Method and system for predicting seismic velocity of formation to be drilled while drilling based on waveform similarity

Abstract

The present invention discloses a method and system for predicting seismic velocity of a formation to be drilled while drilling based on waveform similarity, including: establishing a relationship between amplitude and logging velocity according to the amplitude of a wellside seismic trace of a target well and logging data of a completed well section of the target well; based on the relationship between amplitude and logging velocity, establishing and solving a constrained velocity model containing seismic velocity information of an undrilled well section of the target well according to the amplitude data of the wellside seismic trace and logging velocity data of the drilled well section by using seismic horizon interpolation technology, thereby obtaining the seismic velocity of the undrilled well section of the target well. The present invention can quickly predict the logging velocity in front of the drill bit with high stability, thereby improving drilling efficiency.

Description

Technical Field

[0001] The invention relates to the field of petroleum development and exploration, and in particular to a method and system for predicting seismic velocity of a formation to be drilled while drilling based on waveform similarity. Background Art

[0002] Traditionally, important drilling parameters such as mud density window are usually based on comprehensive analysis of various types of data from previous well completions to establish a model of wellbore stress and formation pressure system, determine the distribution law of the formation pressure system in the exploration area, and provide data support for the next stage of drilling design and construction. These methods are currently very common and well developed. However, with the advancement of drilling technology and the increasing complexity of geological conditions, engineers require that the mechanical properties of the wellbore wall of the formation to be drilled be predicted in advance during actual drilling, so as to detect and effectively deal with complex faults such as overflow, collapse, and leakage as early as possible. Therefore, it is more meaningful and more practical to effectively use seismic data, especially seismic velocity information, to predict important drilling parameter information such as rock mechanical parameters and mud density window while drilling.

[0003] In the process of realizing the present invention, the inventors found that in the prior art, the calculation methods of using seismic velocity data to obtain useful drilling information such as rock mechanical parameters and mud density window have gradually matured, but the solutions for quickly predicting the seismic velocity in front of the drill bit while drilling are limited. In addition, traditional seismic inversion processing is performed in the time domain, only impedance information is provided, and the calculation process is relatively complicated.

[0004] Therefore, in the prior art, there is a need to provide a solution that can quickly and efficiently predict the seismic velocity of an undrilled section. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for predicting the seismic velocity of a formation to be drilled while drilling based on waveform similarity, comprising: step one, establishing a relationship between amplitude and logging velocity according to the amplitude of the seismic trace beside the wellbore of the target well and the logging data of the drilled section of the target well; step two, based on the relationship between amplitude and logging velocity, according to the amplitude data of the seismic trace beside the wellbore and the logging velocity data of the drilled section, using the seismic horizon interpolation technology, establishing and solving a constrained velocity model containing the seismic velocity information of the undrilled section of the target well, thereby obtaining the seismic velocity of the undrilled section of the target well.

[0006] Preferably, in the step 2, based on the relationship between the amplitude and the logging velocity, according to the amplitude data of the seismic trace beside the well and the logging velocity data of the drilled section of the target well, the well logging velocity data of the drilled section of the target well is subjected to layer interpolation processing to establish the constrained velocity model; according to the seismic velocity data of the drilled section of the target well and the seismic wave amplitude data of the seismic trace beside the well, the constrained velocity model is inverted to obtain the seismic velocity prediction result.

[0007] Preferably, when there are multiple drilled adjacent wells around the target well, the step 2 includes: based on the relationship between amplitude and logging velocity, according to the amplitude data of the seismic traces near the well, the logging velocity data of the drilled section of the target well, and the logging velocity data of each adjacent well that matches the depth range of the undrilled section, interpolating the logging velocity data of the adjacent wells, and using the interpolation result as the logging velocity prediction result of the undrilled section of the target well.

[0008] Preferably, the inverse distance weighted interpolation method or the Kriging interpolation method is used to perform interpolation processing on the logging velocity data of adjacent wells.

[0009] Preferably, in the step 1, an initial model containing relationship coefficients is established based on the amplitude data of the seismic traces near the well and the logging data of the completed drilling section of the target well; the minimum mean square error of the initial model is solved to obtain the relationship between the amplitude and the logging velocity, wherein the relationship between the amplitude and the logging velocity is expressed by the following expression:

[0010] α=(v P T v P ) -1 v P T s

[0011] Among them, α represents the relationship coefficient matrix, v P represents the logging data matrix of the completed drilling section of the target well, s represents the amplitude data matrix of the seismic traces near the well, and T represents the transposition sign.

