阅读说明：本技术 海底节点地震数据上下行波场分离的方法及装置 (Method and device for separating up-and-down traveling wave fields of seismic data of submarine nodes ) 是由 高少武 张少华 王成祥 方云峰 詹毅 李鹏 于 2019-02-27 设计创作，主要内容包括：本发明提供了一种海底节点地震数据上下行波场分离的方法及装置,其中,该方法包括：根据水中检波器地震数据,确定水中检波器数据的平均自相关函数；根据水陆检波器数据,确定水陆检波器地震数据的平均互相关函数,陆水检波器数据的平均互相关函数；根据陆地检波器数据,确定陆地检波器数据的平均自相关函数；根据该相关函数,确定分离因子特征方程系数；根据该系数,构造分离因子特征方程；根据该方程,执行迭代步骤,得到最佳分离因子值；根据最佳分离因子值,确定最佳波场分离贡献因子值；根据最佳波场分离贡献因子值,确定纯上行、纯下行波场数据。上述技术方案提高了上下行波场数据分离精度和效率,提高了地震数据信噪比和分辨率。(The invention provides a method and a device for separating an up-and-down traveling wave field of seismic data of a submarine node, wherein the method comprises the following steps: determining an average autocorrelation function of hydrophone data according to the hydrophone seismic data; determining an average cross-correlation function of seismic data of the land and water detectors and an average cross-correlation function of data of the land and water detectors according to the data of the land and water detectors; determining an average autocorrelation function of the geophone data from the geophone data; determining a separation factor characteristic equation coefficient according to the correlation function; constructing a separation factor characteristic equation according to the coefficient; according to the equation, executing iteration steps to obtain an optimal separation factor value; determining an optimal wave field separation contribution factor value according to the optimal separation factor value; and determining pure uplink and pure downlink wave field data according to the optimal wave field separation contribution factor value. By the technical scheme, the accuracy and the efficiency of separating the uplink wave field data from the downlink wave field data are improved, and the signal-to-noise ratio and the resolution of the seismic data are improved.)

1. A method for separating an up-going wave field and a down-going wave field of seismic data of a submarine node is characterized by comprising the following steps:

acquiring seismic data of a hydrophone and seismic data of a land geophone;

determining an average autocorrelation function of the hydrophone seismic data according to the hydrophone seismic data; determining an average cross-correlation function of the hydrophone seismic data and the land geophone seismic data and an average cross-correlation function of the land geophone seismic data and the hydrophone seismic data according to the hydrophone seismic data and the land geophone seismic data; determining an average autocorrelation function of the land geophone seismic data according to the land geophone seismic data;

determining a separation factor characteristic equation coefficient according to the average autocorrelation function of the hydrophone seismic data, the average cross-correlation function of the hydrophone seismic data and the land geophone seismic data, the average cross-correlation function of the land geophone seismic data and the hydrophone seismic data and the average autocorrelation function of the land geophone seismic data;

constructing a separation factor characteristic equation according to the separation factor characteristic equation coefficient;

according to the separation factor characteristic equation, executing an iteration step until an optimal separation factor value is obtained;

determining an optimal wave field separation contribution factor value according to the optimal separation factor value;

pure up-going wavefield data and pure down-going wavefield data are determined based on the optimal wavefield separation contribution factor value.

2. The method for separation of upgoing and downgoing wavefields in ocean bottom node seismic data of claim 1, wherein the step of performing an iteration based on a separation factor characteristic equation until an optimal separation factor value is obtained comprises:

according to the separation factor characteristic equation, executing an iteration step and determining a first-order optimal separation factor value;

according to the separation factor characteristic equation and the first-order optimal separation factor value, executing an iteration step and determining a second-order optimal separation factor value;

according to the separation factor characteristic equation and the second-order optimal separation factor value, executing an iteration step and determining a third-order optimal separation factor value; the third-order optimal separation factor value is an optimal separation factor value.

