EN ISO 19901-10:2022

Petroleum and natural gas industries - Specific requirements for offshore structures - Part 10: Marine geophysical investigations (ISO 19901-10:2021)

This document provides requirements and guidelines for marine geophysical investigations. It is applicable to operators/end users, contractors and public and regulatory authorities concerned with marine site investigations for offshore structures for petroleum and natural gas industries.
This document provides requirements, specifications, and guidance for:
a)   objectives, planning, and quality management;
b)   positioning;
c)   seafloor mapping, including instrumentation and acquisition parameters, acquisition methods, and deliverables;
d)   sub-seafloor mapping, including seismic instrumentation and acquisition parameters, and non-seismic-reflection methods;
e)   reporting;
f)    data integration, interpretation, and investigation of geohazards.
This document is applicable to investigation of the seafloor and the sub-seafloor, from shallow coastal waters to water depths of 3 000 m and more. It provides guidance for the integration of the results from marine soil investigations and marine geophysical investigations with other relevant datasets.
NOTE 1 The depth of interest for sub-seafloor mapping depends on the objectives of the investigation. For offshore construction, the depths of investigation are typically in the range 1 m below seafloor to 200 m below seafloor. Some methods for sub-seafloor mapping can also achieve much greater investigation depths, for example for assessing geohazards for hydrocarbon well drilling.
There is a fundamental difference between seafloor mapping and sub-seafloor mapping: seafloor signal resolution can be specified, while sub-seafloor signal resolution and penetration cannot. This document therefore contains requirements for the use of certain techniques for certain types of seafloor mapping and sub-seafloor mapping (similarly, requirements are given for certain aspects of data processing). If other techniques can be shown to obtain the same information, with the same or better resolution and accuracy, then those techniques may be used.
Mapping of pre-drilling well-site geohazards beneath the seafloor is part of the scope of this document.
NOTE 2 This implies depths of investigation that are typically 200 m below the first pressure-containment casing string or 1 000 m below the seafloor, whichever is greatest. Mapping of pre-drilling well-site geohazards is therefore the deepest type of investigation covered by this document.
In this document, positioning information relates only to the positioning of survey platforms, sources and receivers. The processes used to determine positions of seafloor and sub-seafloor data points are not covered in this document.
Guidance only is given in this document for the use of marine shear waves (A.8.3.3), marine surface waves (A.8.3.4), electrical resistivity imaging (A.8.3.5) and electromagnetic imaging (A.8.3.6).

Erdöl- und Erdgasindustrie - Spezielle Anforderungen für Offshore-Anlagen - Teil 10: Meeresgeophysikalische Untersuchungen (ISO 19901-10:2021)

Industries du pétrole et du gaz naturel - Exigences spécifiques relatives aux structures en mer - Partie 10: Enquêtes géophysiques marines (ISO 19901-10:2021)

Industrija nafte in zemeljskega plina - Posebne zahteve za konstrukcije na morju - 10. del: Morske geofizikalne preiskave (ISO 19901-10:2021)

