Water and land detection data cross ghost reflection calibration method and device

Abstract

The invention relates to the technical field of oil field exploration, in particular to a water and land inspection data cross ghost reflection calibration method and device. The method comprises the following steps: S10, determining a direct wave extraction time window function by calculating a direct wave and primary ghost reflection travel time; s20, extracting a time window function based on the direct wave, calculating a frequency-space domain cross ghost reflection delay factor, a frequency domain common receiving point gather land detection data direct wave primary ghost reflection self-correlation sequence, a frequency domain common receiving point gather land detection data direct wave secondary ghost reflection self-correlation sequence and a frequency domain direct wave self-correlation sum sequence during direct wave primary ghost reflection delay; obtaining a cross ghost reflection calibration factor; s30, separating uplink and downlink wave fields based on the cross ghost reflection calibration factor to obtain frequency-space domain conjugate antisymmetric uplink and downlink wave field data and time-space domain uplink and downlink wave field data; and drawing and storing the time-space domain uplink and downlink wave field data.

Description

Technical Field

[0001] The invention relates to the technical field of oil field exploration, and in particular to a method and a device for calibrating cross virtual reflection of water and land inspection data. Background Art

[0002] The data collected by the marine OBC / OBN provide two types of data: water detection data and land detection data at the same location. These two types of data are recorded using underwater geophones and land geophones, respectively. An underwater geophone is a pressure geophone that records the pressure changes caused by seismic waves, which is a scalar; a land geophone is a particle velocity geophone that records the particle velocity changes, which is a vector. Due to the different recording mechanisms of these two geophones, different characteristics are shown for virtual reflections and seawater ringing multiple wave interferences at the same location. Compared with the seawater ringing and virtual reflection multiple wave interferences recorded by underwater geophones, the seawater ringing and virtual reflection multiple wave interferences recorded by land geophones show differences in polarity and amplitude characteristics. The seawater ringing and virtual reflection multiple wave interferences recorded by the two geophones have different amplitudes, opposite polarities, and differ by a constant proportional to the seabed reflection coefficient. This constant value is the calibration factor. Based on this mechanism, Gao Shaowu and Gao Xuan et al. proposed a constant calibration method for water and land detector data (see Gao Shaowu et al. "A method for inverting calibration factors of water and land detector seismic data", ZL201310736942.1, 2013-11-29; Gao Xuan et al. "OBC water and land detector data calibration factor estimation method", Petroleum Geophysical Exploration, 2016, 51(1)). On the basis of this method, Gao Shaowu et al. proposed to use the time domain matched filter method based on the constant phase correction of water and land detector data to achieve water and land detector data matching (see Gao Shaowu et al. "A method for matching water and land detector seismic data", ZL201310531139.4, 2013-10-31; Gao Shaowu et al. "OBC water and land detector data matching technology", Petroleum Geophysical Exploration, 2015, 50(1)). In addition, Gao Shaowu et al. proposed a method for calibrating water and land inspection data and separating uplink and downlink wave fields in the frequency-wavenumber domain (see Gao Shaowu et al. "A method for calibrating water and land inspection data", 202111667515.3, 2021-12-30).

[0003] Conventional water and land survey data constant calibration methods have achieved certain success in actual data processing. However, since these calibration processes do not consider the characteristics of the upgoing and downgoing wave fields, but pick up a water and land survey data interval that may contain both upgoing and downgoing wave fields to obtain the calibration operator, the operator obtained in this way cannot completely separate the upgoing and downgoing wave fields. Paffenholz and Barr (Western Geophysical, 1995) realized that the seawater ringing in the water survey data is proportional to the virtual reflection factor of the land survey data, and the seawater and virtual reflection in the land water survey data are proportional to the virtual reflection factor of the water survey data, that is, the cross-virtual reflection phenomenon. Conventional methods do not use the cross-virtual reflection characteristics and cannot meet the needs of actual water and land survey data calibration processing. With the development of oil and gas exploration, the requirements for exploration accuracy are getting higher and higher. In theory, to achieve high-precision exploration, a method that can completely separate the upgoing and downgoing wave fields is needed, which is an urgent need. Summary of the invention

[0004] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a method and device for calibrating cross-ghost reflections of water and land inspection data, which aims to quickly and accurately calculate the travel time of direct waves and primary ghost reflections, the direct wave extraction time window function, the direct wave primary ghost reflection delay time, the cross-ghost reflection delay factor, the water and land inspection data direct wave primary ghost reflection and secondary ghost reflection correlation sequence, the direct wave correlation and sequence, etc., realizes the direct calculation of the best water and land inspection data cross-ghost reflection calibration factor in the frequency-space domain, which is used for the best calibration processing of conventional ocean OBC / OBN water inspection data to land inspection data, realizes the best separation of uplink and downlink wave fields of water and land inspection data, and provides the best uplink wave field and downlink wave field data for the subsequent uplink and downlink wave field joint deconvolution and mirror migration imaging processing.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] In a first aspect, in one embodiment provided by the present invention, a method for calibrating cross-ghost reflections of water and land inspection data is provided, the method comprising the following steps:

