Direct estimates of subsurface material properties are obtained by rigorous inversion of conventional seismic data. The inversion procedure employs an iterative model perturbation technique to fine the earth model whose response best fits the input data in a least mean-squared sense. The method is applicable to 1-D, 2-D, or 3-D fluid or solid earth models, and to shot record or CDP stacked data. The synthetic response computed in the inversion process is a rigorous solution of the wave equation appropriate for the chosen earth model and data type.

For 1-D earth models and synthetic CDP stacked data representing various reflection sequences, the modeling method accurately recovers the true acoustic impedance profile. When a nonrigorous recursive technique is applied to the same models, accurate results are obtained only for weak reflection sequences. Also, the modeling technique exhibits greater stability in the presence of noise. For poststack inversion of field data, the processing sequence leading to the CDP stacked trace is of key importance.

For 1-D earth models and shot record input data, the modeling method accurately recovers both density and velocity profiles. A key issue in prestack inversion of field data is the generation of synthetic shot records consistent with data collection geometry.

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