Exxonmobil Upstream Research Company

Lorie K Bear

Jerome R Krebs

Carey M Marcinkovich

Wenyi Hu

Hongchuan Sun

Jonathan Liu

Method for reconstructing subsurface Q depth profiles from common offset gathers () of reflection seismic data by performing migration (), ray tracing (), CDP-to-surface takeoff angle finding (), kernel matrix construction (), depth-to-time conversion and wavelet stretching correction (), source amplitude spectrum fitting, centroid frequency shift calculation (), and box-constrained optimization ().

Reflection seismic data Q tomography

Method for updating a velocity model () for migrating seismic data using migration velocity scans with the objective of building a model that reproduces the same travel times that produced selected optimal images from a scan. For each optimal pick location () in the corresponding test velocity model (), a corresponding location is determined () in the velocity model to be updated, using a criterion that the travel time to the surface for a zero offset ray () should be the same. Imaging travel times are then computed from the determined location to various surface locations in the update model (), and those times are compared to travel times in the test velocity model from the optimal pick location to the same array of surface locations. The updating process consists of adjusting the model to minimize the travel time differences ().

Updating velocity models using migration velocity scans

Method for reducing instability and increasing computational efficiency in tomographic inversion for velocity model building. A system of tomographic equations is developed for a uniform grid. A non-uniform parameterization is found for which a linear mapping exists between the space of the uniform grid and the space of the non-uniform grid. The matrix that relates velocity to the tomographic data in the non-uniform representation is then given by the matrix product of the corresponding matrix in the uniform grid representation and the mapping matrix. Inversion can then be performed for the non-uniform parameterization on a smaller, more stable matrix.

Method for tomographic inversion by matrix transformation

A method for constructing velocity models for stacking seismic data, or, more generally, a method for determining reflection geometries with seismic gathers through the use of trace-to-trace coherency coupled with global editing capability to separate velocity events corresponding to primary reflections from multiple reflections and other noise. A velocity model can be fit to the edited velocity events and used for stacking of seismic data. Alternatively, the measured reflection geometry has other potential uses including providing data to be input to a tomographic velocity updating procedure that produces a migration velocity model.

Method for determining stacking velocity parameters or other reflection geometry information from seismic gather data using multiple attributes and 3-D visualization

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Sugar Land, TX, United States of America

Lorie K Bear