[0007] S10, determining a direct wave extraction time window function by calculating the travel time of the direct wave and a ghost reflection;

[0008] S20, based on the direct wave extraction time window function, calculate the direct wave first ghost reflection delay time, the frequency-space domain cross ghost reflection delay factor, the frequency domain common receiving point gather land inspection data direct wave first ghost reflection autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave second ghost reflection autocorrelation sequence and the frequency domain direct wave autocorrelation sum sequence to obtain the cross ghost reflection calibration factor;

[0009] S30, separating the uplink and downlink wavefields based on the cross ghost calibration factor to obtain frequency-space domain conjugate antisymmetric uplink and downlink wavefield data and time-space domain uplink and downlink wavefield data; and plotting and storing the time-space domain uplink and downlink wavefield data.

[0010] As a further solution of the present invention, step S10 includes:

[0011] S101, calculating the direct wave travel time and the one ghost reflection travel time;

[0012] S102, using the direct wave travel time and the primary ghost reflection travel time to calculate the start and end sample point sequence numbers of the direct wave data;

[0013] S103, using the sequence numbers of the start and end samples of the direct wave data, calculate the direct wave extraction time window function.

[0014] As a further solution of the present invention, step S20 includes:

[0015] Direct wave water detection data and direct wave land detection data are extracted based on the direct wave extraction time window function.

[0016] As a further solution of the present invention, the step S20 further includes:

[0017] The frequency-space domain common reception point gather water detection data is calculated based on the direct wave water detection data, and the frequency-space domain common reception point gather land detection data is calculated based on the direct wave land detection data.

[0018] As a further solution of the present invention, the step S20 further includes:

[0019] Calculate the delay of the first ghost reflection of the direct wave.

[0020] As a further solution of the present invention, the step S20 further includes:

[0021] The direct wave correlation sequence of the water detection data of the common receiving point gather in the frequency-space domain is calculated based on the water detection data of the common receiving point gather in the frequency-space domain, and the direct wave correlation sequence of the land detection data of the common receiving point gather in the frequency-space domain is calculated based on the land detection data of the common receiving point gather in the frequency-space domain.

[0022] As a further solution of the present invention, the step S20 further includes:

[0023] The frequency domain direct wave first ghost reflection correlation sequence is calculated based on the frequency-space domain cross ghost reflection delay factor and the frequency-space domain common receiving point gather direct wave land inspection data.

[0024] As a further solution of the present invention, step S20 further includes:

[0025] The frequency domain direct wave autocorrelation sum sequence is calculated based on the frequency domain common receiving point gather land inspection data direct wave autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave first ghost reflection autocorrelation sequence and the frequency domain common receiving point gather land inspection data direct wave second ghost reflection autocorrelation sequence;

[0026] The frequency domain direct wave cross-correlation and sequence are calculated based on the frequency domain common receiving point gather water and land inspection data direct wave cross-correlation sequence and the frequency domain common receiving point gather water and land inspection data direct wave secondary ghost reflection cross-correlation sequence;

[0027] The cross ghost calibration factor is calculated based on the frequency domain direct wave autocorrelation and sequence and the frequency domain direct wave cross-correlation and sequence.

[0028] As a further solution of the present invention, step S30 includes:

[0029] S301, calibrating the frequency-space domain common receiving point gather land inspection data based on the cross ghost reflection calibration factor to obtain calibrated frequency-space domain common receiving point gather land inspection data;

[0030] S302, calculating frequency-space domain conjugate anti-symmetric upgoing and downgoing wavefield data to obtain frequency-space domain conjugate anti-symmetric upgoing wavefield data and time-space domain conjugate anti-symmetric downgoing wavefield data;

[0031] S303, performing upgoing and downgoing wavefield separation based on the frequency-space domain conjugate antisymmetric upgoing wavefield data and the land inspection data processed by frequency-space domain cross ghost calibration, so as to obtain the frequency-space domain upgoing wavefield above the seabed processed by cross ghost calibration and the frequency-space domain downgoing wavefield above the seabed processed by cross ghost calibration;

[0032] S304, respectively perform inverse Fourier transform on the upgoing wave field above the seabed in the frequency-space domain after the cross-ghost reflection calibration processing and the downgoing wave field above the seabed in the frequency-space domain after the cross-ghost reflection calibration processing to obtain upgoing and downgoing wave field data in the time-space domain, and draw and store the upgoing and downgoing wave field data in the time-space domain.

