GB/T 35065.2-2023
Wet natural gas flow measurement—Part 2:Test and evaluation method of flow meter (English Version)
- Standard No.
- GB/T 35065.2-2023
- Language
- Chinese, Available in English version
- Release Date
- 2023
- Published By
- General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China
- Latest
- GB/T 35065.2-2023
- Introduction
Analysis of the core content of the standard
GB/T 35065.2—2023, as a key part of the wet natural gas flow measurement series standards, systematically regulates the test and evaluation system of wet natural gas flowmeters for the first time. The standard innovatively adopts a dual-track evaluation mode combining laboratory simulation and field verification, and solves the measurement blind spot of traditional single-phase flowmeters under gas-liquid mixed conditions through dual-dimensional measurement of gas volume fraction (GVF) and liquid volume fraction (LVF).
Comparison of test methods
Dimensions Laboratory test Field test Test principle Gas-liquid separation standard table comparison method Process bypass reference measurement method Device requirements Straight pipe section ≥40D, uncertainty ≤1/5MPE Corrosion-resistant design, uncertainty ≤1/3MPE Media control Natural gas (ρ=0.55-0.80) + deionized water Actual wellhead fluid (including flowback fluid) Typical indicators Indication error + repeatability Long-term operation stability Key technical points
1. Flow point control strategy
The standard requires that the test must cover the three characteristic flow points of qmin, 0.5qmax, and qmax. Each point must be set with at least 4 liquid content conditions in the range of 0 to Lfmax. In the example, the DN80 flowmeter test adopts:
- Gas phase flow rate: 50/100/200 m³/h
- Liquid phase content: 0/0.5/1.5/3% (corresponding to flow rate 0/0.75/3/6 m³/h)
2. Error calculation method
Relative indication error formula is adopted:
Eg = (Qg measured - Qg standard)/Qg standard ×100%
Repeatability calculation distinguishes sample size: Bessel formula is used when n≥6, and range method (C(n) coefficient) is used when n<6.
Implementation Suggestions
- Laboratory Construction: It is recommended to configure an independent gas-liquid calibration system. A 0.5-level ultrasonic flowmeter is recommended for the gas phase, and a 0.2-level Coriolis mass flowmeter is recommended for the liquid phase.
- Field Verification: Prioritize wellhead platforms with stable production, and the test cycle should be ≥72 hours.
- Data Processing: The flow conversion from operating condition to standard condition should be performed according to GB/T 18603, and pay attention to the reference conditions of 20℃/101.325kPa.
Standard Evolution Analysis
Compared with international standards such as ISO/TR 11583, the innovations of GB/T 35065.2-2023 are reflected in:
- For the first time, the gradient setting method of liquid phase content test points is clarified.
- Propose pressure adaptability test requirements (ΔP/Pmin≥15%)
- Add static test steps (such as radiation absorption rate calibration)
GB/T 35065.2-2023 Referenced Document
- GB 50251 Code for Design of Gas Transmission Pipeline Engineering
- GB/T 13609 Natural gas sampling guidelines
- GB/T 17611 Measurement of fluid flow in closed conduits--Vocabulary and symbols
- GB/T 18603 Technical requirements for natural gas metering systems
- GB/T 35065.1 Wet natural gas flow measurement.Part 1: General rules
- GB/T 3836.1 Explosive atmospheres—Part 1：Equipment—General requirements
- GB/T 3836.2 Explosive atmospheres—Part 2：Equipment protection by flameproof enclosures “d”
- GB/T 3836.4 Explosive atmospheres—Part 4：Equipment protection by intrinsic safety“i”
- GB/T 8423.4 Petroleum and natural gas industries terminology — Part 4: Measurement and analysis of petroleum and natural gas
GB/T 35065.2-2023 history
- 2023 GB/T 35065.2-2023 Wet natural gas flow measurement—Part 2:Test and evaluation method of flow meter
