Some of the reports on the oil tankers state that many of the tankers are sitting for days/weeks waiting to be offloaded. China is supposedly at the highest reserve levels ever and simply has no additional storage space, hence the reason why tankers are not being unloaded. If true, tankers are still need to transport oil since the production levels have not decreased and ports of exit only have some much capacity to hold. Check out the following link: Oil glut deepens with 100m barrels at sea
I think a few things are in play: 1) tankers are being used as storage, or were while they were cheap. Worth watching to see if it persists now that lease rates are up; 2) everybody wanted to do container shipping and dry bulk when China was the rage, so few ports added tanker capacity— the easy money was in developing ports that served the former rather than the latter; 3) large customers are topping off while oil is cheap; 4) OPEC members are trying to increase market share, which has meant more shipping of product to existing customers and new customers.