ISO/FDIS 13503-5

• Abstract:

  ISO 13503-5:2006 provides standard testing procedures for evaluating proppants used in hydraulic fracturing and gravel packing operations. ISO 13503-5:2006 provides a consistent methodology for testing performed on hydraulic fracturing and/or gravel packing proppants. The "proppants" mentioned henceforth in this part of ISO 13503-5:2006 refer to sand, ceramic media, resin-coated proppants, gravel packing media, and other materials used for hydraulic fracturing and gravel-packing operations. ISO 13503-5:2006 is not applicable for use in obtaining absolute values of proppant pack conductivities under downhole reservoir conditions.

• Status: Not Published
• ICS: 75.100 - Lubricants, industrial oils and related products
• ICS: 75.180.10 - Exploratory, drilling and extraction equipment
• Technical Committee: ISO/TC 67/SC 3 - Drilling and completion fluids, well cements and treatment fluids
• Drafting Committee: ISO/TC 67/SC 3/WG 3 - Well and formation treatment fluids
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 05-Nov-2026
• Completion Date: 05-Nov-2026

• Consolidates: FprEN ISO 13503-5 - Oil and gas industries including lower carbon energy - Completion fluids and materials - Part 5: Measuring conductivity of proppants (ISO/FDIS 13503-5:2026)
• Effective Date: 28-Feb-2026
• Revises: ISO 13503-5:2006 - Petroleum and natural gas industries — Completion fluids and materials — Part 5: Procedures for measuring the long-term conductivity of proppants
• Effective Date: 28-Sep-2024

ISO/FDIS 13503-5 is an ISO document on measuring the conductivity of proppants for oil and gas completion work. It supplements API RP 19D:2021 and gives laboratory procedures for testing proppants used in hydraulic fracturing and gravel packing, including sand, ceramic media, resin-coated proppants, gravel packing media and similar materials.

What does ISO/FDIS 13503-5 specify?

ISO/FDIS 13503-5 specifies how to test proppants so results are comparable from one laboratory to another. It is aimed at consistent test practice, not at producing absolute proppant pack conductivity values under downhole reservoir conditions.

The document is organized into:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Terms and definitions
• Clause 4 - Supplements to API RP 19D:2021
• Bibliography

Clause 4 contains the practical test guidance. It covers general requirements, loading the cell(s), and acquiring data, and it points back to API RP 19D:2021 for the base procedure except where ISO adds specific changes.

What are the key requirements of ISO/FDIS 13503-5?

ISO/FDIS 13503-5 keeps the API RP 19D:2021 requirements as the base and then overrides selected steps in the loading and data-acquisition process. In practice, that means a lab follows API RP 19D, then applies the ISO-specific changes described in Clause 4.

Follow the base method, with stated exceptions

Clause 4.1 says the requirements in API RP 19D:2021 apply, except for the parts identified in 9.7 to 10.3 and Annex C, Figure C.7. This matters because the ISO document is not a stand-alone test method - it is a controlled revision of the API procedure.

Use a levelling device when loading dry proppant

Clause 4.2.1 introduces a new levelling device for loading dry proppant into the cell. The proppant is to be levelled uniformly, and it must not be compacted by vibration or mechanical tamping. In practice, this helps avoid particle segregation and uneven packing, which would distort conductivity results.

Apply the specified loading rate in the load frame

Clause 4.2.2 changes the pressure increase steps and uses a loading rate of 100 kPa/min, with a tolerance of ±10 kPa/min. The procedure covers pressure increases from 350 kPa to 3.5 MPa, then to 6.9 MPa, with back-pressure kept within the stated range. This matters because stress history affects pack structure, so the ramp rate has to be controlled.

Hold the initial stress and record conductivity over time

Clause 4.3 requires an initial absolute stress of 6.9 MPa to be applied for 12 h to 24 h at the required temperature, while maintaining the back-pressure within the stated range. The target stress is then reached at 100 kPa/min, with intermediate stress points added during pressurization and each intermediate point held for 15 min to measure conductivity. Labs use this to observe conductivity change trends and reduce experimental error.

Meet the validity condition for single-point data

Clause 4.3 says the target stress is to be maintained for 50 h ± 2 h, and data from a hold time shorter than 48 h at target stress are not valid single-point conductivity data. In practice, this sets a minimum aging period before a result is accepted as a single-point value.

Use additional stress increments after the initial stage

Clause 4.3 also requires later stress increases in 13.80 MPa increments, still at 100 kPa/min. This gives a repeatable sequence for multi-stress testing and supports comparison between proppants under progressively higher closure stress.

What terms does ISO/FDIS 13503-5 define?

ISO/FDIS 13503-5 uses the terms and definitions from API RP 19D:2021, and it adds the context needed for its own procedures.

• Proppant - the material tested for conductivity in hydraulic fracturing or gravel packing, such as sand, ceramic media or resin-coated material.
• Hydraulic fracturing - a completion operation where proppant is used to help keep flow paths open.
• Gravel packing - a completion method that uses proppant-like material to support flow while limiting sand movement.
• Conductivity - the ability of the proppant pack to transmit fluid under stress.
• Closure stress - the stress applied to the proppant pack during testing to simulate formation loading.
• Back-pressure - the pressure maintained on the system while stress is applied.
• API RP 19D - the reference method that ISO/FDIS 13503-5 supplements and amends.

Who uses ISO/FDIS 13503-5?

