions associated with the computational methods described above and can be used to store encrypted data, during storage operations, and from which encrypted data can be retrieved, during read operations, computer systems, data storage systems and peripheral devices.
    [0070] [00070] The description set out above, for the purpose of explanation, used specific nomenclature to provide a complete understanding of the revelation. However, it will be apparent to those skilled in the art that specific details are not required in order to practice the systems and methods described in this document. For example, any number of different implementations of computational processing methods that perform efficient generation of a three-dimensional imaging of an underground formation can be designed and developed using several different programming languages and computer platforms and by varying different implementation parameters, including structures control, variables, data structures, modular organization and other such parameters. Computational representations of wave fields, operators and other computational objects can be implemented in different ways.
    [0071] [00071] It should be noted that the previous description of the revealed modalities is provided to enable any person skilled in the art to build or use the present disclosure. Various modifications to these modalities will be readily apparent to those skilled in the art, and the generic principles defined in this document can be applied to other modalities without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the modalities shown in this document, but it is to be given the broadest scope consistent with the unpublished principles and resources disclosed in this document.
    权利要求:
    Claims (22)
    [0001]
    Method for computing images of an underground formation to be performed by a computer system that includes one or more processors and one or more data storage devices, the method characterized by the fact that it comprises: calculate a downward wave field from a pressure wave field measured on a source acquisition surface towed by a seismic exploration vessel (1605); decompose a pressure wave field measured on a vessel acquisition surface towed by the ship into an upward pressure wave field and a downward pressure wave field (1607); and compute an image of the underground formation based on the wave field of descending source combined with the wave field of downward pressure and the wave field of upward pressure (1615).
    [0002]
    Method according to claim 1, characterized by the fact that calculating the wave field of descending source from the pressure wave field comprises: calculate theoretical source signatures from near field pressure recordings (1603); and transform theoretical source signatures from a space-time domain to a frequency-wave number domain, where each theoretical source signature is associated with an element of a seismic source towed by the ship (1604).
    [0003]
    Method according to claim 1, characterized by the fact that decomposing the pressure wave field comprises: transforming the measured pressure wave field and the normal velocity wave field from a space-time domain to a frequency-wave number domain (1606); calculate the upward pressure wave field as a function of the pressure wave and normal velocity fields in the frequency-wave number domain (Equation 4); and calculate the downward pressure wave field as a function of the pressure wave and normal velocity fields in the frequency-wave number domain (Equation 5).
    [0004]
    Method according to claim 1, characterized by the fact that calculating the wave field of downward source from the pressure wave field includes: restrict the calculation of theoretical source signatures based on the source wave field measured on the source acquisition surface.
    [0005]
    Method, according to claim 1, characterized by the fact that computing a first image of the underground formation based on the wave field of descending source and the wave field of upward pressure comprises: for each depth level: extrapolate the downward wave field and the upward pressure wave field to a depth level (1610); transform the wave field of the downward source and the wave field of the upward pressure from the frequency domainwave number to the space-frequency domain (1611); and calculate image values using an imaging condition (1612, 1613).
    [0006]
    Method, according to claim 1, characterized by the fact that computing a second image of the underground formation based on the upward and downward pressure wave fields comprises: for each depth level: extrapolate the upward and downward pressure wave fields to a depth level (1609); transform from the frequency-wave number domain to the space-frequency domain (1611); and calculate image values using an imaging condition (1612, 1613).
    [0007]
    Method for enabling one or more processors in a computer system to perform operations characterized by: calculate a downward wave field from a pressure wave field measured on a source acquisition surface towed by a seismic exploration vessel (1605); decompose a pressure wave field measured on a vessel acquisition surface towed by the ship into an upward pressure wave field and a downward pressure wave field (1607); and calculate an image of the underground formation as a function of the wave field of the downward source, the wave field of the upward pressure and the wave field of the downward pressure (1615).
    [0008]
    Method according to claim 7, characterized by the fact that calculating the wave field of downward source from the pressure wave field includes: restrict the calculation of theoretical source signatures based on the source wave field measured on the source acquisition surface.
    [0009]
    Method, according to claim 7, characterized by the fact that calculating the wave field of descending source from the pressure wave field comprises: calculate theoretical source signatures from near field pressure recordings (1603); and transform theoretical source signatures from a space-time domain to a frequency-wave number domain, where each theoretical source signature is associated with an element of a seismic source towed by the ship (1604).
