A method and system for compensating p-wave energy in microseismic monitoring

Abstract

The application provides a microseismic monitoring P wave energy compensation method and system, and belongs to the field of microseismic signal processing. The method firstly constructs a P wave first arrival picking function and performs P wave energy picking, then constructs a P wave energy linear compensation function with a detector transmission angle as an independent variable, and finally performs microseismic P wave energy compensation by using the P wave energy linear compensation function. The prior art is mainly a compensation method based on energy attenuation caused by stratum absorption in the P wave propagation process, and the application does not consider the stratum influence, only aims at the great difference of P wave energy received by the detectors of the same level seismic source at different monitoring distances, and develops an energy consistency correction technology, so that the microseismic P wave signals of the same level seismic source at different monitoring distances are equivalent or as close as possible in the detector terminal P wave energy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of microseismic signal processing, and particularly relates to a microseismic monitoring P-wave energy compensation method and system. BACKGROUND

[0002] In the field of microseismic signal processing, microseismic monitoring includes ground microseismic and wellbore microseismic, wherein the ground microseismic uses a conventional ground detector to collect microseismic signals, the ground microseismic detector has a large number and multiple arrangement modes, and can fully collect microseismic signals, but the received microseismic signals are weak due to a long distance between the underground seismic source and the detector, so that the ground microseismic positioning is stable but the precision is not high enough.

[0003] The wellbore microseismic is to place a downhole three-component detector in an observation well section to receive a microseismic full wave field signal, and compared with the ground microseismic monitoring, the wellbore received data has a higher signal-to-noise ratio, and the number and type of microseismic events are more abundant. However, due to the limited number of wellbore microseismic detectors, the monitoring range is small, and thus unstable positioning results are prone to occur.

[0004] In the process of artificial cracks caused by the broken underground rock in hydraulic fracturing, the detector receives a single P-wave or a single S-wave or a P&S wave combination signal, which is microseismic monitoring data.

[0005] In the process of wellbore microseismic monitoring of carbon dioxide fracturing, hydraulic fracturing cracks, etc., the signal energy is not equal, and even a large number of weak events occur, and these events are the true response of crack development in the fracturing process. At the same time, due to the influence of stratum factors, wellbore environment and various noises, it is difficult to pick up the weak signal first arrival time of the microseismic event. Therefore, processing the weak signal in the microseismic monitoring data record is beneficial to event identification and positioning.

[0006] At present, there are various means to enhance the signal, for example, a denoising method is used to remove random noise and linear interference to improve the signal-to-noise ratio of the data, and an energy compensation method is used, for example, a spherical diffusion energy compensation method, an energy compensation based on a surface or stratum absorption factor. However, these methods cannot realize P-wave energy compensation. SUMMARY

[0007] The present application aims to solve the problems existing in the prior art, and provides a microseismic monitoring P-wave energy compensation method and system, which corrects the energy to a reasonable observation range to realize signal enhancement, so that the microseismic signals received at different positions of the same level seismic source are basically consistent, and reliable guarantee is provided for subsequent microseismic event magnitude statistics.

[0008] The present application is realized by the following technical scheme:

[0009] The first aspect of the application provides a microseismic monitoring P-wave energy compensation method, which comprises the following steps: first, constructing a P-wave first arrival picking function and picking up P-wave energy; then, constructing a P-wave energy linear compensation function with the receiver transmission angle as the independent variable; and finally, using the P-wave energy linear compensation function to compensate the microseismic P-wave energy.

[0010] Preferably, the method comprises:

[0011] Step one: inputting a microseismic event P-wave signal;

[0012] Step two: constructing a first arrival picking function to pick up the first arrival and pick up the P-wave energy;

[0013] Step three: constructing a P-wave energy linear compensation function;

[0014] Step four: using the P-wave energy linear compensation function to compensate the microseismic P-wave energy.

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

[0016] Preferably, the operation of constructing a first arrival picking function to pick up the first arrival in step two comprises:

[0017] (21) defining a long time window L1 and a short time window L2, and constructing a P-wave first arrival picking function by using the following formula:

[0018]

[0019]

[0020] wherein 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 long-short time window energy ratio, and the P-wave first arrival picking function at the i-th microseismic sampling event and the j-th time sample point, respectively;

[0021] (22) using a search method to search for the maximum value of the P-wave first arrival picking function fP i (t j ), finding the maximum value of fP i (t j ), and the time t *is the P-wave first arrival time of the i-th microseismic sampling event, i.e. when t j = t * , the value of fP i (t j ) is the largest.

