ISO 27914:2026

International
Standard
ISO 27914
Second edition
Carbon dioxide capture,
2026-03
transportation and storage —
Geological storage
Captage, transport et stockage du dioxyde de carbone —
Stockage géologique
Reference number
© ISO 2026
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ii
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Integrated project management . 7
4.1 General .7
4.2 Storage project .7
4.2.1 Project phases .7
4.2.2 Project activities that run across multiple phases .7
4.2.3 Site screening and feasibility phase .8
4.2.4 Site characterization phase .8
4.2.5 Design and development phase .8
4.2.6 Operations phase .9
4.2.7 Post-injection phase .9
4.3 Project management plan .9
4.3.1 General .9
4.3.2 Project management plan specifications .9
4.3.3 Project description .10
4.4 Information management .10
4.4.1 Information management plan .10
4.4.2 Project register .10
5 Site screening, feasibility investigation and characterization .11
5.1 General .11
5.2 Site screening .11
5.3 Site feasibility investigation . 12
5.4 Site characterization and assessment. 13
5.4.1 General . 13
5.4.2 Geological and hydrogeological characterization . 13
5.4.3 Geophysical characterization and assessment .14
5.4.4 Geochemical characterization and assessment .14
5.4.5 Geomechanical characterization and assessment. 15
5.4.6 Well characterization and assessment .16
5.5 Modelling and assessment .16
5.5.1 General .16
5.5.2 Geological static modelling .17
5.5.3 Dynamic modelling .17
5.5.4 Area of review .19
6 Risk management . 19
6.1 General .19
6.2 Risk evaluation criteria .19
6.3 Risk management plan . 20
6.4 Risk assessment . 20
6.4.1 General . 20
6.4.2 Risk identification . 20
6.4.3 Risk analysis . .21
6.4.4 Risk evaluation.21
6.5 Risk treatment . 22
6.6 Review and documentation . 22
6.6.1 Review . 22
6.6.2 Documentation. 22
7 Well infrastructure .23

iii
7.1 General . 23
7.1.1 Objective . 23
7.1.2 Documentation. 23
7.2 Materials . 23
7.2.1 Conditions for use . . 23
7.2.2 Materials selection.24
7.3 Design and construction .24
7.3.1 General .24
7.3.2 Risk mitigation .24
7.3.3 Wells .24
7.3.4 Tubulars. 25
7.3.5 Cement and well barrier elements . . 26
7.3.6 Post-cementing evaluation and remediation .27
7.3.7 Completion and stimulation .27
7.3.8 Corrosion control .27
7.3.9 Conversion of legacy wells . 28
7.3.10 Wellbore monitoring requirements . 28
7.4 Recompletion and workover of wells . 28
7.4.1 General . 28
7.4.2 Conditions for recompletion and workover of wells . 28
7.4.3 Well integrity . 29
7.5 Abandonment of wells . 29
7.5.1 General . 29
7.5.2 Evaluation of existing abandoned wells . 29
7.5.3 Abandonment . 29
8 CO storage site operations .30
8.1 General . 30
8.2 Design of CO storage operations . 30
8.2.1 General . 30
8.2.2 Operating parameters . 30
8.3 Operations management plan .31
8.3.1 General .31
8.3.2 Storage site description .31
8.3.3 Roles and responsibilities .31
8.3.4 Operations and maintenance procedures .31
8.3.5 Safety plan.32
8.4 Operating procedures .32
8.4.1 General .32
8.4.2 Initial (start-up) .32
8.4.3 Continuous operations .32
8.4.4 Shutdown .32
8.4.5 Start-up following shutdowns . 33
8.5 Maintenance procedures . 33
8.6 Data acquisition, monitoring and testing . 33
8.6.1 General . 33
8.6.2 CO stream metering . 34
8.6.3 Well integrity monitoring . 34
8.6.4 Well testing during operations . 34
8.6.5 Corrosion monitoring. 35
8.7 Well intervention (workovers) . 35
8.8 Information management . 35
9 Monitoring and verification .36
9.1 Purpose . 36
9.1.1 General . 36
9.1.2 Monitoring activities . 36
9.1.3 Verification activities . 36
9.2 M&V program periods . .37
9.2.1 General .37

