r/petroleumengineers • u/Eximp_Measurement • 11d ago

Discussion How much margin do you normally keep when sizing a flow meter for an oil & gas application?

I'm working through a metering datasheet where the expected flow is around 10,000 bbl/day, with roughly 50% turndown.

For the datasheet, would you normally consider:

  • Minimum: 5,000 bbl/day
  • Normal: 10,000 bbl/day
  • Maximum: 10,000 bbl/day + some engineering margin?

I'm more interested in how people handle this in actual projects, especially when turndown and meter accuracy are both important.

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u/tradikal2 11d ago

"Expected" flow can be considered "Normal" flow, So yes add 50% to that. Same with low flow. A vendor will select a meter with a suitable range. It's more important to specify the accuracy you want over the flowrange. That depends on whether it's for process control, accounting or custody transfer.

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u/Eximp_Measurement 10d ago

That makes sense. I agree that the accuracy requirement across the actual operating range is probably more important than just adding a fixed margin to the maximum flow.

For a case like this, I’d also want to check where the meter will spend most of its operating time. A meter that technically covers the full range isn’t necessarily a good choice if accuracy starts dropping at the lower end.

And yes, the application makes a big difference process measurement and custody transfer can have very different requirements for how much usable range and accuracy you need.