ISO/FDIS 13503-5 is used by test laboratories, proppant manufacturers, completion-fluid specialists, and oilfield service companies. Quality managers and buyers use it when they need comparable conductivity data for product qualification, supplier comparison, or specification checks. Engineers use it to evaluate how a proppant behaves under controlled stress and temperature conditions before field use.

What changed in ISO/FDIS 13503-5 from the previous edition?

ISO/FDIS 13503-5 cancels and replaces ISO 13503-5:2006, and the foreword says it has been technically revised. The stated changes are:

• new levelling devices are used
• the stress increasing rate is reduced to 100 kPa/min ± 10 kPa/min
• additional stress points are added during pressurization

These changes matter because they affect how the sample is prepared, how fast stress is applied, and how the conductivity trend is captured.

Which standards are used with ISO/FDIS 13503-5?

ISO/FDIS 13503-5 uses API RP 19D:2021 as its normative reference. API RP 19D provides the base conductivity test method, terminology, and requirements that ISO 13503-5 supplements, except where this document states different procedures.

What does the ISO/FDIS 13503-5 document contain?

ISO/FDIS 13503-5 contains the scope, the normative reference to API RP 19D:2021, and the terms-and-definitions framework inherited from that reference. Its main technical content is in Clause 4, where it gives the updated loading procedure and data-acquisition procedure for conductivity testing.

The document also includes Figure 1 showing the levelling device used for cell loading. In addition, it points to API RP 19D material such as Figure C.7 and the related clause references, so users can align the ISO supplements with the base method.

The bibliography lists two technical papers on proppant conductivity, which helps readers trace the background of the test approach.

FINAL DRAFT
International
Standard
ISO/TC 67/SC 3
Oil and gas industries including
Secretariat: UNI
lower carbon energy — Completion
Voting begins on:
fluids and materials —
2026-11-05
Part 5:
Voting terminates on:
2026-12-17
Measuring conductivity of
proppants
Industries du pétrole et du gaz, y compris les énergies à faible
teneur en carbone — Fluides de complétion et matériaux —
Partie 5: Mesure de la conductivité des agents de soutènement
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 67/SC 3
Oil and gas industries including
Secretariat: UNI
lower carbon energy — Completion
Voting begins on:
fluids and materials —
Part 5:
Voting terminates on:
Measuring conductivity of
proppants
Industries du pétrole et du gaz, y compris les énergies à faible
teneur en carbone — Fluides de complétion et matériaux —
Partie 5: Mesure de la conductivité des agents de soutènement
© ISO 2026
All rights reserved.
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
This ISO publication is protected by copyright and is owned by ISO and/or its licensors.
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
The content of this ISO publication is provided under licence, not sold. Use is subject to the applicable licence terms issued by ISO,
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
an ISO member body, or an authorized third-party distributor.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
Except as required for implementation or expressly permitted by a separate licence, no part of this ISO publication may be
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
reproduced, distributed, modified, used, or made available in any form or by any means – electronic or mechanical, including
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
photocopying, scanning, recording, or posting on internal or external digital platforms. TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
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Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Supplements to API RP 19D, 2nd edition (2021) . 1
4.1 General requirements .1
4.2 Procedure for Loading the Cell(s) .2
4.2.1 Loading Dry Proppant into the Cell(s) .2
4.2.2 Loading Cell(s) in the Load Frame .4
4.3 Acquiring Data .4
Bibliography . 5

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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
...

ISO/DISFDIS 13503-5 :2026(en)
ISO/TC 67/SC 3
Secretariat: UNI
Date: 2026-07-2410-22
Oil and gas industries including lower carbon energy —
Completion fluids and materials — —
Part 5:
Measuring conductivity of proppants
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© Industries du pétrole et du gaz, y compris les énergies à faible teneur en carbone — Fluides de complétion et
matériaux —
Partie 5: Mesure de la conductivité des agents de soutènement
FDIS stage
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All rights reserved. Unless otherwise specified,
This ISO publication is protected by copyright and is owned by ISO and/or its licensors.
The content of this ISO publication is provided under licence, not sold. Use is subject to the applicable licence terms issued
by ISO, an ISO member body, or an authorized third-party distributor.
Except as required in the context of its for implementation or expressly permitted by a separate licence, no part of this
ISO publication may be reproduced or utilized otherwise, distributed, modified, used, or made available in any form or
by any means, – electronic or mechanical, including photocopying, scanning, recording, or posting on internal or external
digital platforms.
Any use beyond the internet or an intranet, without prior written permission. Permission can be requested from either
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Published in Switzerland
ix
Contents
Foreword . xi
Introduction . xii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Supplements to API RP 19D, 2nd edition (2021) . 1
4.1 General requirements . 1
4.2 Procedure for Loading the Cell(s) . 1
4.3 Acquiring Data . 5
Bibliography . 6

x
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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, Oil and gas industries including lower carbon
energy, Subcommittee SC 3, Drilling and completion fluids, well cements and treatment fluids, in collaboration
with the European Committee for Standardization (CEN) Technical Committee CEN/TC 12, Oil and gas
industries including lower carbon energy, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 13503-5:2006), which has been technically
revised.
The main changes are as follows:
— new levelling devices utilized;
— the stress increasing rate reduced to 100 kPa/min ± 10 kPa/min;
— additional stress points during the pressurization process added.
A list of all parts in the ISO 13503 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.

xi
Introduction
This document supplements API RP 19D, 2nd edition (2021).
The technical requirements of this document and API RP 19D used to be i
...