Ta dokument določa zahteve in smernice za morske geofizikalne preiskave. Uporablja se za upravljavce/končne uporabnike, pogodbenike ter javne in regulativne organe, ki izvajajo morske geofizikalne preiskave za konstrukcije na morju v industriji za predelavo nafte in zemeljskega plina.
Ta dokument določa zahteve, specifikacije in smernice za:
a)   cilje, načrtovanje in vodenje kakovosti;
b)   določanje položaja;
c)   kartiranje morskega dna, vključno s parametri za instrumentacijo in pridobivanje, metodami za pridobivanje in rezultati;
d)   kartiranje območja pod morskim dnom, vključno s parametri za seizmično instrumentacijo in pridobivanje ter metodami za neseizmično refleksijo;
e)   poročanje;
f)   vključevanje in razlago podatkov ter preiskave geoloških nevarnosti.
Ta dokument se uporablja za preiskave morskega dna in območja pod morskim dnom, od obalnih plitvin do globin voda 3000 m in več. Zagotavlja smernice za vključitev rezultatov iz preiskav morskega dna in morskih geofizikalnih preiskav z drugimi ustreznimi nabori podatkov.
OPOMBA 1:   Globina, pri kateri se izvaja kartiranje območja pod morskim dnom, je odvisna od ciljev preiskave. Pri konstrukcijah na morju se preiskave običajno izvajajo na globini od 1 do 200 m pod morskim dnom. Z nekaterimi metodami za kartiranje območja pod morskim dnom je mogoče preiskave izvajati tudi veliko globlje (npr. za ocenjevanje geoloških nevarnosti pri izvrtinah ogljikovodikov).
Kartiranje morskega dna in kartiranje območja pod morskim dnom se bistveno razlikujeta: ločljivost signalov na morskem dnu je mogoče določiti, medtem ko to ne velja za ločljivost signalov v območju pod morskim dnom in njihov prodor. Ta dokument zato vsebuje zahteve za uporabo določenih tehnik za določene vrste kartiranja morskega dna in kartiranja območja pod morskim dnom (podobno so podane tudi zahteve za določene vidike obdelave podatkov). Če je mogoče za druge tehnike dokazati, da podajajo enake informacije – z enako ali boljšo ločljivostjo in točnostjo – se lahko uporabljajo te tehnike. Kartiranje geoloških nevarnosti pod morskim dnom na območjih izvrtin pred vrtanjem je del področja uporabe tega dokumenta.
OPOMBA 2:   To pomeni izvajanje preiskav na globinah, ki so običajno 200 m pod prvim cevnim stebrom za zadrževanje tlaka ali 1000 m pod morskim dnom (odvisno od tega, kaj je globlje). Zato je kartiranje geoloških nevarnosti pod morskim dnom na območjih izvrtin pred vrtanjem najgloblja vrsta preiskav, zajetih v tem dokumentu.
V tem dokumentu se informacije o določanju položaja navezujejo le na določitev položaja raziskovalnih ploščadi, virov in sprejemnikov. Postopki za določanje položajev podatkovnih točk na morskem dnu in v območju pod morskim dnom v tem dokumentu niso zajeti.
V tem dokumentu so podane zgolj smernice za uporabo morskih strižnih valov, morskih površinskih valov, meritev električne upornosti in elektromagnetnega slikanja.

General Information

• Status: Published
• Publication Date: 08-Feb-2022
• Withdrawal Date: 30-Aug-2022
• ICS: 75.180.10 - Exploratory, drilling and extraction equipment
• Technical Committee: CEN/TC 12 - Materials, equipment and offshore structures for petroleum and natural gas industries
• Drafting Committee: CEN/TC 12 - Materials, equipment and offshore structures for petroleum and natural gas industries
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 09-Feb-2022
• Due Date: 01-Jan-2024
• Completion Date: 09-Feb-2022
• Ref Project: SIST EN ISO 19901-10:2022 - Petroleum and natural gas industries - Specific requirements for offshore structures - Part 10: Marine geophysical investigations (ISO 19901-10:2021)

Overview - EN ISO 19901-10:2022 (Marine geophysical investigations)

EN ISO 19901-10:2022 (ISO 19901-10:2021) sets out requirements and guidance for marine geophysical investigations used in the petroleum and natural gas industries for offshore structures. Published by CEN as a harmonized European adoption of the ISO document, it applies to operators, contractors, surveyors, geophysicists and public/regulatory authorities involved in marine site investigations from shallow coastal waters to depths of 3 000 m and more.

