A Robinson, T. Durrani and L. Excellent sets of exercises are provided for the student of those chapters written by E. The processes covered have been, by and large, the workhorses of conventional seismic data processing for the better part of a quarter of a century. The section by E. Robinson is devoted to NMO correction and stacking, predictive deconvolution and time migration: that by T.

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Conference Brown, A. Horizontal slices through a data volume, called Seiscrop sections, have unique properties and structural interpretation from them is fast, convenient, and effective.

An event on a Seiscrop section displays local strike, a property which permits direct contouring of a structural surface without any timing and posting.

The width of an event on a Seiscrop section is a composition of the frequency of the data and the structural dip. Event terminations indicate faults or other discontinuities when they are transverse to structural strike. In practical mapping, we normally contour one fault block before proceeding to the next with the correlation between them being established from the vertical sections. With dual polarity variable area displays, the interpreter can perceive five amplitude levels and normally picks the edge of a trough.

With color amplitude Seiscrop sections, it is possible to pick on the crest of any event. With color phase sections the interpreter can pick at any arbitrary but consistent point on the seismic waveform. Subtle structural features are commonly revealed on horizontal sections which may never have been noticed if working from vertical sections alone.

Geological interpretation and display systems have also been available, but separate from the seismic interpretation work station. The need for integrated geological and geophysical systems is now greater than ever. The title explorationist would nowadays be more characteristic. In this paper, a system for integrated geological and geophysical interpretation and presentation using image processing will be presented.

Composite displays and data bases present a unique way of doing this using an image processor. Seismic interpretation is often based on a previously defined geological model; therefore, it is important to be able to compare seismic interpretation with the geological model and vice versa.

A new method of using image processing in depth conversion on either a single seismic line or on a map using a flexible velocity field will present the explorationist with instant ways to verify the interpretation.

Once an interpretation is performed, the interpreted horizons can be used as input to a geophysical 3D seismic modeling concept. The user can input survey parameters as they were used during acquisition to produce synthetic seismograms and compare results with existing seismic data. When depth conversion parameters are established, the image processor performs this within seconds, and the final depth map is presented to the explorationist.

The Bureau of Indian Affairs funded additional seismic work around the Lake, and an extensive, detailed single-channel marine survey producing more than miles of section, imaging more than ft below the Lake bottom. After advanced seismic analysis including first-arrival velocity optimization and prestack depth migration, the 2d sections show clear fault-plane reflections, in some areas as deep as ft, tying to distinct terminations of the mostly volcanic stratigraphy.

Some lines achieved velocity control to ft depth; all lines show reflections and terminations to ft depth. Three separate sets of normal faults appear in an initial interpretation of fault reflections and stratigraphic terminations, after loading the data into the OpendTect 3d seismic visualization system.

Each preliminary fault set includes a continuous trace more than ft long, and a swarm of short fault strands. The three preliminary normal-fault sets strike northerly with westward dip, northwesterly with northeast dip, and easterly with north dip. The seismic sections do not show the faults connected to the Astor Pass tufa spire, suggesting that we have imaged mostly Tertiary-aged faults. We hypothesize that the Recent, active faults that produced the tufa through hotspring activity do not have enough offset to produce seismic terminations.

We are conducting further high-resolution seismic studies to ft depths at the tufa spire to test this hypothesis. Additional work in progress includes a collaborative, iterative joint interpretation of geologic mapping and the seismic sections for fault locations, building the geologic model; and 3d velocity modeling and imaging to locate additional faultplane images appearing between the 2d lines.

It defines in detail the geologic structure of much of the north margin of Pyramid Lake.


Practical Seismic Interpretation



Practical seismic interpretation






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