International Research Journal of Geology and Mining

International Research Journal of Geology and Mining (IRJGM) (2276-6618)
Vol. 7(1) pp. 001-021, January, 2017
Copyright©2017 International Research Journals

 

Full Length Research Paper

Comparison of Bubbles Pulse Suppression Techniques

*Maunde A, Rufa’i FA, Raji AS and Halilu M.

Department of Geology, School of Pure and Applied Sciences, Modibbo Adama University of Technology, Yola, P.M.B. 2076, Yola, Nigeria

*Corresponding author: abubakarmaunde@yahoo.co.uk

ABSTRACT

The British Antarctic Survey acquired 215-km of 2-channel seismic lines BAS923-s27,-s28, and -s29 at the Antarctic continental margin bordering the Bellingshausen Sea during the RRS James Clark Ross cruise JR04 (February and March, 1993) using a single Bolt 1500C airgun with a 300 cu. in. chamber and two hydrophones at offsets of 165m. This 3000 ms long and 2 ms sampled data was acquired at a ship speed of 8 knots with a shot spacing of 42.3m. The study area is right in the middle of a major trough mouth fan and the depth of the continental shelf was estimated to be 662±15 m. The acquired seismic data are effectively a single-channel section but largely dominated by bubble pulses that conceal useful stratigraphic information in the data. The bubble pulse period was fairly consistent across all the lines except for the effect of changes in the ship’s speed whereby a decrease from 8 knots to 6 knots resulted in source depth increase from 4 m to 8 m causing 18.9% decrease in bubble pulse period while an increase from 6 knots to 8 knots resulted in source depth decrease from 8 m to 4 m causing a 23.3% increase in bubble pulse period. A large number of traces were stacked from a flattened version of the dataset to obtain the observed trace which was muted to contain only the sea-floor reflection and the bubble pulses. An inverse filter operator was then generated from the observed trace such that when this operator is convolved with the observed trace, it suppresses the bubble pulse, leaving the trace with only the sea floor reflection. The bubble pulses were suppressed from the whole data by convolving this inverse filter operator with the data.

Keywords: Bubble pulses, Hydrophones, Airgun, Seismic Lines, Traces and inverse Filter.

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