iv
9.2.2 Pre-injection phase monitoring .37
9.2.3 Injection phase monitoring .37
9.2.4 Post-injection phase monitoring .37
9.3 M&V plan objectives .37
9.4 M&V plan design . . 38
9.4.1 M&V plan procedures and practices . 38
9.4.2 M&V plan specifications . 38
9.4.3 M&V program contingency monitoring . 39
10 Quantification and verification . .39
10.1 General . 39
10.2 Quantification principles . . 40
10.2.1 General . 40
10.2.2 Quantification of input (m ) . 40
input
10.2.3 Quantification of operational loss (m ) .41
loss operations
10.2.4 Loss from the storage complex (m ) .42
loss storage complex
10.2.5 De minimis losses .42
10.2.6 Avoidance of double counting .42
10.2.7 Quantification of native CO .42
10.3 Measurement of input .42
10.3.1 General .42
10.3.2 Defining measurement requirements .42
10.3.3 Metering locations .43
10.3.4 CO stream composition .43
10.4 Methodologies for quantification of loss .43
10.4.1 General .43
10.4.2 Quantification of operational loss (m ) .43
loss operations
10.4.3 Quantification of loss from the storage complex (m ) .43
loss storage complex
10.5 Quantification documentation and data retention . 44
10.5.1 Initial documentation . 44
10.5.2 Periodic documentation . 44
10.5.3 Data management .45
10.6 Verification of the quantification .45
10.6.1 General .45
10.6.2 Type of verification .45
10.6.3 Verification approach .45
10.6.4 Verification opinion . 46
10.6.5 Quantification verification records . 46
11 Project termination .46
11.1 General . 46
11.2 Criteria for project termination . 46
11.3 Project termination plan .47
11.4 Project termination qualification process . 48
11.4.1 General . 48
11.4.2 Qualification process activities . 48
11.4.3 Qualification process documentation . 48
Annex A (informative) General well schematic .49
Annex B (informative) Illustration of quantification principles .51
Bibliography .54

v
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
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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
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This document was prepared by Technical Committee ISO/TC 265, Carbon dioxide capture, transportation,
and storage.
This second edition cancels and replaces the first edition (ISO 27914:2017), which has been technically
revised.
The main changes are as follows:
— revision of Clause 3 in alignment with other revisions of this document;
— deletion of the former Clause 4 regarding management systems, to remove content that is well-covered
by other standards;
— addition of a new Clause 4 regarding integrated project management, to provide guidance on how to
navigate this document;
— addition of Clause 10 regarding quantification and verification.
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.

vi
Introduction
Geological storage of carbon dioxide (CO ) is recognized as a key technology for abatement of CO emissions
2 2
[1]
to the atmosphere or ocean and is an essential component in the process of CO capture and storage (CCS) .
This document aims to address the need for safe and effective long-term storage of CO (see Figure 1) and to
be able to quantify stored CO .
The life cycle of a CO geological storage project covers all phases and activities of the project, from the start
of the project including site screening, feasibility investigation, characterization, assessment, engineering,
permitting and construction, through the start of injection and proceeding through subsequent operations
until cessation of injection and culminating in the post-injection phase, which concludes with project
termination.
This document is supplemented by recommended practice manuals for CO storage and numerous standards
and technical recommendations developed for the oil and gas industry (see References [1] to [12]).
This document does not address the quantification of greenhouse gases (GHGs) other than CO for CO storage
2 2
projects. CCS projects quantifying CO according to this document can address quantifying, monitoring,
reporting, and validating or verifying other GHG emissions reductions or removals through the application
of ISO 14064-2 and other parts of the ISO 14064 series as appropriate. Results from the quantification of CO
stored according to this document can be used according to ISO 14064-2.
NOTE The post-injection phase in this document corresponds with the post-closure phase defined in the EU CCS
[1] [65]
Directive and with the post-injection site closure (PISC) period in the US under the Class VI rule . Termination in
[1]
this document corresponds with the end of the EU Directive post-closure period.
Figure 1 — Entities involved in the storage project life cycle