3. The method for upgoing and downgoing wavefield separation of seismic data at a subsea node of claim 1, wherein the optimal wavefield separation contribution factor value comprises: a value of a contributor factor of hydrophone seismic data to the up-going wavefield, a value of a contributor factor of hydrophone seismic data to the down-going wavefield, a value of a contributor factor of land geophone seismic data to the up-going wavefield, and a value of a contributor factor of land geophone seismic data to the down-going wavefield;

determining pure up-going wavefield data and pure down-going wavefield data based on the optimal wavefield separation contribution factor value, comprising:

determining pure up-going wave field data according to the contribution factor value of the hydrophone seismic data to the up-going wave field and the contribution factor value of the hydrophone seismic data to the down-going wave field;

and determining pure down-going wave field data according to the contribution factor value of the land geophone seismic data to the up-going wave field and the contribution factor value of the land geophone seismic data to the down-going wave field.

4. The method for separation of upgoing and downgoing wavefields in ocean bottom node seismic data of claim 1, wherein said separation factor characteristic equation is:

in the formula, Q represents the cross-correlation function energy of a pure up-going wave field and a pure down-going wave field, α, β and gamma are separation factors of the up-going wave field and the down-going wave field, wherein α is an energy matching coefficient, β is an energy coefficient of the down-going wave field in the up-going wave field, gamma is an energy coefficient of the up-going wave field in the down-going wave field, and f₁,f₂,f₃,f₄,f₅,f₆,f₇,f₈,f₉,f₁₀,f₇₈Are the separation factor characteristic equation coefficients.

5. The method for traveling wavefield separation of seismic data at a subsea node of claim 1, wherein acquiring hydrophone seismic data and land geophone seismic data comprises: and preprocessing the hydrophone seismic data and the land geophone seismic data after acquiring the hydrophone seismic data and the land geophone seismic data.

6. The method for upgoing and downgoing wavefield separation of ocean bottom node seismic data of claim 1, further comprising:

drawing up wave field and down wave field data profiles of a hydrophone and a land geophone according to the pure up wave field data and the pure down wave field data;

the up-going and down-going wavefield data for the hydrophone and the land geophone are stored.

7. A device for separating an upper traveling wave field from a lower traveling wave field of seismic data of a submarine node is characterized by comprising:

the acquisition unit is used for acquiring hydrophone seismic data and land geophone seismic data;

the correlation function determining unit is used for determining an average autocorrelation function of the hydrophone seismic data according to the hydrophone seismic data; determining an average cross-correlation function of the hydrophone seismic data and the land geophone seismic data and an average cross-correlation function of the land geophone seismic data and the hydrophone seismic data according to the hydrophone seismic data and the land geophone seismic data; determining an average autocorrelation function of the land geophone seismic data according to the land geophone seismic data;

a separation factor characteristic equation coefficient determining unit for determining a separation factor characteristic equation coefficient according to the average autocorrelation function of the hydrophone seismic data, the average cross-correlation function of the hydrophone seismic data and the land geophone seismic data, the average cross-correlation function of the land geophone seismic data and the hydrophone seismic data, and the average autocorrelation function of the land geophone seismic data;

the separation factor characteristic equation constructing unit is used for constructing a separation factor characteristic equation according to the separation factor characteristic equation coefficient;

the optimal separation factor value determining unit is used for executing iteration steps according to the separation factor characteristic equation until the optimal separation factor value is obtained;

an optimal wavefield separation contribution factor value determining unit for determining an optimal wavefield separation contribution factor value according to the optimal separation factor value;

and the uplink and downlink wave field data determining unit is used for determining pure uplink wave field data and pure downlink wave field data according to the optimal wave field separation contribution factor value.

8. The apparatus for upgoing and downgoing wavefield separation of seismic data at a subsea node of claim 7, wherein the optimal separation factor value determining unit is specifically configured to:

according to the separation factor characteristic equation, executing an iteration step and determining a first-order optimal separation factor value;

according to the separation factor characteristic equation and the first-order optimal separation factor value, executing an iteration step and determining a second-order optimal separation factor value;

according to the separation factor characteristic equation and the second-order optimal separation factor value, executing an iteration step and determining a third-order optimal separation factor value; the third-order optimal separation factor value is an optimal separation factor value.

9. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor implements the method of any one of claims 1 to 6 when executing the computer program.

10. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program for executing the method of any one of claims 1 to 6.

