This is a wild guess, and I cannot be sure the same pattern will follow. It is for educational only and please feel free to share your opinion and thoughts, whether you agree or disagree with this observation.
In 2008, oil fell from its all-time high from @ $144 to $36 (~75%), and then oil dropped again in 2014 from $107 to $29 (~73%). If the previous two drops are indicators of this one, we can assume oil going to $20, which is about 70% of its recent high and another 55% drop from current level. This cycle should complete within in the next 4-6 months.
In 2008, oil fell from its all-time high from @ $144 to $36 (~75%), and then oil dropped again in 2014 from $107 to $29 (~73%). If the previous two drops are indicators of this one, we can assume oil going to $20, which is about 70% of its recent high and another 55% drop from current level. This cycle should complete within in the next 4-6 months.