Improving the interpretability of air-gun seismic reflection data using deterministic filters; a case history from offshore Cape Leeuwin, southwest Australia

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doi: 10.1190/1.3554396
Author(s): Sargent, Colin; Hobbs, Richard W.; Gröcke, Darren R.
Author Affiliation(s): Primary:
Durham University, Department of Earth Sciences, Durham, United Kingdom
Volume Title: Geophysics
Source: Geophysics, 76(3), p.B113-B125. Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States. ISSN: 0016-8033 CODEN: GPYSA7
Note: In English. 31 refs.; illus., incl. 2 tables, sketch map
Summary: To identify drilling targets for an Integrated Ocean Drilling Program project to investigate high-latitude black shales required reinterpretation of legacy seismic data. The original processing had identified the major structures but was of insufficient resolution to map the more-subtle markers at the top of the shale sequence. By reprocessing these 2004 vintage 2D air-gun marine seismic reflection data we show that the application of filters determined from deepwater data yields subbottom geological imaging superior to statistical methods and arguably better than modeled source deconvolution methods, particularly for recovery of low frequencies. The data were acquired to the southwest of Australia in an area with swells that are typically 2-4 m and cause distortions to the predicted source and receiver response functions. These distortions cannot be incorporated in an idealized modeled source function; hence, we have opted to design the deterministic filters from the seismic data. We applied the deconvolution in two steps: a prestack filter to suppress the air-gun bubble pulse signal and a poststack filter to suppress the notches in the amplitude spectrum caused by the free-surface reflections at the source and the receiver. Through this strategy, we expanded the seismic data bandwidth at the low and high frequencies and improved resolution. The tie with the single borehole in the area was significantly improved and has enabled a more-confident interpretation of the shale horizons.
Year of Publication: 2011
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 20 Geophysics, Applied; Air guns; Australasia; Australia; Cape Leeuwin; Clastic rocks; Data acquisition; Data processing; Geophysical methods; Integrated Ocean Drilling Program; Interpretation; Marine methods; Numerical filters; Offshore; Poststack migration; Reflection methods; Sedimentary rocks; Seismic methods; Seismic migration; Seismic sources; Shale; Statistical analysis; Techniques
Coordinates: S360000 S320000 E1140000 E1100000
Record ID: 2011088163
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States