ISO/TR 12748:2015

Overview

ISO/TR 12748:2015 provides authoritative technical guidance on wet gas flow measurement in natural gas operations. It addresses production flow measurement of gas-dominated streams that contain liquids (water and/or hydrocarbon liquids) using wet gas flow meters (WGFM) in both surface and subsea facilities. The technical report defines terms and symbols, explains the theoretical background of wet gas metering, and presents best practices for meter design, installation, testing, commissioning, operation, maintenance, calibration and verification.

Key topics

• Definitions and symbols: standardized terminology for wet gas measurement and related parameters.
• Flow regimes: horizontal, vertical and inclined wet-gas regimes (stratified, slug, annular/mist, churn) and flow regime mapping.
• Metering principles: in-line approaches including single-phase meters with correction factors, two‑phase and multiphase WGFM technologies.
• Differential pressure (DP) meter issues: DP meter over‑reading drivers, Lockhart‑Martinelli influences, β ratio, orientation, meter size and fluid-property effects.
• Multiphase meter components: phase-fraction devices, PVT modelling, slip models, diagnostics, and subsystem redundancy.
• Design & installation: meter orientation, placement, sampling, redundancy, security and environmental considerations for surface and subsea deployments.
• Testing, verification & calibration: recommendations for facility testing, baseline characterization, field verification and test witnessing.
• Performance & uncertainty: methodologies to evaluate measurement uncertainty and factors influencing wet-gas measurement confidence.
• Operational guidance: maintenance, diagnostics, software/property update procedures and long-term trending.

Practical applications

ISO/TR 12748 is practical for:

• Designing and specifying WGFM systems for production allocation, flow monitoring and flow assurance in upstream facilities.
• Selecting meter technology and defining installation and commissioning practices for surface and subsea metering sites.
• Planning testing, calibration and field verification campaigns to validate meter performance and quantify uncertainty.
• Supporting operators and engineering teams in troubleshooting field metering issues related to two‑phase flow behavior.

Who should use this standard

• Flow metering and production engineers
• Subsea and surface facilities designers
• Meter vendors and integrators
• Test-house and calibration laboratory personnel
• Asset operators, metering specialists and regulators involved in natural gas production measurement

Related standards

ISO/TR 12748 complements broader standards and industry guidance on gas flow measurement, meter testing and metering uncertainty. It should be used alongside established flow‑meter standards and project specifications when developing wet‑gas metering solutions.