Invel System of Velocity Determination (Patent No: 970460)

Inventor: Amoco Canada Petroleum Company Ltd.

Location: Calgary

Comments: N/A

Description: [52] CLASS 349-10
[11] 970,460
[54] INVEL SYSTEM OF VELOCITY DETERMINATION
[72] Widness, Moses B., Houston, Texas U.S.A.
[73] Granted to Amoco Canada Petroleum Company ltd., Calgary, Alberta, Canada
[21] Application No. 180,906
[22] Filed Sep. 10, 1973
[30] Priority date Jan. 8, 1973 (322,056) U.S.A.
5 Claims

[57] This is a new way of compositing multifold common-depth-point data from seismic prospecting operation to improve the making of static corrections, particularly when determining velocity. Such static corrections eliminate time differences in arrival of reflected seismic events on the various traces of a seismic spread due to differences in thickness of the low velocity or "weathered" layer below the geophones, to differences in surface elevation, and the like. Seismic waves are generated successively at generating points, each near the earth's surface. Seismic waves are received and reproducibly recorded at geophones at least one of which in each case is close to the generating point and another is near the location of another generating point. These spatial relationships are symmetrical. Reproduced reflected waves from each generating point received at the respective near geophone locations are composited at approximately equal peak amplitudes. This procedure is then repeated for new generating and receiving paints which maintain approximately constant the mean location of reflection points on the seismic reflecting beds. Visual traces equivalent to the composited "short" traces are reproduced after elimination of the normal moveout correction. The reflections from a common reflecting bed are aligned by introducing a static correction into each composited trace to produce substantial time alignment at a mean reflection time. The identical seismic static correction is then applied to any further record processing of the seismic data from the "far" geophones, similarly composited, before producing visual traces of such data. The procedure Is valuable both for malting velocity panels for determination of velocity vs. depth in seismic prospects, and in determining depth and/or dip of reflecting sub-surface discontinuities.