[0012] Preferably, the amplitude data of the wellside seismic traces are also constructed as amplitude data corresponding to the full seismic trace in the seismic profile where the target well is located.

[0013] Preferably, the constrained velocity model is expressed using the following expression:

[0014] v P =(sα T +λv Pm c T )(αα T +λcc T ) -1

[0015] Among them, α represents the relationship coefficient matrix, v P represents the logging data matrix of the completed drilling section of the target well, s represents the amplitude data matrix of the seismic trace near the well, λ represents the Lagrange multiplier, c=[1 0 … 0] T , v Pm represents the seismic velocity data matrix of the undrilled section of the target well, and T represents the transposed sign.

[0016] On the other hand, the present invention also provides a system for predicting seismic velocity while drilling of formations to be drilled based on waveform similarity, comprising: an amplitude and logging velocity relationship generation module, which is configured to establish an amplitude and logging velocity relationship based on the amplitude of the wellside seismic trace of the target well and the logging data of the drilled section of the target well; a seismic velocity prediction module, which is configured to establish and solve a constrained velocity model containing seismic velocity information of the undrilled section of the target well based on the amplitude and logging velocity relationship, according to the wellside seismic trace amplitude data and the logging velocity data of the drilled section, using seismic layer interpolation technology, so as to obtain the seismic velocity of the undrilled section of the target well.

[0017] Preferably, the seismic velocity prediction module is further configured to perform stratum interpolation processing on the logging velocity data of the drilled section of the target well section based on the relationship between the amplitude and the logging velocity, according to the amplitude data of the seismic trace beside the well and the logging velocity data of the drilled section of the target well, to establish the constrained velocity model, and then invert the constrained velocity model according to the seismic velocity data of the drilled section of the target well and the seismic wave amplitude data of the seismic trace beside the well to obtain the seismic velocity prediction result.

[0018] Preferably, when there are multiple drilled adjacent wells around the target well, the seismic velocity prediction module is further configured to interpolate the logging velocity data of the adjacent wells based on the relationship between the amplitude and the logging velocity, according to the amplitude data of the seismic traces near the well, the logging velocity data of the drilled section of the target well, and the logging velocity data of each adjacent well that matches the depth range of the undrilled section, and use the interpolation result as the logging velocity prediction result of the undrilled section of the target well.

[0019] Compared with the prior art, one or more embodiments of the above scheme may have the following advantages or beneficial effects:

[0020] The present invention discloses a method and system for predicting the seismic velocity of a formation to be drilled while drilling based on waveform similarity. The method and system first establish a relationship between the amplitude data of the wellside seismic trace of the target well and the logging velocity data of the drilled section of the target well based on the principle of waveform similarity; then, based on the current relationship, according to the logging velocity data of all the drilled sections, combined with the seismic layer interpolation technology, a constrained velocity model is constructed to use the model to predict the seismic velocity of the formation to be drilled. In this way, the velocity prediction scheme provided by the present invention can quickly (within 1 hour) provide the latest velocity model of the drill bit before drilling, reliably and stably help drillers predict the mechanical properties of the well wall of the formation to be drilled in advance, formulate countermeasures, and improve drilling efficiency.

[0021] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 It is a step diagram of a method for predicting seismic velocity while drilling a formation to be drilled based on waveform similarity according to an embodiment of the present application.

[0024] Figure 2 It is a specific example of a constrained velocity model in a method for predicting seismic velocity while drilling a formation to be drilled based on waveform similarity in an embodiment of the present application.

[0025] Figure 3 It is a specific example of a one-dimensional seismic velocity model for predicting the formation to be drilled in the method for predicting the seismic velocity of the formation to be drilled while drilling based on waveform similarity in an embodiment of the present application.

[0026] Figure 4 It is a specific example of a two-dimensional seismic velocity model for predicting the formation to be drilled in the method for predicting the seismic velocity of the formation to be drilled while drilling based on waveform similarity in an embodiment of the present application.