[0033] In a second aspect, in another embodiment provided by the present invention, a device for calibrating cross ghost reflections of water and land inspection data is provided, the device comprising: a module for determining an extraction time window function, a module for obtaining a cross ghost reflection calibration factor, and a module for obtaining uplink and downlink wave field data;

[0034] The module for determining the extraction time window function determines the direct wave extraction time window function by calculating the travel time of the direct wave and the primary ghost reflection;

[0035] The module for obtaining the cross ghost reflection calibration factor calculates the direct wave first ghost reflection delay time, the frequency-space domain cross ghost reflection delay factor, the frequency domain common receiving point gather land inspection data direct wave first ghost reflection autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave second ghost reflection autocorrelation sequence and the frequency domain direct wave autocorrelation sum sequence based on the direct wave extraction time window function to obtain the cross ghost reflection calibration factor;

[0036] The uplink and downlink wavefield data acquisition module separates the uplink and downlink wavefields based on the cross ghost calibration factor to obtain frequency-space domain conjugate antisymmetric uplink and downlink wavefield data and time-space domain uplink and downlink wavefield data; and draws and stores the time-space domain uplink and downlink wavefield data.

[0037] The technical solution provided by the present invention has the following beneficial effects:

[0038] The method and device for calibrating cross-ghost reflections of water and land inspection data provided by the present invention determine the direct wave extraction time window function by calculating the travel time of the direct wave and the primary ghost reflection; based on the direct wave extraction time window function, calculate the direct wave primary ghost reflection delay time, the frequency-space domain cross-ghost reflection delay factor, the frequency domain common receiving point gather land inspection data direct wave primary ghost reflection autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave secondary ghost reflection autocorrelation sequence and the frequency domain direct wave autocorrelation sum sequence to obtain the cross-ghost reflection calibration factor; based on the cross-ghost reflection calibration factor, separate the uplink and downlink wave fields to obtain the frequency-space domain conjugate antisymmetric uplink and downlink wave field data and the time-space domain uplink and downlink wave field data; and draw and store the time-space domain uplink and downlink wave field data. The present invention makes full use of the cross-ghost reflection characteristics of water and land inspection data, calculates the travel time of the direct wave and the primary ghost reflection, the direct wave extraction time window function, the direct wave primary ghost reflection delay time, the frequency-space domain cross-ghost reflection delay factor, the frequency-domain water and land inspection data direct wave primary ghost reflection and secondary ghost reflection correlation sequence, the frequency-domain direct wave correlation and sequence, etc., directly calculates and determines the optimal cross-ghost reflection calibration factor in the frequency-space domain, and realizes the optimal separation of the uplink and downlink wave fields of the water and land inspection data.

[0039] These and other aspects of the present invention will be more clearly understood in the following description of the embodiments. It should be understood that the above general description and the following detailed description are only exemplary and explanatory and cannot limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0041] Figure 1 It is a flow chart of a method for calibrating cross ghost reflections of water and land inspection data according to an embodiment of the present invention;

[0042] Figure 2 This is a specific flow chart of step S10 in a method for calibrating cross-ghost reflections of water and land inspection data according to an embodiment of the present invention;

[0043] Figure 3 This is a specific flow chart of step S30 in a method for calibrating cross ghost reflections of water and land inspection data according to an embodiment of the present invention;

[0044] Figure 4 The present invention is a structural block diagram of a device for calibrating cross-ghost reflections of water and land inspection data according to an embodiment of the present invention.

[0045] In the figure: a module 100 for determining and extracting a time window function, a module 200 for obtaining a cross ghost reflection calibration factor, and a module 300 for obtaining uplink and downlink wave field data. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The flowcharts shown in the accompanying drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0048] It should be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0049] Specifically, the embodiments of the present invention are further described below in conjunction with the accompanying drawings.

[0050] See also Figure 1 , Figure 1 : is a flow chart of a method for calibrating cross ghost reflections of water and land inspection data provided by an embodiment of the present invention. Figure 1 As shown, the method for calibrating cross-ghost reflections of water and land inspection data includes steps S10 to S30.

[0051] S10. Determine the direct wave extraction time window function by calculating the direct wave and the travel time of a ghost reflection.

[0052] In an embodiment of the present invention, the step S10 includes:

[0053] S101, calculating the direct wave travel time and the one-time ghost reflection travel time.

[0054] In the embodiment of the present invention, the direct wave travel time T of the i-th spatial channel is calculated by the following formula: Bi ,

[0055]

[0056] The travel time T of the first virtual reflection of the direct wave of the i-th spatial channel is calculated by the following formula: Gi

[0057]

[0058] Where i represents the sequence number of the spatial channel in the time-space domain, i = 1, 2, 3, ..., NI, NI represents the total number of spatial channels in the common receiving point gather; T Bi represents the travel time of the direct wave of the ith spatial channel, in seconds (s); T Gi represents the travel time of a virtual reflection of the direct wave of the ith spatial channel, in seconds (s); x i is the i-th spatial offset, in meters (m); h Si is the depth of the ith spatial channel shot point, in meters (m); h R is the seawater depth at the receiving point, in meters (m); V is the seawater velocity, in meters / second (m / s), which is given by the user.

[0059] S102, using the direct wave travel time and the one-time ghost reflection travel time, calculate the start and end sample point sequence numbers of the direct wave data.