Key scope points:

• Defines objectives, planning and quality management for geophysical surveys
• Covers seafloor mapping (e.g., multibeam, side scan) and sub‑seafloor mapping (seismic and non‑seismic)
• Addresses positioning, data deliverables, reporting, integration and geohazard assessment
• Typical depths of interest: ~1 m to 200 m below seafloor for construction; much greater depths for pre‑drilling well‑site geohazard mapping

Key topics and technical requirements

• Objectives & project planning: desk study, scoping, georeferencing and ground model development; quality plans and data‑quality management.
• Positioning systems: coordinate reference systems, GNSS, gyro compasses, INS, USBL, Doppler velocity logs, altimeters and pressure‑depth sensors for platform, source and receiver positioning.
• Seafloor mapping: instrumentation and acquisition parameters for multibeam echo sounders and side‑scan sonar, acquisition methods for reconnaissance to detailed engineering mapping, and deliverables.
• Sub‑seafloor mapping: seismic reflection (high, ultra‑high and ultra‑ultra‑high resolution), sub‑bottom profilers and non‑seismic methods such as refraction, magnetics, shear and surface waves, electrical resistivity and electromagnetic imaging. Emphasis on the difference between seafloor resolution (specifiable) and sub‑seafloor trade‑off between resolution and penetration.
• Reporting & integration: standardized reporting requirements, interpretation, data integration with marine soil investigations and other datasets, and geohazard investigation workflows.

Practical applications and users

EN ISO 19901-10:2022 is used to:

• Plan and execute geophysical surveys for offshore platform, pipeline and well‑site projects
• Identify and map seafloor hazards (obstructions, erosional features) and sub‑seafloor geohazards (shallow gas, buried channels, faults)
• Define survey specifications, quality control procedures and deliverables for contractors and operators Primary users include offshore operators, geophysical and geotechnical survey contractors, engineering consultancies, well planners, and regulatory authorities overseeing offshore construction and drilling safety.

Related standards

• Part of the ISO 19901 series for offshore structures and geotechnical/site investigation guidance. Users should align EN ISO 19901-10 with other ISO 19901 parts and national regulations when preparing survey specifications and reporting.

Keywords: EN ISO 19901-10:2022, marine geophysical investigations, seafloor mapping, sub‑seafloor mapping, offshore geohazards, seismic, multibeam, side scan, positioning, offshore survey standards.

Standards Content (Sample)

SLOVENSKI STANDARD
01-april-2022
Industrija nafte in zemeljskega plina - Posebne zahteve za konstrukcije na morju -
10. del: Morske geofizikalne preiskave (ISO 19901-10:2021)
Petroleum and natural gas industries - Specific requirements for offshore structures -
Part 10: Marine geophysical investigations (ISO 19901-10:2021)
Erdöl- und Erdgasindustrie - Spezielle Anforderungen für Offshore-Anlagen - Teil 10:
Meeresgeophysikalische Untersuchungen (ISO 19901-10:2021)
Industries du pétrole et du gaz naturel - Exigences spécifiques relatives aux structures
en mer - Partie 10: Enquêtes géophysiques marines (ISO 19901-10:2021)
Ta slovenski standard je istoveten z: EN ISO 19901-10:2022
ICS:
75.180.10 Oprema za raziskovanje, Exploratory, drilling and
vrtanje in odkopavanje extraction equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 19901-10
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2022
EUROPÄISCHE NORM
ICS 75.180.10
English Version
Petroleum and natural gas industries - Specific
requirements for offshore structures - Part 10: Marine
geophysical investigations (ISO 19901-10:2021)
Industries du pétrole et du gaz naturel - Exigences Erdöl- und Erdgasindustrie - Spezielle Anforderungen
spécifiques relatives aux structures en mer - Partie 10: für Offshore-Anlagen - Teil 10: Meeresgeophysikalische
Enquêtes géophysiques marines (ISO 19901-10:2021) Untersuchungen (ISO 19901-10:2021)
This European Standard was approved by CEN on 7 February 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 19901-10:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
The text of ISO 19901-10:2021 has been prepared by Technical Committee ISO/TC 67 "Materials,
equipment and offshore structures for petroleum, petrochemical and natural gas industries” of the
International Organization for Standardization (ISO) and has been taken over as EN ISO 19901-10:2022
by Technical Committee CEN/TC 12 “Materials, equipment and offshore structures for petroleum,
petrochemical and natural gas industries” the secretariat of which is held by NEN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2022, and conflicting national standards shall
be withdrawn at the latest by August 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 19901-10:2021 has been approved by CEN as EN ISO 19901-10:2022 without any
modification.
INTERNATIONAL ISO
STANDARD 19901-10
First edition
2021-03
Petroleum and natural gas
industries — Specific requirements
for offshore structures —
Part 10:
Marine geophysical investigations
Industries du pétrole et du gaz naturel — Exigences spécifiques
relatives aux structures en mer —
Partie 10: Enquêtes géophysiques marines
Reference number
ISO 19901-10:2021(E)
©
ISO 2021
ISO 19901-10:2021(E)
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

