Developing Seismic Velocity Models from Shot Data- A Comprehensive Background Guide

How to Get Seismic Velocity Model Background from Shot Data

The acquisition of seismic data is a crucial step in the exploration and production of oil and gas resources. Among various processing techniques applied to seismic data, obtaining a seismic velocity model is essential for interpreting the subsurface structures accurately. This article aims to provide an overview of the process of how to derive a seismic velocity model background from shot data.

Understanding the Importance of Seismic Velocity Model

A seismic velocity model is a fundamental component for seismic data processing and interpretation. It describes the subsurface velocity distribution, which is vital for converting seismic wave travel times into depths. By accurately determining the velocity model, geoscientists can better understand the geological structures, reservoir characteristics, and fluid distribution beneath the Earth’s surface.

Shot Data as the Foundation

Shot data, which consists of recorded seismic waveforms, serves as the foundation for constructing a seismic velocity model. These data are acquired during seismic surveys by measuring the arrival times of seismic waves at various locations on the Earth’s surface. The analysis of these arrival times allows us to estimate the velocity of the subsurface layers.

Steps to Derive a Seismic Velocity Model

1.

Pre-processing

Before deriving the velocity model, it is necessary to preprocess the shot data. This includes tasks such as deconvolution, normalization, and noise reduction to enhance the quality of the data.

2.

Stacking

Stacking is a process that combines multiple seismic traces with similar offset and azimuth to improve signal-to-noise ratio. This step helps in identifying the seismic events more clearly.

3.

Velocity Analysis

Velocity analysis is the process of determining the velocity of seismic waves in the subsurface. This can be achieved through several methods, such as traveltime analysis, moveout analysis, and ray tracing. The choice of method depends on the data quality and the geological complexity of the area.

4.

Velocity Model Construction

Based on the velocity analysis results, a velocity model is constructed. This model represents the velocity distribution of the subsurface layers. Various interpolation techniques, such as kriging or spline interpolation, can be applied to obtain a smooth velocity model.

5.

Refinement and Validation

The derived velocity model needs to be refined and validated. This involves comparing the model with geological and geophysical information, as well as performing sensitivity tests to ensure the model’s accuracy.

Conclusion

Obtaining a seismic velocity model from shot data is a critical step in seismic data processing and interpretation. By following the outlined steps, geoscientists can construct an accurate velocity model that aids in understanding the subsurface structures and improving exploration and production efforts.