PDVSA's tumbling crude production, chronic breakdowns of its heavy crude up-graders and difficulty importing critical light crude and naphtha are progressively reducing the amount of oil available for export, Argus said.
The arrests of Carlos Algarra and Rene Vasquez, by intelligence agents at Chevron's Puerto La Cruz offices, spooked other foreign companies operating in the OPEC nation in partnership with state oil company PDVSA.
The company has told some customers it may declare force majeure, allowing it to temporarily suspend export contracts, if they do not accept new delivery terms, including seaborne transfers.
PDVSA's oil production has been plummeting and it is currently around 1.4 million bpd, according to estimates.
One of PDVSA's Indian customers confirmed it had received a request to load its cargoes via ship-to-ship transfers.
The cash-strapped company pulled back from several Caribbean islands where it prepares cargoes for export after ConocoPhillips COP.N seized assets to enforce a $2 billion (£1.5 billion) arbitration award in a dispute over the socialist government's nationalisation of the U.S. oil producer's Venezuela assets.
The lack of export and storage terminals, especially those with deep water docks to load large vessels bounded for Asia, has forced PDVSA to divert tankers to Venezuela in recent weeks.
It did not say if the employees were charged with any crimes.
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.
Venezuela, the oil country, has problems with gasoline and other derivatives of black gold.
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 has to be trained to perform the operation, a shipper said.
Venezuela's exports of crude declined 28 percent in the first four months of 2018 to 1.19 million bpd compared with 1.65 million bpd in the same period last year, according to Reuters trade flows data. "The question is who will take responsibility for that", said Robert Campbell, head of oil products markets at consultancy Energy Aspects. PDVSA will still have to load vessels at its Jose port for transporting the crude to its proposed offshore loading facility.
Insurance coverage for tankers and cargoes would also have to be changed to include the STS operation if customers accepted the option, Campbell added.