ISO 19901-10:2021(E)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
3  Terms and definitions . 2
4 Symbols and abbreviated terms .12
4.1 Symbols .12
4.2 Abbreviated terms .13
5  Objectives, planning, and quality management .14
5.1 General .14
5.1.1 Objectives and project specifications .14
5.1.2 Georeferencing and GIS .15
5.1.3 Ground model .15
5.2 Desk study .16
5.2.1 General.16
5.2.2 Use of exploration 2D and 3D seismic data in a desk study .17
5.2.3 Desk study for pre-drilling well-site investigations .17
5.3 Scoping and planning .17
5.3.1 General.17
5.3.2 Scoping of seafloor mapping and sub-seafloor mapping .19
5.4 Operations planning and data quality management .22
5.4.1 Quality plan .22
5.4.2 Effects of attenuation .23
5.4.3 Data quality management .23
6 Positioning .23
6.1 General .23
6.2 Coordinate reference systems .24
6.2.1 Horizontal coordinate reference system .24
6.2.2 Vertical coordinate reference system.24
6.3 Surface positioning requirements .25
6.4 Vessel heading .25
6.4.1 General.25
6.4.2 Gyro compass .25
6.4.3 GNSS based heading reference .26
6.4.4 Alignment .26
6.5 Sub-sea positioning — Ultra-short baseline system .26
6.6 Inertial navigation system .27
6.7 Auxiliary sensor: doppler velocity log .27
6.8 Auxiliary sensor: altimeter .27
6.9 Auxiliary sensor: pressure-depth sensor .28
7  Seafloor mapping .28
7.1 General .28
7.2 Instrumentation and acquisition parameters .29
7.2.1 Multi-beam echo sounder .29
7.2.2 Side scan sonar .31
7.2.3 Auxiliary sensor: velocity of sound in seawater .31
7.3 Data acquisition methods .32
7.3.1 General.32
7.3.2 Reconnaissance seafloor mapping .32
7.3.3 Engineering seafloor mapping .33
7.3.4 Detailed engineering seafloor mapping .33
7.4 Seafloor mapping deliverables .33
ISO 19901-10:2021(E)
8  Sub-seafloor mapping .34
8.1 General .34
8.1.1 Resolution and signal penetration .34
8.1.2 Equipment selection for sub-seafloor mapping methods .35
8.1.3 Assessment of data quality .35
8.1.4 Deliverables .36
8.2 Acquisition equipment and parameters for seismic data .36
8.2.1 Equipment performance .36
8.2.2 Acquisition and processing parameters .37
8.2.3 High resolution seismic reflection .40
8.2.4 Ultra-high-resolution seismic reflection .44
8.2.5 Ultra-ultra-high resolution seismic reflection .44
8.2.6 Sub-bottom profiling .45
8.3 Non-seismic reflection methods .46
8.3.1 Seismic refraction .46
8.3.2 Magnetometer and magnetic gradiometer.47
8.3.3 Marine shear waves .47
8.3.4 Marine surface waves .48
8.3.5 Electrical resistivity imaging .48
8.3.6 Electromagnetic imaging .48
9  Reporting of seafloor mapping and sub-seafloor mapping .48
9.1 General .48
9.2 Record of data acquisition operations .48
9.3 Record of data processing .49
9.4 Results report .49
10 Data integration, interpretation and investigation of geohazards.50
10.1 General .50
10.2 Horizons, isopachs and isochores .50
10.3 Mapping stratigraphic units and defining geochronology .50
10.4 Time-to-depth conversion .51
10.5 Borehole geophysical logging .51
10.6 Investigation of geohazards .52
10.7 Integrated studies . .52
Annex A (informative) Additional information and guidance .53
Bibliography .78
iv © ISO 2021 – All rights reserved

