method for depth calibration of a plurality of seismic receiver channels

专利摘要:
The present invention relates to a seismic receiver matrix that has a plurality of seismic receiver channels, each coupled to a surrounding location in an earth formation. A material-dependent response of each seismic receiver channel is determined, and associated with a depth considered for the corresponding seismic receiver channel. Responses dependent on formation material as a function of the depth considered are compared to a depth profile independent of at least one petrophysical parameter of land formation as a function of depth along the unfinished well. Based on the comparison, a set of delays between said depth considered and depth in the independent depth profile is determined, since it provides the best correlation between the response dependent on training material and the depth profile independent of at least one petrophysical parameter. land formation. The considered depth of each seismic receiver channel can then be aligned to the corresponding depths in the independent depth profile.
公开号:BR112017027708B1
申请号:R112017027708-5
申请日:2016-06-24
公开日:2021-03-02
发明作者:Johan Cornelis Hornman；Albena Alexandrova Mateeva；Paul Maarten Zwartjes
申请人:Shell Internationale Research Maatschappij B.V.；
IPC主号:

专利说明:

FIELD OF THE INVENTION
[001] The present invention relates to a method of calibrating the depths of a plurality of seismic receiver channels in a seismic receiver array arranged in an unfinished well in an earth formation. BACKGROUND OF THE INVENTION
[002] Various seismic techniques have been developed that employ a matrix of seismic receptors arranged in an unfinished well in an earth formation. Examples include tomographic techniques (such as including unfinished well seismic tomography in section), and Vertical Seismic Profile (VSP).
[003] Distributed Acoustic Sensors (DAS) consist of an innovative technology useful for providing such a seismic receiver matrix in an unfinished well in a land formation for purposes of seismic data acquisition. A description of this technology is provided in an article "Distributed acoustic sensing for reservoir monitoring with vertical seismic profiling" by Albena Mateeva et al., Which was shown in Geophysical Prospecting, Volume 62, pages 679 to 692 (2014). Conceptually, DAS measurements are simple. A DAS interrogator unit sends laser pulses along an optical fiber arranged in a well bore, and measures signals from backscattered light. The optical fiber can be subdivided into DAS receiver channels (which correspond, for example, to VSP receiver levels) based on the flight time of a laser pulse over them. However, the exact physical depth analyzer of a DAS receiver channel in relation to geology is not trivial, and requires some calibration of optical depths versus depths in the unfinished well.
[004] Similarly, there may be a need for depth calibration of seismic receiver arrays from other types of seismic receiver channels, such as geophone arrays.
[005] A method for determining the location of a fiber optic channel is described in US 2013/0279841. The location of one or more fiber optic channels in this method is determined by: a) having an electrical conductor and a magnetic source in a known location adjacent to at least one of the channels; b) transmit an electric current through the electric conductor, thereby deforming the electric conductor by Lorenz forces close to the magnetic source;
[006] c) conduct the deformation of the electrical conductor to deform an adjacent channel;
[007] d) transmit the light pulses through the fiber optic cable and use variations in the light pulses retroreflected by the deformed channel and the known location of the magnetic source to determine the location of the deformed channel.
[008] A disadvantage of this known method for determining the location of an optical fiber channel is that it requires additional equipment in the well hole in order to locally deform the optical fiber to a known depth in order to be able to use the variations in the pulses of light retroreflected by the deformed channel and the known depth to determine the depth of the deformed channel in relation to an external frame of reference (such as a geology). SUMMARY OF THE INVENTION
[009] In accordance with a first aspect of the present invention, a method of calibrating the depths of a plurality of seismic receiver channels in a seismic receiver array arranged in an unfinished well in an earth formation is provided, wherein said method comprises:
[0010] - select a seismic receiver matrix arranged in an unfinished well in a land formation, in which said seismic receiver matrix comprises a plurality of seismic receiver channels, whereby, each seismic receiver channel is locally coupled to the earth formation that is present adjacent to the seismic receiver channel;
[0011] - assign a considered depth to each seismic receiver channel in the plurality of seismic receiver channels;
[0012] - determine a response dependent on the formation material of each seismic receiver channel induced by seismic waves that propagate through the formation of earth adjacent to each respective seismic receiver channel location;
[0013] - provide a depth profile independent of at least one petrophysical parameter of land formation as a function of depth along the unfinished well;
