ISO/TR 26762:2008

TECHNICAL ISO/TR
REPORT 26762
First edition
2008-07-15
Natural gas — Upstream area —
Allocation of gas and condensate
Gaz naturel — Zone amont — Allocation du gaz et du condensat

Reference number
©
ISO 2008
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ii © ISO 2008 – All rights reserved

Contents Page
Foreword. v
Introduction . vi
1 Scope .1
2 Normative references .1
3 Economic aspects .1
3.1 Overview.1
3.2 Uncertainty and costs .3
3.3 Allocation system overview.4
4 Allocation from different viewpoints and terminology .7
4.1 Physical system.7
4.2 Gas/condensate system overview .7
4.3 Physical system terms .12
4.4 Definitions for allocation systems .14
4.5 Allocation from a commercial viewpoint.16
5 Quantity measurement for gas and condensate .21
5.1 Introduction.21
5.2 Quantity measurement by type of fluid streams .23
6 Quality measurement .33
6.1 Sampling and analysis .33
6.2 Analysis .35
6.3 Uncertainties .35
6.4 Other .36
7 Data processing.38
7.1 Calculation at the measurement point.38
7.2 Balancing and reconciliation.39
7.3 Process simulation.40
7.4 Line packing and stock change .41
8 Lift, injection and utility gas .42
8.1 General.42
8.2 Lift gas .42
8.3 Injection gas .43
8.4 Utility gas.43
8.5 Uncertainty considerations for lift, injection and utility gas.44
9 Uncertainty — General considerations .45
9.1 Economic consequences.45
9.2 Sensitivity.47
9.3 Allocation principle.48
9.4 Uncertainty determination .48
10 Validation.49
10.1 General.49
10.2 Meter validation.49
10.3 Allocation procedures and process validation.50
10.4 Data validation .50
10.5 Process-model validation .50
10.6 Allocation-process results validation.50
10.7 Software validation.50
11 Classification of allocation processes. 51
11.1 General descriptions and calculations . 51
11.2 Allocation systems layout. 60
12 Mis-measurements — Measurement-correction and estimations . 65
Annex A (informative) Adjust for impurities . 66
Annex B (informative) Adjustments for fuel/utility/vent/flare gas . 67
Annex C (informative) Wet gas. 68
Annex D (informative) Codes, abbreviations and acronyms . 71
Annex E (informative) Conversion of molar percent to mass percent. 73
Annex F (informative) Conversion of mole percent to per cent of the calorific value. 74
Annex G (informative) Conversion of mole per cent to volume percent . 75
Annex H (informative) Components of gas and liquid reported . 76
Bibliography . 77

iv © ISO 2008 – All rights reserved

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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
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.
ISO/TR 26762 was prepared by Technical Committee ISO/TC 193, Natural gas.

Introduction
Hydrocarbon gas and condensate from onshore or offshore concessions is often transported by shared
pipelines to shared main treatment facilities. The concessions are often owned by or licensed to a number of
oil companies. At the main treatment facilities, the gas and condensate are processed to sales specifications.
The gas is sold to shippers in terms of standard volume (standard cubic metres) or combustion energy
(joules), and the condensate is sold in terms of standard volume (standard cubic metres) or mass (kilograms
or tonnes). All the gas and condensate sold at the main treatment facility and the associated money should be
allocated back to the individual concessions and, ultimately, to the individual reservoirs or wells, as illustrated
in Figure 1.
When gas from two or more entry sources (e.g. two or more different companies) is commingled and
processed in a common pipeline and terminal system and the sources have different ownership and/or
operate under different tax regimes, then a gas allocation system is required. It is necessary that the allocation
system provide a fair, equitable and auditable means of sharing out the products from the system to the entry
sources and to the associated partners, recognizing the specific delivery requirements of each participant.

Figure 1 — Offshore gas distributions

vi © ISO 2008 – All rights reserved

TECHNICAL REPORT ISO/TR 26762:2008(E)

Natural gas — Upstream area — Allocation of gas and
condensate
1 Scope
This Technical Report describes the production measurements, in terms of both hardware and procedures,
that can be used to allocate the gas and condensate back to the individual concessions, reservoirs and wells
in a fair and equitable way. The objective is to give an approach that is recognized to be current best practice
and that has a wide support in the oil and gas industry.
2 Normative references
ISO 5167-1, Measurement of fluid flow by means of pressure differential devices inserted in circular cross-
section conduits running full — Part 1: General principles and requirements
ISO 5168, Measurement of fluid flow — Procedure
...