ISO 19901-10:2021(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore
structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 7, Offshore
structures.
A list of all parts in the ISO 19901 series can be found on the ISO website.
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.
ISO 19901-10:2021(E)
Introduction
The general objective of a marine site investigation is to provide information about the seafloor, the
sub-seafloor and geological processes affecting both, geohazards, and human-made objects at or
below the seafloor. Marine site investigations can encompass both marine soil investigations and
marine geophysical investigations, as shown in Figure 1. This document provides requirements for
marine geophysical investigations to support oil and gas developments offshore, is complementary to
ISO 19901-8 on marine soil investigations, and provides guidance on the integration of both types of
investigations.
Figure 1 — Marine geophysical investigations as part of marine site investigations.
NOTE Subjects denoted in grey boxes in Figure 1 are neither covered in ISO 19901-8 nor in this document.
However, marine geophysical investigations can provide information about soils and rocks, whereas rocks are
only covered by ISO 19910-8 to the extent that ordinary marine soil investigation tools can be used, e.g. for chalk.
Marine site investigations for a specific project can comprise both geophysical and geotechnical
investigations, depending on project scale and complexity. It is common practice to conduct first a
marine geophysical investigation, sometimes in combination with a limited marine soil investigation
consisting of shallow soil sampling and/or in situ testing. A more extensive marine soil investigation
is often conducted at a later stage. In some cases, a marine site investigation can consist solely of a
stand-alone geophysical survey that has a specific and limited purpose. A marine site investigation
can also consist solely of a stand-alone marine soil investigation, for which details on soil investigation
equipment and procedures are provided in ISO 19901-8.
Particular objectives of a marine geophysical investigation should be addressed in project specifications,
which should specify desired investigation depths, desired resolutions (horizontal and vertical), and
whether the objective is to illuminate the seafloor and/or the sub-seafloor. Caution is necessary in
the selection of the type of equipment to be used, and operational parameters for that equipment, in
order to meet those desired depths, resolutions, and illumination targets, particularly because local
site conditions can affect the abilities of certain equipment to meet those objectives. This document
includes discussion of the selection and operation of appropriate geophysical equipment.
Marine geophysical investigations and marine soil investigations can be (and often are) carried out as
separate exercises, the results of which can be integrated into a ground model. This document applies
to critical stages in the development of a ground model, from the initial conception stage through
successive stages of increased detail.
In this document, the following verbal forms are used:
— “shall” indicates a requirement;
— “should” indicates a recommendation;
— “can” indicates a possibility or a capability;
— “may” indicates a permission.
Annex A provides additional information intended to assist the understanding or use of this document.
vi © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 19901-10:2021(E)
Petroleum and natural gas industries — Specific
requirements for offshore structures —
Part 10:
Marine geophysical investigations
1 Scope
This document provides requirements and guidelines for marine geophysical investigations. It is
applicable to operators/end users, contractors and public and regulatory authorities concerned with
marine site investigations for offshore structures for petroleum and natural gas industries.
This document provides requirements, specifications, and guidance for:
a) objectives, planning, and quality management;
b) positioning;
c) seafloor mapping, including instrumentation and acquisition parameters, acquisition methods, and
deliverables;
d) sub-seafloor mapping, including seismic instrumentation and acquisition parameters, and non-
seismic-reflection methods;
e) reporting;
f) data integration, interpretation, and investigation of geohazards.
This document is applicable to investigation of the seafloor and the sub-seafloor, from shallow coastal
waters to water depths of 3 000 m and more. It provides guidance for the integration of the results from
marine soil investigations and marine geophysical investigations with other relevant datasets.
NOTE 1 The depth of interest for sub-seafloor mapping depends on the objectives of the investigation. For
offshore construction, the depths of investigation are typically in the range 1 m below seafloor to 200 m below
seafloor. Some methods for sub-seafloor mapping can also achieve much greater investigation depths, for
example for assessing geohazards for hydrocarbon well drilling.
There is a fundamental difference between seafloor mapping and sub-seafloor mapping: seafloor signal
resolution can be specified, while sub-seafloor signal resolution and penetration cannot. This document
therefore contains requirements for the use of certain techniques for certain types of seafloor mapping
and sub-seafloor mapping (similarly, requirements are given for certain aspects of data processing). If
other techniques can be shown to obtain the same information, with the same or better resolution and
accuracy, then those techniques may be used.
Mapping of pre-drilling well-site geohazards beneath the seafloor is part of the scope of this document.
NOTE 2 This implies depths of investigation that are typically 200 m below the first pressure-containment
casing string or 1 000 m below the seafloor, whichever is greatest. Mapping of pre-drilling well-site geohazards
is therefore the deepest type of investigation covered by this document.
In this document, positioning information relates only to the positioning of survey platforms, sources
and receivers. The processes used to determine positions of seafloor and sub-seafloor data points are
not covered in this document.
Guidance only is given in this document for the use of marine shear waves (A.8.3.3), marine surface
waves (A.8.3.4), electrical resistivity imaging (A.8.3.5) and electromagnetic imaging (A.8.3.6).
ISO 19901-10:2021(E)
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 19901-8, Petroleum and natural gas industries — Specific requirements for offshore structures —
Part 8: Marine soil investigations
3  Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
abyssal water
water depths greater than 3 000 m
3.2
acoustic impedance
seismic velocity multiplied by density
Note 1 to entry: Compressional-wave impedance uses compressional-wave velocity, and shear-wave impedance
uses shear-wave velocity.
3.3
acoustic noise
unwanted acoustic signal
3.4
active tail buoy
buoy fitted with a global navigation satellite system transponder attached to the end of a streamer
3.5
airgun
seismic source that injects a bubble of highly compressed air into the water
Note 1 to entry: Whereas single airguns can be used, it is common practise to deploy and fire several airguns in
arrays to produce an acoustic pulse that has certain temporal and spatial characteristics.
3.6
aliasing
effect that causes signals to be misrepresented in recorded data as a result of undersampling
Note 1 to entry: Undersampling can be in time or spatial domain.
3.7
anisotropy
dependence of velocity on direction or upon angle of wave propagation
3.8
array
system of linked hydrophones or seismic sources arranged in a geometric pattern to increase sensitivity
and/or directionality and/or in the case of a seismic source, the pulse characteristics
2 © ISO 2021 – All rights reserved