[0027] Figure 5 It is a module block diagram of a system for predicting seismic velocity while drilling in a formation to be drilled based on waveform similarity according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] The following will describe the implementation methods of the present invention in detail with reference to the accompanying drawings and embodiments, so that the implementation process of how the present invention applies technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly. It should be noted that as long as there is no conflict, the various embodiments of the present invention and the various features in the embodiments can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0029] In addition, the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions. Also, although a logical sequence is shown in the flowchart, in some cases, the steps shown or described can be performed in a sequence different from that here.

[0030] Traditionally, important drilling parameters such as mud density window are usually based on comprehensive analysis of various types of data from previous well completions to establish a model of wellbore stress and formation pressure system, determine the distribution law of the formation pressure system in the exploration area, and provide data support for the next stage of drilling design and construction. These methods are currently very common and well developed. However, with the advancement of drilling technology and the increasing complexity of geological conditions, engineers require that the mechanical properties of the wellbore wall of the formation to be drilled be predicted in advance during actual drilling, so as to detect and effectively deal with complex faults such as overflow, collapse, and leakage as early as possible. Therefore, it is more meaningful and more practical to effectively use seismic data, especially seismic velocity information, to predict important drilling parameter information such as rock mechanical parameters and mud density window while drilling.

[0031] In the process of realizing the present invention, the inventors found that in the prior art, the calculation methods of using seismic velocity data to obtain useful drilling information such as rock mechanical parameters and mud density window have gradually matured, but the solutions for quickly predicting the seismic velocity in front of the drill bit while drilling are limited. In addition, traditional seismic inversion processing is performed in the time domain, only impedance information is provided, and the calculation process is relatively complicated.

[0032] Therefore, in order to solve the above technical problems, the embodiment of the present invention proposes a method and system for predicting the seismic velocity of the formation to be drilled while drilling based on waveform similarity. The method and system first use the waveform similarity principle to establish the relationship between amplitude and logging velocity, and then use the aforementioned relationship to construct a constrained velocity model to predict the seismic velocity of the formation to be drilled. As a result, the present invention can quickly correct the velocity model in front of the drill bit during the actual drilling process, help drillers predict the mechanical properties of the well wall of the formation to be drilled in advance, formulate countermeasures, and improve drilling efficiency.

[0033] Figure 1 This is a step diagram of a method for predicting seismic velocity while drilling in a formation to be drilled based on waveform similarity according to an embodiment of the present application. Figure 1 As shown, the method for predicting seismic velocity while drilling of a formation to be drilled based on waveform similarity (hereinafter referred to as the "seismic velocity prediction method") described in an embodiment of the present invention includes the following steps: Step S110 establishes a relationship between amplitude and logging velocity according to the amplitude of the wellside seismic trace of the target well and the logging data of the drilled section of the target well, and then, Step S120 first establishes a constrained velocity model containing seismic velocity information of the undrilled section of the target well based on the amplitude and logging velocity relationship obtained in Step S110, according to the wellside seismic trace amplitude data obtained in Step S110 and the logging velocity data for the drilled section of the target well, using the seismic layer interpolation technology, and after solving the current constrained velocity model, the seismic velocity of the undrilled section of the target well is obtained, thereby realizing the prediction of seismic velocity while drilling for the formation to be drilled.

[0034] Since the inventors found in the process of implementing the present invention that in the actual application process, the seismic velocity waveform of the borehole seismic trace of the target well is similar to the seismic velocity waveform of the target well, the embodiment of the present invention is based on this waveform similarity principle, and in step S110, a relationship is established between the seismic velocity data of the drilled section of the target well and the seismic wave amplitude data of the borehole seismic trace in the same depth range as the drilled section of the target well. Specifically, in the first step, an initial model containing a relationship coefficient is established based on the amplitude data of the borehole seismic trace and the logging data of the completed drilling section of the target well. That is to say, in the first step, it is necessary to determine the depth range of the drilled section of the target well, so as to obtain the logging data (the logging data includes: logging velocity data) of the target well (completed drilling section) in the current depth range of the drilled section, and obtain the seismic wave amplitude data of the borehole seismic trace of the target well in the current depth range of the drilled section, so as to establish an initial model containing a relationship coefficient. It should be noted that, in the embodiment of the present invention, the drilled section of the target well refers to one or several sections before the current undrilled section (the section to be predicted).

