A method for picking the first arrivals of shear wave logging while logging in a well

Abstract

The present invention discloses a method for picking first arrivals of shear wave micro-logging received in a well, comprising the steps of acquiring data, forming a shear wave component trace shot collection, displaying the shear wave component trace shot collection records, and picking dual indefinite first arrivals. The present invention overcomes the stereotype of picking first arrivals of shear waves based on a fixed phase of the same seismic trace. By forming and displaying all shear wave component seismic trace records and comprehensively comparing their waveform phase characteristics in the first arrival zone, a method for picking first arrivals with indefinite traces and indefinite phases is implemented, thereby resolving the problem of difficulty in identifying and picking first arrivals of shear waves. The present invention enables first arrival picking with indefinite traces and indefinite phases, thereby obtaining the position of the first arrival.

Description

Technical Field

[0001] The invention belongs to the technical field of seismic exploration and relates to micro-well logging, in particular to a first arrival picking method of shear wave micro-well logging. Background Art

[0002] As exploration targets deepen, the application prospects of shear-wave exploration are expanding. In 2020, Oriental Geophysical Company launched China's first three-dimensional shear-wave exploration project in the Qaidam Basin, collecting numerous shear-wave micro-logs. Micro-logging is a key tool for surface surveys and has wide applicability. Compared to shallow refraction methods, micro-logging offers higher precision. Micro-logging results are widely used to build high-precision near-surface models. Based on experience with compressional wave exploration, near-surface models are fundamental to ensuring and improving the quality of exploration data.

[0003] Shear-wave micrologging typically uses surface excitation and in-well three-component geophones for data acquisition. A three-component geophone contains three mutually perpendicular sensors (X, Y, and Z component geophones) that rotate randomly within the well. The energy of the seismic signal detected by the geophones fluctuates, resulting in a weak signal-to-noise ratio microlog single-shot record. This weak signal-to-noise ratio results in a weak first-arrival jump, making it difficult to identify. Conventional first-arrival picking methods for micrologging only pick a fixed phase of a component seismic trace record (Xn or Yn), such as a peak, trough, or first arrival, with the peak typically being the chosen phase. This makes first arrivals difficult to pick in most shear-wave micrologs, and unsatisfactory interpretation results are often unattainable. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for picking the first arrival of shear wave micro-logging received in a well. The method forms a shear wave component channel shot collection by observing the shear wave micro-logging data, displays the shear wave component channel shot collection records, and performs a "double-indefinite" first arrival picking method with indefinite channels and indefinite phases.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions:

[0006] A method for picking up the first arrival of shear wave micro-logging received in a well, the method is performed in the following order:

[0007] S1. Obtaining data

[0008] Use three-component geophones to perform shear wave micro-logging, and obtain shear wave micro-logging data received at different depths at the same shot point.

[0009] S2. Formation of shear wave component channel shot gathers

[0010] The deepest shear wave micro-logging data at the same shot point location are extracted using processing software to generate shot gather data ɑ1 with the same depth and file number and containing all shear wave component trace data; the second deepest shear wave micro-logging data are generated into shot gather data ɑ2 using the same method, and the shallowest shear wave micro-logging data are generated into shot gather data ɑn, ultimately forming shot gather data ɑ1 to ɑn containing only shear wave component traces at that location;

[0011] S3. Display the shear wave component shot gather record

[0012] Use software B to display the shot gather data ɑ1 to ɑn;

[0013] S4. Double indefinite first arrival picking

[0014] The seismic trace signal Xn recorded on the three-component geophone in the micro-logging is used as the projection of the shear wave seismic signal collected by the X-component seismic trace onto the X-axis of the observation direction, and the seismic trace signal Yn is used as the projection of the shear wave seismic signal collected by the Y-component seismic trace onto the Y-axis of the observation direction. According to the waveform characteristics of all the recorded component trace signals, the first arrival picking of indefinite trace and indefinite phase is performed.

[0015] As a limitation, in step S1, the shear wave micro-logging data includes X-component trace data, Y-component trace data, and Z-component trace data.

