The Incident

On 27th July 2005, a multi-purpose supply vessel (MSV) – The Samundra Suraksha was in the final stages of completing a diving campaign. At around mid day, a crew member aboard the MSV had been injured and was in need of immediate medical attention.

Upon recovery of the diving bells from the water, the MSV’s master requested the injured personnel be transported to the platform for medical treatment. Weather conditions were extremely unfavorable due to high winds that rendered the situation unsafe to operate the chopper on-board the platform.

The MSV was located on the leeward side of the platform. However, as the leeward side crane was out of commission at the time, it could not be used to perform the personnel transfer. The MSV therefore, approached the platform from the windward side.

The MSV’s master noticed that the starboard thrusters of the vessel were sluggish. Nevertheless, the transfer of the injured person was completed successfully and the MSV started to back away from the platform when a sudden heave forced the MSV towards the platform.

The MSV’s helipad struck several of the platform’s marine export risers resulting in a gas leak that ignited and exploded rapidly. Hydrocarbon flow in the risers could not be contained by the emergency shutdown systems and 11 lives were lost as the fire destroyed the entire MHN platform. 11 other members were reported lost at sea and were never found.

The Aftermath

The intensity of the fire could not be controlled and hence resulted in the abandonment of the MHN platform. Within a few hours of the main explosion, the entire platform collapsed into the sea with only a few foundation piles left exposed. The MSV Samundra Suraksha was also severely damaged by explosions and fire. The vessel was towed away by another MSV but sank later on 1st August 2005, 12 nautical miles from the Mumbai coastline.

Root Causes

The two primary causes of the MHN incident were identified to be:

• The lack of a regulatory body for the governance of offshore safety in India.
• The lack of adequate procedures and measures for risk mitigation.

MSV, Samundra Suraksha.

The Samundra Suraksha was a dynamically positioned supply vessel that was stationed along side the MHN platform. The DP capability of the vessel would have allowed for adequate thruster output in order to control the position of the vessel with respect to the platform efficiently, even in rough seas.

Records indicate that when the injured person transfer was about to begin, the MSV captain noticed discrepancies with the DP system of the vessel; the thrusters were observed to be sluggish. The captain of the MSV should have called for an all-stop when the discrepancies with the thrusters were observed. However, due to the urgency of medical help for the injured person, the MSV was moved closer to the platform when the DP system was operated manually.

MHN Platform Export Risers.

The export risers on the MHN platforms contained large volumes of flammable gas flowing through them. Therefore, adequate number of safety valves capable of stopping flow through the risers should have been installed. Contingency valves should have been installed at a subsea location. Once the integrity of the risers was lost following the collision, there were no means to stop the gas flow from the well.

Way Forward

Following the incident, production was restored in about 5 weeks. The pipelines were routed to the Mumbai High South (MHS) facility. The platform was reconstructed by ONGC in 2006 with heavy expenditure. The incident marked the formation of an offshore safety regulatory body in India to monitor and govern offshore oil and gas activities.