US 4,736,347 AGranted

Multiple stacking and spatial mapping of seismic data

OwnerBernard Goldberg, David A. Goldberginventors

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Abstract

Seismic traces are stacked in a plurality of orthogonal measures to form multiple stacked traces at a positive offset. The stacking process determines the apparent velocities as functions of the travel time at the positive offset. The interval acoustic velocity of the first layer is then determined from knowledge of surface topography, source-receiver offset, two-way travel times and the first reflector apparent velocities. The first layer velocity information enables the incident and emergent angles of the raypaths at the surface to be calculated, as well as enabling the dip angles and spatial coordinates of the reflection points on the first reflecting boundary to be determined. Seismic data corresponding to the second reflecting boundary are then spatially mapped to the first reflecting boundary by ray tracing and by a new method for calculating the apparent velocities at the first boundary. The process is repeated for each succeedingly deeper boundary. The derived acoustic velocity model of the earth is displayed as a stacked seismic section in spatial coordinates. This process may be applied to obtain earth models and seismic sections in both two and three dimensions.

Claims11

Dependent claims

A method of representing the locations, shapes, and interval velocities between reflecting boundaries of the earth's layers as a section of the earth from data obtained in response to seismic waves imparted during a seismic survey, comprising the steps of:

(a) collecting seismic data during said survey from a plurality of seismic energy sources and receivers;
(b) sorting said collected data into a plurality of gathers of seismic traces, each said gather comprising seismic traces with a common source or receiver or midpoint location;
(c) subsetting each said gather into a plurality of bundles of seismic traces, each said bundle spanning a different range of seismic trace offsets and comprising a plurality of seismic traces;
(d) stacking said seismic traces in each said bundle to obtain first apparent velocity functions as a function of travel times at an average offset of said seismic traces in each said bundle;
(e) further stacking said stacked traces corresponding to common average offset ones of said bundles from successive groups of said gathers to obtain second apparent velocity functions as a function of travel times at said average offset in at least one additional orthogonal coordinate for said stacked trace at the midpoint of each said successive group of gathers;
(f) determining interval velocities of the earth's layers and the locations and shapes of the earth's reflecting boundaries from said first and second functions and said average offset;
and
(g) representing said determined interval velocities, said locations, and said shapes.

5 more elements

Dependencies are inferred from the claim text.