Method for quickly establishing three-dimensional near-seafloor speed model in shallow sea area

A velocity model and shallow sea technology, applied in seismology, geophysical measurement, seismic signal processing, etc., to achieve the effect of eliminating influence, convenient calculation and high calculation efficiency

CN109188527AActive Publication Date: 2019-01-11CHINA PETROLEUM & CHEM CORP +1
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2019-01-11
Patent Text Reader

Abstract

The invention provides a method for quickly establishing a three-dimensional near-seafloor speed model in a shallow sea area; the method comprises the following steps of extracting initial informationand extracting a common-center-point gather; calculating the slope of the initial travel time in the common-center-point gather; judging whether a shot point is located in the seawater layer or not,and if yes, correcting the shot point to the seafloor; calculating the speed and the depth of inflection points corresponding to respective offset distances; performing linear interpolation on the speed at each depth to obtain a one-dimensional speed model of the common center point; after all the common-center point domain gathers are processed, adopting the linear interpolation method, calculating the speed values of the rest grid points by utilizing the one-dimensional speed model of all common center points, and a speed model is output. By adoption of the method for quickly establishing the three-dimensional near-seafloor speed model in the shallow sea area, the influence of the seawater layer on ray propagation is overcome, and the influence of multiple excitation receiving modes on an inversion result is eliminated, and the problem that the conventional method needs to carry out multi-ray tracing forward modeling is avoided.
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Description

technical field

[0001] The invention relates to the technical field of surface velocity modeling in seismic exploration, in particular to a method for quickly establishing a three-dimensional near-bottom velocity model in shallow sea areas. Background technique

[0002] In shallow sea areas, the surface velocity structure changes drastically, and there are tidal flats, silt, intertidal zones, etc. The complex surface velocity structure distorts the seismic reflection wave event, which seriously affects the final imaging quality. At present, the commonly used solution is to establish the surface velocity model with the first-arrival travel-time tomographic velocity modeling method, and then carry out static correction. The statically corrected seismic data is used for stacking imaging, so as to improve the accuracy of imaging.

[0003] However, in shallow sea areas, there are multiple excitation and reception methods such as sea surface excitation, sea bottom reception, lan...

Examples

Embodiment Construction

[0042] In order to make the above and other objects, features and advantages of the present invention more comprehensible, the preferred embodiments are listed below and shown in the accompanying drawings in detail as follows.

[0043] Such as figure 1 as shown, figure 1 A flowchart of a method for quickly establishing a three-dimensional near-bottom velocity model for the shallow sea region of the present invention.

[0044] Step 1: Extract the first arrival information, and obtain the first arrival travel time, shot point coordinates, and receiver point coordinates from the seismic data;

[0045] Step 2: Extract the common midpoint gather;

[0046] Step 3: Calculate the slope of the first arrival travel time in the common center point gather. The calculation formula of the slope is as follows:

[0047]

[0048]Among them, Δt represents the difference of first arrival travel time of adjacent traces, Δx represents the difference of offset distance of adjacent traces, and...