vii
International Standard ISO 27914:2026(en)
Carbon dioxide capture, transportation and storage —
Geological storage
1 Scope
1.1 This document:
a) establishes requirements for the geological storage of CO streams in a way that minimizes risk of CO
2 2
losses;
b) is applicable for both onshore and offshore geological storage within permeable and porous geological
strata including hydrocarbon reservoirs where a CO stream is not being injected for the purpose of
enhancing hydrocarbon production;
c) includes activities associated with site screening and feasibility investigation, characterization, design
and development, operation of storage projects, and preparation for project termination;
d) recognizes that the geological characteristics, physical boundaries, management, intrinsic technical
risk and uncertainties, of each site are likely to be unique for each project and that intrinsic technical
risk and uncertainty will be dealt with on a site-specific basis;
e) provides requirements for integrated project management, including elements of risk management
unique to the geological storage of CO streams; and
f) establishes a methodology for quantifying the net mass of CO that geological storage projects store in
storage unit(s).
Figure 1 illustrates the limits of this document.
1.2 This document does not apply to:
a) temporary storage in tanks or by other means;
b) the post-termination phase;
c) injection of CO for enhancing production of hydrocarbons or for storage associated with CO -EOR;
2 2
d) disposal of other acid gases except as considered part of the CO stream;
e) disposal of waste and other matter added for purpose of disposal; or
f) underground storage using any form of buried container.
If production of hydrocarbons in commercial quantities occurs from the storage unit(s), the storage project
is outside of the scope of this document and ISO 27916 applies to CO storage. A CO -EOR project that has
2 2
stored CO in association with CO -EOR can transition to operate under this document after all production
2 2
of hydrocarbons from the storage unit(s) has ceased.
2 Normative 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
abandonment
process and procedures used to permanently end the operation of a well in a manner that meets project
objectives (3.30)
Note 1 to entry: Well abandonment is designed to eliminate the physical hazard of the well (the hole in the ground),
eliminate a pathway for leakage and prevent changes in the hydrogeological system, such as the changes in hydraulic
head and the mixing of formation fluids between hydraulically distinct strata.
3.2
area of review
geographical area(s) designated for assessment of the extent to which a storage project (3.47) can affect life
and human health, the environment, competitive development of other resources, or infrastructure
Note 1 to entry: The delineation of an area of review defines the outer perimeters on the land surface or seabed and
water surface within which assessments will be conducted as can be required by regulatory authorities.
3.3
baseline
reference basis for comparison against which variance of a measured parameter is monitored or measured
3.4
CO plume
carbon dioxide plume
region within geological strata where injected CO is present in free phase
3.5
CO stream
carbon dioxide stream
stream consisting overwhelmingly of CO
Note 1 to entry: The stream is a fluid mixture that may include any incidental associated substances (impurities)
derived from the source materials or the capture process and any substances added to the stream to enable or improve
the injection process or trace substances added to assist in CO migration detection.
3.6
confining unit
geological strata that are part of a storage complex (3.45) and effectively restrict migration of fluids out of
the storage unit (3.50) and leakage (3.16) out of the storage complex
Note 1 to entry: Described in reservoir engineering as caprock and in hydrogeology as aquitard or aquiclude.
3.7
compartment
portion of a storage unit (3.50) that is geologically and hydraulicly separated from other portions of the
storage unit
3.8
containment
retention of CO within a storage complex (3.45)
3.9
custody transfer meter
measurement instrument that furnishes quantity and quality information used for quantification and the
basis for a change in responsibility for the CO stream
3.10
decommission
process of taking an engineered system or component out of service, render it inoperative, dismantle and
decontaminate it
3.11
detection threshold
smallest value of a property of a substance or effect that can be reliably detected by a specific method of
measurement in a specified context
3.12
element of concern
project objective (3.30) for which risk (3.36) is evaluated and managed
3.13
elevated pressure zone
geographical area where there is sufficient pressure in the storage unit (3.50) to cause flow of formation
fluids from the storage unit through the confining unit (3.6) along an accessible pathway
3.14
geological storage
safe, long-term containment (3.8) of CO stream (3.5) in subsurface geological formations
Note 1 to entry: Long-term means the minimum period necessary for CO geological storage to be considered an
effective and environmentally safe climate change mitigation option.
Note 2 to entry: The term “sequestration” has been used by a number of countries and organizations instead of
“storage” (e.g. the international “Carbon Sequestration Leadership Forum”). While the two terms are considered to be
synonymous, only “storage” is used in this document.
3.15
injectivity
sustainable rate at which fluids can be pumped into the storage unit(s) (3.50) given pressure constraints
3.16
leakage
unintended release of CO out of a pre-defined containment (3.8)
[SOURCE: ISO 27917:2017, 3.2.14, modified — "CO " has been removed from the term and Note 1 to entry has
been deleted.]
3.17
legacy well
pre-existing well within the area of review (3.2) of a CO storage project (3.47)
3.18
likelihood
chance of something happening, expressed qualitatively or quantitatively
3.19
loss
leakage (3.16), intended and unintended releases of CO from a storage facility (3.46), and transfers of the
CO stream (3.5) to outside of the storage site (3.49)
Note 1 to entry: Refer to 10.2 for the usage within quantification.

3.20
management of change
process used when making changes to equipment or procedures, which includes risk (3.36) management,
technical assurance, documentation and communication of changes to relevant personnel and stakeholders
(3.44)
3.21
mechanical integrity
mechanical condition of a well, such that its ability to function properly and safely is maintained
3.22
mechanical integrity test
MIT
test performed on a well to confirm that it maintains mechanical integrity (3.21)
Note 1 to entry: MITs are a means of measuring the adequacy of the construction of a well and a way to detect problems
within the well system.
3.23
monitoring
continuous or periodic ch
...