ISO 3482:2022

INTERNATIONAL ISO
STANDARD 3482
First edition
2022-05
Ships and marine technology —
Technical guidelines for active source
exploration with ocean bottom
seismometers (OBS)
Navires et technologie maritime — Lignes directrices techniques
relatives à l'exploration des sources actives avec des sismomètres de
fond de mer (OBS)
Reference number
ISO 3482:2022(E)
© ISO 2022

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ISO 3482:2022(E)
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© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
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ISO 3482:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 S c op e . 1
2 Nor m at i ve r ef er enc e s . 1
3 Terms and definitions . 1
4 R e qu i r ement s . 3
4.1 General . 3
4.2 S tandard of time and space . 3
4.2.1 S tandard of time . 3
4.2.2 C oordinate system . 3
4.2.3 Vertical reference . 3
4.2.4 P ositioning system . 3
4.3 O BS technical indicators . 3
4.3.1 OBS acquisition system . 3
4.3.2 O BS deployment/recovery system . 3
4.3.3 Power supply system . 4
4 .4 S ei s m ic s ou r c e s . 4
4 . 5 F ield de s i g n . 4
4.6 Marine exploration process . 5
4.6.1 OBS preparation . 5
4.6.2 R elevant software, media and files . 5
4.6.3 OBS parameter setting . 5
4.6.4 G lass ball sealing . 6
4.6.5 P ressure tubes . . 6
4.6.6 O BS deployment and recovery . 6
4.6.7 Voyage requirements. 7
4.6.8 T iming and positioning . 7
4.6.9 O peration log . 7
4.7 F ield data . 8
4.7.1 R aw data . 8
4.7.2 R elevant data . 8
4.8 D ata processing and archiving . 8
4.8.1 Data processing . 8
4.8.2 D ata archiving and reports . 9
Bibliography .10
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ISO 3482:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
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www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 8, Ships and marine technology,
Subcommittee SC 13, Marine technology.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
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ISO 3482:2022(E)
Introduction
Exploration for the structures and movement of deep earth on the seafloor is one of the important
approaches for human beings to recognize earth system evolution, predict seabed resources formation,
and understand natural disaster mechanisms. Unlike the multi-channel seismic method which only
obtains primary waves by hydrophone streamers on the ocean surface, the ocean bottom seismometer
(OBS) is directly placed on the seabed and can receive both primary and shear waves, even Rayleigh
and Love waves from earth interior. Such a new seismic method gives an opportunity to better image
the structures, movement and rheology for the deep targets in solid earth beneath ocean which cover
up to ≈71 % of the earth’s surface. This method has been widely used in research on not only global
continental margins, subduction zones, mid-ocean ridges, but also regional oil and gas fields, marine
engineering constructions.
The signals received in OBS exploration can be either natural earthquakes or artificial excited seismic
sources. Accordingly, OBS exploration is divided into passive and active source methods. Passive source
exploration with OBS is a method by which OBSs just receive global natural earthquakes and obtain
deeper and wider information from the earth interior. Active source exploration with OBS is usually
used in a target region to reveal the structures, tectonics and composition of underground geological
bodies or crust and upper mantle by a special designed array of OBSs and sources. Because of its
strong pertinence, this active source method gradually becomes the main tool for regional deep earth
exploration, and is widely used by industry and academia.
OBS is a mature technical product and widely used in various deep earth imaging. However, there is a
lack of such a standard about active source exploration with OBS, which will seriously affect the testing,
identifying, evaluating of the performance requirements and data quality of such products. It should
therefore be necessary to standardize its technical requirements and basic procedures to promote
healthy development of this industry of seabed OBS exploration. In view of the above, this document
establishes the technical guidelines covering the main content of active source exploration with OBS
from OBS instruments, seismic sources and fieldwork processes, to data services.
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INTERNATIONAL STANDARD ISO 3482:2022(E)
Ships and marine technology — Technical guidelines for
active source exploration with ocean bottom seismometers
(OBS)
1 S cope
This document specifies the technical requirements for system makeup, ocean bottom seismometer
(OBS) instruments, active sources, field design, exploration operation, data processing for active source
exploration with OBS, and their relative terms.
This document is applicable to active source exploration with OBS, but also a useful reference to the
passive source exploration with OBS. It can be used in seabed resource exploration, geological disaster
surveillance and submarine geoscience research.
2 Normat ive references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
ocean bottom seismometer
OBS
seismic observation system with a seismic sensor placed on the seabed to record ground motions and
an acoustic sensor to record signals in the water column
Note 1 to entry: The main components include seismic sensing system (3.3) and acoustic sensing system (3.4),
recording and storage unit (3.5), release unit (3.8), acoustic communication unit (3.7), compass, internal clock,
power supply, lighting system, cargo compartment and protective cover etc.
Note 2 to entry: There are mainly two types of OBS, broadband and short period. The short period OBS, with the
lower corner of its frequency band not less than 2 Hz, usually used for active seismic source exploration.
3.2
active source exploration
exploration method in which sound wave signals are emitted in the water by ship-borne seismic sources
such as air gun, propagated downward through the crust and upper mantle, finally return to the seabed
and recorded by ocean bottom seismometers (3.1)
Note 1 to entry: The crust and upper mantle information carried by ocean bottom seismometers is in the form of
elastic wave.
Note 2 to entry: Active source is artificially excited at sea by physical or/and chemical means. Air gun sources are
used in arrays.
Note 3 to entry: Multiple sources of same or different volume are towed at designed offsets and field at defined
time delay to shape the resulting pressure wave used as seismic source.
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ISO 3482:2022(E)
3.3
seismic sensing system
system of earthquake sensing by ocean bottom seismometer (3.1) composed mostly of a low gain
geophone or a high gain seismometer, mostly with three components, one vertical and two perpendicular
horizontal components (XYZ) or, as an alternative, three identical sensors in three directions (UVW)
3.4
acoustic sensing system
system of sound sensing by ocean bottom seismometer (3.1) composed of a pressure sensor, mostly a
high impedance hydrophone
3.5
recording and storage unit
ocean bottom seismometer (3.1) recording unit which is used to control data acquisition, signal filtering,
signal amplification, analogue-to-digital conversion and storage
Note 1 to entry: The recording unit is composed of microprocessor and circuit components, the storage unit is
composed of a buffer and one or more internal or external memory devices.
3.6
breakout box
device for ocean bottom seismometer (3.1) to set up a cabled or wireless communication for status
checking or parameter setting
3.7
acoustic communication unit
acoustic wave sensing device which communicates with the deck control unit (3.9) through the acoustic
wave, starts the release decoupling program, and sends the position or distance to the deck control unit
(3.9) through the acoustic wave
3.8
release unit
device for driving the ocean bottom seismometer (3.1) placed on the seabed to separate from the anchor
which is mainly composed of a physical fixing device, a power supply and a circuit, and is matched with
an acoustic wave sensing device
Note 1 to entry: There are usually two release modes, one is that the deck unit drives the acoustic wave sensing
device to start the release procedure, the other is to set the release start-up time in advance, and the built-in
circuit and power supply realize the timing release.
Note 2 to entry: Release is usually accomplished by mechanical or electrochemical means.
3.9
deck control unit
acoustic communication device composed of a controller, a special cable and an acoustic transducer
which is used to di
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