I found an article by
Clifford Krauss and one of the reasons for falling oil prices is as follows:
"There are a number of conspiracy theories floating around. Even some oil executives are quietly noting that the Saudis want to hurt Russia and Iran, and so does the United States - motivation enough for the two oil-producing nations to force down prices. Dropping oil prices in the 1980s did help bring down the Soviet Union, after all.
But there is no evidence to support the conspiracy theories, and Saudi Arabia and the United States rarely coordinate smoothly. And the Obama administration is hardly in a position to coordinate the drilling of hundreds of oil companies seeking profits and answering to their shareholders."