Acoustic equation frequency domain reverse time migration fast imaging method for steering while drilling

A technology of acoustic wave equation and reverse time migration, which is used in earthwork drilling, seismology for logging records, measurement, etc. It can solve the problems of gap, huge amount of calculation, complicated extraction of angle gathers, etc., and achieve fast imaging speed. , the effect of high computational efficiency and strong algorithm portability

Active Publication Date: 2021-12-07
TONGJI UNIV
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the extraction of angle gathers is complex and computationally intensive
Kirchhoff Gaussian beam prestack depth migration (Duan Pengfei et al., 2013) applies a reasonable approximation without affecting the accuracy, which can reduce the computational cost of Gaussian beam synthesis and migration imaging in anisotropic media (Duan Pengfei et al., 2014), is The fastest of the above imaging algorithms, but there is still a large gap with the fast imaging requirements of drilling steering

Method used

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  • Acoustic equation frequency domain reverse time migration fast imaging method for steering while drilling
  • Acoustic equation frequency domain reverse time migration fast imaging method for steering while drilling
  • Acoustic equation frequency domain reverse time migration fast imaging method for steering while drilling

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Embodiment

[0058] Such as figure 1 As shown, the present invention proposes a fast imaging method for acoustic wave equation frequency domain reverse time migration oriented to steering while drilling. This method regards the logging update model as a scattering source, and then uses the The interaction of the secondary wave field generated by the source enables rapid imaging of the medium below the updated model. Schematic diagram of the fast imaging principle figure 2 Shown:

specific Embodiment approach

[0059] Such as image 3 Shown, the specific embodiment of the present invention is as follows:

[0060] (1) The data collector 1 collects seismic wave signals, performs preprocessing on the original seismic data such as filtering, denoising, wavelet estimation, and removing transmitted waves, and performs Fourier transform to obtain frequency-domain reflected wave data d(g). Count the number and location information of non-repeated shot points and receiver points;

[0061] (2) The input device 4 establishes the initial migration velocity model m by using techniques such as tomography and migration velocity analysis according to the subsurface prior information 0 (x), and set parameters such as imaging frequency range and interval;

[0062] (3) On the current migration velocity model, the processor 2 uses the observation system of actual data to carry out the forward simulation of the acoustic wave equation in the frequency domain, and obtains and stores the forward wave fiel...

Embodiment 1

[0068] In this embodiment, the two-dimensional Overthrust model will be used as the real model (such as Figure 4 shown), the model has a total of 801×187 grids, and the grid spacing is 25m×25m. The sound wave forward simulation is carried out on this model, with a total of 401 forward shots, the shot spacing is 50m, the first shot is at the position of 0m, the maximum offset distance of each shot is 4000m, and the minimum offset distance is 0m. The track spacing is 25m. While applying the steering-while-drilling fast imaging algorithm proposed by the present invention, the traditional model-based reverse time migration imaging is also applied simultaneously to prove the effectiveness of the present invention. The following is a quick imaging display of the Overthrust model. Figure 5 is the initial offset model, Figure 6 The shown local perturbation model represents the Figure 5 The background model is updated based on the local model obtained from logging while drillin...

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Abstract

The invention relates to a rapid imaging method for acoustic wave equation frequency domain reverse time migration oriented to guidance while drilling, comprising the following steps: 1) Obtaining reflected wave information in the frequency domain; coordinates; 3) Obtain the initial migration velocity model; 4) Obtain all non-repeated forward wave fields in the frequency domain at the shot point end, Green's function in the frequency domain at the receiver point end, and the forward operator LU matrix in the frequency domain under the current migration velocity model ;5) Obtain the update amount of the local migration velocity model; 6) Perform rapid reverse time migration in the frequency domain of the acoustic wave equation to generate underground imaging; 7) Repeat steps 5) to 6) along with the drilling process to continuously update and display the underground imaging; 8) When the cumulative update amount exceeds the set threshold or the number of drilling times reaches the set value, update the current migration velocity model, and repeat steps 4) to 7). Compared with the prior art, the present invention has the advantages of high calculation efficiency and no influence on inversion precision.

Description

technical field [0001] The invention relates to the field of seismic exploration imaging, in particular to a rapid imaging method for acoustic wave equation frequency domain reverse time migration oriented to guidance while drilling. Background technique [0002] The near surface of my country's Tarim, Sichuan, and Ordos basins is very complex, with complex geological structures after multi-stage tectonic movements. Deep-ultra-deep oil and gas reservoirs are mainly carbonate rocks with strong heterogeneity, and some are tight clastic rocks. Reflection seismic data have low signal-to-noise ratio and low resolution, making it difficult to determine deep-ultra-deep drilling targets. Over the past ten years, although Sinopec, PetroChina and other related units have carried out a large number of geological, geophysical prospecting and a small amount of drilling work for deep-ultra-deep oil and gas exploration in Tarim, Sichuan, Ordos and other basins, and achieved deep-ultra-dee...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01V1/28G01V1/32G01V1/34G01V1/36G01V1/40E21B47/14
CPCE21B47/14G01V1/282G01V1/325G01V1/345G01V1/36G01V1/364G01V1/40G01V2210/20G01V2210/32G01V2210/40G01V2210/51G01V2210/74
Inventor 刘玉柱
Owner TONGJI UNIV
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