[0060] In the embodiment of the present invention, the starting sample point sequence number ITA of the direct wave data extraction time window is calculated by the following formula: i

[0061]

[0062] The direct wave data extraction time window termination sample point sequence number ITB is calculated by the following formulai

[0063]

[0064] In the formula, the symbol “[·]” indicates the rounding operation; i indicates the sequence number of the spatial channel in the time-space domain, i = 1, 2, 3, …, NI, NI indicates the total number of spatial channels in the common receiving point gather; ITA i Indicates the starting sample point sequence number of the direct wave data extraction window, ITB i Indicates the sequence number of the end sample point of the direct wave data extraction time window; Δt is the seismic data time sampling interval, in seconds (s); T D It is the time window length for extracting direct wave data, in seconds (s), given by the user.

[0065] S103, using the sequence numbers of the start and end samples of the direct wave data, calculate the direct wave extraction time window function.

[0066] In the embodiment of the present invention, the direct wave extraction time window function W is calculated by the following formula: d [i,j]

[0067]

[0068] Wherein, i represents the sequence number of the spatial channel in the frequency-space domain, i=1,2,3,…,NI, and NI represents the total number of spatial channels in the common receiving point gather.

[0069] S20. Based on the direct wave extraction time window function, calculate the direct wave first ghost reflection delay time, the frequency-space domain cross ghost reflection delay factor, the frequency domain common receiving point gather land inspection data direct wave first ghost reflection autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave second ghost reflection autocorrelation sequence and the frequency domain direct wave autocorrelation sum sequence to obtain the cross ghost reflection calibration factor.

[0070] In an embodiment of the present invention, the step S20 includes:

[0071] Direct wave water detection data and direct wave land detection data are extracted based on the direct wave extraction time window function.

[0072] In the embodiment of the present invention, the direct wave water detection data h is extracted by the following formula: d [i,j]

[0073] h d [i,j]=W d [i,j]h[i,j],(6)

[0074] The direct wave water and land data g is extracted by the following formula d [i,j]

[0075] g d [i,j]=W d [i,j]g[i,j],(7)

[0076] In the formula, h d [i,j] represents the direct wave water detection data of the common receiving point gather in the time-space domain, g d [i,j] represents the direct wave water and land data of the common receiving point gather in the time-space domain; h[i,j] represents the water inspection data of the common receiving point gather in the time-space domain, g[i,j] represents the land inspection data of the common receiving point gather in the time-space domain; i represents the sequence number of the space channel in the time-space domain, i=1,2,3,…,NI, NI represents the total number of space channels in the common receiving point gather; j represents the sequence number of the time sampling point in the time-space domain, j=1,2,3,…,NJ, NJ represents the total number of time sampling points in the common receiving point gather.

[0077] The step S20 further includes:

[0078] The frequency-space domain common reception point gather water detection data is calculated based on the direct wave water detection data, and the frequency-space domain common reception point gather land detection data is calculated based on the direct wave land detection data.

[0079] In an embodiment of the present invention, the calculation of frequency-space domain common reception point gather water detection data based on the direct wave water detection data and the calculation of frequency-space domain common reception point gather land detection data based on the direct wave land detection data include:

[0080] According to the following formula, the frequency-space domain common receiving point gather water inspection data H[i,j]

[0081]

[0082] The frequency-space domain common receiving point gather land inspection data G[i,k] is calculated according to the following formula:

[0083]

[0084] The direct wave water detection data H of the common receiving point gather in the frequency-space domain is calculated according to the following formula d [i,k]

[0085]

[0086] The frequency-space domain common receiving point gather direct wave land inspection data G is calculated according to the following formula d [i,k];

[0087]

[0088] in,

[0089] F NT =e -l2π / NT , (12)

[0090] In the formula, l is the imaginary unit, and l 2 =-1; k represents the sequence number of the frequency sampling point in the frequency-space domain, k=1, 2, 3,…, NK+1, NT=2NK represents the total number of frequency sampling points of water and land inspection data in the frequency-space domain.

[0091] The step S20 further includes:

[0092] Calculate the delay of the first ghost reflection of the direct wave.

[0093] In the embodiment of the present invention, the first ghost reflection delay time τ of the direct wave of the i-th spatial channel is calculated according to the following formula: i ;

[0094] τ i =T Gi -T Bi , (13)

[0095] In the formula, i=1,2,3,…,NI; τ i It represents the first ghost reflection delay of the direct wave of the i-th spatial channel, in seconds (s).

[0096] The step S20 further includes:

[0097] Based on the first ghost reflection delay of the direct wave, a frequency-space domain cross ghost reflection delay factor is calculated.

[0098] In the embodiment of the present invention, the frequency-space domain cross-ghost delay factor Z[i,k] is calculated according to the following formula:

[0099]

[0100] Where i = 1, 2, 3, ..., NI, k = 1, 2, 3, ..., NK + 1; Δf is the frequency sampling interval, in Hertz (Hz); and

[0101]

[0102] The step S20 further includes:

[0103] The direct wave correlation sequence of the water inspection data of the common receiving point gather in the frequency-space domain is calculated based on the water inspection data of the common receiving point gather in the frequency-space domain, and the direct wave correlation sequence of the land inspection data of the common receiving point gather in the frequency-space domain is calculated based on the land inspection data of the common receiving point gather in the frequency-space domain.