[0016] As another limitation, step S2 is implemented using GeoEast processing software;

[0017] The shear wave component channel information includes X component channel information and Y component channel information.

[0018] As a third limitation, step S3 is implemented using KLseis near-surface survey interpretation software.

[0019] The present invention has another limitation. In step S4, the positive direction of the X-axis is the observation direction, and the positive direction of the Y-axis is the counterclockwise direction perpendicular to the X-axis.

[0020] Due to the adoption of the above technical solution, the present invention has achieved the following technical advancements compared with the prior art:

[0021] ① The present invention breaks the stereotype of fixed phase of the same seismic trace in the shear wave first arrival picking method. By forming and displaying seismic trace records of all shear wave components and comprehensively comparing their waveform phase characteristics in the first arrival area, a method of first arrival picking with indefinite trace and indefinite phase is implemented.

[0022] ② All component channel signals recorded by the present invention are projections of true signals, thereby improving the accuracy of the method;

[0023] ③ The present invention solves the problem of difficulty in identifying and picking up the first arrival of micro-logging in shear wave wells. With the widespread promotion of shear wave exploration, it has broad application prospects.

[0024] The present invention belongs to the technical field of seismic exploration, can realize first arrival picking with indefinite path and indefinite phase, and is used for obtaining the position of the first arrival. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0026] In the attached figure:

[0027] Figure 1 This is a three-component micro-logging record in an embodiment of the present invention;

[0028] Figure 2 This is the shear wave component channel shot gather record in the embodiment of the present invention;

[0029] Figure 3 This is the first arrival picking result in the embodiment of the present invention;

[0030] Figure 4 Schematic diagram of XY component detectors and observation directions of a three-component detector in an embodiment of the present invention;

[0031] Figure 5 2 is a schematic diagram of an XY waveform when X is in the first quadrant and Y is in the second quadrant in an embodiment of the present invention;

[0032] Figure 6 FIG. 1 is a schematic diagram of an XY waveform when X is in the second quadrant and Y is in the first quadrant in an embodiment of the present invention. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0034] Embodiment: A method for picking up first arrivals of shear wave micro-logging received in a well

[0035] This embodiment is a shear wave micro-logging first arrival picking method performed in the 2020 Taidong shear wave 3D seismic acquisition project in the Qaidam Basin, and is performed in the following steps:

[0036] S1. Obtaining data

[0037] Using a three-component geophone for shear wave micro-logging, we obtained micro-logging data from 32 wells at different locations. Since the depth of each micro-logging well is different, multiple micro-logging data will be obtained based on the depth and observation density. Each three-channel shot collection has the same file number and receiving depth, as shown in the following example: Figure 1 As shown, a total of 15 micro-logging data are obtained in this embodiment;

[0038] S2. Formation of shear wave component channel shot gathers

[0039] Using the software GEOeast, the shear wave component channel data of each shot point was converted into shot gather data ɑ1 to ɑ15 with the same file number, which contains all the shear wave component channel data.

[0040] S3. Display the shear wave component shot gather record

[0041] Use the software KLseis to display the shot gather data ɑ1 to ɑ15 for subsequent first arrival picking, such as Figure 2 As shown, every two traces are a shot collection with the same file number and receiving depth, the first two traces are ɑ1, and so on ɑ2...ɑ15;

[0042] S4. Picking up the first arrival of "double indefinite" with indefinite path and indefinite phase

[0043] Assuming that the X-component detector of the three-component detector is fixed in the first quadrant, the Y-component detector must be in the second or fourth quadrant, and the projection value is positive or negative;

[0044] When the projection value is positive, the two waveforms are similar, the first arrival is the peak, and the two traces pick up the first peak together; when the projection value is positive or negative, the two waveforms are opposite, the first arrival is the peak and the trough, and the first peak and the first trough are picked up respectively;

[0045] Similarly, when the projection value is negative, pick up the first trough, and when the projection value is negative, pick up the first trough and the first peak, such as Figure 3 As shown;

[0046] The schematic diagram of the XY component detector and observation direction of the three-component detector is as follows Figure 4 As shown, Xn and Yn are seismic trace signals in the component detectors, X is the observation direction, and 0 is the intersection of the coordinate axes;

[0047] When X is in the first quadrant and Y is in the second quadrant, the XY waveform diagram is as follows Figure 5 As shown, A is the initial arrival position;

[0048] When X is in the second quadrant and Y is in the first quadrant, the XY waveform diagram is as follows Figure 6 As shown, A is the initial arrival position.

