Micro-seismic monitoring P-wave energy compensation method and system

Abstract

The invention provides a micro-seismic monitoring P-wave energy compensation method and system, and belongs to the field of micro-seismic signal processing. The method comprises the steps of firstly constructing a P-wave first arrival pickup function, performing P-wave energy pickup, then constructing a P-wave energy linear compensation function by taking a transmission angle of a detector as an independent variable, and finally performing micro-seismic P-wave energy compensation by using the P-wave energy linear compensation function. In the prior art, a compensation method for energy attenuation caused by stratum absorption in a P wave propagation process is mainly used, but in the invention, the stratum influence is not considered, and an energy consistency correction technology is developed only aiming at large difference of P wave energy received by detectors at different monitoring distances of a same-level seismic source of a horizontal well. The P-wave energy of microseism P-wave signals excited by the same level of seismic sources at different monitoring distances at the detector terminal is equivalent or as close as possible.

Description

Technical Field

[0001] The present invention belongs to the field of microseismic signal processing, and in particular relates to a microseismic monitoring P-wave energy compensation method and system. Background Art

[0002] In the field of microseismic signal processing, microseismic monitoring includes: ground microseismic and in-well microseismic. Among them, ground microseismic uses conventional ground geophones to collect microseismic signals. There are many ground microseismic geophones with various arrangements, which can fully collect microseismic signals. However, due to the long distance between the underground source and the geophone, the received microseismic signal is weak. Therefore, the ground microseismic positioning is relatively stable but the accuracy is not high enough.

[0003] Microseismic detection in wells is to place three-component geophones in the observation well section to receive the full wavefield signal of microseismic detection. Compared with ground microseismic monitoring, the data received in the well has a higher signal-to-noise ratio and richer number and types of microseismic events. However, due to the limited number of microseismic geophones in the well and the small monitoring range, unstable positioning results are prone to occur.

[0004] During the process of artificial fractures caused by hydraulic fracturing and breaking of underground rocks, the detector will receive a single P wave or a single S wave or a P&S wave combination signal, which is the microseismic monitoring data.

[0005] In the process of microseismic monitoring in wells such as carbon dioxide fracturing and hydraulic fracturing, the signal energy varies, and even a large number of weak events appear, which are the true reflection of the development of fractures during the fracturing process. At the same time, due to formation factors, the influence of the surrounding environment of the well and the interference of various noises, it is difficult to pick up the first arrival time of the weak signal of the microseismic event. Therefore, the weak signal processing in the microseismic monitoring data record is conducive to event identification and positioning.

[0006] At present, there are many ways to enhance the signal, such as using denoising methods to improve the signal-to-noise ratio of data by removing random noise and linear interference; using energy compensation methods, such as spherical diffusion energy compensation method, energy compensation based on surface or formation absorption factors. However, these methods cannot achieve P-wave energy compensation. Summary of the invention

[0007] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and to provide a method and system for compensating P-wave energy in microseismic monitoring, which corrects its energy to a reasonable observation range to achieve signal enhancement, so that the microseismic signals received at different locations of the same level of source points are generally consistent, thereby providing reliable guarantee for the subsequent magnitude statistics of microseismic events.

[0008] The present invention is achieved through the following technical solutions:

[0009] The first aspect of the present invention provides a method for P-wave energy compensation in microseismic monitoring. The method first constructs a P-wave first arrival picking function and performs P-wave energy picking. Then, a P-wave energy linear compensation function is constructed with the detector transmission angle as the independent variable. Finally, the P-wave energy linear compensation function is used to perform microseismic P-wave energy compensation.

[0010] Preferably, the method comprises:

[0011] Step 1, inputting the P wave signal of the microseismic event;

[0012] Step 2: construct a first arrival picking function to pick the first arrival and pick the P wave energy;

[0013] Step 3, constructing a linear compensation function for P-wave energy;

[0014] Step 4: Use the P-wave energy linear compensation function to perform microseismic P-wave energy compensation.

