The world price of crude oil, which has been around 100 dollars a barrel for the past 6 years, has suddenly collapsed and is now tending below 50 dollars.  Many are trying to understand this rapid decrease and have proposed various explanations. Of course, the ready explanation is simply in terms of supply and demand; but this just begs the question.  The supply of oil has increased sharply in recent months – mainly because of the prolific production of shale oil in the United States, thanks to the technologies of fracking and horizontal drilling.  In fact, the US is now the world’s largest producer of crude oil and US imports of oil have dropped to the lowest level in 10 years.  At the same time, the demand for oil has not increased greatly -- because of depressed economic conditions and more efficient use in cars and trucks throughout the world.  US imports peaked 10 years ago at 10 mbd [million barrels per day], about 50% of...(Read Full Article)