Firstly, the below site stated is extremely informative:
Basically (clearly non-exhaustive, but just for my reference):
Global economic crisis/ recession –> Downward pressure on prices of crude oil. This happens as demand decreases, thereby causing an “oversupply” of crude oil, hence pressure for suppliers to sell lower to maintain their margins.
Hence, same can be said vice versa. Global boom –> DD > SS –> prices hike.
WTI – West Texas Intermediate – a grade of crude oil used as a benchmark in oil pricing.