[0015] Preferably, the microseismic event P wave signal refers to N microseismic P wave sampling data at different monitoring distances of the same level of earthquake source in the horizontal well; from the first microseismic P wave sampling data to the last microseismic P wave sampling data, the monitoring distance gradually increases.

[0016] Preferably, the operation of constructing a first arrival picking function to perform first arrival picking in step 2 includes:

[0017] (21), define the long time window L1 and the short time window L2, and construct the P wave first arrival picking function using the following formula:

[0018]

[0019]

[0020] Where i represents the i-th microseismic sampling event, i = 1, ... N, j represents the j-th time sample point, j = 1, ... M, N is the total amount of microseismic sampling data, M is the total amount of time sample points, AP i,j , ER Pi,j ,fP i (t j ) are respectively the i-th microseismic sampling event, the P-wave amplitude value at the j-th time sample point, the energy ratio of the long and short time windows, and the P-wave first arrival picking function;

[0021] (22) Using the search method, the P wave first arrival picking function fP i (t j ) to find the maximum value of fP i (t j ), the time sample point corresponding to the maximum value is t *It is the first arrival time of the P wave of the i-th microseismic sampling event, that is, when t j =t * When fP i (t j ) has the largest value.

[0022] Preferably, the operation of picking up P-wave energy in step 2 includes:

[0023] Define a time window W P , the P-wave energy PEN of microseismic events is calculated using the following formula: i :

[0024]

[0025] Preferably, the time window W P The size of is the time sample length corresponding to the wavelet length.

[0026] Preferably, the operation of step three includes:

[0027] (31), based on the known coordinates of the locations of the N horizontal well sampling microseismic events (Sx i , Sy i ), and the known coordinates of a geophone (Rx, Ry), the transmission angle θ of the microseismic event geophone is calculated using the following formula: i :

[0028]

[0029] (32), construct the detector transmission angle θ i The P wave energy linear compensation function fPEN(θ i ):

[0030] fPEN(θ i )=C1*sin(θ i )+C2,(i=1,N)

[0031] (33) Through the P-wave energy PEN of microseismic events i , forming N equations, and establishing an overdetermined matrix equation system:

[0032]

[0033] (34), and solve the overdetermined matrix equations to obtain the values ​​of coefficients C1 and C2.

[0034] Preferably, the operation of step 4 includes:

[0035] (41), assuming that the spatial coordinates of any event are known to be (event X , event Y), the detector transmission angle θ of this event is calculated using the following formula * :

[0036]

[0037] (42) The event energy compensation factor PQ is calculated using the following formula: * :

[0038]

[0039] (43) Multiply the value by the P wave amplitude of the event to obtain the compensated P wave amplitude value.

[0040] A second aspect of the present invention provides a microseismic monitoring P-wave energy compensation system, the system comprising:

[0041] Input unit: used to input P wave signal of microseismic events;

[0042] Picking unit: connected to the input unit, used to construct the first arrival picking function to pick the first arrival and pick the P wave energy;

[0043] Function construction unit: connected with the pickup unit, used to construct the P-wave energy linear compensation function;

[0044] Compensation unit: connected to the function construction unit, used to perform microseismic P-wave energy compensation using the P-wave energy linear compensation function.

[0045] The third aspect of the present invention provides a computer-readable storage medium, which stores at least one computer-executable program. When the at least one program is executed by the computer, the computer executes the steps of a microseismic monitoring P-wave energy compensation method of the present invention.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows: the prior art is mainly a compensation method for energy attenuation caused by formation absorption during P-wave propagation, while the present invention does not take the influence of formation into consideration, and only develops an energy consistency correction technology for the large difference in P-wave energy received by detectors at different monitoring distances from the same level of seismic sources in horizontal wells, so that the P-wave energy of microseismic P-wave signals excited by the same level of seismic sources at different monitoring distances is equivalent or as close as possible at the detector terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of the microseismic P-wave energy compensation operation of the present invention;

[0048] Figure 2 is the microseismic velocity model with N microseismic event locations and 1 geophone location;

[0049] Figure 3 is the original forward microseismic P-wave data profile;

[0050] Figure 4 It is the intersection diagram of the energy of microseismic P-wave energy compensation function and the independent variable;

[0051] Figure 5 yes Figure 3 Microseismic P-wave data profile after energy compensation processing. DETAILED DESCRIPTION

[0052] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0053] The microseismic signal energy compensation method proposed in the present invention solves the problem of weak signals caused by the observation method. The present invention corrects its energy to within a reasonable observation range to achieve signal enhancement, so that the microseismic signals received at different locations at the same level of source points are generally consistent, providing reliable guarantee for subsequent microseismic event magnitude statistics.

