And of course can be used for electricity once the recoverable oil is gone.

Why not just freeze the oil instead and then drill down a mine shaft and mine it like coal?

Seems like a good move...but when its cloudy...does that mean they shut down all oil pumping operations?

The plant will be very productive, in Oman there's very little precipitation and cloud cover, with only a few days of rain each year.

Ironic at a number of levels, I think, that novel solar technology is being used to extract more fossil fuel from the ground, whose burning enhances global warming of an area already amongst the hottest in the world. Oman has the solar and financial resources to generate massive amounts of renewable energy, without recourse to damaging greenhouse gas emissions. But the mindset is hard to change.

Oil refineries aren't going away and it seems like an interesting enough idea. Natural gas may have been an import for them and now they are less dependent on it too.
I like how people talk about electric cars as "coal burners" comparing grid power generation to ICE's themselves but in order for that comparison to be apples to apples you would need to measure energy used to refine the oil before burning it in the combustion engine too. I'm not sure how much energy that is exactly but looking at this solar power plant it's apparently not trivial.
People make this oversight all the time and are rarely called on it.

I wonder what the pay-back time is? It looks hugely expensive. Will they extract and re-cycle the heat from the hot oil? This oil may cost more to extract than it is worth.

I see the irony. But it makes a lot of sense and is just temporary. Once oil demand drops to electrification of transportation over the next decade, these solar plants can still be used, but now to generate electricity.
At this point oil producers are producing the product that is in demand, oil. To produce oil you need a lot of energy. Using renewable energy for that purpose is a good move and also sets them up for an easier transition in many respects. But this is just a short-term or stop-gap measure. Oil demand will start to drop dramatically in 5 years and drop off a cliff in 10 years. We will always use oil. And a lot of it. Oil is not just used to lubricate and power internal combustion engines in personal vehicles. It will still be needed for powering ships, planes and big trucks (trucks not for too long though, but powering ships and planes won't change soon). And off course there we use tens of millions of barrels per day world wide for purposes other than transportation.
But dropping demand from 95 mbpd to 60 mbpd or less due to electrification of transportation over the next 2 decades will send prices to the floor in short order.

Of course any effort to extract fossil fuels to burn is nuts. Doing so by use of solar energy is just a cleaner method. It's probably too late to save mankind from the destructive effects of climate change. What this plant does is to simply delay the inevitable.

Hopefully they'll be using deionized water as the heat transfer medium. Anything less will leave mineral residue in the pipes which will lead to more frequent down-time for cleaning. I used to do that myself - crawling into the boiling chamber of a steam heating system to scrape-off the mineral build-up.
Maybe they could use mineral oil in the pipes to transfer the heat to a boiling chamber (where the oil passes through a coil immersed in the water) which is easier to access for cleaning?
They might want to consider microwaves for heating the water at the point of use too. Pump water through a ceramic coil inside a shielded chamber. Inside the coil use ferrite coated refractory ceramic honeycomb (identical to that used in exhaust system catalytic converters). Focus the microwave magnetrons on the coil. The microwaves are absorbed by the honeycomb which heats-up the water to the boiling point. The power for the magnetrons could come from an array of solar panels. I imagine they get plenty of sunshine ;-)