[0014] - for numerous seismic receiver channels, determine a set of delays between said depth considered and the depth in the independent depth profile that provides the best correlation between the material-dependent response of the seismic receiver channels and the profile depth independent of at least one petrophysical parameter of land formation; and
[0015] - issue a set of corrected depths or correction values for the plurality of seismic receiver channels to align the considered depth of each seismic receiver channel from the plurality of seismic receiver channels to the corresponding depths in the independent depth profile. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] Figure 1 shows a schematic longitudinal section of an unfinished well in a land formation; Figure 2 shows a schematic view of a DAS cable; Figure 3 shows several profiles of independent depth (3a = gamma ray profile; 3b = sonic profile; 3c = density profile) and a zero deviation VSP (3d) measured using a DAS cable; Figure 4 shows a gamma ray profile (4a), a sonic profile (4b), a blocked sonic profile (4c) and scalars consistent in DAS channel (4d), all of which are derived from the data in Figure 2 between D1 and D3; and Figure 5 shows a gamma ray profile (5a), a density profile (5b), a sonic profile (5c), a blocked sonic profile (5d), an acoustic impedance profile (5e), an impedance profile blocked acoustics (5f), and consistent scalars in DAS channel (5g), all of which are derived from the data in Figure 2 between D2 and D3.
[0017] These Figures are not drawn to scale. The identical numerical references used in different Figures refer to similar components. DETAILED DESCRIPTION OF THE INVENTION
[0018] The invention will be further illustrated hereinafter by way of example only and with reference to the drawing without limitation.
[0019] People skilled in the art will readily understand that, while the invention is illustrated with reference to one (01) or more specific combinations of resources and measures, many of those resources and measures are functionally independent of other resources and measures, so that they can be applied in the same or similar way, independently, in other modalities or combinations.
[0020] In the description and in the claims, the term "formation material dependent response" is a response in the seismic receiver channel that is affected by the elastic properties of the earth formation material to which the receiver channel is coupled. This is the formation material of the earth formation adjacent to the position of the seismic receiver channel. Suitably, the response dependent on training material can be expressed in the form of a channel-consistent scalar amplitude as can be determined using a channel-consistent scalar derivation technique known in the art. A channel-consistent scalar, as understood by those skilled in the art, is a unique numerical value that characterizes the response of a specific channel as configured within its local environment coupled with land formation, by removing contributions or effects from other circumstances that can produce a real response, such as differences in seismic source signatures, or differences in locations of seismic sources, etc. The concept of consistency in seismic detection is well known to those skilled in the art and adequately explained, for example, in a reference document by MT Taner and F Koehler, entitled "Surface consistent corrections" published in Geophysics Volume 46 no 1 ( 1981) pages 17 to 22. Receiver consistency and / or channel consistency as introduced in the present description and claims are considered as physical analogues to surface consistency, applicable when the receiver channels are disposed in an unfinished well in the formation of earth instead of the earth's surface.
[0021] Furthermore, in the context of the present disclosure, the term "depth" is generally understood to mean the measured depth (MD) unless otherwise specified. MD is a term of the technique used to denote length measured along the trajectory or path of the unfinished well. This measurement differs from the true vertical depth (DTV) of the unfinished well in all but unfinished wells. However, it is sometimes convenient to convert MD to TVD or vice versa. Such a conversion is possible if the trajectory of the unfinished well is known. Such a conversion may be convenient, for example, to link the seismic channel depths to a seismic velocity model. It is not essential which point is defined as zero depth. For convenience, it is proposed to define the top end of the unfinished well on the earth's surface as zero depth.
[0022] In its broadest sense, the term "countless" means one or more. In specific embodiments, the term "countless" can mean a plurality of, or, two or more.
[0023] A method of calibrating the depths of a plurality of seismic receiver channels in a seismic receiver array arranged in an unfinished well in an earth formation is proposed in this document. The seismic receiver matrix comprises a plurality of seismic receiver channels, which can form a column of interconnected seismic receiver channels. A considered depth is assigned to each seismic receiver channel. Each seismic receiver channel is locally coupled to the earth formation that is present adjacent to the seismic receiver channel location. In the context of the present disclosure, adjacent to the seismic receiver channel, it means the formation of earth directly outside the unfinished well in a direction exclusively transversal to the location of the seismic receiver channel compared to the longitudinal direction of the unfinished well. A material-dependent response of each seismic receiver channel is determined. Such material-dependent response of each seismic receiver channel is suitably represented by a unique numeric value (which can be a scalar), which is preferably a signal amplitude value, for each seismic receiver channel.