[0054] The present invention provides a method for compensating P-wave energy in microseismic monitoring. The method first constructs a P-wave first arrival picking function, then obtains the microseismic P-wave signal energy, and then constructs a P-wave energy linear compensation function with the detector transmission angle as the independent variable. Finally, any known spatial position of a microseismic event is input to calculate the P-wave energy compensation factor of the event, thereby realizing P-wave energy compensation in microseismic monitoring of horizontal well fracturing.

[0055] like Figure 1 As shown, the present invention provides a method for monitoring P-wave energy of horizontal well fracturing microseismic, and the method comprises the following four steps:

[0056] Step 1, inputting a microseismic event P wave signal; a microseismic event P wave signal refers to N microseismic P wave sampling data of different monitoring distances of the same level of earthquake source in a horizontal well, and the monitoring distance gradually increases from the first microseismic P wave sampling data to the last microseismic P wave sampling data, that is, the monitoring distance of the first microseismic P wave sampling data is the shortest, and the monitoring distance of the last microseismic P wave sampling data is the farthest;

[0057] Step 2: construct a first arrival picking function to pick the first arrival and pick the P wave energy;

[0058] Step 3, constructing a linear compensation function for P-wave energy;

[0059] Step 4: Use the P-wave energy linear compensation function to perform microseismic P-wave energy compensation.

[0060] The embodiments of the method of the present invention are as follows:

[0061] [Example 1]

[0062] The operations of step 2 specifically include:

[0063] The operations of constructing the first arrival picking function for first arrival picking include:

[0064] (21), define a long time window L1 and a short time window L2, the time window length of L1 is greater than the time window length of L2, and use the following formula to construct the P wave first arrival picking function:

[0065]

[0066]

[0067] Where i represents the i-th microseismic sampling event, i = 1, ... N, j represents the j-th time sample point, j = 1, ... M, N is the total amount of microseismic sampling data, M is the total amount of time sample points, AP i,j , ER Pi,j ,fP i (t j ) are the P-wave amplitude value, the energy ratio of the long-short time window, and the P-wave first arrival picking function at the j-th time sampling point of the i-th microseismic sampling event, respectively;

[0068] (22) Using the search method, the P wave first arrival picking function fP i (t j ) to find the maximum value of fP i (t j ), the time sample point corresponding to the maximum value is t * It is the first arrival time of the P wave of the i-th microseismic sampling event, that is, when t j =t * When fP i (t j ) has the largest value.

[0069] The operations for P-wave energy picking include:

[0070] Define a time window W P (Time Window W P The size is generally the time sample length corresponding to the sub-wave length), and the P-wave energy PEN of the microseismic event is calculated using the following formula i :

[0071]

[0072] [Example 2]

[0073] The operations in step three include:

[0074] Using the monitoring distance and the location of the geophone, the transmission angle θ of N microseismic geophones is calculated. i , construct the P wave energy linear compensation function fPEN(θ i ), as follows:

[0075] (31), based on the known coordinates of the locations of the N horizontal well sampling microseismic events (Sx i , Sy i ), and the known coordinates of a geophone (Rx, Ry), the transmission angle θ of the microseismic event geophone is calculated using the following formula: i :

[0076]

[0077] (32), construct the transmission angle θ i The P wave energy linear compensation function fPEN(θ i ):

[0078] fPEN(θ i )=C1*sin(θ i )+C2

[0079] (33) Through the P-wave energy PEN of microseismic events i , forming N equations, and establishing an overdetermined matrix equation system:

[0080]

[0081] (34), the existing singular value decomposition (SVD) method is used to solve the above matrix and calculate the coefficients C1 and C2, thereby realizing the P-wave energy compensation function fPEN(θ i ) construction.