    [0010]
    Method according to claim 7, characterized by the fact that decomposing the pressure wave field and the normal velocity wave field comprises: transforming the measured pressure wave field and a measured normal velocity wave field on the receiver acquisition surface from a space-time domain to a frequency-wave number domain (1606); calculate the upward pressure wave field as a function of the pressure wave and normal velocity fields in the frequency-wave number domain (Equation 4); and calculate the downward pressure wave field as a function of the pressure wave and normal velocity fields in the frequency-wave number domain (Equation 5).
    [0011]
    Method, according to claim 7, characterized by the fact that calculating an image of the underground formation comprises: compute a first image of the underground formation based on the wave field of descending source and the wave field of upward pressure (1612); compute a second image of the underground formation based on the fields of upward and downward pressure waves (1613); and add the first image and the second image to form the image of the underground formation (1615).
    [0012]
    Method according to claim 11, characterized by the fact that computing the first image of the underground formation based on the wave field of descending source and the wave field of upward pressure comprises: for each depth level: extrapolate the downward wave field and the upward pressure wave field to a depth level (1610); transform the wave field of the downward source and the wave field of the upward pressure from the frequency domainwave number to the space-frequency domain (1611); and calculate image values using an imaging condition (1612, 1613).
    [0013]
    Method, according to claim 11, characterized by the fact that computing the second image of the underground formation based on the upward and downward pressure wave fields comprises: for each depth level: extrapolate the upward and downward pressure wave fields to a depth level (1609); transform from the frequency-wave number domain to the space-frequency domain (1611); and calculate image values using an imaging condition (1612, 1613).
    [0014]
    System for measuring wave fields in fluid volume, the system characterized by the fact that it comprises: a seismic source (404) to be connected to a ship (402) and towed below a surface free of a volume of fluid; a source acquisition surface (406) to be connected to the ship and towed under the source to measure pressure wave fields generated by the source; and a receiver acquisition surface (408 to 415, 426) to be connected to the vessel and towed behind the source acquisition surface to measure pressure and normal speed wave fields associated with the pressure wave fields generated by the source.
    [0015]
    System according to claim 14, characterized by the fact that the source acquisition surface comprises one or more floating source seismographic cables (408 to 415), each floating source seismographic cable having one or more pressure sensors distributed to the along the length of the source floating seismographic cable.
    [0016]
    System according to claim 15, characterized in that the source acquisition surface still comprises a cross data transmission cable having a first end connected to a first source data transmission cable and a second end connected to a second data transmission cable, in which the floating source seismographic cables are connected to the transverse data transmission cable and the source data transmission cables are connected to the vessel.
    [0017]
    System according to claim 15, characterized by the fact that the source acquisition surface still comprises one or more transverse cables (804) connected to the floating source seismographic cables.
    [0018]
    System according to claim 15, characterized by the fact that the floating source seismographic cables are weighed to form a curved source acquisition surface (702).
    [0019]
    System according to claim 15, characterized by the fact that the floating source seismographic cables have approximately the same weight for placing the floating source seismographic cables at approximately the same depth.
    [0020]
    System according to claim 15, characterized in that each floating source seismographic cable still comprises one or more depth controllers to control the depth and position of the floating source seismographic cable.
    [0021]
    System according to claim 15, characterized by the fact that the floating source seismographic cables are crossed.
    [0022]
    System according to claim 14, characterized by the fact that the source acquisition surface to be connected to the ship and towed under the source still comprises a single floating seismographic cable towed under the source to measure a downward wave field. and one or more floating seismographic cables towed on a first side of the source and one or more floating seismographic cables towed on a second side of the source located opposite the first side, the one or more floating seismographic cables to measure downward and propagating wave fields horizontally.
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    同族专利:
    公开号 | 公开日
    US20130322208A1|2013-12-05|
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    BR102013013084A2|2015-06-23|
    EP2669713B1|2021-04-07|
    SG10201509074VA|2015-12-30|
    AU2013205827A1|2013-12-19|
    EP2669713A3|2015-08-19|
    MX339234B|2016-05-16|
    MX2013006122A|2013-11-29|
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    EP2669713A2|2013-12-04|
    AU2013205827B2|2016-08-18|
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    法律状态:
    2015-06-23| B03A| Publication of an application: publication of a patent application or of a certificate of addition of invention|
    2018-12-04| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|
    2019-11-05| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|
    2020-11-24| B09A| Decision: intention to grant|
    2021-02-17| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 27/05/2013, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    US13/484,556|2012-05-31|
    US13/484,556|US9291737B2|2012-05-31|2012-05-31|Methods and systems for imaging subterranean formations with primary and multiple reflections|
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