Temperature tutorial

[magnusbj]

I wonder if you could give a guided tour of the temperature plot and show the effects working at different steps. My guess would be a higher temperature on the pipe flow than in annulus, as there is more friction generated within the pipe than within the annulus (unless very tight annulus?). Why does the temperature drop so heavily at the bottom, and why with such a curve as shown above? Maybe the pressure drop over the bit creates a large temperature drop, but that would be a straight line, not as a curve?

[jcamiloangarita]

The temperature is higher in the annular section because hot fluid from the bottom is flowing and also this section is more affected by the formation temperature. Besides, the temperature drops at the bottom mainly due to the fluid circulation (it depends on the flow rate), coming colder fluid from the drill string reaches warmer fluid in the annular.

To see this closer we can check the effect of the parameters using the function param_effect( ); for example, running the default data at circulation time of 40 hours, the result comes from: 64.97% fluid circulation, 21.68% heat source terms and 13.35% formation temperature.

[magnusbj]

Can we show just the pipe and annulus temperature along the well?

[magnusbj]

Can we see the contribution of friction (flow, rotation), fluid temperature and formation temperature contribution over time. So I want to start circulating, and see how the fluid temperature evolves along the wellpath, and see how the different functions are contributing to the temperature change.

[magnusbj]

I still would like to understand the drop at the bottom of the string, entering annulus. Is this a calculation issue to make the model merge, or is it a physical property?

[elyngvi]

I am also confused by this.

"the temperature drops at the bottom mainly due to the fluid circulation (it depends on the flow rate), coming colder fluid from the drill string reaches warmer fluid in the annular." I dont understand what you mean..

I would expect the temperature inside the pipe to increase all the way down to the bottom of the well, due to friction, and heat exchange with the annulus via the pipe wall (both positive contributions). In the annulus, I would expect heat exchange with the formation (major positive contribution, unless the mud is somehow hotter than the formation), and with the pipe (negative contribution, tiny in the beginning, increasing towards the top of the well as the temperature difference increases), and some friction (positive).

So since thats not what we are seeing here, what is the physical property or effect at the bottom of the pipe, which causes the temperature to drop?