[0082] [Example 3]

[0083] The operation of step 4 includes: knowing the location of any microseismic event, calculating the transmission angle θ of the event detector * , substitute into the P wave energy linear compensation function fPEN(θ i ), and compare the energy with the first sampled P wave energy PEN1 with the closest monitoring distance and the strongest energy to obtain the energy compensation factor PQ of the event * , multiply the P wave amplitude value of the event by The microseismic P wave signal with the same energy as the first sampled P wave is obtained, and then the P wave energy compensation is realized, as follows:

[0084] (41), assuming that the spatial coordinates of any event are known to be (event X , event Y), the detector transmission angle θ of this event is calculated using the following formula * :

[0085]

[0086] (42), the detector transmission angle θ of this event * Substitute the P wave energy linear compensation function fPEN(θ i ), and the first sampled P wave energy PEN1 with the closest monitoring distance and the strongest energy is compared to obtain the event energy compensation factor PQ * , that is, the event energy compensation factor PQ is calculated using the following formula: * :

[0087]

[0088] (43) The compensated P-wave amplitude value is obtained by point multiplication with the P-wave amplitude value of the event, thereby realizing the P-wave energy compensation of the microseismic event.

[0089] The method of the present invention is tested by theoretical model data, and the energy compensation effect of the present invention on microseismic P-wave signals is analyzed.

[0090] like Figure 2 As shown, set 1 detector position ( Figure 2 white triangles) and 111 perforation locations ( Figure 2 The horizontal distance range of the simulated horizontal well monitoring is 150 meters to 2350 meters, and the adjacent distance between sampling events is 20 meters. Figure 3 As shown. The P wave energy of the microseismic event is calculated by the above formula, and the detector transmission angle of the event is calculated according to the above formula from the known microseismic event coordinates. The P wave energy linear compensation function of the present invention is constructed, and 111 equations are formed by sampling microseismic events, an overdetermined matrix formula is established, and the singular value decomposition SVD is used to calculate the coefficients in the P wave energy linear compensation function, thereby realizing the construction of the P wave energy compensation function. Figure 4 As shown in the figure, the grey dots are the intersection diagram of the energy and independent variables of the microseismic P-wave energy compensation function, and the black straight line is the P-wave energy compensation function curve.

[0091] Finally, according to the P-wave energy compensation function calculated in the previous step, the energy compensation is performed on the 111 microseismic event data, as follows: Figure 5 As shown. Figure 3Compared with the original P-wave data shown, it can be seen that the P-wave energy of the microseismic event is well compensated. The farther the distance, the better the compensation effect. In particular, when the horizontal distance is above 1,500 meters, the P-wave signal changes from weak to strong, proving that the present invention has a good compensation effect on the P-wave energy of the microseismic event.

[0092] The present invention also provides a microseismic monitoring P-wave energy compensation system, and the embodiments of the system are as follows:

[0093] [Example 4]

[0094] The system comprises:

[0095] Input unit: used to input P wave signal of microseismic events;

[0096] Picking unit: connected to the input unit, used to construct the first arrival picking function to pick the first arrival and pick the P wave energy;

[0097] Function construction unit: connected with the pickup unit, used to construct the P-wave energy linear compensation function;

[0098] Compensation unit: connected to the function construction unit, used to perform microseismic P-wave energy compensation using the P-wave energy linear compensation function.

[0099] The present invention also provides a computer-readable storage medium, which stores at least one computer-executable program. When the at least one program is executed by the computer, the computer executes the steps of a microseismic monitoring P-wave energy compensation method of the present invention.

[0100] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0101] In the description of the present invention, unless otherwise specified, the terms "upper", "lower", "left", "right", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0102] The above technical solution is only one implementation mode of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the present invention, and it is not limited to the technical solution described in the above specific embodiments of the present invention. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A P-wave energy compensation method for microseismic monitoring, characterized in that: The method first constructs a P-wave first arrival picking function and performs P-wave energy picking, then constructs a P-wave energy linear compensation function with the detector transmission angle as the independent variable, and finally uses the P-wave energy linear compensation function to perform microseismic P-wave energy compensation.

