[QUOTE=alcor;39936]CM1 is correct. The WH Temp will decrease.[/QUOTE]
If this were true, then expansion is being driven by pressure ( read : leak or seep ). I’m inclined to think WH temp will increase during flow. Heat from the mud/or fluids from the bottom is taken along up to the surface (mudline) where it is dissipated to the surrounding cooler seawater regime via the well head. However, when shut-in, flow stops. Heat already brought up to the WH, will dissipate into the cooler seawater surroundings and not be replenished with hotter fluids flowing from the bottom - WH temp will drop, relatively. Hence I’d expect to see heat during flow, followed by a drop in temperature during shut -in (stop flow) and then gradually a relatively slow build in temperature as heat from lower sections of the fluid column slowly, via thermal conduction (not flow), makes its way to the now relatively cooler wellhead, which over time will begin to get hotter than it was at shut-in. Aslo, as pressure at the WH slowly builds so will temperature.