[0104] In the embodiment of the present invention, the direct wave autocorrelation sequence AA0[k] of the frequency domain common receiving point gather land inspection data is calculated according to the following formula:

[0105]

[0106] The direct wave cross-correlation sequence BB0[k] of the water and land inspection data of the common receiving point gather in the frequency domain is calculated according to the following formula:

[0107]

[0108] In the formula, k = 1, 2, 3,…, NK+1.

[0109] The step S20 further includes:

[0110] The frequency domain direct wave first ghost reflection correlation sequence is calculated based on the frequency-space domain cross ghost reflection delay factor and the frequency-space domain common receiving point gather direct wave land inspection data.

[0111] In the embodiment of the present invention, the autocorrelation sequence AA1[k] of the direct wave first ghost reflection of the frequency domain common receiving point gather land inspection data is calculated according to the following formula:

[0112]

[0113] In the formula, k = 1, 2, 3,…, NK+1.

[0114] The step S20 further includes:

[0115] The frequency domain direct wave secondary ghost reflection correlation sequence is calculated based on the frequency-space domain cross ghost reflection delay factor and the frequency-space domain common receiving point gather direct wave land inspection data. Among them, the frequency domain direct wave secondary ghost reflection correlation sequence includes the direct wave secondary ghost reflection autocorrelation sequence of the frequency domain common receiving point gather land inspection data and the direct wave secondary ghost reflection cross-correlation sequence of the frequency domain common receiving point gather water and land inspection data.

[0116] The direct wave secondary ghost reflection autocorrelation sequence AA2[k] of the frequency domain common receiving point gather land inspection data is calculated according to the following formula:

[0117]

[0118] The direct wave secondary ghost reflection cross-correlation sequence BB2[k] of the water and land inspection data of the common receiving point gather in the frequency domain is calculated according to the following formula:

[0119]

[0120] In the formula, k = 1, 2, 3,…, NK+1.

[0121] The step S20 further includes:

[0122] The frequency domain direct wave autocorrelation and sequence are calculated based on the direct wave autocorrelation sequence of the frequency domain common receiving point gather land inspection data, the direct wave first ghost reflection autocorrelation sequence of the frequency domain common receiving point gather land inspection data and the direct wave second ghost reflection autocorrelation sequence of the frequency domain common receiving point gather land inspection data.

[0123] In the embodiment of the present invention, the frequency domain direct wave autocorrelation and sequence AA[k] are calculated according to the following formula:

[0124] AA[k]=AA0[k]+AA1[k]+AA2[k], (21)

[0125] The direct wave cross-correlation and sequence in the frequency domain are calculated based on the direct wave cross-correlation sequence of the water and land inspection data of the frequency domain common receiving point gather and the direct wave secondary ghost reflection cross-correlation sequence of the water and land inspection data of the frequency domain common receiving point gather.

[0126] In the embodiment of the present invention, the frequency domain direct wave cross correlation and sequence BB[k] are calculated according to the following formula:

[0127] BB[k]=BB0[k]+BB2[k], (22)

[0128] In the formula, k = 1, 2, 3,…, NK+1.

[0129] The step S20 further includes:

[0130] The cross ghost calibration factor is calculated based on the frequency domain direct wave autocorrelation and sequence and the frequency domain direct wave cross-correlation and sequence.

[0131] In the embodiment of the present invention, the cross ghost calibration factor C is calculated according to the following formula: d [k]

[0132]

[0133] Wherein, k = 1, 2, 3, ..., NK+1; α is a very small positive real number, for example, α = 0.000001, to prevent equation (32) from being divided by zero.

[0134] S30, separating the uplink and downlink wavefields based on the cross ghost calibration factor to obtain frequency-space domain conjugate antisymmetric uplink and downlink wavefield data and time-space domain uplink and downlink wavefield data; and plotting and storing the time-space domain uplink and downlink wavefield data.

[0135] The step S30 comprises:

[0136] S301, calibrating the frequency-space domain common reception point gather land inspection data based on the cross-ghost reflection calibration factor to obtain calibrated frequency-space domain common reception point gather land inspection data.

[0137] The cross frequency is calculated according to the following formula: the frequency after the cross ghost reflection calibration in the spatial domain: the land inspection data G of the spatial domain common receiving point gather c [i,k]

[0138] G c [i,k]=C d [k]G[i,k], (24)

[0139] Where i = 1, 2, 3, ..., NI, k = 1, 2, 3, ..., NK + 1; G[i, k] is the land inspection data of the common receiving point gather in the frequency-space domain.

[0140] The step S30 further includes:

[0141] S302 , calculating frequency-space domain conjugate anti-symmetric upgoing and downgoing wavefield data to obtain frequency-space domain conjugate anti-symmetric upgoing wavefield data and time-space domain conjugate anti-symmetric downgoing wavefield data.

