Typing picks to horizons in migration velocity analysis

#This invention relates to geophysical prospecting using seismic signals, and in particular to systems and methods for estimating seismic velocity.

#Effectively searching for oil and gas reservoirs often requires imaging the reservoirs using three-dimensional (3-D) seismic data. Seismic data is recorded at the earth's surface or in wells, and an accurate model of the underlying geologic structure is constructed by processing the data. 3-D seismic imaging is perhaps the most computationally intensive task facing the oil and gas industry today. The size of typical 3-D seismic surveys can be in the range of hundreds of gigabytes to tens of terabytes of data. Processing such large amounts of data often poses serious computational challenges.

#Obtaining high-quality earth images necessary for contemporary reservoir development and exploration is particularly difficult in areas with complex geologic structures. In such regions, conventional seismic technology may either incorrectly reconstruct the position of geological features or create no usable image at all. Moreover, as old oil fields are depleted, the search for hydrocarbons has moved to smaller reservoirs and increasingly hostile environments, where drilling is more expensive. Advanced imaging techniques capable of providing improved knowledge of the subsurface detail in areas with complex geologic structures are becoming increasingly important.

#FIG. 1 is a flow chart outlining a preferred migration velocity analysis method of the present invention.

#FIG. 2-A illustrates an exemplary angle-domain common image gather (ACIG) according to the present invention.

#FIG. 2-B illustrates an exemplary offset-domain common image gather (common reflection point, CRP) gather according to the present invention.

#The following description illustrates the present invention by way of example and not necessarily by way of limitation. In the following description, unless explicitly specified otherwise, the term velocity will be understood to encompass both speeds and slownesses. As the skilled artisan appreciates, it is understood that the equations disclosed herein are not changed by the mere use of other equivalent variables (velocity instead of slowness, angle instead of ray parameter, etc.) to represent the same equation. Thus, the statement that a path is generated according to an equation is understood to encompass generating the path by any method that satisfies the equation, regardless of the particular names of the variables employed in that method. Any reference to an element is understood to refer to at least one element. A set of elements is understood to include one or more elements.

#FIG. 1 is a flowchart illustrating the steps of a preferred velocity analysis method of the present invention.

#1. Initialization