What is the impact of fracking on oil prices? I read an article about the recent fall of gas prices in the US claiming that the fall in gas prices was due to the expansion of fracking within the US.  The article said that, over the past few months, the oil harvested from fracking had come onto the market reducing the price of gas at road-vehicle refueling stations. 

Obviously, I realize that an increase of supply with a constant demand will decrease prices.  But, is there any way to validate the article and conclude that the decrease in oil prices was due to fracking?  The article I read did not go into detail on how they reached their conclusion.
over the past few months, the oil harvested from fracking had come onto the market reducing the price of gas.

Obviously, this makes no sense insofar as the oil harvested from fracking displaces oil harvested by other means.  

Absent changes in supply or demand, the price of oil has to rise at the rate of interest.

The development of a new extraction technology is a one-shot increase in supply, which should lead to a one-shot fall in price, followed by a resumption of the ongoing increase at the rate of interest.  It can't (by itself) explain an ongoing fall in price.