Either you produce it or you lose the lease. If you shut a well in (close the valves), there is no guarantee it will produce like it did when you open the valve back up--in fact, most don't.
So most producers will continue to produce the well or plug and abandon it. The latter is done with cement pumped into the wellbore. It can be drilled out, but that costs almost as much as a new well, and the plugging process damages the porosity in the rock along the original wellbore. You can't just turn them on and off. It is a popular misconception with horizontal oil wells, but it just doesn't work that way.
Ok, agreed, “shutter” is the wrong term / way to look at it. But, the point is, there is a LOT of oil now available at moderate cost in relatively short time frames (under a year), all over the planet. The odds that, barring a major war, oil could go back up over $100 / barrel for over a year (in 2016 dollars), anytime in the next, oh, 20 years or so, seem pretty low.
Granted, Obama HAS set the world up for a major war in the next generation or so, with the likelihood of significant numbers of nukes involved increasing with time...