Lecture 3c - Reflection Seismics and Joint inversion

Flashcards covering reflection seismics data collection, processing, applications, and joint inversion techniques.

Joint Inversion

A technique for combining data from different geophysical methods to improve interpretations.

Seismic Reflections

Interfaces between layers with different seismic velocities.

The angle of reflection from an interface is equal to what?

The angle of incidence.

What are the characteristics of reflection surveys?

Multiple shot points and multiple geophones/detectors.

What is done during processing to improve the outcome of surveys?

Combining multiple rays imaging any subsurface point to increase the signal to noise and improve the outcome.

Reflection data processing uses what type of techniques?

Numerical data inversion techniques.

Shot Records

A collection of primary seismic data.

Two-Way Travel Time

The time taken for the seismic signal to go down to the reflector and then return to the detector.

On a shot gather, what does the horizontal distance represent?

The individual separation between the geophones and their traces.

What are some sources of noise in land-based seismic surveys?

Wind, problems with deploying the geophones, or nearby uncontrolled anthropogenic sources such as traffic, railways.

Stacking

A process that allows data to be combined that image the same subsurface point, but for data collected along different ray paths.

What does CDP stand for?

Common Depth Point.

Move Out

The travel time from a reflector increases with the increasing distance between the source and the detector.

In a shot gather, what do the signals in the center represent?

Detectors closest to the source.

What is the source of the cone of large amplitude but low frequency signals in the center of the shot gather?

Surface waves.

What terms should be used when interpreting seismic sections?

Reflectors and interfaces.

What is the main use of the seismic reflection method?

Detailed data from the subsurface.

What is joint inversion used for?

To combine seismic data with other geophysical methods to improve interpretations.

What is the underpinning assumption used to constrain modeling through linking seismic and electrical properties?

Assumes that where one property is changing, the other property is also likely be changing too.

What does joint inversion result in?

An interpretive structural model of the subsurface, which will be equally consistent with both datasets.