Technical Field

The invention relates to the technical field of geophysical seismic exploration, in particular to a method and a device for separating an upper traveling wave field from a lower traveling wave field of seismic data of a submarine node.

Background

With the development of seismic exploration technology, the difficulty and depth of offshore oil and gas exploration are increased, and the requirements on the signal-to-noise ratio and the resolution of seismic data are increased. Three-dimensional seismic can accurately describe reservoirs. The method comprises the steps of collecting data of an offshore submarine Node (OBN) land and water detector, fixing the land and water detectors together, and respectively receiving a pressure wave field and a velocity wave field generated by an air gun seismic source to obtain high-resolution three-dimensional seismic data. The seismic detector is fixedly placed on the sea bottom by using a fixed connecting cable to receive seismic waves, and a ship only drags a seismic source to carry out seismic wave excitation. In Ocean Bottom Cable (OBC) data acquisition, at least three vessels: the seismic source ship only drags the air gun seismic source arrangement to carry out seismic wave excitation; a receiving vessel, which is stationary, is connected to the submarine cable and receives seismic waves; a vessel or several vessels, laying and recovering the submarine cables. OBC is currently limited to only sea areas with water depths not exceeding 150 meters. However, with improvements in cable and cable recovery systems, OBC technology is advancing to deeper ocean locations. In some special areas, in order to facilitate the reservoir monitoring test, a test system is designed, and a receiving cable is reserved on the seabed for years, so that data acquisition is convenient for many times. In OBN data acquisition, at least two vessels: the seismic source ship drags an air gun seismic source array to carry out seismic wave excitation; a line carrier is provided, which receives and releases detectors (a hydrophone and a land detector) at a fixed arrangement position during operation, and extracts data. The OBN collection is suitable for deeper sea areas. In order to obtain a highly accurate three-dimensional image of the subsurface medium, the location of all shot and receiver points must be known accurately. GPS (Global Positioning System) data or coast-based radio Positioning provides the shot-boat accurate position. At the same time, the cable ship is accurately positioned, and each detector is placed at a preset position.

Submarine node land and water detector data acquisition provides two kinds of data of the same position water detector data and land detector data, and the two kinds of data are recorded by using a water detector and a land detector respectively. The hydrophone is a pressure geophone, and records pressure changes generated by seismic waves; the land geophone is a particle velocity geophone that records particle velocity changes. The two detectors have different recording mechanisms and show different characteristics for sea level multiple interference at the same position. Sea level multiples recorded by land receivers exhibit differences in polarity and amplitude characteristics compared to sea level multiples recorded by hydrophones. The two detectors record sea level multiple interference with opposite polarity, different amplitude and constant proportional to sea bottom reflection coefficient, and the constant value is energy matching coefficient. Therefore, by utilizing the amplitude and polarity characteristic difference, the sea level multiple interference can be effectively eliminated. The calibrated land detector data and the corresponding hydrophone data are added to obtain land detector calibration data (uplink wave field data), so that sea level multiple wave interference is eliminated; and subtracting the calibrated land detector data from the corresponding hydrophone data to obtain multiple wave data (downlink wave field data) related to sea level, and using the multiple wave data (downlink wave field data) for processing such as joint deconvolution, denoising, migration and the like of a subsequent uplink wave field and a downlink wave field so as to further improve the resolution and the signal-to-noise ratio.

And in a conventional processing method, an energy matching coefficient is calculated and determined by adopting a scanning method. The method comprises the steps of presetting an energy matching coefficient range value and a scanning step length, giving a series of energy matching coefficient values by a scanning method, then calculating the data sum of hydrophone data and terrestrial geophone data, calculating an autocorrelation function for the data sum, calculating a maximum variance module by the autocorrelation function, and finally determining an energy matching coefficient value by the maximum variance module value. This method requires a large number of autocorrelation calculations and maximum variance module calculations, and therefore the calculations are very time consuming. Meanwhile, because the data includes noise, after the up-going wave field and the down-going wave field are separated by using the energy matching coefficient, the separated up-going wave field includes the down-going wave field, and the separated down-going wave field includes the up-going wave field, that is, the up-going wave field and the down-going wave field cannot be completely separated.