ISO 19901-10:2021(E)
3.9
attenuation
reduction in amplitude or energy
Note 1 to entry: Attenuation in seismic data is related in part to soil conditions.
3.10
attribute
characteristic of a given object, structure or feature
Note 1 to entry: A seismic attribute is a quantity or property derived or extracted from seismic data that provides
specific information contained within the data as an aid in interpretation.
3.11
backscatter
amplitude of echo sounder energy reflected by the seafloor that can be processed into information
about seafloor features and texture
3.12
bandwidth
range of frequencies in an acoustic signal between the two half power points
Note 1 to entry: This corresponds with the frequencies at which the power drops to half the peak power (3 dB).
3.13
boomer
seismic source that operates by the rapid movement of a restricted metal plate
3.14
chirp
type of sub-bottom profiler that emits a frequency-modulated pulse of acoustic energy over a specified
range of frequencies
3.15
common depth point
CDP
common reflection point at depth on a reflector, or the halfway point when a wave travels from a source
to a reflector to a receiver
Note 1 to entry: In the case of flat layers, the common depth point is vertically below the common mid-point.
3.16
common mid-point
CMP
in multichannel seismic acquisition, the point on the surface halfway between the source and receiver
that is shared by a number of source-receiver pairs
Note 1 to entry: CMP gather refers to the set of traces that have a common mid-point.
3.17
common reference point
datum point on a vessel to which all positioning systems are referenced in three dimensions
3.18
cone penetration test
CPT
CPTU
in situ soil strength testing device that makes direct measurements of cone resistance, sleeve friction
and pore pressure response as it is pushed into the sub-seafloor
Note 1 to entry: See ISO 19901-8.
ISO 19901-10:2021(E)
3.19
contractor
party or person responsible for an assigned scope of work described in project specifications
3.20
coordinate reference system
coordinate system that is related to an object by a datum
Note 1 to entry: Geodetic and vertical datums are referred to as reference frames.
Note 2 to entry: For geodetic and vertical reference frames, the object will be the Earth. In planetary applications,
geodetic and vertical reference frames can be applied to other celestial bodies.
[SOURCE: ISO 19111:2019, 3.1.9]
3.21
deconvolution
filtering process that undoes the effect of another filter
Note 1 to entry: There are many applications in seismic data processing. One example is removing the filtering
effect of the sub-seafloor.
3.22
deep water
water depths between 750 and 1 800 m
3.23
demultiple
seismic processing application that attenuates multiple energy
3.24
designature
filtering process to compensate for the non-minimum phase characteristics of a seismic source
3.25
digital terrain model
DTM
digital representation of a mapped surface usually defined by xyz values for defined cells
3.26
dip move-out
DMO
difference in the arrival times or travel times of a reflected wave, measured by receivers at two different
offset locations, that is produced from dipping reflectors
Note 1 to entry: Dip move-out can be compensated for in processing.
3.27
direct arrival
recorded seismic energy that has travelled directly from source to receiver and has neither been
reflected nor refracted
3.28
doppler velocity log
DVL
instrument to measure the speed of a survey platform by measuring the frequency shift of acoustic
pulses reflected from the seafloor
3.29
dynamic range
ratio of the largest recoverable signal to the smallest recoverable signal
4 © ISO 2021 – All rights reserved