[0035] The above initial model is expressed by the following expression:

[0036]

[0037] Among them, x represents the sampling point index, s represents the seismic amplitude data of the seismic trace near the well, and v P Indicates the logging velocity data of the completed drilling section of the target well, α i represents the relationship coefficient, m represents the total number of seismic traces near the well, and i represents the number of the seismic trace near the well.

[0038] After the initial model is established, the second step is to solve the minimum mean square error of the initial model to obtain the relationship between the amplitude and the logging velocity containing the relationship coefficient. In the second step, it is necessary to rewrite the above expression (1) into a matrix form and use the following expression to express the matrix form of the initial model, that is, v P α=s:

[0039]

[0040] Among them, α represents the relationship coefficient matrix, v P represents the logging velocity data matrix of the completed drilling section of the target well, s represents the amplitude data matrix of the wellside seismic trace, and n represents the total number of sampling points (in the embodiment of the present invention, the total number of sampling points of the amplitude data of each wellside seismic trace in the completed drilling section is the same as the total number of sampling points of the logging velocity data of the target well in the completed drilling section).

[0041] Furthermore, in order to solve the relationship coefficient matrix in the above initial model matrix, it is necessary to minimize the mean square prediction error corresponding to the above expression (2) that represents the mapping relationship between the wellbore seismic trace amplitude data and the target well logging velocity data of the completed drilling section, that is, to satisfy Condition. At this time, we need to rewrite the mean square error corresponding to expression (2) into a function form:

[0042]

[0043] Among them, F represents the mean square error function. Then, the partial derivative of the function F with respect to the relationship coefficient matrix α is calculated and the partial derivative is set to 0, thereby obtaining the relationship between the amplitude and the logging velocity.

[0044] Furthermore, the above relationship between amplitude and logging velocity is expressed by the following expression:

[0045] α=(v P T v P ) -1 v P T s (4)

[0046] Here, T represents the transposition symbol. In this way, the embodiment of the present invention completes the establishment of the relationship between the amplitude and the logging velocity through the above process, and then enters step S120.

[0047] In the seismic migration profile of the target well area, in order to predict the P-wave velocity of the undrilled section of the target well, it is necessary to make the P-wave velocity data of the section to be predicted, on the one hand, satisfy the minimum mean square error condition of the amplitude calculated by the mapping relationship (1) or (2) and the amplitude of the migration profile, and at the same time be constrained by the constrained velocity model. Therefore, in the embodiment of the present invention, it is necessary to further construct a constrained velocity model in step S120 that can constrain the seismic velocity data of the section to be predicted based on the relationship between the amplitude and the logging velocity established in step S110, so that the stability of the velocity prediction result can be greatly improved by using the current constrained velocity model.

[0048] Specifically, in step S120, based on the relationship between amplitude and logging velocity established in step S110, the logging velocity data of the drilled section of the target well is interpolated according to the amplitude data of the seismic trace beside the well and the logging velocity data of the drilled section of the target well, and a corresponding constrained velocity model is established, so that after inverting the current constrained velocity model, the seismic velocity prediction result is obtained.

[0049] First, based on the above relationship between amplitude and logging velocity, the corresponding prediction constraints are obtained according to the logging data matrix of the target well in the depth range of the completed drilling section and the seismic velocity data matrix to be predicted for the undrilled section of the target well, combined with the seismic interpretation horizon interpolation and expansion technology. The prediction constraints are expressed using the following expression:

[0050]

[0051] Among them, v Pm represents the seismic velocity data matrix of the undrilled section of the target well. Then, the above expression (5) is rewritten in the form of Lagrangian function:

[0052]

[0053] Where G represents the Lagrangian function, λ represents the Lagrangian multiplier, and c = [1 0 … 0] T Then, find the function G for the logging velocity data matrix v of the completed drilling section of the target well P The partial derivative of is set to 0 to obtain the constrained velocity model. Figure 2 It is a specific example of a constrained velocity model in the method for predicting seismic velocity of a formation to be drilled while drilling based on waveform similarity in an embodiment of the present application. The constrained velocity model is represented by the following expression:

[0054] v P =(sα T +λv Pm c T )(αα T +λcc T ) -1 (7)

[0055] Among them, the Lagrange multiplier λ can be understood as a model tendency factor. The larger the λ is, the more the velocity inversion result tends to the model. In actual application, the Lagrange multiplier λ can be obtained based on the experience of the area where the target well is located. In a preferred embodiment of the present invention, the value of λ is 0.5.