In view of the above problems, no effective solution has been proposed.

Disclosure of Invention

The embodiment of the invention provides a method for separating an uplink wave field and a downlink wave field of seismic data of a submarine node, which is used for improving the precision of the separation of the uplink wave field and the downlink wave field of the seismic data and comprises the following steps:

acquiring seismic data of a hydrophone and seismic data of a land geophone;

determining an average autocorrelation function of the hydrophone seismic data according to the hydrophone seismic data; determining an average cross-correlation function of the hydrophone seismic data and the land geophone seismic data and an average cross-correlation function of the land geophone seismic data and the hydrophone seismic data according to the hydrophone seismic data and the land geophone seismic data; determining an average autocorrelation function of the land geophone seismic data according to the land geophone seismic data;

determining a separation factor characteristic equation coefficient according to the average autocorrelation function of the hydrophone seismic data, the average cross-correlation function of the hydrophone seismic data and the land geophone seismic data, the average cross-correlation function of the land geophone seismic data and the hydrophone seismic data and the average autocorrelation function of the land geophone seismic data;

constructing a separation factor characteristic equation according to the separation factor characteristic equation coefficient;

according to the separation factor characteristic equation, executing an iteration step until an optimal separation factor value is obtained;

determining an optimal wave field separation contribution factor value according to the optimal separation factor value;

pure up-going wavefield data and pure down-going wavefield data are determined based on the optimal wavefield separation contribution factor value.

The embodiment of the invention also provides a device for separating the uplink wave field and the downlink wave field of the seismic data of the ocean bottom nodes, which is used for improving the precision of the separation of the seismic data of the uplink wave field and the downlink wave field, and comprises the following components:

the acquisition unit is used for acquiring hydrophone seismic data and land geophone seismic data;

the correlation function determining unit is used for determining an average autocorrelation function of the hydrophone seismic data according to the hydrophone seismic data; determining an average cross-correlation function of the hydrophone seismic data and the land geophone seismic data and an average cross-correlation function of the land geophone seismic data and the hydrophone seismic data according to the hydrophone seismic data and the land geophone seismic data; determining an average autocorrelation function of the land geophone seismic data according to the land geophone seismic data;

a separation factor characteristic equation coefficient determining unit for determining a separation factor characteristic equation coefficient according to the average autocorrelation function of the hydrophone seismic data, the average cross-correlation function of the hydrophone seismic data and the land geophone seismic data, the average cross-correlation function of the land geophone seismic data and the hydrophone seismic data, and the average autocorrelation function of the land geophone seismic data;

the separation factor characteristic equation constructing unit is used for constructing a separation factor characteristic equation according to the separation factor characteristic equation coefficient;

the optimal separation factor value determining unit is used for executing iteration steps according to the separation factor characteristic equation until the optimal separation factor value is obtained;

an optimal wavefield separation contribution factor value determining unit for determining an optimal wavefield separation contribution factor value according to the optimal separation factor value;

and the uplink and downlink wave field data determining unit is used for determining pure uplink wave field data and pure downlink wave field data according to the optimal wave field separation contribution factor value.

The embodiment of the invention also provides computer equipment which comprises a memory, a processor and a computer program which is stored on the memory and can run on the processor, wherein the processor executes the method for separating the up-traveling wave field and the down-traveling wave field of the seismic data of the submarine nodes.

An embodiment of the present invention also provides a computer-readable storage medium storing a computer program for executing the method for separating the up-traveling wave field and the down-traveling wave field of the seismic data of the ocean bottom node.

Compared with the scheme that the complete separation of the uplink wave field and the downlink wave field can not be completely realized in the prior art, the technical scheme provided by the embodiment of the invention comprises the following steps:

firstly, in the technical scheme provided by the embodiment of the invention, the coefficient of the characteristic equation of the separation factor is obtained according to the autocorrelation and cross-correlation functions of the mean correlation function of the data of the land and water detectors and is the fourth-order cumulant of the seismic data of the land and water detectors, and the fourth-order cumulant has strong noise resistance, so that the separation processing of the uplink wave field and the downlink wave field has strong noise resistance.