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

[0023] Defining a time window W P , the P-wave energy PEN i of the microseismic event is calculated by the following formula:

[0024]

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

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

[0027] (31), according to the known coordinates (Sx i , Sy i ) of N horizontal well sampling microseismic event positions and the known coordinates (Rx, Ry) of 1 receiver, the receiver transmission angle θ i of the microseismic event is calculated by the following formula:

[0028]

[0029] (32), a P-wave energy linear compensation function fPEN(θ i ) is constructed with the receiver transmission angle θ i as the independent variable:

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

[0031] (33), by the P-wave energy PEN i of the microseismic event, N equations are formed to establish an over-determined matrix equation group:

[0032]

[0033] (34), the values of coefficients C1 and C2 are obtained by solving the over-determined matrix equation group.

[0034] Preferably, the operation of step four comprises:

[0035] (41), assuming that the coordinates of any one event space position are known (event X , event Y), the detector transmission angle θ of the event is calculated by using the following formula * :

[0036]

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

[0038]

[0039] (43), the product of and the P-wave amplitude value of the event is taken, and the compensated P-wave amplitude value is obtained.

[0040] The second aspect of the present application provides a microseismic monitoring P-wave energy compensation system, the system comprises:

[0041] The input unit is used for inputting the microseismic event P-wave signal.

[0042] The pickup unit is connected with the input unit and is used for constructing the first arrival pickup function to perform the first arrival pickup and the P-wave energy pickup.

[0043] The function construction unit is connected with the pickup unit and is used for constructing the P-wave energy linear compensation function.

[0044] The compensation unit is connected with the function construction unit and is used for performing the microseismic P-wave energy compensation by using the P-wave energy linear compensation function.

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

[0046] Compared with the prior art, the present application has the beneficial effects that: the prior art is mainly a compensation method based on the energy attenuation caused by the stratum absorption in the P-wave propagation process, and the present application does not consider the stratum influence, only aims at the large difference of the P-wave energy received by the detectors of the same level seismic source at different monitoring distances, and develops an energy consistency correction technology, so that the microseismic P-wave signals of the same level seismic source at different monitoring distances are equivalent or as close as possible in the P-wave energy at the detector terminal. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is the microseismic P-wave energy compensation operation flowchart of the present application;

[0048] Figure 2 is the microseismic velocity model and the position of N microseismic events and the position of one detector.

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

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

[0051] Figure 5 is Figure 3 the microseismic P wave data profile after energy compensation processing. DETAILED DESCRIPTION

[0052] The application will be described in further detail below with reference to the drawings:

[0053] The microseismic signal energy compensation method provided by the application solves the problem of weak signals caused by observation methods, and the energy of the signals is corrected to a reasonable observation range to achieve signal enhancement, so that the microseismic signals received at different positions by the same level of seismic source are generally consistent, which provides reliable guarantee for subsequent microseismic event magnitude statistics.

[0054] The application provides a microseismic monitoring P wave energy compensation method, which comprises the following steps: first, constructing a P wave first arrival picking function; then, obtaining microseismic P wave signal energy; taking a detector transmission angle as an independent variable, constructing a P wave energy linear compensation function; finally, inputting an arbitrary known microseismic event spatial position, calculating a P wave energy compensation factor of the event, and then realizing P wave energy compensation for horizontal well fracturing microseismic monitoring.

[0055] As shown in Figure 1 The application provides a horizontal well fracturing microseismic monitoring P wave energy method, which comprises the following four steps:

[0056] Step 1: inputting a microseismic event P wave signal; the microseismic event P wave signal refers to N microseismic P wave sampling data of different monitoring distances of the same level of seismic source of a horizontal well, and the monitoring distance is gradually increased 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 nearest, and the monitoring distance of the last microseismic P wave sampling data is the farthest;

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

[0058] Step 3: constructing a P wave energy linear compensation function;

[0059] Step 4: using the P wave energy linear compensation function to compensate microseismic P wave energy.

[0060] The implementation of the method of the application is as follows:

[0061] Example One

[0062] The operation of step two specifically includes:

[0063] The operation of constructing the primary pick-up function for primary pick-up includes:

[0064] (21), defining a long time window L1 and a short time window L2, the time window length of L1 is greater than that of L2, and constructing the P-wave primary pick-up function by using the following formula:

[0065]

[0066]

[0067] Wherein, i represents the i-th microseismic sampling event, i = 1, …, N, j represents the j-th time sample, j = 1, …, M, N is the total amount of microseismic sampling data, M is the total amount of time samples, AP i,j , ER Pi,j , fP i (t j ) are the P-wave amplitude value, long-short time window energy ratio and P-wave primary pick-up function of the j-th time sample of the i-th microseismic sampling event respectively;

[0068] (22), using search method to search the maximum value of the P-wave primary pick-up function fP i (t j ), find the maximum value of fP i (t j ), the time t * of the time sample corresponding to the maximum value is the P-wave primary time of the i-th microseismic sampling event, that is, when t j = t * , the value of fP i (t j ) is maximum.

