Pressure conversions for Subsea Systems

[Phani Y]

Hi All,

I recently noticed a pressure transmitter for a Subsea well, where the downhole pressure transmitter is showing pressure in bara, but not barg. Considering a water depth of 'w' at the well location and well depth of 'd' (depth of downhole gauge), I was confused if barg to bara conversion here would be

1. bara = barg + atmospheric pressure (i.e 1 bar)

or

2. bara = barg + hydrostatic head of the fluid.

My understanding is that we can't go with the 2nd option, as the fluid is not traveling from top to bottom but vice-versa. Also, I'm not very sure if the 1st option is valid here because the pressure measurement is happening some thousands of metres below the Earth's surface. Someone please help. Thanks in advance.

 

[LittleInch]

It's 1.

The pressure is being compared to a near perfect vacuum sealed inside the transmitter.

The pressure transmitter is in fact a differential pressure transmitter, with one side connected to this sealed vacuum as the reference pressure.

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