GSO SRL

GSO.srl is one of the pioneers of modern italian seismic using experienced staff and equipment availability was sufficient to meet the diverse techincal needs of each individual project.
Acquisition,processing and interpretation of acoustic data,and ultracustici magnetometry for the following areas of ivestigation.

• research submarine pipelines,electrical cables,wrecksand gas reservoirs
• image stratigraphic
• assessment of potential risks associated with the design of marine works,pipeliness and drilling
• environmental impact study for the establishment of marine works
• miners-geology

Through the use of sound waves can carry out investigations,inspections and measurements of each tipe to determinate water deep and the bottom morphology,using the instrumentation(depth sounder,sonar scanning,sonar etc),that use different bands frequency appropriate to the purpose.You can also make exploration below the level of background nois to determinate the nature,extent and stratigraphy,in case the presence of solid objects,artifacts of relics embedded in sediment and not detected by simple observation of research visual.The principle on which this assessment is based,is the different speed at which sound waves propagate through the different means of propogation and the defferent substances.

• air 330m/sec
• water 1490m/sec
• moraine,gravel 1600-2700 m/sec
• limestone 3500-6500 m/sec
• granite 4600-7000m/sec

Air gun.This system is based on the emission of impulse noise,based on frequency generated by the launch of a small volume of compressed air at high pressure volley of shots into the water.
After each launch,the reservoir of the instrument is recharged with an instrument suitable compressor from a reserve kept always ready.The air cannon provides high-resolution,but penetration is limited,and the whole system is too complex for installatin in a small boats operating on coastal and in shallow water.
To obtain high resolution images yield is necessary to have a short acoustic pulse,while sistems that emit low-frequency pulses capable of penetrating more deeper into the bottom sediments,generally produce longer pulses at higher frequencies. The systems tend to produce low-frequencies pulses as a result of multiple cavitation generating.In this way,the result of penetration and resolution appear to be antagonistic and opuse and it is necessary to reach a compromise that favors the kind of desired result depending on the purpose of exploring.Anather problem is the power with which the pulse is emitted,because a higher power tend to produce multiple reflections in the water column,obscuring reflections that come from deeper layers.In addition,the power also affects the rate of emission of the pulse,but the high emission values must be slower,involving as a consequence a lower horizontal resolution(eg.continuous coverage of the executation parth of prospecting).Again, the compromise must be based on the objectives and purpose of exploring.This need to reconcile opposites and different operating characteristics of the instrument,makes the exploration of deep sea floor a very connected fact on the experience and expertise of the geologist or geophysicist who perform.Informationalready have a clue about the nature of the bottom and can be extracted from simple data recording of a dual frequency sounder,normally used to carry out surveys and bathymetric profiles.More detailed results and diagnostically reliable should be search with a modern systems of Sub Bottom Profilers,which are able to provide evidence of considerable help to the geologist interpretation.

Sub Bottom Profiler, which uses the name derives from the english<<bottom>>,derived from the classical english into german Boden(Boden-Fu0floor) and the function of investigatin that appears beneath it,consist an instrument installed on bord a vessel and a sensor-transducer(tow fish),that is driven by emitting pulses vertically to the bottom and collecting the echo return.The external structure of the instrument is similar to that of the scanning noise(Side Scan Sonar),so in many cases the two instruments are mounted an the same sensor and simultaneously perform the dual function of exploring the surface morphology and underground structural exploration.
Sub Bottom Profiler transducer emits a pulse of relatively high power(usually up to a maximum of 10kw)with multiple frequencies raging from 500Hz to 23kHz and modulated according to the type of bottom and purpose of exploring.The impulse noise,penetrates the sedimentary cover of the bottom for a few meters,stopping at the reflacting horizons(eg. Sediment layers,more compact ,horizons of rocks,pieces of metal)from witch reflection are rejected and consequently you get a resolution between 0.6 and 1 meter in the view of th substrate.

The appearance of these applications for the detection of the acoustic characteristics of the oil,and in particular the bottom of the sea is relatively recent and has benefited from an enhance technological development an its application for the detection of hydrocarbon reserves and the identification of <<traps>> in which deep structural natural gas and oil are trapped.Derived from this development are also the instruments used for the surface layers of the seabed und for industrial and archaeological reseach,direct detection of burid pipelines,wrecks or objects coverd by developed based on the concept of simple frequency fishfinder properly requlated and modulated.In fact the low frequency sound wave propagation corresponds to a large spread(=penetration),while another frequency corresponds to another definition,relatively low propagation.Fishfinder with frequency over 40kHz have a total reflection of the emitted signal,which is send from the bottom without penetrating.The signal emitted by lower frquencies will penetrate to various degrees and ways with different intensities,and then subjected various phenomena of reflaction and refraction whenever the density of the material change,because it is several seccessive layers of sediment,the underlying rocks or inclusions contained therein (eg. Pipelines,wrecks,plantes,vases etc. ).The instruments of various types have been developed,reseaching to the most modern systems of Sub Bottom Profiler,included various methods and concepts of underwater acoustic pulse generation,many electric,some piezoelectric other pneumatic or hydraulic.Among these should be mentioned:

Pinger. Tge ginger is based on a piezoelectric trensucer that produces acoustic pulses with frequencies up to 10-12 kHz.The penetration of this impulse is very influenced by the nature of the fond and its size.In the sand shall not exceed two or three feet,in clay and dirt can penetrate up to ten meters in deep.

Bommer (surface boomers,unibomer,deep tow boomer,Uniboom):The boomers generates an electric discharge in a spiral(coil), which produces induced currents in a metal plate. The metal plate,with its electrically,induced movement,that consequently generates an acoustic pulse.

Sparker (sparkarrays,multi-electrode sparker,depptow sparker):The sparker literally ‘’produces of sparks’’,work on the principale of an high-voltage electric power and low between tow ore more electrodes immeresed in a wave shock followed,in the old systems,pluse-secondary(bubble pulses) generated by the expansion an subsequent contraction of gas bubbles that are produced.