ISO 19901-10:2021(E)
3.30
exploration seismic data
seismic data containing frequencies between 0 Hz and 100 Hz, typically acquired for the purpose of
exploring for oil and gas rather than site investigation
Note 1 to entry: In this document, “exploration seismic data” also includes data acquired for the purposes of
hydrocarbon reservoir management (assessment, development, and monitoring).
3.31
far-field source signature
characteristic wave shape of a particular seismic source recorded at a remote distance, so that the wave
front is close to a straight line
Note 1 to entry: In practice this is difficult to achieve, and a mid-field source signature is more common.
3.32
feather angle
angle between the line connecting the near and far receivers of a streamer and course made good of the
nearest receiver
Note 1 to entry: Differences are caused by a cross current.
3.33
feature
item observed in seafloor mapping data or sub-seafloor mapping data that characterizes the site or
renders it unique
Note 1 to entry: A featureless seafloor is completely smooth and flat, for example.
3.34
first break
first recorded signal attributable to seismic-wave travel from a known source
3.35
first pressure containment string
first casing installed in a well that will enable the pressure inside the well to be controlled
3.36
frequency spectrum
function of power versus frequency that illustrates the frequency content of a wavelet or signal
Note 1 to entry: A frequency spectrum is produced by a Fourier transform.
3.37
Fresnel zone
generally circular area on a reflecting interface from which all reflections contribute to the
recorded signal
Note 1 to entry: The Fresnel zone is dependent on the period of the wave and determines lateral resolution.
3.38
geohazard
geological condition that has the potential to have adverse effects on persons, operations, infrastructure
or the environment
3.39
geological model
explanation of geological conditions
ISO 19901-10:2021(E)
3.40
ghost
spurious seismic reflection that occurs when energy is reflected between sources and/or receivers and
the sea surface
3.41
global navigation satellite system
GNSS
satellite based navigation system that provides autonomous global positioning of a receiving device
Note 1 to entry: Global positioning system (GPS), and global navigation satellite system (Glonass), Galileo and
BeiDo are typical examples of global navigation satellite systems.
3.42
ground model
2- or 3-dimensional representation of the seafloor (bathymetry) and, where applicable, the sub-seafloor
conditions, at a given time, that is specific to the offshore structure(s) considered
3.43
ground-truthing
integration of seafloor or sub-seafloor geophysical data with data acquired by marine soil investigation
and other dataNote 1 to entry: See, for example, ISO 19901-8 for marine soil investigation data.
3.44
high-resolution seismic
HR seismic
seismic reflection method that acquires seismic data containing frequencies between 75 Hz and 300 Hz
3.45
horizon
seismic reflector associated with the surface separating two strata
3.46
hydrophone
sensor that detects variations in pressure
3.47
inertial navigation system
navigation aid that uses accelerometers and gyroscopes to continuously calculate position, orientation
and velocity by dead reckoning without external input
3.48
interval velocity
seismic velocity measured over a depth interval
3.49
isochore
line drawn on a map through points of equal vertical thickness of a soil unit, bed, formation or group
of these
3.50
isochron
line drawn on a map through points at which a characteristic reflection time or interval has the
same value
3.51
isopach
line drawn on a map through points of equal stratigraphic thickness of a sub-seafloor stratum or a
group of these
6 © ISO 2021 – All rights reserved