2. The microseismic monitoring P-wave energy compensation method according to claim 1, characterized in that: The method comprises: Step 1, inputting the P wave signal of the microseismic event; Step 2: construct a first arrival picking function to pick the first arrival and pick the P wave energy; Step 3, constructing a linear compensation function for P-wave energy; Step 4: Use the P-wave energy linear compensation function to perform microseismic P-wave energy compensation.

3. The microseismic monitoring P-wave energy compensation method according to claim 2, characterized in that: The microseismic event P wave signal refers to N microseismic P wave sampling data of different monitoring distances of the same level of earthquake source in the horizontal well; from the first microseismic P wave sampling data to the last microseismic P wave sampling data, the monitoring distance gradually increases.

4. The microseismic monitoring P-wave energy compensation method according to claim 2, characterized in that: The operations of constructing the first arrival picking function in step 2 for first arrival picking include: (21), define the long time window L1 and the short time window L2, and construct the P wave first arrival picking function using the following formula: Where i represents the i-th microseismic sampling event, i = 1, ... N, j represents the j-th time sample point, j = 1, ... M, N is the total amount of microseismic sampling data, M is the total amount of time sample points, AP i,j , ER Pi,j ,fP i (t j ) are respectively the i-th microseismic sampling event, the P-wave amplitude value at the j-th time sample point, the energy ratio of the long and short time windows, and the P-wave first arrival picking function; (22) Using the search method, the P wave first arrival picking function fP i (t j ) to find the maximum value of fP i (t j ), the time sample point corresponding to the maximum value is t * It is the first arrival time of the P wave of the i-th microseismic sampling event, that is, when t j =t * When fP i (t j ) has the largest value.

5. The microseismic monitoring P-wave energy compensation method according to claim 2, characterized in that: The operation of picking up P-wave energy in step 2 includes: Define a time window W P , the P-wave energy PEN of microseismic events is calculated using the following formula: i :

6. The microseismic monitoring P-wave energy compensation method according to claim 5, characterized in that: Time Window W P The size of is the time sample length corresponding to the wavelet length.

7. The microseismic monitoring P-wave energy compensation method according to claim 2, characterized in that: The operations in step three include: (31), based on the known coordinates of the locations of the N horizontal well sampling microseismic events (Sx i , Sy i ), and the known coordinates of a geophone (Rx, Ry), the transmission angle θ of the microseismic event geophone is calculated using the following formula: i : (32), construct the detector transmission angle θ i The P wave energy linear compensation function fPEN(θ i ): fPEN(θ i )=C1*sin(θ i )+C2,(i=1,N) (33) Through the P-wave energy PEN of microseismic events i , forming N equations, and establishing an overdetermined matrix equation system: (34), and solve the overdetermined matrix equations to obtain the values ​​of coefficients C1 and C2.

8. The microseismic monitoring P-wave energy compensation method according to claim 2, characterized in that: The operations in step 4 include: (41), assuming that the spatial coordinates of any event are known to be (event X , event Y ), the detector transmission angle θ of this event is calculated using the following formula * : (42) The event energy compensation factor PQ is calculated using the following formula: * : (43) Multiply the value by the P wave amplitude of the event to obtain the compensated P wave amplitude value.

9. A microseismic monitoring P-wave energy compensation system, characterized in that: The system comprises: Input unit: used to input P wave signal of microseismic events; Picking unit: connected to the input unit, used to construct the first arrival picking function to pick the first arrival and pick the P wave energy; Function construction unit: connected with the pickup unit, used to construct the P-wave energy linear compensation function; Compensation unit: connected to the function construction unit, used to perform microseismic P-wave energy compensation using the P-wave energy linear compensation function.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores at least one computer-executable program, and when the at least one program is executed by the computer, the computer executes the steps in the microseismic monitoring P-wave energy compensation method described in any one of claims 1-8.

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