If you study the history of petroleum you will find that the price of oil has occasionally dropped to zero. This possibility terrifies the oil industry and for good reason.
The rule of supply and demand is always present and when there is too much supply the price of anything will drop. In an industry that has extraordinarily expensive overhead and infrastructure (like the oil industry) the risk of your product being worthless (or nearly worthless) is a real concern. In the early 1930's, overproduction of oil drove the price of oil below 13 cents per barrel and resulted in martial law being declared in parts of Texas.
In the current situation we had the confluence of two events: A price war between major producers (over-production) AND a dramatically reduced use of oil due to COVID19 (reduced demand). That combination resulted in a huge abundance of oil and no place to sell it.
If you're interested in the history of oil - An EXCELLENT book is, "The Prize, the epic quest for oil, money & power", by Daniel Yergin. There is also an 8 part documentary of the same name that is directly based on that book. I believe it's available on Amazon Prime.