Three dimensional before stack depth migration of two dimensional or three dimensional seismic data

Claim 1

A method to provide a three dimensional before stack depth migration of seismic data comprising the steps of: receiving seismic data as seismic traces; receiving an approximate depth mode; determining approximate locations for predetermined segments of said seismic traces; moving said predetermined segments to said approximate locations; scaling said predetermined segments to depth by obtaining three dimensional source and receiver positions on each trace and deriving a three dimensional raypath from the source to a primary objective map and to the receiver by locating raypaths having emergence points within a predetermined area around said receiver position; binning said scaled predetermined segments according to reflection point location; stacking said scaled predetermined segments contained in each bin; comparing said stacked scaled segments to said three dimensional model; and modifying said three dimensional model to conform to said stacked scaled segments.

Claim 2

A method to provide a three dimensional before stack depth migration of seismic data comprising the steps of: receiving seismic data as seismic traces; receiving an approximate depth mode; determining approximate locations for predetermined segments of said seismic traces; moving said predetermined segments to said approximate locations; scaling said predetermined segments to depth by obtaining three dimensional source and receiver positions on each trace and deriving a three dimensional raypath from the source to a primary objective map and to the receiver by locating raypaths having emergence points within a predetermined area around said receiver position; binning said scaled predetermined segments according to reflection point location; stacking said scaled predetermined segments contained in each bin; comparing said stacked scaled segments to said three dimensional model; and modifying said three dimensional model to conform to said stacked scaled segments.

Claim 7

A method for migrating seismic data comprising the steps of: obtaining a seismic model including a depth map and seismic data including seismic traces; gathering said seismic traces at a dense reflection point area by obtaining three dimensional source and receiver positions for each trace and deriving a three dimensional raypath from the source to a primary objective map and to the receiver by locating raypaths having emergence points within a predetermined area around said receiver position; evaluating the velocity of said gathered seismic traces by noting their alignment; binning data from said gathered seismic traces within a predetermined area of said dense reflection point area; stacking said binned data; comparing said stacked binned data with said seismic model; and changing the depth map whenever said stacked binned data differs from said seismic model by a predetermined amount.

Claim 8

A method for migrating seismic data comprising the steps of: obtaining a seismic model including a depth map and seismic data including seismic traces; gathering said seismic traces at a dense reflection point area by obtaining three dimensional source and receiver positions for each trace and deriving a three dimensional raypath from the source to a primary objective map and to the receiver by locating raypaths having emergence points within a predetermined area around said receiver position; evaluating the velocity of said gathered seismic traces by noting their alignment; binning data from said gathered seismic traces within a predetermined area of said dense reflection point area; stacking said binned data; comparing said stacked binned data with said seismic model; and changing the depth map whenever said stacked binned data differs from said seismic model by a predetermined amount.

Claim 16

A method for tracing rays from a source position to a receiver position comprising the steps of: receiving input data including a seismic model, north-south minimum and maximum values, east-west minimum and maximum values, an angle increment value, a source position and a receiver position; obtaining a plurality of paths for rays traveling from said source position, through said seismic model, to a depth map and to a location near said receiver position; selecting four paths from said plurality of paths that straddle said receiver position; determining new north-south and east-west minimum and maximum values from said four paths; changing said minimum and maximum values whenever said location deviates from said receiver position by a predetermined amount; and interpolating said four ray paths to obtain a single ray path representing a path traveled from said source, through said model, to said depth map and to said receiver position.

Claim 17

A method for tracing rays from a source position to a receiver position comprising the steps of: receiving input data including a seismic model, north-south minimum and maximum values, east-west minimum and maximum values, an angle increment value, a source position and a receiver position; obtaining a plurality of paths for rays traveling from said source position, through said seismic model, to a depth map and to a location near said receiver position; selecting four paths from said plurality of paths that straddle said receiver position; determining new north-south and east-west minimum and maximum values from said four paths; changing said minimum and maximum values whenever said location deviates from said receiver position by a predetermined amount; and interpolating said four ray paths to obtain a single ray path representing a path traveled from said source, through said model, to said depth map and to said receiver position.