2ECHOES product LineSub-Bottom Profiling is a mean to acoustically form vertical images of the sub-soil.It traditionally differs from reflection seismic in the way that: Higher frequencies are used to obtain thinner vertical resolution Pulse modulation – chirp – is used to bring an additional gain to dataWhile using chirp pulse modulation to obtain optimal data quality, IXSEA employs particular transducer types to reach lower frequencies and thus deeper penetration.IXSEA has an extensive experience in developing high-quality sub-bottom profilers, they are now available in a complete product family: ECHOES.
3The great dilemma : Resolution versus Penetration Selectinga sub-bottom profiler is a trade-off between higher resolution and deeper penetration. Still, it is possible to balance between those using different sensors and software technologies 10kHZ 5kHZ
4ECHOES RangeECHOES is a range of wide-band chirp Sub-Bottom Profilers From very-low frequency and deep penetration model to very high resolution systems.Special acoustic designs provide lower frequencies than conventional chirp SBPsThe transducer quality results in flat-spectrum output (within 3dB) over the entirebandwidth, thus allowing fully tuneable pulse models and optimal efficiency.
5Transducer Design – Tonpilz Transducer Tonpilz Transducer: Stack of ceramic rings Heavy tail mass ECHOES 3500 ECHOES 10000 Light radiating head mass The ceramic rings are compressed between the tail and head
6Transducer Design - Janus Helmholtz Janus Helmholtz: Two Tonpilz transducers mounted back to back. Cylindrical housing creates Helmholtz cavity. ECHOES 1500 ECHOES 5000 Helmholtz resonance caused by fluid inertia. Helmotz resonance extends the operating frequency of the transducer at the low end of the spectrum, while having a compact design. Typical Signal Level response of a transducer.
7Chirp technology• Correlation process – Matched Filtering - improves the signal to noise ratio• Additional gain, referred as processing gain, is defined as: PG = 10 log (B * T) where : • B = bandwidth of the pulse • T = pulse lengthExamples:a) Pulse definition• ECHOES 1500: B = 2850 Hz T=100ms PG=24dB• ECHOES 5000: B = 5500 Hz T=50ms PG=24dBb) Measured Emitted Acoustic power:• ECHOES 1500: 201dB re 1 μPa at 1m• ECHOES 5000: 203dB re 1 μPa at 1mc) Results• ECHOES 1500 has an apparent acoustic power of 225dB• ECHOES 5000 has an apparent acoustic power of 227dB
8Resolution of conventional systems Fora monochromatic Sub-Bottom Profiler system such as a boomer or a sparker, the resolution may be calculated by: R=C*L Where: R = Resolution (m) C = sound speed (1470 m/s) L = Pulse Length (s) Typical boomer: At low energy, 120 µs pulse Resolution = 17 cm More often resolution in the range of 25 cm. The longer the pulse, the worst the resolution
9Resolution of Chirp systems Resolution is function of the sweep bandwidth R=C/2*B Where • B= bandwidth of the pulse (Hz) • C= Sound speed (1470 m/s)
10Improve the resolution: Enlarge the bandwidth ... OneJanus-Helmholtz transducer has 3 kHz bandwidth around 3000 Hz. Mounting three tuned transducer increase the bandwidth up to 8000 Hz
11Improve the penetration: Increase the power ... Boomer 200J= 212dB 26cm resolution. Increasingthe Power of a boomer adversely impacts resolution. ECHOES 1500 223dB 27cm resolution ECHOES 5000 227dB 13 cm resolution Increasing ECHOES power has no effect on resolution.
12 Improve the quality: Choose the best deployment Hull/Pole Mount Advantages Fixed installation Motion compensation Multi-Ping Limitation factors: Sea State Water-depth Surface Tow Advantages Easy deployment No sea surface reflection Disadvantages Motion Vessel Noise “Deep Tow” Advantages No Vessel Noise Reduced Motion Disadvantages Winch and Cable Sea Surface Reflections
13DELPH Seismic Acquisition Software A New Philosophy ONLINE Acquisition systems are generally under utilised. Only need basic signal processing to monitor the Acquisition quality of the gathered data. Extreme processing during acquisition can hide poor quality data, that may only come to light when it is too Storage late to do anything about it. Acquisition systems must be reliable. QC The more features a software product has the larger the code base needs to be and inevitably there is more potential for bugs. Bugs are really bad in acquisition. Vessel time is expensive! OFFLINE Keep the acquisition simple. Processing Keeping the acquisition simple involves a separate package dedicated to processing and interpretation. Interpretation It no more needs a scrolling waterfall display …
14DELPH Seismic Processing & Interpretation Software ONLINE XTF or Acquisition SEGY Storage QC OFFLINE Processing XTF or SEGY Interpretation
16DELPH Seismic Processing & Interpretation Software Whole line approach for processing Processing is no more linked to data replay. Escape from the Change-Replay- Change-Replay- Change-Replay- cycle … Processing changes can be done on the displayed area or the whole line without scrolling Whole line approach for interpretation Zoom from sample resolution to large geological features on-screen Speed-Corrected and Geo-Referenced profile to perform thickness, slope measurements Direct access to geo-referenced data at any scale The processing and interpretation software is no more based on an acquisition package
18 ECHOES 1500 Data processed in DELPH Seismic Interpretation55ms145ms 3km
19 ECHOES 1500 Data processed in DELPH Seismic Interpretation55ms145ms 3km
20 ECHOES 3500 Data processed in DELPH Seismic Interpretation325ms640ms 14km
21 ECHOES 3500 Data processed in DELPH Seismic Interpretation1865ms2165ms 15.5km
22 ECHOES 3500 Data processed in DELPH Seismic Interpretation605ms870ms 5km
23ECHOES 5000 Data processed in DELPH Seismic Interpretation5ms50ms 2km
24ECHOES 10000 Data processed in DELPH Seismic Interpretation0ms25ms 2km
25 Evolution IXSEA masters a broad range of subsea technologies: Inertial navigation and motion sensing Acoustic positioning Acoustic imaging systems (sonars, sub-bottom profilers) Software To higher data quality in standard products or fully integrated system.ECHOES 1500 ECHOES 3500 ECHOES 5000