Injecting cold water into an oil reservoir will cool the oil in the reservoir. In time the magma will heat the water and oil in the reservoir again.
Exactly who injects cold water into a reservoir? Extreme care is taken in injecting fluids into reservoirs to avoid “shocking” the reservoir and risking the creation of emulsions. Do you think oil operators who have been in the business for decades are somehow dumb?
The problem is that even with a constant temperature in the reservoir only on average 35 percent of the oil in the reservoirs globally can be extracted economically. The lighter oil is extracted and heavier oil remains in the reservoir.
A lot of misunderstanding here. First off reservoir and fluid temperature have zero to do with recovery. Secondly there are reservoirs that have greater than 50% primary recovery and many such as the Arab in Ghawar that will achieve greater than 70% under secondary recovery. As well the reason why oil is left behind isn’t because it has a different gravity, it has to do with the bonds between residual oil and grains in the reservoir. The oil in the pore space is produced and would be replaced with water or in some cases natural gas. Oil that is bound to sand or carbonate grains in the reservoir is termed residual oil. It is very difficult to breakdown those bounds under primary recovery given permeability from the open pore space is generally high enough that the adverse mobility ratio between oil/water or oil/gas takes over (you produce water or gas versus oil due to oil’s lower apparent permeability). So sorry, complete BS
To extract the heavier oil more energy must be transferred into the reservoir. More energy must be used to refine heavier oil. The energy cost to continue oil production increases as the quality of the oil declines.
This is not the case generally. API gravity does not always speak to cold oil flow. In Colombia, as an example, there are numerous fields that produce oil with API <15 with no additional energy needed as the oil has a viscosity of around 65 cp. Heavy oil in Alberta and Venezuela oil sands is different given it has undergone extensive biodegradation. As a consequence, you have very high viscosities (up to several thousand cp). But that is not the case universally. Not all low API oil requires additional energy to be produced. If you look at cost/bbl in some cases even heavy oils that need some processing and mixing in order to pipeline them are cheaper to produce than ultra-deep water sub-salt offshore oils. That cost is a direct measure of whatever energy might be used.
The oil prices are too high for the global economy.
That’s ridiculous. Current high supply is governed by US being at record output and OPEC having not cut back as much as promised. That being said World consumption and World production are currently quite close. If prices were too high you would see a serious drop off in demand/consumption which is not the case. Why would the world be buying more and more oil (consumption/demand is increasing) if they can't afford it?