Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Results
ABSTRACT Common-Shot migration to Zero Offset (CS-MZO), analyzed in this paper, transforms a common-shot section into a zero-offset section. It can be realized as a Kirchhoff-type stacking operation for 3D wave propagation in a 2D laterally inhomogenous medium. By application of suitable weight function, amplitudes of the data are either preserved or transformed by replacing the geometrical-spreading factor of the input reflections by the correct one of the output zero-offset reflections. The necessary weight function can be computed via 2D dynamic ray tracing in a given macro-velocity model without any a-priori knowledge regarding the dip or curvature of the reflectors. We derive the general expression of the weight function in the general 2.5D situation and specify its form for the particular case of constant velocity. A numerical example validates this expression and highlights the differences between amplitude preserving and true-amplitude CS-MZO.
ABSTRACT We review the derivation of a new prestack operator, the Topographic Datuming Operator (TDO). TDO, unlike static corrections, allows for the movement of reflections laterally to their true locations corresponding to the new datum level. Thus, it mitigates mis-positioning of events and velocity bias introduced by the unphysical time-invariant vertical shifts carried out by static corrections. In the particular case of infinite (in practice, very high with respect to the shallow layers) velocity beneath the datum, the TDO impulse response collapses to the conventional surface-consistent time shift (static correction), which may, therefore, be regarded as a special case of the newly derived operator. Low sub-weathering velocity also shrinks the spatial extension of the TDO impulse response. The application of TDO on onshore data from the Arabian Peninsula provided better continuity of reflections at the new datum than those obtained by static corrections with only a minor additional cost. Moreover, stacking velocities after TDO are not affected by a spurious positive bias.
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
ABSTRACT Reflected seismic signals, surface waves, or ambient noise recorded in a seismic survey are used for the evaluation of individual geophone coupling. Frequency-dependent correction operators derived using a model-driven approach are applied to seismic data to compensate for inconsistent coupling. The method requires point-receiver data in which the signals recorded by the individual geophones are digitized.