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Help settle a debate

Help settle a debate

Help settle a debate

(OP)
My work involves heat transfer analysis of subsea oil production and processing equipment. Often, we have to simulate the heat transfer behavior of subsea wellheads and trees to design insulation geometry among other things.

There are 2 schools of thought in the company:

1. One group of people firmly believe that the wellbore is a great source of heat (via natural convection) even when the flow is stopped (shut-in or shutdown).

2. The second group of people believes that the equipment above the mudline and the bore fluid will cool at a rate faster than the wellbore can replenish. And, natural convection will not be sufficient to maintain the fluids within subsea equipment above a certain temperature.

How can I settle this debate? I think the key concept involves natural convection within a long, vertical tube.

Can you please help?

zdas04, does this look better?

RE: Help settle a debate

I suspect that the startup and operations team on deep water platforms like Thunderhorse and Atlantis have lots of comparison data between the design assumptions and actual operation.

RE: Help settle a debate

Most deepwater wells will have some sort of smart system where downhole temperature and pressue along with temperature and pressure at the tree can be measured. This seems like an easy debate to solve by just going to any operator and asking for the data during shut in as jlseagull mentioned. So long as you can make the operator understand the value of this I doubt they would have much problem providing you with the data.

My opinion is based on drilling and not production senarios where we have had temperature sensors in the subsea stack. In my opinion:

Very little convection actually takes place particularly if the wellbore fluid is a med to heavy vis fluid. Even if some convection does take place the heat that is lost via conduction: in the last cold hundred feet or so below the mudline, at the wellhead, and in the tree/production equipment would outweigh that brought in through convection in a static state (non-flowing well). The cold deepwater ocean is one hell of a heat sink.

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