Methods For Subsurface Parameter Estimation In Full Wavefield Inversion And Reverse-Time Migration
First Claim
1. A method for determining a model of a physical property in a subsurface region from inversion of seismic data, acquired from a seismic survey of the subsurface region, or from reverse time migration of seismic images from the seismic data, said method comprising determining a seismic resolution volume for the physical property and using it as a multiplicative scale factorin computations performed on a computer to eitherconvert a gradient of data misfit in an inversion, orcompensate reverse-time migrated seismic images,to obtain the model of the physical property or an update to an assumed model.
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Abstract
Method for converting seismic data to obtain a subsurface model of, for example, bulk modulus or density. The gradient of an objective function is computed (103) using the seismic data (101) and a background subsurface medium model (102). The source and receiver illuminations are computed in the background model (104). The seismic resolution volume is computed using the velocities of the background model (105). The gradient is converted into the difference subsurface model parameters (106) using the source and receiver illumination, seismic resolution volume, and the background subsurface model. These same factors may be used to compensate seismic data migrated by reverse time migration, which can then be related to a subsurface bulk modulus model. For iterative inversion, the difference subsurface model parameters (106) are used as preconditioned gradients (107).
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Citations
21 Claims
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1. A method for determining a model of a physical property in a subsurface region from inversion of seismic data, acquired from a seismic survey of the subsurface region, or from reverse time migration of seismic images from the seismic data, said method comprising determining a seismic resolution volume for the physical property and using it as a multiplicative scale factor
in computations performed on a computer to either convert a gradient of data misfit in an inversion, or compensate reverse-time migrated seismic images, to obtain the model of the physical property or an update to an assumed model.
Specification