[0056] In this way, after obtaining the above-mentioned constrained velocity model containing the relationship coefficient matrix, it is necessary to invert the current constrained velocity model according to the seismic velocity data of the drilled section of the target well and the seismic wave amplitude data of the seismic trace beside the well, so as to obtain the seismic velocity prediction result. Specifically, according to the seismic velocity data of the drilled section of the target well, the seismic wave amplitude data of the seismic trace beside the well in the same depth range as the drilled section of the target well, and the seismic wave amplitude data of the seismic trace beside the well in the same depth range as the undrilled section of the target well, the currently constructed constrained velocity model is inverted, so as to use the obtained inversion result as the logging velocity data prediction result of the undrilled section of the target well.

[0057] Therefore, the embodiment of the present invention breaks the principle of traditional velocity prediction technology being implemented in the time domain, and directly establishes a relationship between the logging velocity data of the drilled section of the target well and the amplitude data of the seismic trace near the well based on the waveform similarity principle. Figure 2 , the acoustic logging velocity data of the completed well section is processed by the layer interpolation technology to realize the rapid prediction of the logging velocity data of the undrilled well section. Furthermore, the seismic velocity prediction method provided by the embodiment of the present invention can meet the real-time requirements of while-drilling prediction, the prediction result is highly stable, and the drilling efficiency is greatly improved.

[0058] Furthermore, in the embodiment of the present invention, the seismic amplitude data of the wellside seismic trace of the target well may be the seismic amplitude data of one wellside seismic trace of the target well (i.e., m=1 above). At this time, after predicting the seismic velocity data of the undrilled section of the target well using the above steps S110 and S120, a corresponding one-dimensional seismic velocity model can be obtained. Figure 3 It is a specific example of a one-dimensional seismic velocity model for predicting the formation to be drilled in the method for predicting the seismic velocity of the formation to be drilled while drilling based on waveform similarity in an embodiment of the present application. Figure 3 An example of a data model corresponding to a one-dimensional seismic velocity data matrix for formation prediction of a target well to be drilled is shown.

[0059] In addition, in the embodiment of the present invention, the seismic amplitude data of the wellside seismic trace of the target well can also be constructed as the seismic amplitude data corresponding to multiple or all seismic traces around the well in the seismic profile of the target well (i.e., the above m>1). At this time, after predicting the seismic velocity data of the undrilled section of the target well using the above steps S110 and S120, the corresponding two-dimensional seismic velocity model can be obtained. Figure 4 It is a specific example of a two-dimensional seismic velocity model for predicting the formation to be drilled in the method for predicting the seismic velocity of the formation to be drilled while drilling based on waveform similarity in an embodiment of the present application. Figure 4 An example of a data model corresponding to a two-dimensional seismic velocity data matrix for formation prediction of a target well to be drilled is shown.

[0060] On the other hand, when there are multiple neighboring wells that have been drilled around the current target well, the above step S120 will, based on the relationship between amplitude and logging velocity obtained in the above step S110, interpolate the logging velocity data of the neighboring wells according to the amplitude data of the seismic traces near the well, the logging velocity data of the drilled section of the target well, and the logging velocity data of each neighboring well that matches the depth range of the current undrilled section, and directly use the difference result as the logging velocity prediction result of the undrilled section of the target well.

[0061] If there are multiple neighboring wells that have been drilled around the current target well, at this time, step S120 will first obtain the logging velocity data of each neighboring well under the depth range of the undrilled section of the current target well, the logging velocity data of the drilled section of the target well, and the amplitude data of the wellside seismic trace of the target well, and rewrite these data into a matrix form; then based on the relationship between amplitude and logging velocity obtained in step S110, according to these drilled section velocity data matrices and wellside seismic trace amplitude data matrices, (neighboring well) seismic horizon interpolation technology is used to interpolate the logging velocity data of the neighboring wells under the depth range of the undrilled section (in the interpolation process, a model for interpolation processing is established and used as a constraint velocity model), so that the interpolation result is used as the logging velocity prediction result of the undrilled section of the target well.