[0142] The frequency-space domain conjugate antisymmetric upgoing wavefield data U[i,k] is calculated according to the following formula:

[0143] U[i,k]=U Q [i,NT+2-k], (25)

[0144] The time-space domain conjugate antisymmetric downlink wave field data D[i,k] is calculated according to the following formula;

[0145] D[i,k]=D Q [i,NT+2-k], (26)

[0146] Where, i = 1, 2, 3, ..., NI, k = NK + 2, NK + 3, NK + 4, ..., NT; the symbol "· Q ” represents the complex conjugate operation.

[0147] S303, performing upgoing and downgoing wavefield separation based on the frequency-space domain conjugate antisymmetric upgoing wavefield data and the land inspection data after the frequency-space domain cross ghost calibration processing, so as to obtain the frequency-space domain upgoing wavefield above the seabed after the cross ghost calibration processing and the frequency-space domain downgoing wavefield above the seabed after the cross ghost calibration processing.

[0148] In the embodiment of the present invention, the upgoing wave field U[i,k] above the seabed in the frequency-space domain after the cross-ghosting calibration process is calculated according to the following formula:

[0149]

[0150] The downgoing wave field D[i,k] above the seafloor in the frequency-space domain after the cross-ghost calibration is calculated according to the following formula:

[0151]

[0152] Where i = 1, 2, 3, ..., NI, k = 1, 2, 3, ..., NK + 1; H[i, j] is the water inspection data of the common receiving point gather in the frequency-space domain.

[0153] In the present invention, the frequency-space domain direct wave cross-ghost reflection upgoing wave field is

[0154]

[0155] In the formula, O g [i,k] = 1 + Z[i,k] is the ghost reflection factor of land inspection data, also known as the cross ghost reflection factor of water inspection data; h [i,k] = 1-Z[i,k] is the ghost reflection factor of water inspection data, also known as the cross ghost reflection factor of land inspection data; U d [i,j] is the direct wave cross-ghost reflection upgoing wave field separated from the direct wave water and land inspection data. Minimize the following objective function:

[0156]

[0157] The method for calculating the cross-ghost reflection calibration factor of land and water inspection data based on the objective function (20) is called the cross-ghost reflection calibration method. From equation (19), we have

[0158]

[0159] Substituting equation (21) into equation (20), we have

[0160]

[0161] The frequency domain cross-ghosting calibration factor C on both sides of equation (22) d [k] Take the derivative, we have

[0162]

[0163] Let the right side of equation (23) be zero and simplify it to get

[0164]

[0165] Substituting equations (16)-(22) into equation (34), we have

[0166]

[0167] Wherein, α is a very small positive real number, such as α = 0.000001, to prevent equation (35) from being divided by zero;

[0168] Through equation (35), the optimal frequency domain water and land inspection data cross-ghost reflection calibration factor C can be solved: d [k].

[0169] S304, respectively perform inverse Fourier transform on the upgoing wave field above the seabed in the frequency-space domain after the cross-ghost reflection calibration processing and the downgoing wave field above the seabed in the frequency-space domain after the cross-ghost reflection calibration processing to obtain upgoing and downgoing wave field data in the time-space domain, and draw and store the upgoing and downgoing wave field data in the time-space domain.

[0170] The upgoing wave field above the seabed in the frequency-space domain after the cross-ghost calibration processing and the downgoing wave field above the seabed in the frequency-space domain after the cross-ghost calibration processing are respectively subjected to inverse Fourier transform to obtain the upgoing and downgoing wave field data in the time-space domain, including:

[0171] The upgoing wavefield data u[i,j] in the time-space domain is calculated according to the following formula:

[0172]

[0173] The downlink wave field data d[i,j] in the time-space domain is calculated according to the following formula:

[0174]

[0175] Where i represents the sequence number of the spatial channel in the time-space domain, i = 1, 2, 3, ..., NI, NI represents the total number of spatial channels in the common receiving point gather; j represents the sequence number of the time sampling point in the time-space domain, j = 1, 2, 3, ..., NJ, NJ represents the total number of time sampling points in the common receiving point gather.

[0176] The present invention makes full use of the cross-ghost reflection characteristics of water and land inspection data, calculates the travel time of the direct wave and the primary ghost reflection, determines the direct wave extraction time window function, and then calculates the direct wave data in the near-offset channel, thereby determining the seabed primary ghost reflection data and the primary reflection wave (upward wave field) data between the direct wave and the seabed primary ghost reflection. The direct wave received at the seabed is a downward wave field, and the seabed primary ghost reflection is also a downward wave field, so these downward wave fields can be used to separate the upward and downward wave fields of water and land inspection data, thereby improving the upward and downward wave field separation and processing capability of water and land inspection data. The invention calculates the travel time of the direct wave and the primary ghost reflection, the direct wave extraction time window function, the direct wave primary ghost reflection delay time, the frequency-space domain cross ghost reflection delay factor, the frequency-domain water and land inspection data direct wave primary ghost reflection and secondary ghost reflection related sequence, the frequency-domain direct wave related and sequence, etc., realizes direct calculation and determination of the best cross ghost reflection calibration factor in the frequency-space domain, so that the calibration processing of the water inspection data and the land inspection data and the up-going and down-going wave field separation processing can be performed quickly and accurately, so as to eliminate the interference of seawater ringing and ghost reflection multiple waves in the seismic data (i.e., the up-going wave field data), provide the best up-going and down-going wave field data for the subsequent up-going and down-going wave field joint deconvolution and mirror offset imaging processing, and the calculation is accurate, time-saving, fast and efficient.

