The Research On ADCIGs Extraction And Parametric Inversion In Visco-acoustic Media

With the continuous improvement of seismic exploration accuracy,the influence of the absorption and attenuation characteristics of the Earth’s medium on seismic wave imaging has received increasing attention.The absorption and attenuation of the actual medium not only causes the loss of seismic wave energy,but also causes the main frequency of the seismic signal to decrease continuously,which seriously affects the imaging quality of the deep reflectio n interface.Therefore,research on imaging methods considering the absorption and attenuatio n characteristics of actual media has become a research hotspot in recent years.The quality factor Q is one of the commonly used parameters describing the absorption and attenuation of seismic waves in the media.How to obtain the quality factor distribution of the earth medium from the seismic data,and then effectively compensate the energy loss during the seismic wave propagation is a difficult point in current research.As to these issues,this paper mainly does the following two aspects of work:(1)The paper systematically studies the mechanism of seismic wave absorption attenuatio n,analyzes the factors affecting seismic wave absorption attenuation,introduces several commonly used parameters and attenuation models describing seismic wave absorption attenuation,and selects standard linear solid model to simulate seismic records.Prestack depth migration imaging is realized by using second-order wave equation without memory variables.Regularization operator is added to visco-acoustic wave equation to suppress high frequency instability,and analyse the sensitivity of ADCIGs.(2)Several commonly used Q-value estimation methods are discussed in this paper,especially the spectral ratio method.The paper improves the traditional spectral ratio method,establishes the spectral ratio relation equation between adjacent CDP in the same layer,solves the spectral ratio relation equation by LSQR method,and picks up more accurate seismic wave attenuation travel time.The paper assumes that the Q-value model has a similar distribut io n with the velocity model,and adds velocity gradient constraints to the Q-valued ray tomography equation to improve the stability and convergence of the method.The paper method can obtain the quality factor distribution efficiently and stably,and proves the correctness and adaptabilit y of the paper method through model trial calculation.