[0062] It should be noted that the embodiment of the present invention does not specifically limit the above-mentioned (neighboring well) seismic horizon interpolation technology, and the art can select it according to factors such as actual prediction accuracy and efficiency. In a preferred embodiment of the present invention, the above-mentioned (neighboring well) seismic horizon interpolation technology can adopt the inverse distance weighted interpolation method or the Kriging interpolation method.

[0063] On the other hand, based on the above seismic velocity prediction method, the present invention also proposes a seismic velocity prediction system for the formation to be drilled based on waveform similarity (hereinafter referred to as the "seismic velocity prediction system"). Figure 5 1 is a block diagram of a module of a system for predicting seismic velocity while drilling in a formation to be drilled based on waveform similarity according to an embodiment of the present application. Figure 5 As shown, the seismic velocity prediction system according to the embodiment of the present invention includes: an amplitude and logging velocity relationship generation module 51 and a seismic velocity prediction module 52.

[0064] The amplitude and logging velocity relationship generation module 51 is implemented according to the method described in step S110, and is configured to establish the amplitude and logging velocity relationship according to the amplitude of the wellside seismic trace of the target well and the logging data of the drilled section of the target well. The seismic velocity prediction module 52 is implemented according to the method described in step S120, and is configured to establish and solve the constrained velocity model containing the seismic velocity information of the undrilled section of the target well based on the amplitude and logging velocity relationship output by the amplitude and logging velocity relationship generation module 51, according to the wellside seismic trace amplitude data and the logging velocity data of the drilled section, using the seismic horizon interpolation technology, so as to obtain the seismic velocity of the undrilled section of the target well.

[0065] Further, in a preferred embodiment, the seismic velocity prediction module 52 is also configured to perform stratum interpolation processing on the logging velocity data of the drilled section of the target well section based on the above-mentioned relationship between amplitude and logging velocity, according to the amplitude data of the seismic trace beside the well and the logging velocity data of the drilled section of the target well, to establish a constrained velocity model, and then invert the current constrained velocity model according to the seismic velocity data of the drilled section of the target well and the seismic wave amplitude data of the seismic trace beside the well to obtain a seismic velocity prediction result.

[0066] Furthermore, in a preferred embodiment, when there are multiple drilled adjacent wells around the target well, the seismic velocity prediction module 52 is further configured to interpolate the adjacent well logging velocity data based on the above-mentioned relationship between amplitude and logging velocity, according to the amplitude data of the seismic traces near the well, the logging velocity data of the drilled section of the target well, and the logging velocity data of each adjacent well that matches the depth range of the undrilled section, and use the interpolation result as the logging velocity prediction result of the undrilled section of the target well.

[0067] The present invention discloses a method and system for predicting the seismic velocity of a formation to be drilled while drilling based on waveform similarity. The method and system first establish a relationship between the amplitude data of the wellside seismic trace of the target well and the logging velocity data of the drilled section of the target well based on the principle of waveform similarity; then, based on the current relationship, according to the logging velocity data of all the drilled sections, combined with the seismic layer interpolation technology, a constrained velocity model is constructed to use the model to predict the seismic velocity of the formation to be drilled. In this way, the velocity prediction scheme provided by the present invention can quickly (within 1 hour) provide the latest velocity model of the drill bit before drilling, reliably and stably help drillers predict the mechanical properties of the well wall of the formation to be drilled in advance, formulate countermeasures, and improve drilling efficiency.

[0068] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person familiar with the technology within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0069] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0070] The "one embodiment" or "embodiment" mentioned in the specification means that the specific features, structures or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present invention. Therefore, the phrases "one embodiment" or "embodiment" appearing in various places throughout the specification do not necessarily refer to the same embodiment.

