Explosive and Non-Explosive Energy

Sources In Marine Acquisition

By: Ali M. Ismael El-Baklishy

Content:

Introduction.

Explosive Energy Sources.

- Air Gun.

- Dynamite.

Non-Explosive Energy Sources.

- Water Gun.

- Boomer.

- Sparker.

- Chirp System.

Reference.

Introduction:

Seismic method become the major geophysical technique now

days and this is because the massive importance of this method

in oil and gas prospecting as they are main sources of Energy.

Behind using Seismic method on land (on shore) for oil and gas

detection seismic method is used also in marine (offshore) for

the same aspect.

But the methodology of the seismic method onshore already

differs from that offshore. This difference in the Configuration

we use, the Energy source, the Receivers and in the all tools we

use.

In this paper we will discuss the Energy Sources in the Marine

Seismic prospecting.

https://www.youtube.com/watch?v=oFGNN4YFoH0

Explosive sources

It is the sources in which we use explosive material or using

explosion techniques to generate seismic energy in the sea.

These sources are 1- Airgun

2- Dynamite.

1-Airgun.

An airgun is used to inject a bubble of highly compressed

air into the surrounding water and is the most commonly

used of all seismic sources.

Work Criteria:

High pressure air flows continuously into the upper chamber

and through the shuttle into the lower chamber Opening the

solenoid valve puts high pressure air under the upper shuttle

seat, causing the shuttle to move upward, opening the lower

chamber and allowing its air to discharge through the ports to

form a bubble of high pressure air in the surrounding water. https://www.youtube.com/watch?v=iMBq4xFNYU0

Airgun

1- Dynamite.

In the past and before the technology revolution, companies

used to use the Dynamite as seismic energy source in the

marine acquisition. Then and due to its bad and dangerous

effect on the environment and marine lives companies

started to search another substitutes.

Non-Explosive Sources

In which no explosive material is used but mechanical

Devices are used to generate the seismic energy.

These sources are: 1- Water gun.

2- Boomer.

3- Sparker.

4- Chirp System.

1- Water gun:

are adaptations of air guns to avoid the bubble pulse

problem. The compressed air, rather than being released into

the water layer, is used to drive a piston that ejects a water jet

into the surrounding water.

2- Boomer.

Comprise a rigid aluminum plate attached below a heavy

duty electrical coil by a spring-loaded mounting. A

capacitor bank is discharged through the coil and the

electromagnetic induction thus generated forces the

aluminum plate rapidly downwards, setting up a

compressional wave in the water.

https://www.youtube.com/watch?v=benSICqJfAo

3- Sparker.

- Devices for converting electrical energy into acoustic

energy. The sparker pulse is generated by the discharge of a

large capacitor bank directly into the sea water through an

array of electrodes towed in a frame behind the survey

vessel.

- This electrical discharge leads to the formation and rapid

growth of a plasma bubble and the consequent generation of

an acoustic pulse. For safety reasons, sparkers are

increasingly being replaced by other sources.

4- Chirp System.

Are electro-mechanical transducers that produce an

extended, repeatable, source waveform which allows

greater energy output. This longer signal can be

compressed in processing to give greater resolution and/or

better signal-to-noise ratio.

Reference

• An introduction to applied and environmental geophysics,

seismic energy sources, JOHN M.REYNOLD 1997.

• An introduction to geophysical exploration, seismic data

acquisition systems, Philip Kearey, Michael Brooks, Ian

Hill,2002.

• USGS OFR 02-002: Seismic Data discussion.

• http://en.wikipedia.org/wiki/Seismic_source.

• http://www.appliedacoustics.com/sub-bottom-profiling.

• https://nees.org/warehouse/photos/project/516/experiment/

825.

• http://ontario

geofish.blogspot.com/2009_04_01_archive.html