Sensitivity kernels for wave equation based migration velocity analysis in local angle-domain are formulated. These sensitivity kernels serve as operators to backproject the residual moveout in local angle-domain common image gathers to migration models for velocity updating. To validate the theoretical formulation, we directly measure sensitivity kernels using a perturb-measuring approach. For...

Estimating an accurate velocity model is crucial for seismic imaging to obtain a good understanding of the subsurface structure. The objective of this thesis is to investigate methods of velocity analysis by optimizing seismic images. A conventional seismic image is obtained by zero-lag crosscorrelation of wavefields extrapolated from a source wavelet and recorded data on the surface using a ve...

The neural network, using an unsupervised generalized Hebbian algorithm (GHA), is adopted to find the principal eigenvectors of a covariance matrix in different kinds of seismograms. We have shown that the extensive computer results of the principal components analysis (PCA) using the neural net of GHA can extract the information of seismic reflection layers and uniform neighboring traces. The ...

Multiple reflections contain subsurface reflectivity information which often complements that found in primary reflections. Previous attempts to combine the additional information by summing prestack images of the primaries and multiples have generally failed because of crosstalk leakage between the images. We present a general linear least-squares inversion method, Least-Squares Joint Imaging ...

Tight, low-porosity reservoirs can produce significant amounts of hydrocarbons if fracture networks provide the necessary permeability. Characterization of naturally fractured reservoirs using surface seismic data is an important exploration problem that has attracted much attention in the literature. TLE, for example, had an entire issue (August 1996) on this subject. While the data and modeli...

We have conducted a series of experiments designed to investigate elastic and electromagnetic (EM) velocity anisotropy associated with a preferentially aligned fracture system on a temperate valley glacier in south-central Alaska, USA. Measurements include a three-dimensional compressional wave (P-wave) seismic reflection survey conducted over a 300m 300m survey patch, with uniform source grid ...