[0177] It should be understood that, although described in a certain order, these steps are not necessarily performed in sequence in the above order. Unless there is clear explanation in this article, the execution of these steps does not have strict order restriction, and these steps can be performed in other orders. Moreover, a part of the steps of the present embodiment may include a plurality of steps or a plurality of stages, and these steps or stages are not necessarily performed at the same time, but can be performed at different times, and the execution order of these steps or stages is not necessarily performed in sequence, but can be performed in turn or alternately with at least a part of the steps or stages in other steps or other steps.

[0178] In one embodiment, see Figure 4 As shown, in an embodiment of the present invention, a device for calibrating cross ghost reflections of water and land inspection data is also provided, which includes a module 100 for determining an extraction time window function, a module 200 for obtaining a cross ghost reflection calibration factor, and a module 300 for obtaining uplink and downlink wave field data.

[0179] The module 100 for determining the extraction time window function determines the direct wave extraction time window function by calculating the travel time of the direct wave and the primary ghost reflection.

[0180] The module 200 for obtaining the cross ghost reflection calibration factor calculates the direct wave first ghost reflection delay time, the frequency-space domain cross ghost reflection delay factor, the frequency domain common receiving point gather land inspection data direct wave first ghost reflection autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave second ghost reflection autocorrelation sequence and the frequency domain direct wave autocorrelation sum sequence based on the direct wave extraction time window function to obtain the cross ghost reflection calibration factor.

[0181] The uplink and downlink wavefield data acquisition module 300 separates the uplink and downlink wavefields based on the cross ghost calibration factor to obtain frequency-space domain conjugate antisymmetric uplink and downlink wavefield data and time-space domain uplink and downlink wavefield data; and plots and stores the time-space domain uplink and downlink wavefield data.

[0182] In one embodiment, a computer device is provided in an embodiment of the present invention, including a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other through the communication bus.

[0183] Memory, used to store computer programs;

[0184] The processor is used to execute the computer program stored in the memory to execute the water and land inspection data cross-ghost reflection calibration method. The processor implements the steps in the above method embodiment when executing instructions.

[0185] The communication bus mentioned in the above terminal can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. The communication bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, only one thick line is used in the figure, but it does not mean that there is only one bus or one type of bus.

[0186] The communication interface is used for communication between the above terminal and other devices.

[0187] The memory may include a random access memory (RAM) or a non-volatile memory, such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0188] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0189] The computer device includes user devices and network devices. The user devices include but are not limited to computers, smart phones, PDAs, etc. The network devices include but are not limited to a single network server, a server group consisting of multiple network servers, or a cloud consisting of a large number of computers or network servers based on cloud computing (Cloud Computing), wherein cloud computing is a type of distributed computing, a super virtual computer consisting of a group of loosely coupled computer sets. The computer device can be operated alone to implement the present invention, or it can be connected to the network and implement the present invention through interactive operations with other computer devices in the network. The network where the computer device is located includes but is not limited to the Internet, wide area network, metropolitan area network, local area network, VPN network, etc.

[0190] It should be further understood that the term “and / or” used in the present specification and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0191] In one embodiment of the present invention, a storage medium is further provided, on which a computer program is stored. When the computer program is executed by a processor, the steps in the above method embodiment are implemented.

[0192] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiment method can be implemented by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the process of the embodiment of the above-mentioned method. Among them, any reference to memory, storage, database or other media used in the embodiments provided by the present invention can include at least one of non-volatile and volatile memory.

[0193] It should be understood that, as used herein, the singular form "a" or "an" is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations of one or more of the items listed in association. The serial numbers of the embodiments disclosed in the above embodiments of the present invention are for description only and do not represent the advantages and disadvantages of the embodiments.

[0194] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for calibrating cross-ghost reflections of water and land inspection data, characterized in that: The method includes: S10, determining a direct wave extraction time window function by calculating the travel time of the direct wave and a ghost reflection; S20, based on the direct wave extraction time window function, calculate the direct wave first ghost reflection delay time, the frequency-space domain cross ghost reflection delay factor, the frequency domain common receiving point gather land inspection data direct wave first ghost reflection autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave second ghost reflection autocorrelation sequence and the frequency domain direct wave autocorrelation sum sequence to obtain the cross ghost reflection calibration factor; S30, separating the uplink and downlink wavefields based on the cross ghost calibration factor to obtain frequency-space domain conjugate antisymmetric uplink and downlink wavefield data and time-space domain uplink and downlink wavefield data; and plotting and storing the time-space domain uplink and downlink wavefield data.

