Abstract: Image Processing
of Seismic
Lines: a Tool for Stratigraphic Interpretation
Rossetti, Enio Luiz - Petrobras/E&P
A new developed methodology aimed to
help the integration of geological and geophysical data sets was tested
in some Brazilian sedimentary basins. Conventional seismic data, either
2D and 3D, after digital
imaging
processing
, has the potential to reveal
subtle aspects of the seismic data, not readily available on conventional
plots and on-screen seismic displays. The methodology uses PC-based commercial
digital
-imaging software, like Photopaint®, to unravel seismic stratigraphic
features hidden in high resolution seismic data.
The research strategy was to process the seismic
data as pixel-based, grayscale images instead of a set of digital
, trace-organized
seismic samples. Disguised by the gray shades of on-screen displays are
hidden information that represents geological complexities regarding the
stratigraphic architecture, like subtle stratal truncations, prograding
clinoform geometry, channels, turbidites, unconformities, or downlap surfaces
that may help to correlate 4th or even 5th order
stratigraphic sequences, or to infer lithologic variations and depositional
environments.
By enhancing the contrast, and after the application of some filters in seismic images from conventional 10-60 Hz seismic data, it was possible to discriminate seismic stratigraphic details such as prograding clinoforms, unconformities and channels that help to define 4th order stratigraphic sequences in the Neocomian rift sequence of the Apodi Graben.
Fig. 01 shows a zoomed portion of a 3D seismic
line from the Apodi Graben. Fig. 1a is a variable-density standard image,
after digital
imaging
processing
, like contrast, brightness and intensity.
The final effect is a better image of the seismic data. Fig. 1b shows another
version of the same data, after the application of a contour filter, resulting
in a less diffused presentation of the image. Fig. 2a shows a line-drawing
version of the same data set (dashed lines). This drawing plot has been
superimposed over original plots (Fig. 2b) which indicates that this methodology
does not create anything new on the original data, since that the drawn
lines involve perfectly the original seismic reflectors.
This methodology may be applied to reservoir analyses as well as to exploratory purposes, extracting potentially hidden information of most of conventional seismic data.
AAPG Search and Discovery Article #90933©1998 ABGP/AAPG International Conference and Exhibition, Rio de Janeiro, Brazil