ISO 19901-10:2021(E)
3.52
magnetic gradiometer
system which measures magnetic gradient using two or more closely spaced magnetometers
3.53
magnetometer
instrument used to measure the strength and/or direction of a magnetic field
3.54
marine geophysical investigation
type of marine site investigation of seafloor or sub-seafloor that uses non-destructive methods
involving marine deployment of geophysical tools
3.55
marker horizon
seismic reflector that maintains its characteristics over an area or distance so that it can be used as an
interpretation reference
3.56
metadata
metacontent
information describing the content and context of the data within the given file or format
3.57
migration
seismic data processing step in which seismic events are geometrically re-located to the true location at
which the event occurs in the sub-seafloor rather than the location at which it was recorded at the surface
Note 1 to entry: A more accurate image of the sub-seafloor will be created by applying migration.
3.58
motion reference unit
MRU
instrument for measuring pitch, roll, yaw, surge, sway and heave
Note 1 to entry: The primary use is to provide observations needed to correctly determine the position of
geophysical sensors and in the processing of the sensor data.
3.59
multiple energy
noise on seismic records caused by reverberations between strong reflecting interfaces, such as the
seafloor and the sea surface
3.60
mute
removal of certain components of traces prior to common mid-point stacking
3.61
near-field signature
pulse shape measured within the near-field range of a seismic source, generally less than 1 wavelength
3.62
noise
unwanted signal
3.63
normal moveout
NMO
variation in reflection arrival time caused by variation in seismic source to receiver (offset) distance
ISO 19901-10:2021(E)
3.64
offset
horizontal distance from the seismic source to the seismic receiver
3.65
offset well
existing well from which information is available to tie back to and assist with making predictions
about conditions at another well location
3.66
penetration
greatest depth below seafloor from which geophysical signals (such as seismic reflections) can be
recognized with reasonable certainty
3.67
pinger
transducer or array of transducers using piezo-electric effects used as seismic source in sub-bottom
profiling profilers
3.68
pitch
up-and-down motion of the bow or stern of a survey platform about the horizontal axis that passes
across it from port to starboard through its centre of gravity
3.69
positioning
process to derive a three-dimensional coordinate, which uniquely defines a location within the project
coordinate reference system, that should include the time of the observations used to derive the
coordinate
3.70
pre-stack depth migration
PSDM
migration applied to seismic data in depth domain, calculated from seismic data in time coordinates,
and applied before the data is stacked
3.71
pre-stack time migration
PSTM
migration applied to seismic data in time domain before it is stacked
3.72
project specification
scope of work for marine site investigation assigned by the client to a contractor
3.73
P-wave
primary wave
elastic body wave in which the particle motion is in the direction of
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