[0024] In this way, pairs of response dependent on training material and the depth considered will be available for each seismic receiver channel, and, thus, the response dependent on training material can be considered as a function of the depth considered. The response dependent on formation material as a function of the depth considered is compared to a depth profile independent of at least one petrophysical parameter of the earth formation as a function of depth along the unfinished well. Based on the comparison, a set of delays between said depth considered and depth in the independent depth profile is determined, since it provides the best correlation between the response dependent on training material and the depth profile independent of at least one petrophysical parameter. land formation.
[0025] In this way, a set of corrected depth or a set of correction values can be issued for the plurality of seismic receiver channels, to align the considered depth of each seismic receiver channel from the plurality of seismic receiver channels to the depths corresponding to the independent depth profile. By correlating the material-dependent responses of the seismic receptor channels to the independent depth profile, essentially the entire receptor matrix or at least a large portion of the receptor matrix can align with petrophysical training resources, rather than having that depend on the interpolation between some fixed points, such as nozzle test points and matrix end alignment. Another advantage is that this can be accomplished without the need to install additional equipment in the unfinished well. In addition, it can be applied retrospectively to existing systemic data sets that were acquired using the seismic receiver matrix.
[0026] In addition, an advantage of the method is that the considered depth of each seismic receiver channel of the plurality of seismic receiver channels is aligned with the corresponding depths in the independent depth profile. This may not be the same at the true depth, but it is for many more important purposes to know the relative location of the seismic receiver channels in relation to the geological resources in land formation.
[0027] The method can also be applied in time interval mode, to maximize the repeatability between seismic harvests. The method can reveal displacements of seismic receiver channels over time. In case the seismic receiver channels are DAS receiver channels, the method can also be used to protect against potential changes within the DAS optical fiber, such as changes in the refractive index over time, which can occur under the influence of temperature changes. Such temperature changes may occur, for example, during the course of improved oil recovery operations (EOR) which may, for example, involve steam injection. The term "DAS optical fiber" refers to any type of optical fiber that is optically coupled to an interrogation unit that is capable of grouping continuous distributed signals into channel signals. The term "DAS cable" refers to one or more DAS optical fibers packaged in a single cable, whereby the DAS optical fibers are embedded and / or surrounded by at least one protective material.
[0028] Earth formation material affects the seismic receptor response to incident seismic waves. As indicated above, the term "formation material dependent response" is a response in the seismic receiver channel that is affected by the local elastic properties of the earth formation material to which the receiver channel is coupled. The seismic waves that propagate through the material by particle movement can be chosen by a movement sensor or a deformation sensor, such as geophones or DAS optical fibers. The deformation of the material in response to a seismic wave is controlled by the elastic tensor of the material and, therefore, the local elastic properties of the material to which the receiver channel is attached affect the response. The elastic properties of the material also affect responses to seismic waves that propagate through the material as a pressure wave. This can be understood as the pressure pulse that manifests itself under a constant particle speed through the material's acoustic impedance.
[0029] Suitably, the petrophysical parameter of the earth formation of the independent depth profile is a parameter that is dependent on an elastic property of the earth formation.
[0030] The response dependent on training material and at least one petrophysical parameter of the independent profile are preferably both sensitive to the elastic properties of the earth formation that surrounds the seismic receiver channels. Examples include a sonic profile, a density profile and an acoustic impedance profile. An acoustic impedance profile can be constructed by combining a sonic profile and a density profile. In some cases, for example, in certain clastic environments, including formations of sand and shale, a gamma ray profile can be indicative of acoustic impedance and therefore also be suitable for that purpose.
