Inversion techniques

Seismic Data Inversion


I. Post-Stack Inversion

In the classic post-stack domain, analysis of 2D or 3D post-stack seismic volumes is carried on to produce an acoustic impedance volume.

Seismic inversion may be based on the following methods:

1. Model-Based Inversion
2. Sparse-Spike Inversion-
3. Bandlimited - recursive-fast track Inversion
4. Colored Inversion
5. Neural Network Inversion

The data input to a post-stack STRATA project typically consist of a set of wells, with sonic and density logs, a series of interpreted horizons, and a seismic volume.

Current fast track methods for band-limited inversion to relative impedance are usually direct unconstrained transforms of the seismic data, such as phase rotation, trace integration and recursive inversion, and as such are prone to error because no account is taken of the seismic wavelet or calibration made to the earth.  More sophisticated techniques such as sparse-spike inversion do take account of these factors, but require specialist skills to implement correctly. 

Coloured Inversion implicitly takes into accounts for the seismic wavelet, is consistent with log data, yet is easy and fast to implement. Additionally it benchmarks well against unconstrained Sparse-Spike inversion. Coloured Inversion ( CI ) invert data within hours and establish a base-case against which all subsequently more sophisticated techniques must be judged.

II. Prestack Inversion

In the pre-stack domain, STRATA analyzes angle gathers or angle stacks to produce volumes of acoustic impedance, shear impedance and density.

This can be especially useful for analyzing data with AVO anomalies. The seismic input for this option is typically angle gathers of NMO corrected data. Tools such as Super Gather, Trim Statics, Noise Attenuation, and Angle Gather are used as the input data to enhance the AVO inversion process.