Ewing Oil decides to shoot two marine seismic surveys. For the first survey, tar

Question

Ewing Oil decides to shoot two marine seismic surveys. For the first survey, targeting shallow layers, air guns are fired every 17 m, the hydrophone streamer is 2.45 km long and consists of 72 separate hydrophone sections and both the source and the streamers are t o w ed at 5m depth. In the second survey, targeting deeper layers, air guns are fired every 50 m, the streamer is 5 km long and consists of 100 sections and both the source and the hydrophones are towed at 15 m depth.

a) If the velocity of sea water is 1.5 km/s, what is the peak frequency of each survey?

b) What is the fold of each survey?

Explanation / Answer

Peak or ghost or notch frequency is

A. 1/Time period = 1/(5/1500)=1/( 0.0033 sec)= 500hz

B. Similarly, for second survey, 1500/15 = 100hz.

As we put hydrophone streamers to the higher depth, peak frequency shifts toward lower values.

b. Fold =( N/2)*(receiver interval/ source interval)

A. = 72/2*((2368/72)/17)

B. = 100/2*((4900/100)/50)

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