Secondly, the technical scheme provided by the embodiment of the invention realizes the calculation of the characteristic equation coefficient of the separation factor of the submarine node hydrophone gather data and the land geophone gather data, and realizes the inversion of the optimal separation factor and the calculation of the optimal wave field separation contribution factor, thereby realizing the optimal uplink and downlink wave field separation processing of the hydrophone seismic data and the land geophone seismic data and improving the separation precision of the uplink and downlink wave field data.

In addition, in the technical scheme provided by the embodiment of the invention, the optimal separation factor value is obtained through iteration, and the optimal wave field separation contribution factor value is obtained according to the optimal separation factor value.

In summary, the technical scheme provided by the embodiment of the invention improves the precision and efficiency of the separation of the uplink wave field data and the downlink wave field data, is the most effective method in eliminating the multiples in the land and water detector seismic data, realizing the combination processing method of the land and water detector seismic data, realizing the effective and rapid separation processing of the uplink wave field and the downlink wave field of the land and water detector data of the submarine node, eliminating the interference influence of the sea and water multiples in the seismic data, effectively improving the signal-to-noise ratio and the resolution of the seismic data, and providing the high-precision uplink wave field and downlink wave field data for the subsequent processing.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a schematic flow chart of a method for separating up and down wavefields of seismic data at a subsea node in an embodiment of the invention;

2(a) -2 (f) are schematic diagrams comparing data of a common geophone gather in an embodiment of the invention, wherein the abscissa is a track number (Trace, corresponding to a sequence number of a parameter channel of a Time window of water and land geophone data), and the ordinate is seismic data propagation Time (Time/ms, corresponding to a sequence number of a Time sampling point of a Time window of water and land geophone data); wherein: fig. 2 (a): hydrophone data; fig. 2 (b): land detector data; fig. 2 (c): up-going wavefield data; fig. 2 (d): down-going wavefield data; fig. 2 (e): omega up-going wavefield data; fig. 2 (f): omega down-going wavefield data;

3(a) -3 (d) are schematic diagrams comparing results of geophone shot data in an embodiment of the invention, wherein the abscissa is a track number (Trace, corresponding to a sequence number of a Time window parameter track of water and land survey data), and the ordinate is seismic data propagation Time (Time/ms, corresponding to a sequence number of a Time sampling point of a Time window parameter of water and land survey data); wherein: fig. 3 (a): hydrophone data; fig. 3 (b): land detector data; fig. 3 (c): up-going wavefield data; fig. 3 (d): down-going wavefield data;

4(a) -4 (f) are schematic diagrams comparing stacked data of land and water detectors in an embodiment of the invention, wherein the abscissa is a common midpoint channel number (CMP number) and the ordinate is seismic data propagation Time (Time/ms, corresponding to a Time window parameter Time sample sequence number of land and water detection data); wherein: fig. 4 (a): hydrophone data; fig. 4 (b): land detector data; fig. 4 (c): up-going wavefield data; fig. 4 (d): down-going wavefield data; fig. 4 (e): omega up-going wavefield data; fig. 4 (f): omega down-going wavefield data;

FIG. 5 is a schematic structural diagram of a device for separating the up-and-down wavefield of seismic data of a submarine node in the embodiment of the invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the following embodiments and accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.

In Ocean Bottom Node (OBN) data acquisition, two kinds of data of hydrophone data and land geophone data can be recorded at the same position. Since both data are located at the same position, they are simultaneously recorded to the multiples generated at sea level. Through reasonable combination of the two data, multiple waves generated by seawater in the seismic data can be effectively eliminated. The invention relates to the exploration, development and exploitation technology of oil fields, in particular to a method for separating an uplink wave field from a downlink wave field of seismic graph and seabed node data with high resolution for reflecting underground stratum horizons and oil reservoir description, which is particularly suitable for combining and processing seismic data of a pre-stack hydrophone and a land geophone acquired at sea, and achieves the purposes of eliminating sea level multiples of the seismic data, improving the signal-to-noise ratio and resolution of the seismic data and providing the uplink wave field and the downlink wave field data for subsequent processing.