2. The method for calibrating cross-ghost reflections of water and land inspection data according to claim 1, characterized in that: The step S10 further includes: S101, calculating the direct wave travel time and the one ghost reflection travel time; S102, using the direct wave travel time and the primary ghost reflection travel time to calculate the start and end sample point sequence numbers of the direct wave data; S103, using the sequence numbers of the start and end samples of the direct wave data, calculate the direct wave extraction time window function.

3. The method for calibrating cross ghost reflections of water and land inspection data according to claim 2, characterized in that: The step S20 further includes: Direct wave water detection data and direct wave land detection data are extracted based on the direct wave extraction time window function.

4. The method for calibrating cross ghost reflections of water and land inspection data as claimed in claim 3, characterized in that: The step S20 further includes: The frequency-space domain common reception point gather water detection data is calculated based on the direct wave water detection data, and the frequency-space domain common reception point gather land detection data is calculated based on the direct wave land detection data.

5. The method for cross-ghost reflection calibration of water and land inspection data as claimed in claim 4, characterized in that: The step S20 further includes: Calculate the delay of the first ghost reflection of the direct wave.

6. The method for cross-ghost reflection calibration of water and land inspection data as claimed in claim 5, characterized in that: The step S20 further includes: The direct wave correlation sequence of the water inspection data of the common receiving point gather in the frequency-space domain is calculated based on the water inspection data of the common receiving point gather in the frequency-space domain, and the direct wave correlation sequence of the land inspection data of the common receiving point gather in the frequency-space domain is calculated based on the land inspection data of the common receiving point gather in the frequency-space domain.

7. The method for cross-ghost reflection calibration of water and land inspection data as claimed in claim 6, characterized in that: The step S20 further includes: The frequency domain direct wave first ghost reflection correlation sequence is calculated based on the frequency-space domain cross ghost reflection delay factor and the frequency-space domain common receiving point gather direct wave land inspection data.

8. The method for cross-ghost reflection calibration of water and land inspection data as claimed in claim 7, characterized in that: The step S20 further includes: The frequency domain direct wave autocorrelation sum sequence is calculated based on the frequency domain common receiving point gather land inspection data direct wave autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave first ghost reflection autocorrelation sequence and the frequency domain common receiving point gather land inspection data direct wave second ghost reflection autocorrelation sequence; The frequency domain direct wave cross-correlation and sequence are calculated based on the frequency domain common receiving point gather water and land inspection data direct wave cross-correlation sequence and the frequency domain common receiving point gather water and land inspection data direct wave secondary ghost reflection cross-correlation sequence; The cross ghost calibration factor is calculated based on the frequency domain direct wave autocorrelation and sequence and the frequency domain direct wave cross-correlation and sequence.

9. The method for cross-ghost reflection calibration of water and land inspection data as claimed in claim 8, characterized in that: The step S30 further includes: S301, calibrating the frequency-space domain common receiving point gather land inspection data based on the cross ghost reflection calibration factor to obtain calibrated frequency-space domain common receiving point gather land inspection data; S302, calculating frequency-space domain conjugate anti-symmetric upgoing and downgoing wavefield data to obtain frequency-space domain conjugate anti-symmetric upgoing wavefield data and time-space domain conjugate anti-symmetric downgoing wavefield data; S303, performing upgoing and downgoing wavefield separation based on the frequency-space domain conjugate antisymmetric upgoing wavefield data and the land inspection data processed by frequency-space domain cross ghost calibration, so as to obtain the frequency-space domain upgoing wavefield above the seabed processed by cross ghost calibration and the frequency-space domain downgoing wavefield above the seabed processed by cross ghost calibration; S304, respectively perform inverse Fourier transform on the upgoing wave field above the seabed in the frequency-space domain after the cross-ghost reflection calibration processing and the downgoing wave field above the seabed in the frequency-space domain after the cross-ghost reflection calibration processing to obtain upgoing and downgoing wave field data in the time-space domain, and draw and store the upgoing and downgoing wave field data in the time-space domain.

10. A device for calibrating cross-ghost reflection of water and land inspection data, characterized in that: The device comprises: a module for determining and extracting a time window function, a module for obtaining a cross ghost reflection calibration factor, and a module for obtaining uplink and downlink wave field data; The module for determining the extraction time window function is configured to determine the direct wave extraction time window function by calculating the travel time of the direct wave and the primary ghost reflection; The module for obtaining cross ghost reflection calibration factors is configured to calculate the direct wave first ghost reflection delay time, the frequency-space domain cross ghost reflection delay factor, the frequency domain common receiving point gather land inspection data direct wave first ghost reflection autocorrelation sequence, the frequency domain common receiving point gather land inspection data direct wave second ghost reflection autocorrelation sequence and the frequency domain direct wave autocorrelation sum sequence based on the direct wave extraction time window function to obtain the cross ghost reflection calibration factor; The uplink and downlink wavefield data acquisition module is configured to separate the uplink and downlink wavefields based on the cross ghost calibration factor to obtain frequency-space domain conjugate antisymmetric uplink and downlink wavefield data and time-space domain uplink and downlink wavefield data; and to plot and store the time-space domain uplink and downlink wavefield data.

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