[0031] The method described in this document can be used for any type of seismic receiver matrix, including geophones and DAS optical fiber matrices. However, for the sake of brevity, the rest of the description will be done using DAS optical fibers as an example. The main advantages of DAS optical fibers are that the coverage is usually greater than with geophones and / or the seismic receiver channel spacing may be less (that is, a higher number of seismic receiver channels per unit length) . Both of these factors make it easier to correlate receptor responses dependent on training material to independent profiles. The person skilled in the art will be able to apply the same principles to other types of seismic receiver matrices.
[0032] Referring now to Figure 1, a schematic longitudinal section of an unfinished well 10 in a land formation 50 is shown. The unfinished well 10 traverses numerous geological layers (schematically indicated by areas 51 to 55), each having its own characteristics. own properties, including elastic properties. An optical fiber of DAS 20 is disposed in the unfinished well 10. The optical fiber (DAS) 20 is subdivided into a plurality of DAS 22 receiver channels. Only a few of these DAS 22 receiver channels are shown in Figure 1 with interest of visual clarity. In reality, hundreds of DAS receiver channels, with a receiver channel spacing between 2 m and 10 m, are not uncommon. Each seismic receiver channel 22 is locally coupled to the earth formation 50 that is present adjacent to the location of the seismic receiver channel 22 in question. This can be done by cementing the DAS cable behind the well casing, for example. For the avoidance of doubt, in the context of the disclosure, a seismic receiver channel is locally coupled to the earth formation that is present adjacent to the location of the seismic receiver channel in question if there is a physical contact path between the location of the receiver channel seismic and said earth formation within a plane that is transversal to the longitudinal direction of the unfinished well between the seismic receiver channel and the earth formation, directly or through the intermediate materials that could include cement and / or tubular well elements such as a coating.
[0033] An interrogator unit 30 is configured on the surface of the earth 35. The interrogator unit 30 is connected to the DAS 20 optical fiber and arranged to transmit optical laser pulses to the DAS 20 optical fiber and detect backscattered optical signals that are influenced by deformations along the optical fiber, which can be caused by the collision of seismic waves. Since any part of the optical fiber can be deformed and interrogated in relation to seismic information, this type of measurement is called distributed acoustic capture. The location of any deformation can be determined from the known flight time of the optical laser pulse that captured it. In this way, the DAS 20 optical fiber can be subdivided into the DAS 22 receiver channels (which correspond to VSP receiver levels, for example) based on the flight time of the optical laser pulse along it.
[0034] Suitably, the DAS 20 optical fiber is packaged in a DAS 40 cable. A schematic view of an example is shown in Figure 2. The DAS cable can comprise a plurality of DAS optical fibers, which when used simultaneously can improve the signal-to-noise ratio. Two straight longitudinal optical fibers 20a are shown in Figure 2 as an example, however, more such as five can be provided. Alternatively or in addition to this, one or more helically wound optical fibers 20b can be configured on the DAS 40 cable. Suitably, these helically wound optical fibers 20b can be wound around a core 45. Everything can be embedded in protective materials, and covered by one or more protective outer layers. A protective outer layer 42 is shown as an example. Unlike straight longitudinal optical fibers 20a, cables comprising helically wound optical fibers 20b are sensitive to broad-sided waves (waves with a propagation component within a plane that extends perpendicular to the longitudinal direction of the cable at the intersection of the cable and the plane).
[0035] A considered depth can be assigned to each seismic receiver channel 22 in the plurality of seismic receiver channels. A common procedure is to determine where the distal end of the DAS 20 optical fiber 1 is located in the unfinished pit, and, from that point, to derive the considered depths of the DAS 22 receiver channels above it. The considered depths of the DAS 22 receiver channels can also be derived from the optical distance (based on assumptions about the fiber path) as determined from the flight time of the reflected optical pulses. This optical depth does not necessarily coincide with the depth measured along the unfinished well 10, due to the fact that there may be causes of deviations, such as clearance in the optical fiber in relation to the unfinished well 10 or erroneous assumptions about the refractive index of the fiber DAS 20 optics.
[0036] Figure 3, 3rd part, shows seismic traces of a zero deviation VSP collection acquired by the use of DAS simultaneously in the five optical fibers employed in an unfinished well. The five optical fibers can be configured on a single DAS cable. Response times are plotted on a horizontal plane and DAS receiver channels are plotted along a vertical geometric axis, using depths considered on a DTV scale. Three depth levels (D1, D2, D3) are indicated for reference. The direct (descending) arrival can be seen in the rising and left waves due to the fact that the reflections at the geological interfaces are also visible. Considerably, a large number of rising waves caused by reflections in the resources below a D2 depth are observed. The modalities of the present invention allow the alignment of the depths considered to the most significant geological depths.