[0069] The operation of P-wave energy pick-up includes:

[0070] Defining a time window W P (the size of time window W P is generally the time sample length corresponding to the length of wavelet), calculating the P-wave energy PEN i of microseismic event by using the following formula:

[0071]

[0072] Example Two

[0073] The operation of step three includes:

[0074] Using the monitoring distance and the detector position, the N microseismic detector transmission angle θ is calculated i , the P wave energy linear compensation function fPEN(θ i ) is constructed, and the specific process is as follows:

[0075] (31), according to the known coordinates (Sx i , Sy i ) of the N horizontal well sampling microseismic event position, and the known coordinates (Rx, Ry) of the 1 detector, the microseismic event detector transmission angle θ i is calculated by using the following formula:

[0076]

[0077] (32), the P wave energy linear compensation function fPEN(θ i ) is constructed with the transmission angle θ i as the independent variable:

[0078] fPEN(θ i ) = C1*sin(θ i ) + C2

[0079] (33), by the P wave energy PEN i of the microseismic event, N equations are formed, and an over-determined matrix equation group is established:

[0080]

[0081] (34), the above matrix is solved by using the existing singular value decomposition SVD method, the coefficients C1 and C2 are calculated, and the construction of the P wave energy compensation function fPEN(θ i ) is realized.

[0082]

Example three

[0083] The operation of step four includes: knowing the position of any microseismic event, calculating the detector transmission angle θ * of the event, substituting the P wave energy linear compensation function fPEN(θ i ), and performing energy ratio with the 1st sampling P wave energy PEN1 which is the nearest and strongest in the known monitoring distance, to obtain the event energy compensation factor PQ * , multiplying the event P wave amplitude value by to obtain a microseismic P wave signal equivalent to the 1st sampling P wave energy, and then realizing P wave energy compensation, and the specific process is as follows:

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

[0085]

[0086] (42) The detector transmission angle θ of the event * Substituting into the P-wave energy linear compensation function fPEN(θ) i The event energy compensation factor PQ is obtained by comparing the energy of the first sampled P-wave (PEN1) which is the closest and strongest known monitoring signal. * The event energy compensation factor PQ is calculated using the following formula. * :

[0087]

[0088] (43), will By multiplying the P-wave amplitude value of the event by the p-wave amplitude value, the compensated P-wave amplitude value is obtained, thereby realizing P-wave energy compensation for microseismic events.

[0089] The method of the present invention is tested using 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, one detector position is set ( Figure 2 (white triangle in the middle) and 111 firing positions ( Figure 2 The row of horizontal black dots at the bottom of the image simulates a horizontal well monitoring horizontal distance range of 150 meters to 2350 meters, with adjacent sampling events spaced 20 meters apart. Microseismic P-wave data are shown below. Figure 3 As shown. The P-wave energy of a microseismic event is calculated using the above formula. Given the coordinates of the microseismic event, the detector transmission angle is calculated using the above formula. The linear compensation function for P-wave energy of this invention is constructed by generating 111 equations from sampled microseismic events, establishing an overdetermined matrix formula, and using singular value decomposition (SVD) to calculate the coefficients in the linear compensation function for P-wave energy, thus realizing the construction of the P-wave energy compensation function. (See figure) Figure 4 As shown in the figure, the gray dots represent the intersection of energy and independent variables of the microseismic P-wave energy compensation function, and the black line represents the curve of the P-wave energy compensation function.

[0091] Finally, based on the P-wave energy compensation function calculated in the previous step, energy compensation was performed on the data of 111 microseismic events, such as... Figure 5 As shown. With Figure 3Compared with the original P wave data, 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, especially the horizontal distance is more than 1500 meters, the P wave signal is changed from weak to strong, which proves that the application has a good compensation effect on the P wave energy of the microseismic event.

[0092] The application also provides a microseismic monitoring P wave energy compensation system, and the implementation of the system is as follows:

[0093]

Example four

[0094] The system comprises:

[0095] The input unit is used for inputting the P wave signal of the microseismic event;

[0096] The pickup unit is connected with the input unit and is used for constructing a first arrival pickup function to perform first arrival pickup and P wave energy pickup;

[0097] The function construction unit is connected with the pickup unit and is used for constructing a P wave energy linear compensation function;

[0098] The compensation unit is connected with the function construction unit and is used for performing microseismic P wave energy compensation by using the P wave energy linear compensation function.

