Posted on 08/25/2019 10:32:54 AM PDT by DUMBGRUNT
Thank you, thank you!
I was hoping some would discuss the potential heat source.
I retired from BP R&D Naperville, Il.
A thought problem or puzzle like this is something I would draw on the board for all of us play with. Lots of ‘SWAG’ estimates and a few hard numbers.
All work, no play, not good!
I’m not looking for hard answers, just chewing on it, at the edges with round numbers.
... probably not get much in the way of steam.
Depends on the temperature gradient and surface area.
Need just enough to heat the building?
If filled with water to the top, NOT RECOMMENDED, 40k ft down ~ 20k PSI at 400F. High-Temperature Water (HTW).
Best to leave a cushion above the water for expansion.
...You might get steam if you picked up heat at the bottom of the hole and prevented heat exchange with cooler rocks on the way up
The water in the casing would thermosyphon (convection) up, heating the casing/ rock. Loss rate????
BIG GUESS...Sufficient heat would be carried upward to exceed the loss. And hopefully, the loss rate should drop with time. 23 CM (8”) casing all the way???
You would also have a bomb on your hands with a pressure cooker like that.
As noted in #1 a large atmospheric relief is required. IIRC twice max output?
At about 800 ft water level the 400 F HTW will flash to steam IF it has not given up all the BTUs????
Also any steam will be expanding as the pressure drops.
Steam and water in the casing will NOT mix well.
The ideal would have minimal steam pressure at ground level. Less energy available but safer.
That is a thermal gradient of less than 1 degree F per 100’ in the Russian Kola well.
A key number.
Every day we went where no man had gone before and it was a hoot!
That is exciting and makes it fun to go off to work each day.!
We used mud chillers in those operations.
Was most of the theat geo, or from the drilling???
Our best prospect for clean, long lasting, plentiful energy that we need is probably Thorium
I thought this was the answer, until 911 and increased security costs.
https://en.wikipedia.org/wiki/Toshiba_4S
Some people like to increase the performance of their car, to go faster.
I spend too much time attempting to increase the performance of my boiler/ heating system to make it go slower.
Wells are hard to model thermally. We mostly did it empirically and built the models from there. CFD is OK but you need the proper heat transfer coefficients and casing coupling to the rock is highly variable. There is almost no temperature gradient for the first 1,000 feet and in fact cools down for a bit (your basement). Deep heat transfers to the lower temp shallow stuff on the way back up the annulus, cooled fluid begins to warm as it goes down from the increasing formation temp on the way down and the exchange from the hotter fluid coming up in what is effectively a counter current heat exchanger. We won’t get into the specific heat capacity of the drilling mud and / or cuttings.
Thermosiphons are of such low intensity that you need either a very large container or two flow paths. What is more, within the wellbore the two fluids temperatures become normalized to about the same. It takes at least an inner string an annulus to effectively move heat plus enough flow rate and insulation to move it to the surface. Some people theorize that fracture strength of the rock will increase when deeper temperatures are moved up in the well and expand and increase the hoop stress in the rock. That idea has little support by the margins of temperature increase even locally let alone moving beyond the wellbore where the changed temperature falls away quickly to the native state.
You can circulate a well that extends into high temperature and get heat to the surface. You can also flow product from the reservoir to the surface and get heat to the surface. If the flow rate is high enough sometimes you can get a lot of heat to the surface.
Way back when DOE drilled a well, I think it was in Grady County, Oklahoma, to see how much hot water they could get by flowing salt water from the reservoir to kick start steam generation. The project was abandoned but they had a HUGE wellhead left behind and mad a lot of contractors very happy with all the money they left on the table.
...you need the proper heat transfer coefficients and casing coupling to the rock is highly variable.
From https://en.wikipedia.org/wiki/Kola_Superdeep_Borehole,
at the depth of about 7 km (4.3 mi), where the velocity of seismic waves has a discontinuity. Instead the change in the seismic wave velocity is caused by a metamorphic transition in the granite rock. In addition, the rock at that depth had been thoroughly fractured and was saturated with water, which was surprising. This water, unlike surface water, must have come from deep-crust minerals and had been unable to reach the surface because of a layer of impermeable rock.[9]
Would this water fill the annular space between the bore and the casing with water?
That would assist in heat transfer.
Thermosiphons are of such low intensity that you need either a very large container or two flow paths. What is more, within the wellbore the two fluids temperatures become normalized to about the same.
Not to disagree, but as long there is a temperature difference there should be convection currents, yes slow at first until the surrounding rock is heated moving up.
IF a big if, it warms to the flashpoint, steam bubbles will move a bit faster.
Guessing the bubbles in the center will cause a downward current, it clearly cannot all go up.
Problem; as we approach the flashpoint, some heat value has been lost to the rock.
Yes, slow and may take a very long time...
No, I’d rather not have to pick up a few thousand feet of tubing from Home Depot. And pump head!!!
Beginning to suspect you are correct, that little usable heat will make it to the surface?
One of the things I miss about work, I could put this problem up and maybe someone in the building or elsewhere on campus was familiar with the question. My team would find them and prove me wrong, maybe.
Sadly the entire 200-acre campus is for sale only about a third of the people are still there.
The accident in the Gulf changed everything.
This is a favorite puzzle, I’d bring it out every few years for the new guys.
https://www.ringofsaturn.com/games/stringandringpuzzle.php
I had an elderly aunt that quickly solved it, many cannot without internet help.
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