[0037] For this purpose, independent depth profiles, representative of the parameters referring to the elastic properties of the earth formation 50 as a function of depth along the unfinished well 10, are provided. Figures 3a to 3c show several independent profiles plotted on the same depth scale as Figure 3d and measured in the same unfinished well. Horizontal scales are linear scales. Figure 3a is a gamma ray profile - the horizontal scale range ranges from 0.0 to 150 API units (a standard measure of natural gamma radiation measured in an unfinished well defined by the American Petroleum Institute). Figure 3b is a sonic velocity profile for waves - the horizontal scale range ranges from 2,000 to 6,000 m / s. Figure 3c is a density profile - the horizontal scale range ranges from 1.45 to 2.95 g / cm3. Horizontal scales are revealed for reference purposes only; since it will be evident that the absolute values are not necessary to carry out the modalities of the invention.
[0038] In order to correlate the seismic traces of Figure 3d with the independent profiles, the channel consistent scalars (in this case: DAS channel consistent scalars) were derived from DAS VSP data, in a similar way to the derivation surface-consistent scalar for surface seismic data (reference is made again to the document by Taner and Koehler). Channel-consistent scalars are inversely proportional to the average signal amplitude on each seismic receiver channel.
[0039] Suitably, the signal amplitude value is determined in relation to a reference signal amplitude for each seismic receiver channel. Suitably, the signal amplitude value corresponds to an average square root mean amplitude (RMS) of a plurality of coherent seismic events, such as all signals that correspond to the rising waves seen in Figure 3d. Suitably, multiple recoils are considered, such as multiple recoils considered with mutually different source receiver deviations, to derive the scalar consistent in DAS channel. The distance VSP trigger pickups are an example of suitable multiple pickups. The channel-consistent scalars thus derived are a convenient measure of a response dependent on training material.
[0040] In any case, a material-dependent response of each seismic receiver channel 22 induced by seismic waves that propagate through the formation of earth 50 can then be determined using current measurements of backscattered light signals. of the optical fiber of DAS 20, and considered as a function of the considered depth of the seismic receiver channel by which the response dependent on formation material was determined.
[0041] A result of this procedure is illustrated in Figure 4. Figure 4d in this figure shows a plot of the scalars consistent in DAS channel, derived from the seismic traces of a 2D distance VSP survey with dynamite sources, on a linear scale against depth. The depths are based on the considered depths of the DAS receiver channels. (Depth is plotted as MD). Only data between D1 and D3 are considered. For easy comparison, a segment of the gamma ray profile of Figure 3a is reproduced in Figure 4a, and a segment of the sonic profile of Figure 3b is reproduced in Figure 4b.
[0042] Figure 4c corresponds to the sonic profile of Figure 4b after increasing. The increase serves to facilitate the comparison of the independent profile with the receiver-consistent scalars of the DAS receiver channels. This is particularly useful if the depth sampling of the independent depth profile is thinner than the DAS receiver channel sampling (values for at least one petrophysical parameter of land formation in the independent depth profile - such as the velocity of p-wave - are available for numerous depths per unit of length, where the number is greater than the number of DAS receiver channels per said unit of length). In the case presented, the increase was achieved by blocking data, which is essentially to represent blocks of profiling values as single data points. Suitably, the increased depth profile has a unique value of at least one petrophysical parameter of earth formation per DAS receiver channel.
[0043] As can be seen by comparing Figure 4c with Figure 4d, a notorious correlation is considered between the scalars consistent in DAS channel of Figure 4d with the blocked sonic profile of Figure 4c. The correlation can also be seen based on the unlocked data in Figure 4b, but the similarity is most notably seen in Figure 4c.
[0044] Once a correlation has been established, a set of delays between said depth considered and the depth in the independent depth profile can be determined for numerous seismic receiver channels. This can be done based on the correspondence of some distinct pronounced features, such as those indicated by the connection of the lines between Figures 4c and 4d, or by maximizing the correlation between the two sets of data using computational techniques. One possible computational technique to maximize the correlation is to choose the maximum cross correlation in a sliding window between the two sets of data. The last objective is to determine a set of delays that provides the best correlation between the response dependent on formation material (for example, the scalars consistent in seismic channels) and the depth profile independent of at least one petrophysical parameter of land formation. (for example, the sonic profile). A set of correction values can then be established and output to the plurality of seismic receiver channels. The set of correction values can then be used to align the considered depth of each seismic receiver channel from the plurality of seismic receiver channels to the corresponding depths in the independent depth profile.