[0099] The application also provides a computer readable storage medium, which stores at least one computer executable program, and the at least one program makes the computer execute the steps of the microseismic monitoring P wave energy compensation method of the application when the computer executes the at least one program.

[0100] In the description of the application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0101] In the description of the application, unless otherwise specified, the terms "upper", "lower", "left", "right", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the application.

[0102] The above technical solution is only one embodiment of the present application, and for those skilled in the art, on the basis of the disclosed principles, various types of improvements or modifications can be easily made, and the technical solution described in the above specific embodiments is not limited. Therefore, the above description is only preferred, and is not limited in meaning.

Claims

1. A method of microseismic monitoring P-wave energy compensation, characterized in that: The method firstly constructs a P-wave first arrival pick-up 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 performs microseismic P-wave energy compensation by using the P-wave energy linear compensation function. The method comprises: Step one, inputting a microseismic event P-wave signal; Step two, constructing a first arrival pick-up function to perform first arrival picking and P-wave energy picking; Step three, constructing a P-wave energy linear compensation function; Step four, performing microseismic P-wave energy compensation by using the P-wave energy linear compensation function; The operation of step three comprises: (31), from known N horizontal well sampled microseismic event location coordinates (Sx i , Sy i ), and known 1 receiver coordinates (Rx, Ry), the microseismic event receiver transmission angle θ i is calculated using the following equation: (32), constructing a P-wave energy linear compensation function fPEN(0 i as an argument i ): fPEN(θ i ) = C1*sin(θ i ) + C2, (i = 1, N) (33) by microseismic event P-wave energy PEN i , forming N equations, establishing an overdetermined matrix equation set: (34), solving the overdetermined matrix equation to obtain the values of coefficients C1 and C2; The operation of step four comprises: (41), assuming that the coordinates of any one event space position are known (event X , event Y ), the detector transmission angle θ * of the event is calculated using the following formula: (42) The event energy compensation factor PQ is calculated using the following equation * : (43), multiplying The compensated P-wave amplitude value is obtained by multiplying the P-wave amplitude value of the event.

2. The microseismic monitoring P-wave energy compensation method according to claim 1, characterized in that: The microseismic event P-wave signal refers to N microseismic P-wave sampling data of different monitoring distances of a horizontal well with the same level of seismic source; the monitoring distance is gradually increased from the first microseismic P-wave sampling data to the last microseismic P-wave sampling data.

3. The microseismic monitoring P-wave energy compensation method according to claim 1, characterized in that: The operation of constructing a first arrival pick-up function to perform first arrival picking in step two comprises: (21), defining a long time window L1 and a short time window L2, and constructing a P-wave first arrival pick-up function by using the following formula: wherein i represents the i-th microseismic sampling event, i = 1, …, N, j represents the j-th time sample, j = 1, …, M, N is the total amount of microseismic sampling data, M is the total amount of time samples, AP i,j , ER Pi,j , fP i (t j ) are the P-wave amplitude value, the long-short time window energy ratio, and the P-wave first arrival picking function at the i-th microseismic sampling event and the j-th time sample, respectively. (22) Using the search method to select the P-wave first arrival pickup function fP i (t j Perform a maximum value search on the value of fP to find the maximum value. i (t j The maximum value of ), and the time t of the time sample corresponding to the maximum value. * This refers to the first arrival time of the P-wave in the i-th microseismic sampling event, i.e., when t j =t * At that time, fP i (t j The value of ) is the largest.

4. The microseismic monitoring P-wave energy compensation method according to claim 1, characterized in that: The operation of performing P-wave energy picking in step two comprises: Defining a time window W P The microseismic event P-wave energy PEN is calculated using the following formula i :

5. The microseismic monitoring P-wave energy compensation method according to claim 4, characterized in that: Window W P has a size of a time sample length corresponding to the wavelet length.

6. A system for microseismic monitoring P-wave energy compensation, for implementing the method of microseismic monitoring P-wave energy compensation according to any one of claims 1-5, characterized in that: The system comprises: An input unit for inputting a microseismic event P-wave signal; A picking unit connected with the input unit, for constructing a first arrival pick-up function to perform first arrival picking and P-wave energy picking; A function construction unit connected with the picking unit, for constructing a P-wave energy linear compensation function; A compensation unit connected with the function construction unit, for performing microseismic P-wave energy compensation by using the P-wave energy linear compensation function.

7. A computer-readable storage medium, characterized in that: The computer readable storage medium stores at least one computer executable program, and the at least one program is executed by the computer to make the computer execute the steps in the microseismic monitoring P-wave energy compensation method of any one of claims 1-5.

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