The FlowPak® flow meter excels in flow loop test program with high accuracy, low permanent pressure loss, and zero straight pipe requirement.
Achievements
- The FlowPak® flow meter showed excellent accuracy in single-phase and multiphase test scenarios, including gas, wet gas, produced water, viscous fluid, and multiphase flow.
- Permanent pressure loss was as low as 17% of DP when tested with produced water despite the introduction of a plate-type flow conditioner.
- Choking the flow upstream of the meter had negligible impact to the measurement deviation.
Introduction
The FlowPak® flow meter offers unique differentiation versus the traditional legacy products such as orifice plates, Venturis, and nozzles. The uniqueness includes:
- High accuracy (±0.5%) due to a known Cd value which can be further increased by testing at an accredited ISO 17025 flow calibration loop.
- Minimal pressure drop in the region of 20% of the differential pressure, whilst requiring zero up and downstream straight length.
This recent uniqueness gave justification to test the FlowPak® flow meter at Equinor’s R&D Facility in Porsgrunn, Norway. The curriculum of testing includes performance of multiple phase regimes as benchmarked versus a traditional Venturi and a newer technology, Coriolis.
Test Setup
Picture 1: Flow loop setup (click to enlarge)
The FlowPak® flow meter has been tested on gas, wet gas (multiple GVF), produced water, high viscous oil, high viscous oil with increasing gas phase, i.e. multiphase flow. Reference flow rates of the individual phases of oil, gas, and recombined water were measured by individual Coriolis flow meters post-separation to obtain the reference rates. A full bore ball valve was positioned upstream of the FlowPak® flow meter to mimic turbulent flow. A gamma density meter monitored the flow media’s density value.
Picture 2: Cross section view of the FlowPak® flow meter (click to enlarge)
The flow meter was configured as follows:
Line Size: 3″, Flange rating: 900#, Material: Duplex, Beta: 0.4, Upstream Flow Conditioner, Downstream Thermowell, 3 x DP Transmitters to measure permanent pressure loss (PPL), differential pressure (DP), differential pressure recovered (DPr).
Picture 3: FlowPak® flow meter with manifolds and DP transmitters
Picture 4: Gas (click to enlarge)
Test Results
Gas (6 test points)
Average relative deviation* – 2.0%, permanent pressure loss – 31% of DP
Choking the flow upstream of the meter had negligible impact on the measurement deviation.
Picture 5: Wet gas (click to enlarge)
Wet Gas (17 tests points)
Average relative deviation* – 2.8%, permanent pressure loss – 29% of DP
Tested from 100…90% GVF (gas with oil)
Choking the flow upstream of the meter had negligible impact on the measurement deviation.
Picture 6: Produced water (click to enlarge)
Produced Water – saltwater w/ approx. 7% salt (7 tests points)
Average relative deviation* – 1.1%, permanent pressure loss – 17% of DP
The FlowPak® flow meter maintained a good accuracy over a wide flow range. Choking the flow upstream of the meter had negligible impact on the measurement deviation.
Picture 7: Viscous fluid (click to enlarge)
Viscous Fluid (heavy oil mixed with water to obtain an emulsion) > 400 cP (8 tests points)
Average relative deviation* – 3.3%, permanent pressure loss – 28% of DP
Accuracy was maintained due to adjusting the CD value from 0.985 … 0.81.
Picture 8: Multiphase flow (click to enlarge)
Multiphase flow (85 tests points)
Average relative deviation* – 3.5 %, permanent pressure loss – 37 % of DP
Despite a wide range of gas fraction and water cuts, test results confirm good match of the FlowPak® flow meter’s flow rates with the reference flow rates.
* “Average relative deviation” reflects the system’s complete measurement chain including the differential pressure transmitter, not just the FlowPak® flow meter.
Conclusion
FlowPak flow meter
The FlowPak® flow meter showed excellent accuracy in single-phase and multiphase test scenarios including gas, wet gas, produced water, viscous fluid, and multiphase flow. Permanent pressure loss was as low as 17% of DP when tested with produced water despite the introduction of a plate-type flow conditioner being positioned in the flow meter’s upstream.
Even lower permanent pressure loss can be achieved by removing the plate-type flow conditioner. If removed, only few pipe diameters of straight pipe would have to be introduced, keeping the space requirement still very low. Choking the flow upstream of the meter had negligible impact on the measurement deviation.
The FlowPak® flow meter’s design is robust and versatile. It offers both mechanical piping benefits beyond the differential pressure flow concepts’ perception performance regarding accuracy and permanent pressure loss within compact spaces.
Oil & gas applications include subsea single-phase measurement of water, gas & MEG, gas lift on FPSO, wellhead measurement on platforms, pre- and post-production separator measurement, coke gas measurement, compressor measurement, Coriolis alternative for single to dual phase flow, and many more.
Depending on the flow meter’s configuration, many of the maintenance operations can be carried out whilst the line being still under pressure, isolated by DBB requirements, thus mitigating all of the challenges faced with safety, pipe isolation, depressurization, and breaking of pipeline integrity.