Page 32: of Offshore Engineer Magazine (Oct/Nov 2013)

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New marine vibrator offers

Geology & Geophysics improved performance

Houston-based Geokinetics showed its latest source advance in their booth at the SEG

Convention this September. , Geokinetics’ vice president explains the technology.Bill Pramik ore and more, statements regarding the harm the oil and that seismic airguns might do gas industry to the environment. Many of

M is being asked to reduce its these statements are based impact on the environments in on incomplete, incorrect, or which it works. In one sense, anecdotal reports about envi- this is ironic, because the ronmental damages caused by industry recognized a long time airguns. The truth is that there ago that reducing its envi- are very few scientifc studies ronmental footprint has a about the impact of airguns on positive effect on proftabil- the environment, and those that ity. In simple terms, if the exist generally focus on one or two environment is minimally specifc species (e.g. cetaceans), impacted, there is no need to spend rather than the environment as a

The marine source is set in a time, resources, and money correcting whole. Nonetheless, it is prudent frame for installation on a vessel.

problems. Nonetheless, the industry that we begin looking at alternate also recognizes that it has a respon- want to do this? seismic energy sources for the marine sibility, as good corporate citizens, to There can be little doubt that environment.

perform work in a manner consistent humans have an impact on the envi- A marine vibrator will probably with environmental best-practices and ronment. These impacts can be divided never replace airguns as the energy guidelines. into three basic categories: good, bad, source for marine seismic acquisi-

Geokinetics has been proactive or inconsequential. Which category an tion, just as land vibrators have not when it comes to protecting the envi- impact falls into depends on the nature replaced explosives for land acquisi- ronment. In many areas, the company’s of the impact and somewhat from the tion. However, there are a number of internal policies are more stringent perspective it is examined. In the seis- situations where a marine vibrator can than prevailing regulations and it mic industry, “inconsequential” envi- be advantageous. Some of these advan- constantly monitors performance look- ronmental impact is the goal. There tages relate to environmental concerns, ing for improvement opportunities. is some environmental impact from others involve seismic data quality and

One such opportunity being devel- operations; the goal is for that impact acquisition effciency.

oped by the Technology Research and to have no consequences or, at least,

Development team in Houston is the the smallest consequences practical.

Diferences

Geokinetics Marine Vibrator. It is a Offshore, where seismic companies One of the major differences between major step forward to the goal of being acquire ocean bottom and transition airguns and vibrators is the sound good environmental stewards. zone seismic data, the source of choice pressure level that is transmitted for over 50 years has been the air- into the water. It is like comparing a gun. Before that, dynamite and other shotgun blast to the hum of a room

Seismic acquisition

So exactly what is a marine vibrator? explosive charges were detonated air conditioner. The shotgun, like

As the name implies, it is a seismic in the water as the energy source. the airgun, releases all of its acoustic vibration source that’s used in the The airgun was hailed as a safer and energy in a single pulse with a very water. In much the same way that “friendlier” seismic source and was high sound-pressure level, but with a

Vibroseis trucks are used to acquire quickly adopted by the industry. Now, very short duration. In contrast, a room land seismic data, marine vibrators can 50 years later, airguns are beginning to air conditioner, like a marine vibrator, be used to collect seismic data in the lose their status as an environmentally- has a very low sound-pressure level, marine environment. That, of course, friendly source. but it runs for a relatively long period raises the question: Why would we The relevant literature is full of of time.

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