The inventor considers the technical problem that the complete separation of the up-going wave field and the down-going wave field cannot be completely realized, so a scheme for quickly and accurately separating the up-going wave field and the down-going wave field of the seismic data of the sea bottom nodes is provided. The scheme introduces two parameters of an energy coefficient of a downlink wave field in an uplink wave field and an energy coefficient of an uplink wave field in a downlink wave field, and simultaneously adopts direct calculation to determine an optimal energy matching coefficient, three separation factor parameters of the energy coefficient of the downlink wave field in the uplink wave field and the energy coefficient of the uplink wave field in the downlink wave field, and four wave field separation contribution factor parameters so as to realize complete separation of the uplink wave field and the downlink wave field, wherein the separated uplink wave field does not contain the downlink wave field, and the separated downlink wave field does not contain the uplink wave field. The following provides a detailed description of the scheme for separating the up-traveling wave field and the down-traveling wave field of the seismic data of the ocean bottom nodes.

Fig. 1 is a schematic flow chart of a method for separating an upper traveling wavefield from a lower traveling wavefield of seismic data of a submarine node in an embodiment of the present invention, and as shown in fig. 1, the method includes the following steps:

step 101: acquiring seismic data of a hydrophone and seismic data of a land geophone;

step 102: determining an average autocorrelation function of the hydrophone seismic data according to the hydrophone seismic data; determining an average cross-correlation function of the hydrophone seismic data and the land geophone seismic data and an average cross-correlation function of the land geophone seismic data and the hydrophone seismic data according to the hydrophone seismic data and the land geophone seismic data; determining an average autocorrelation function of the land geophone seismic data according to the land geophone seismic data;

step 103: determining a separation factor characteristic equation coefficient according to the average autocorrelation function of the hydrophone seismic data, the average cross-correlation function of the hydrophone seismic data and the land geophone seismic data, the average cross-correlation function of the land geophone seismic data and the hydrophone seismic data and the average autocorrelation function of the land geophone seismic data;

step 104: constructing a separation factor characteristic equation according to the separation factor characteristic equation coefficient;

step 105: according to the separation factor characteristic equation, executing an iteration step until an optimal separation factor value is obtained;

step 106: determining an optimal wave field separation contribution factor value according to the optimal separation factor value;

step 107: pure up-going wavefield data and pure down-going wavefield data are determined based on the optimal wavefield separation contribution factor value.

Compared with the scheme that the complete separation of the uplink wave field and the downlink wave field can not be completely realized in the prior art, the technical scheme provided by the embodiment of the invention comprises the following steps:

firstly, in the technical scheme provided by the embodiment of the invention, the coefficient of the characteristic equation of the separation factor is obtained according to the autocorrelation and cross-correlation functions of the mean correlation function of the data of the land and water detectors and is the fourth-order cumulant of the seismic data of the land and water detectors, and the fourth-order cumulant has strong noise resistance, so that the separation processing of the uplink wave field and the downlink wave field has strong noise resistance.

Secondly, the technical scheme provided by the embodiment of the invention realizes the calculation of the characteristic equation coefficient of the separation factor of the submarine node hydrophone gather data and the land geophone gather data, and realizes the inversion of the optimal separation factor and the calculation of the optimal wave field separation contribution factor, thereby realizing the optimal uplink and downlink wave field separation processing of the hydrophone seismic data and the land geophone seismic data and improving the separation precision of the uplink and downlink wave field data.

In addition, in the technical scheme provided by the embodiment of the invention, the optimal separation factor value is obtained through iteration, and the optimal wave field separation contribution factor value is obtained according to the optimal separation factor value.

In summary, the technical scheme provided by the embodiment of the invention improves the precision and efficiency of the separation of the uplink wave field data and the downlink wave field data, is the most effective method in eliminating the multiples in the land and water detector seismic data, realizing the combination processing method of the land and water detector seismic data, realizing the effective and rapid separation processing of the uplink wave field and the downlink wave field of the land and water detector data of the submarine node, eliminating the interference influence of the sea and water multiples in the seismic data, effectively improving the signal-to-noise ratio and the resolution of the seismic data, and providing the high-precision uplink wave field and downlink wave field data for the subsequent processing.