[0049] As can be seen above, if only the first data record in the shot gather data ɑ1-ɑ15 is displayed and the fixed-phase peak is picked, all shots in the shot gather data ɑ1-ɑ15 cannot be identified and the first arrival cannot be picked. If the trough is picked, the first arrival of ɑ4 cannot be identified, and ɑ10 is difficult to identify. Similarly, if only the second data record is displayed and the peak is picked, the first arrival of shot gather data ɑ2, ɑ5, ɑ6, ɑ9, ɑ10, ɑ12, ɑ13, ɑ14, and ɑ15 cannot be identified and the first arrival cannot be picked. Only by displaying all the data traces of the shot gather data ɑ1-ɑ15 simultaneously and performing variable-phase picking can the first arrival be identified and picked.

Claims

1. A method for picking up the first arrival of shear wave micro-logging in a well, characterized by: The method proceeds in the following order: S1. Obtaining data Use three-component geophones to perform shear wave micro-logging, and obtain shear wave micro-logging data received at different depths at the same shot point. S2. Formation of shear wave component channel shot gathers The deepest shear wave micro-logging data at the same shot point location are extracted using processing software to generate shot gather data ɑ1 with the same depth and file number and containing all shear wave component trace data; the second deepest shear wave micro-logging data are generated into shot gather data ɑ2 using the same method, and the shallowest shear wave micro-logging data are generated into shot gather data ɑn, ultimately forming shot gather data ɑ1 to ɑn containing only shear wave component traces at that location; S3. Display the shear wave component shot gather record Use software B to display the shot gather data ɑ1 to ɑn; S4. Double indefinite first arrival picking The seismic trace signal Xn recorded on the three-component geophone in the micro-logging is used as the projection of the shear wave seismic signal collected by the X-component seismic trace onto the X-axis of the observation direction, and the seismic trace signal Yn is used as the projection of the shear wave seismic signal collected by the Y-component seismic trace onto the Y-axis of the observation direction. According to the waveform characteristics of all the recorded component trace signals, the first arrival picking of indefinite trace and indefinite phase is performed.

2. A method for picking first arrivals of shear wave micro-logging received in a well according to claim 1, characterized in that: In step S1, the shear wave micro-logging data includes X-component trace data, Y-component trace data, and Z-component trace data.

3. A method for picking first arrivals of shear wave micro-logging received in a well according to claim 1 or 2, characterized in that: Step S2 is implemented using GeoEast processing software; The shear wave component channel information includes X component channel information and Y component channel information.

4. A method for picking first arrivals of shear wave micro-logging received in a well according to claim 1 or 2, characterized in that: Step S3 is implemented using KLseis near-surface survey interpretation software.

5. The method for picking first arrivals of shear wave micro-logging received in a well according to claim 3, characterized in that: Step S3 is implemented using KLseis near-surface survey interpretation software.

6. A method for picking first arrivals of shear wave micro-logging received in a well according to claim 1, 2 or 5, characterized in that: In step S4, the positive direction of the X-axis is the observation direction, and the positive direction of the Y-axis is the counterclockwise direction perpendicular to the X-axis.

7. The method for picking first arrivals of shear wave micro-logging received in a well according to claim 3, characterized in that: In step S4, the positive direction of the X-axis is the observation direction, and the positive direction of the Y-axis is the counterclockwise direction perpendicular to the X-axis.

8. The method for picking first arrivals of shear wave micro-logging in a well according to claim 4, characterized in that: In step S4, the positive direction of the X-axis is the observation direction, and the positive direction of the Y-axis is the counterclockwise direction perpendicular to the X-axis.

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