RIG's shares are trading 3.90% lower on the day at $65.36 as of 12 45 p.m. (ET) after The Wall Street Journal reported that Transocean Ltd. was involved in "73% of rig incidents investigated by the authorities since 2008".
The visit was intended to repair the damage to bilateral relations caused by the oil-rig incident.
The Libor rigging incident, first exposed in 2012 when Barclays was fined £290m, hammered the reputation of the industry and further fines for manipulating the benchmark rate are expected before the end of the year.
It was further claimed in the paper's article that Oldham Athletic player Cristian Montano failed to get a yellow card in return for money in a match against Wolverhampton Wanderers and offered to take part in another rigging incident.
The Super Puma AS332 L2 had been carrying 16 passengers and two crew from the Borgsten Dolphin oil rig when the incident happened at about 18 20 BST on Friday.
A separate Transocean presentation, which was provided to rig workers after the incident, cited a "lack of clear" procedures for controlling well pressure, "weakness in planning" the job's risk assessment and an absence of data about conditions in the well.
Although the Chinese removed the rig two months later, the incident continues to rankle Vietnam.
The grounding of Shell's drilling rig is not an isolated incident.
Despite having been built in 2009, the Discoverer Clear Leader had "a few notable safety related incidents on the rig during its relatively short operational history".
Last year, an incident at an Australian rig unleashed an oil drift the size of Maryland.
