Venezuela has been wracked by political turmoil and a severe recession and hyperinflation.
Oil is the financial lifeline for the embattled socialist government of President Nicolas Maduro, but his cash-strapped administration has failed to invest enough in the industry to prevent its decline.
Svilen Petrov is 31 years old marketing manager and co-Chief Editor of Maritime Herald.
If they do not accept the terms, PDVSA is considering force majeure, in essence declaring its contracts incapable of being fulfilled, the sources familiar with the matter said.
Most customers have so far refused the ship-to-ship transfer request due to the lack of a third party supervising the operations, according to shippers and traders. Additional costs for completing the transfer also contributed to the refusals.
The delays have mounted since May, when asset seizures forced PDVSA to stop using Caribbean facilities for storing and loading export cargoes.
There were OVER 70 tankers off the coast of Venezuela on Tuesday, according to Thomson Reuters vessel tracking data.
These transfers require specialised equipment, handling by specialists and facilitated by mooring masters, according to a provider of the service. The captain of the receiving tanker also had to be trained to perform the operation, a shipper said.
The price of Venezuela's Merey crude, the main grade exported from Jose port, rose to $60.24 a barrel in April.
Venezuela's crude exports fell 6 percent in May to 1.168 million bpd following U.S. ConocoPhillips' (COP.N) legal actions to seize PDVSA's assets in four Caribbean islands, according to Reuters data.
The shortfall, which has not been previously reported, shed new light on the depth of the company's problems extracting and refining crude - despite repeated promises by Maduro and PDVSA President Manuel Quevedo to grow 2018 production by 1 million bpd. "The question is who will take responsibility for that", said Robert Campbell, head of oil products markets at consultancy Energy Aspects.
Insurance coverage for tankers and cargoes would also have to be changed to include the STS operation if customers accept the option, Campbell added.
Crude spills affecting the waters surrounding several of PDVSA's ports at Venezuela's western coast is another risk some customers see as an obstacle for the transfers.