| 主权项 |
1. A method of seismic exploration above a region of the subsurface of the earth containing structural or stratigraphic features conducive to the presence, migration, or accumulation of hydrocarbons, wherein is provided a seismic survey collected proximate to the region of the subsurface of the earth, said seismic survey comprising a plurality of seismic traces, comprising the steps of:
(a) accessing at least a portion of said plurality of seismic traces; (b) obtaining a dip field associated with said accessed plurality of seismic traces, said dip field at least being defined at a plurality of (x,y,z) image points within said seismic survey; (c) specifying an upper specular index threshold and a lower specular index threshold different from said upper specular index threshold at each of said plurality of (x,y,z) image points; (d) for each of said plurality of (x,y,z) image points,
(i) obtaining one or more source/receiver propagation direction pairs at said (x,y,z) image point,(ii) for each of said obtained one or more source/receiver propagation direction pairs at said (x,y,z) image point, using said dip field to obtain an associated specular index value;(iii) determining an associated upper specular index threshold and an associated lower specular index threshold associated with said (x,y,z) image point,(iv) selecting any source/receiver propagation direction pairs associated with said (x,y,z) image point that have a specular index value greater than said associated upper specular index threshold or less than said associated lower specular index threshold, and,(v) using any of said selected source/receiver propagation direction pairs to form a migrated image at said (x,y,z) image point,wherein said migrated images at said plurality of (x,y,z) image points taken together form a migrated seismic dataset; and, (e) using at least a portion of said migrated seismic dataset in exploration for hydrocarbons within the region of the subsurface of the earth. |
