It's a chess match,but with multiple players, with low cost producers and high cost producers. There are importing nations and exporting nations. Changes in capex spending takes time before it is reflected in production. Some countries just don't like each other, like Iran vs Iraq, or the US vs Russia. Other countries need oil revenue to fund their social programs. Then we have the speculators who can bid on options and futures.
The collapse in oil prices seems pretty drastic. It won't stay this low forever, but it's anyone's guess what action might start a rebound.