Venezuela has raised the prospect of declaring force majeure on contracts with major crude buyers amid plummeting output from its oil fields and tanker bottlenecks at ports, Reuters reports.
It did not say if the employees were charged with any crimes.
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.
Svilen Petrov is 31 years old marketing manager and co-Chief Editor of Maritime Herald.
Venezuela is nearly a month behind delivering crude to customers from its main oil export terminals, according to shipping data, as chronic delays and production declines could breach state-run PDVSA's supply contracts if they are not cleared soon.
Venezuelan ports - facing lack of spare parts, limited operation hours and a dwindling workforce - have struggled to handle the increasing number of tankers, leaving customers with growing delays and unfulfilled supply contracts.
But the government of President Nicolas Maduro, condemned by the West and major Latin American nations over a May 20 re-election critics said was a farce cementing dictatorship, has been trying to project a more benign image in recent days. Venezuela's crude exports in the first five months of 2018 were 27 percent lower than in the same period of 2017.
Venezuela's crude exports fell 6% in May to 1.168-million barrels a day following US ConocoPhillips' legal actions to seize PDVSA's assets in four Caribbean islands, according to the data.
These transfers require specialised equipment, handling by specialists and facilitated by mooring masters, according to a provider of the service.
But the official, who spoke on condition of anonymity, said he had doubts over whether PDVSA could deliver on time and who would be given priority.
"A STS operation adds at least $1 per barrel to the purchase cost". The move would allow large vessels to be loaded from tankers temporarily used by PDVSA for storage, the source added.
It has separately begun notifying all its customers that it will no longer receive new tankers for loading at Jose or Paraguana, its main export terminals, until ships already in line are served.
Crude spills affecting the waters surrounding several PDVSA's ports at Venezuela's western coast is another risk some customers see as an obstacle for the transfers.