Newcastle borehole drilling starts in search of heat

BBC ^ | February 23, 2011 | Unknown

[thackney]

There are many, many active geothermal wells currently in use.

This is just for California:
ftp://ftp.consrv.ca.gov/pub/oil/maps/Geothermal/MapS-11.pdf

[Pontiac]

They're talking about 176F. Superheated.

To be superheated it would have to be over 212 degrees F.

Superheated means that the water has been heated above the boiling point for water at a given pressure.

[Sherman Logan]

Only need to overcome friction loss.

I don't think so. That would be for horizontal movement.

There is a specific energy requirement, in addition to frictional losses, to raise a pound of anything a foot above its starting point.

In fact, I think it's a unit of measurement called a foot-pound. :)

[thackney]

, there have been a number of movies based on the notion of deep drilling. Few turned out well.

A bit over a mile deep isn't all that deep. We have many, many oil wells far deeper.

[PSYCHO-FREEP]

At 5300 feet deep (Vertical Hole) the temperatures average about 175 degrees F.. At 11,000 feet they average around 300 deg. F.

[Sherman Logan]

What I was told was the water is warm enough to prevent your pipes from freezing in the winter, and cool enough to ac the house in summer. All free, after the 20k hole is paid off.

You don't need to drill any mile down to do that in most of the USA.

The temperature of the ground six or eight feet down in most areas is the same as the average air temperature over the course of the year.

So if you dig down the appropriate distance and lay a bunch of pipe, the water that comes out the end of the system will be at (about) average air temperature for the year.

Here's a link to a map for US annual air temperatures.

http://www.maps.com/ref_map.aspx?cid=680,747,1304&pid=11583

(I don't know how to post pics.)

Designing such a system is not for the faint-hearted. Dramatically affected by soil type, water table level and a bunch of other factors. But the basic principle is valid.

If you look at the map you can see ground temperature won't provide effective AC in the South, and it sure won't heat the house in the North.

[Sherman Logan]

People who make movies don’t care about facts.

[Pontiac]

A bit over a mile deep isn't all that deep. We have many, many oil wells far deeper.

We have mines deeper.

"The deepest mine in this region (Witwatersrand) is currently Western Deep mine, a network of tunnels which penetrates 3.5 km into the Earth's crust."

[PapaBear3625]

There is a specific energy requirement, in addition to frictional losses, to raise a pound of anything a foot above its starting point.

Unless they have the water in a loop, in which case the weight of the water in the down-going side of the loop balances the water in the upcoming side, leaving only frictional losses in the round trip.

[PSYCHO-FREEP]

That's correct. Use the Hydrostatic Pressure formula of;

HP = wt. per gallon (water @ 8.3 ppg) x depth x.052 = Hydrostatic Pressure.

At 5300 feet vertical, the bottom hole pressure (hydrostatic) is 2287 psi. One would need to maintain a pump pressure exceeding that pressure to move a column of fluid at that depth. Velocity also increases circulation density which also requires more power to maintain the flow of the fluid column. It also varies due to the rheology of the fluid used. (Viscosity/yield point)

[Sherman Logan]

Ignore the map I posted. It’s for average air temperature in January.

Surprisingly difficult to find an annual average temperature map.

Here’s a vintage version. 1887.

http://www.etsy.com/listing/26672589/1887-temperature-and-rainfall-map-of-the

[sima_yi]

At 11,000 feet they average around 300 deg. F.

Are you sure of these figures? Didn't Al Gore, who invented the Internet and won the Nobel Prize in Climatology, say that just a couple of miles below the surface the temperature was millions of degrees?

[Sherman Logan]

True. However, that would require a closed loop, with essentially a heat exchanger somehow installed at the base. My take on the story was that they were planning to pump out the water they found at that depth, not inject water from the surface and heat it.

When I lived in NM they were working on the inject water and heat it model in the mountains west of Los Alamos. This was several decades ago. Last I heard they were still working on it.

[bert]

You drill a shallower hole.

At some point you strike surface water table that is going to be the approximate average temperature and lower than the surface.

[PSYCHO-FREEP]

I must have missed that one.....Damn!

[Melas]

Man made earthquakes? About as realistic as man made global warming.

[sima_yi]

About as realistic as man made global warming.

It is, to a lawyer, who reasons as follows: "Someone drilled a hole. Later, and earthquake happened. Therefore, the hole caused the earthquake and whoever drilled it is liable for the damages and my fee."

In the case of Global Warming, liberals reason in a similar fashion: "The temperature rises. Years later, the carbon dioxide rises. Therefore, the carbon dioxide caused the temperature rise, and the government must control even more of the economy."

[PapaBear3625]

However, that would require a closed loop, with essentially a heat exchanger somehow installed at the base.

A heat exchanger would be more compact than sticking a pump down at the bottom.

You can't suck water up from that far down, you have to have the pump down below pushing it up.

[Strategerist]

Man made earthquakes?

Earthquakes (small to moderate) being caused by the filling of reservoirs and the INJECTION of fluids underground have been extremely well documented in multiple locations for some years now.

[decimon]

To be superheated it would have to be over 212 degrees F.

Like superheated steam. Thought of that after posting.