[0071] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A method for predicting seismic velocity of a formation to be drilled while drilling based on waveform similarity, comprising: Step 1: Establish the relationship between amplitude and logging velocity based on the amplitude of the wellside seismic trace of the target well and the logging data of the completed drilling section of the target well; Step 2: Based on the relationship between amplitude and logging velocity, according to the amplitude data of seismic traces near the well and the logging velocity data of the drilled section, a constrained velocity model containing the seismic velocity information of the undrilled section of the target well is established and solved by using seismic horizon interpolation technology, so as to obtain the seismic velocity of the undrilled section of the target well, including: Based on the relationship between amplitude and logging velocity, the logging velocity data of the drilled section of the target well is interpolated according to the amplitude data of the seismic trace beside the well and the logging velocity data of the drilled section of the target well, and the constrained velocity model is established; then, according to the seismic velocity data of the drilled section of the target well and the seismic wave amplitude data of the seismic trace beside the well, the constrained velocity model is inverted to obtain the seismic velocity prediction result, wherein, When there are multiple drilled adjacent wells around the target well: Based on the relationship between amplitude and logging velocity, the logging velocity data of the adjacent wells are interpolated according to the amplitude data of the seismic traces near the well, the logging velocity data of the drilled section of the target well, and the logging velocity data of each adjacent well that matches the depth range of the undrilled section, and the interpolation result is used as the logging velocity prediction result of the undrilled section of the target well.

2. The method for predicting seismic velocity of a formation to be drilled while drilling according to claim 1, characterized in that: The inverse distance weighted interpolation method or Kriging interpolation method is used to interpolate the velocity data of adjacent well logging.

3. The method for predicting seismic velocity of a formation to be drilled while drilling according to claim 1 or 2, characterized in that: In the step 1, An initial model containing relationship coefficients is established based on the amplitude data of seismic traces near the well and the logging data of the completed drilling section of the target well; The minimum mean square error of the initial model is solved to obtain the relationship between the amplitude and the logging velocity, wherein the relationship between the amplitude and the logging velocity is expressed by the following expression: α=(v P T v P ) -1 v P T s Among them, α represents the relationship coefficient matrix, v P represents the logging data matrix of the completed drilling section of the target well, s represents the amplitude data matrix of the seismic traces near the well, and T represents the transposition sign.

4. The method for predicting seismic velocity of a formation to be drilled while drilling according to claim 1 or 2, characterized in that: The amplitude data of the wellside seismic traces are also constructed as amplitude data corresponding to the full seismic trace in the seismic profile where the target well is located.

5. The method for predicting seismic velocity of a formation to be drilled while drilling according to claim 2, characterized in that: The constrained velocity model is expressed using the following expression: v P =(sα T +λv Pm c T (aa) T +λcc T ) -1 Among them, α represents the relationship coefficient matrix, v P represents the logging data matrix of the completed drilling section of the target well, s represents the amplitude data matrix of the seismic trace near the well, λ represents the Lagrange multiplier, c=[10…0] T , v Pm represents the seismic velocity data matrix of the undrilled section of the target well, and T represents the transposed sign.

6. A system for predicting seismic velocity while drilling of a formation to be drilled based on waveform similarity, comprising: A module for generating a relationship between amplitude and logging velocity, configured to establish a relationship between amplitude and logging velocity based on the amplitude of a wellside seismic trace of a target well and logging data of a completed well section of the target well; The seismic velocity prediction module is configured to establish and solve a constrained velocity model containing seismic velocity information of the undrilled section of the target well based on the relationship between the amplitude and the logging velocity, according to the amplitude data of the seismic traces near the well and the logging velocity data of the drilled section, using the seismic horizon interpolation technology, so as to obtain the seismic velocity of the undrilled section of the target well, wherein: The seismic velocity prediction module is further configured to perform stratum interpolation processing on the well logging velocity data of the drilled section of the target well section based on the relationship between the amplitude and the well logging velocity, according to the amplitude data of the seismic trace beside the well and the well logging velocity data of the drilled section of the target well, establish the constrained velocity model, and then invert the constrained velocity model according to the seismic velocity data of the drilled section of the target well and the seismic wave amplitude data of the seismic trace beside the well to obtain the seismic velocity prediction result, wherein, when there are multiple drilled adjacent wells around the target well, The seismic velocity prediction module is further configured to interpolate the logging velocity data of adjacent wells based on the relationship between the amplitude and the logging velocity, according to the amplitude data of the seismic traces near the well, the logging velocity data of the drilled section of the target well, and the logging velocity data of each adjacent well that matches the depth range of the undrilled section, and use the interpolation result as the logging velocity prediction result of the undrilled section of the target well.

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