[0045] There is also a correlation between the gamma ray profile in Figure 4a and the DAS channel consistent scalars in Figure 4d, but in the present example, this is a much weaker correlation, due to the fact that the profile of gamma ray is only indirectly related to the elastic properties of earth formation. The gamma ray profile is often correlated to the acoustic impedance for a given deposition environment, but that correlation is not always present. Thus, sonic profiles, density profiles or acoustic impedance profiles, which are direct measurements of various elastic properties of earth formation, are typically preferred for this purpose of depth calibration. However, gamma ray profiles can also be useful in some situations.
[0046] As an example, Figure 5 explores the complex region between depths D2 and D3. As can be seen in Figure 3c, a density profile is available for most of this depth range, which allows the acoustic impedance to be derived in this region since the acoustic impedance is equal to the product of sonic velocity in the medium and density of the quite. The density profile is shown in Figure 5b, and the relevant section of the sonic profile is reproduced in Figure 5c. For general reference, the corresponding section of the gamma ray profile of Figure 3a is reproduced in Figure 5a. Figure 5d is the blocked sonic profile (again, p-wave velocity). Figure 5e corresponds to the acoustic impedance obtained by multiplying Figures 5b and 5c by a depth range in which data for both the sonic profile and the density profile are available. Figure 5f represents the data in Figure 5e after augmentation using the blocking technique. Figure 5g shows the scalars consistent in DAS channel. Even in this complex geology in that particular depth range, a noticeable correlation between the scalar consistent in DAS channel of Figure 5g and the sonic profile of Figure 5d as well as the acoustic impedance profile of Figure 5f is possible, based on the depth considered of each seismic receiver channel of the plurality of seismic receiver channels can be corrected to match the corresponding depths in the independent depth profile.
[0047] A computational implementation of the invention may involve correlating the response dependent on formation material as a depth function with the independent profile of the ground parameter as a depth function, and determining the delay for each seismic receiver channel that maximizes the correlation. However, it is clearly not always necessary to compute the delay of all seismic receiver channels with the independent profile. Considering, for example, Figure 4, it may be sufficient to determine delays for a selected number of clear matching resources in the data and then interpolate to generate the correction values output based on a much smaller number of determined delays. However, in more complex data sets such as those shown, for example, in Figure 5, a greater number of delays can be established to ensure that the best correlation is found.
[0048] The method explained so far advantageously employs the observed correlation between responses dependent on training material and certain depth profiles, particularly depth sonic profiles and depth acoustic impedance profiles, to calibrate the depth of the seismic receiver channels by aligning the depths to the independent depth profiles.
[0049] Conversely, the same observed correlation can be used to create a close to an acoustic impedance profile or a sonic profile in cases where the seismic receiver channel depths are reasonably known and accurate. This can be a powerful addition in cases where no depth profile is available, or only small profiles are available. In this way, missing lithological information can be inferred from the unfinished wells that have seismic data of considered depth.
[0050] The reverse method can have several useful applications. For example, low frequency surface seismic data can be linked to well synthetics based on pseudoacoustic impedance profiles derived from DAS channel factors. This is useful in those cases where the sonic and / or density profiles are too short (in a vertical direction) to allow conventional well mooring for low frequency surface seismic data. Correspondence can be considered among the resources of responses dependent on training material, particularly responses related to acoustic impedance, in an unfinished well and independent profiles that are available for distant unfinished wells. This is a new way of mooring wells, and it may be useful to restrict immersions in the shallow subsurface where profiles are often not available, or to detect and / or verify stratigraphic terminations between adjacent unfinished wells.
[0051] Another example is considered in the calibration of vertical depth of geological models. Particularly, in the case of DAS fiber optic acquisitions, a higher resolution can be obtained than using standard VSP data or using the results of seismic inversion based on seismic path times.
[0052] Those skilled in the art will understand that the present invention can be accomplished in several ways, without departing from the scope of the appended claims.

