National foreword

This British Standard is the UK implementation of ISO 25206‑1:2026.

The UK participation in its preparation was entrusted to Technical Committee PSE/17, Materials and equipment for petroleum, petrochemical and natural gas industries.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 September 2026.

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 10, Enhanced oil recovery.

A list of all parts in the ISO 25206 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.

Introduction

As enhanced oil recovery (EOR) technologies continue to advance and international collaborative projects increase in number, there is a growing global demand for international standardization in this field. As a universal technical language, terminology standards play a foundational role in international collaboration by clearly defining the scope of the field and delineating boundaries with related disciplines.

To maintain terminological coherence across international EOR standards and to prevent conflicts in application arising from ambiguous or contradictory definitions, coordinated efforts in standardization are essential. The ISO 25206 series is being developed to establish a coherent framework of mutually reinforcing definitions, ensuring conceptual alignment across all relevant international standards. This systematic approach guarantees that precisely defined common terminology forms the essential basis for both the understanding and implementation of EOR standards worldwide.

Based on the displacement medium and underlying mechanism, EOR is generally classified into the following main types:

thermal recovery;
gas flooding;
chemical flooding;
microbial enhanced oil recovery.

This document provides general terms and definitions related to EOR, including fundamental concepts covering the field and its subdivisions, as well as terms describing the major EOR technologies and their associated processes. More specialized terminology for each specific category is defined in other parts of the ISO 25206 series.

1 Scope

This document defines fundamental definitions for enhanced oil recovery (EOR) concepts and core methodologies, specifically addressing thermal recovery, gas flooding, chemical flooding, and microbial enhanced oil recovery technologies.

This document excludes specialized terminology from reservoir engineering, production engineering, and surface engineering, as well as any applications unrelated to petroleum exploration and production.

2 Normative references

3 Terms and definitions

3.1 Basic concepts

3.2 Terms related to thermal recovery methods

3.3 Terms related to gas flooding methods

3.4 Terms related to chemical flooding methods

3.5 Terms related to microbial enhanced oil recovery methods

Bibliography