A method and device for radial compensation of das acquisition vsp variable offset wave field

Abstract

The invention discloses a DAS acquisition VSP variable offset wave field radial compensation method and device. The method includes the following steps: S1. establishing a velocity model by using the first arrival time of the direct wave with zero well source distance; S2. forward modeling Incidence angles of excitation points with different offsets reaching detection points at different depths; S3. Perform spherical diffusion correction and surface consistency compensation on the recordings of excitation points with different offsets, pick excitation points with different offsets to record the direct access to detection points at different depths Wave amplitude peak; S4. Plot the incident angle of different offset excitation points reaching different depth detection points and the normalization relationship diagram of direct wave amplitude peaks recorded at different depth detection points from different offset excitation points; S5. Fit incident angle - Normalized wave peak amplitude trend function, S6. Use compensation coefficient to perform radial compensation of wave field for different offset incident angles and different detection point depth records. The invention provides a wave field radial compensation method suitable for DAS VSP optical fiber acquisition data, conforms to the wave field propagation law, and improves the amplitude preservation effect of the recorded wave field in the processing process.

Description

technical field [0001] The invention relates to the processing and correction of the wave field of seismic VSP data in variable offset wells, in particular to a method and device for radial compensation of the variable offset wave field of VSP acquired by DAS. Background technique [0002] The distributed optical fiber sensing well geophysical technology is a new well geophysical technology emerging in recent years. With the continuous progress of distributed optical fiber acoustic sensing (DAS), DAS has achieved certain results in the fields of border security, oil and gas pipeline monitoring, geological disaster prediction, engineering tunnel and bridge monitoring. The application of well-sensing seismic (DAS VSP) has also gradually matured, and is expanding towards applications such as hydraulic fracturing microseismic monitoring, oilfield temperature and pressure, and stress-strain long-term monitoring. [0003] Fiber optic well geophysical technology is the application...

AI Technical Summary

Problems solved by technology

Conventional three-component geophones are generally used for VSP acquisition in existing borehole seismic. When the offset changes, the space vector wave field is recorded by the X, Y, and Z three-component geophones in the Cartesian coordinate system, which can be processed by vector rotation synthesis. Synthesize scalar wave field vectors collected on different components into the spatial radial direction of the actual wave field; since DAS VSP can only perform single-component acquisition at present, unlike conventional three-component detectors, it can only respond to scalar waves along the direction of the fiber field, when the offset changes, due to the lack of other component information of the space coordinate system, the conventional vector rotation synthesis processing method cannot be used to correct the actual radial wave field, so the existing vector rotation synthesis processing method is only suitable for the three-component conventional The detector cannot realize the effective radial compensation of the wave field of the DAS VSP optical fiber acquisition data

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