# Filter formulation and wavefield separation of cross-well seismic data

## Abstract

Multichannel filtering to obtain wavefield separation has been used in seismic processing for decades and has become an essential component in VSP and cross-well reflection imaging. The need for good multichannel wavefield separation filters is acute in borehole seismic imaging techniques such as VSP and cross-well reflection imaging, where strong interfering arrivals such as tube waves, shear conversions, multiples, direct arrivals and guided waves can overlap temporally with desired arrivals. The authors investigate the effects of preprocessing (alignment and equalization) on the quality of cross-well reflection imaging wavefield separation and they show that the choice of the multichannel filter and filter parameters is critical to the wavefield separation of cross-well data (median filters, f-k pie-slice filters, eigenvector filters). They show that spatial aliasing creates situations where the application of purely spatial filters (median filters) will create notches in the frequency spectrum of the desired reflection arrival. Eigenvector filters allow one to work past the limits of aliasing, but these kinds of filter are strongly dependent on the ratio of undesired to desired signal amplitude. On the basis of these observations, the authors developed a new type of multichannel filter that combined the best characteristics of spatial filters and eigenvector filters.more »

- Authors:

- Publication Date:

- Research Org.:
- CEPHAG-ENSIEG, Saint Martin d'Heres (FR)

- Sponsoring Org.:
- USDOE

- OSTI Identifier:
- 20000406

- Resource Type:
- Journal Article

- Journal Name:
- Geophysical Prospecting

- Additional Journal Information:
- Journal Volume: 47; Journal Issue: 5; Other Information: PBD: Sep 1999; Journal ID: ISSN 0016-8025

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 58 GEOSCIENCES; SEISMIC SURVEYS; DATA ANALYSIS; CALCULATION METHODS; WELL SPACING; EIGENVECTORS

### Citation Formats

```
Mars, J., Rector, J.W. III, and Lazaratos, S.K.
```*Filter formulation and wavefield separation of cross-well seismic data*. United States: N. p., 1999.
Web. doi:10.1046/j.1365-2478.1999.00147.x.

```
Mars, J., Rector, J.W. III, & Lazaratos, S.K.
```*Filter formulation and wavefield separation of cross-well seismic data*. United States. doi:10.1046/j.1365-2478.1999.00147.x.

```
Mars, J., Rector, J.W. III, and Lazaratos, S.K. Wed .
"Filter formulation and wavefield separation of cross-well seismic data". United States. doi:10.1046/j.1365-2478.1999.00147.x.
```

```
@article{osti_20000406,
```

title = {Filter formulation and wavefield separation of cross-well seismic data},

author = {Mars, J. and Rector, J.W. III and Lazaratos, S.K.},

abstractNote = {Multichannel filtering to obtain wavefield separation has been used in seismic processing for decades and has become an essential component in VSP and cross-well reflection imaging. The need for good multichannel wavefield separation filters is acute in borehole seismic imaging techniques such as VSP and cross-well reflection imaging, where strong interfering arrivals such as tube waves, shear conversions, multiples, direct arrivals and guided waves can overlap temporally with desired arrivals. The authors investigate the effects of preprocessing (alignment and equalization) on the quality of cross-well reflection imaging wavefield separation and they show that the choice of the multichannel filter and filter parameters is critical to the wavefield separation of cross-well data (median filters, f-k pie-slice filters, eigenvector filters). They show that spatial aliasing creates situations where the application of purely spatial filters (median filters) will create notches in the frequency spectrum of the desired reflection arrival. Eigenvector filters allow one to work past the limits of aliasing, but these kinds of filter are strongly dependent on the ratio of undesired to desired signal amplitude. On the basis of these observations, the authors developed a new type of multichannel filter that combined the best characteristics of spatial filters and eigenvector filters. They call this filter a constrained eigenvector filter. They use two real data sets of cross-well seismic experiments with small and large well spacing to evaluate the effects of these factors on the quality of cross-well wavefield separation. They apply median filters, f-k pie-slice filters and constrained eigenvector filters in multiple domains available for these data sets (common-source, common-receiver, common-offset and common-midpoint gathers). They show that the results of applying the constrained eigenvector filter to the entire cross-well data set are superior to both the spatial and standard eigenvector filter results.},

doi = {10.1046/j.1365-2478.1999.00147.x},

journal = {Geophysical Prospecting},

issn = {0016-8025},

number = 5,

volume = 47,

place = {United States},

year = {1999},

month = {9}

}