权利要求:
Claims (13)
[0001]
1. Method for depth calibration of a plurality of seismic receiver channels (22) in a seismic receiver matrix arranged in an unfinished well (10) in a land formation (50), in which the method comprises: selecting a matrix of seismic receiver arranged in an unfinished well (10) in an earth formation (50), in which the seismic receiver matrix comprises a plurality of seismic receiver channels (22), thereby, each seismic receiver channel (22) it is locally coupled to the earth formation (50) which is present adjacent to the seismic receiver channel location (22); assigning a considered depth to each seismic receiver channel (22) in the plurality of seismic receiver channels (22); the method characterized by the fact that it comprises: determining a response dependent on the formation material of each seismic receiver channel (22) induced by seismic waves that propagate through the formation of earth adjacent to each respective seismic receiver channel (22), in that the material-dependent response of each seismic receiver channel (22) is determined as a signal amplitude value; provide a depth profile independent of at least one petrophysical parameter of land formation as a function of depth along the unfinished well (10); for numerous seismic receiver channels (22), determine a set of delays between the depth considered and depth in the independent depth profile that provides the best correlation between the material-dependent response of the seismic receiver channels (22) and the profile depth independent of at least one petrophysical parameter of land formation (50); and outputting a set of corrected depths or correction values for the plurality of seismic receiver channels (22) to align the considered depth of each seismic receiver channel (22) of the plurality of seismic receiver channels (22) with corresponding depths in the independent depth profile.
[0002]
2. Method according to claim 1, characterized by the fact that the independent depth profile comprises values for at least one petrophysical parameter of the earth formation (50) for various depths per unit length that is greater than the number of seismic receiver channels (22) per unit length, wherein the method comprises increasing the independent depth to obtain an increased depth profile that has a unique value of at least one petrophysical parameter of earth formation (50) per receiver channel seismic (22).
[0003]
Method according to claim 1 or 2, characterized by the fact that at least one petrophysical parameter of the earth formation (50) of the independent depth profile is dependent on an elastic property of the earth formation (50).
[0004]
4. Method according to any one of the previous 1 to 3, characterized by the fact that the independent depth profile is one of: a sonic profile, a density profile and an acoustic impedance profile.
[0005]
Method according to any one of claims 1 to 4, characterized in that the signal amplitude value corresponds to an average amplitude of the inverse mean square root of a plurality of seismic events.
[0006]
Method according to any one of claims 1 to 5, characterized by the fact that the signal amplitude value is determined using a channel-consistent scalar technique.
[0007]
Method according to any one of claims 1 to 6, characterized in that the seismic receiver channels (22) in the seismic receiver matrix form a column of seismic receiver channels (22).
[0008]
Method according to any one of claims 1 to 7, characterized by the fact that the seismic receiver matrix is formed by a system of Distributed Acoustic Sensors (DAS) that subdivides an optical fiber (20) into a plurality of channels of DAS receiver, thereby, the seismic receiver channels (22) are the DAS receiver channels.
[0009]
Method according to claim 8, characterized in that the optical fiber (20) is packaged in a cable (40) and operated as an optical fiber (20) from DAS.
[0010]
Method according to claim 9, characterized by the fact that a plurality of optical fibers (20) are bundled in the cable (40), with all optical fibers being operated as DAS optical fibers.
[0011]
Method according to either of Claims 9 and 10, characterized in that the optical fiber (20) is helically wound around a core (45) in the cable (40).
[0012]
Method according to any one of claims 9 to 11, characterized in that the material-dependent response of each seismic receiver channel (22) is determined using current measurements of backscattered light signals from the optical fiber (20).
[0013]
13. Method according to claim 12, characterized by the fact that the depth considered corresponds to an optical distance, as determined, by measuring the flight time of the back-scattered light and taking into account a fiber path through the formation of earth (50).

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WO2016207341A1|2016-12-29|

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US10746887B2|2020-08-18|

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CN107810431B|2019-06-11|

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CA2988953A1|2016-12-29|

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法律状态:
2020-05-26| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|

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2020-12-08| B09A| Decision: intention to grant|

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2021-03-02| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 24/06/2016, OBSERVADAS AS CONDICOES LEGAIS. |

优先权:

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申请号 | 申请日 | 专利标题

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EP15174021|2015-06-26|

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EP15174021.4|2015-06-26|

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PCT/EP2016/064654|WO2016207341A1|2015-06-26|2016-06-24|Method of calibrating depths of a seismic receiver array|

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