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A platform lost

Print edition : Aug 26, 2005 T+T-

The ONGC loses one of its most productive processing platforms in the offshore Mumbai High field in a devastating fire.

IN one of the worst accidents in the Oil and Natural Gas Corporation's (ONGC) history, a massive platform called the Bombay High North (BHN) in the offshore Mumbai High field was gutted in a devastating fire on July 27. In a matter of two hours, the BHN platform, which had remained a beehive of activity for 24 years separating oil from gas, was reduced to molten metal. The fire broke out when the multi-purpose support vessel, Samudra Suraksha belonging to the Shipping Corporation of India ruptured a riser (pipeline) carrying oil from the wells to the BHN facility. In the resulting blaze, Samudra Suraksha, also caught fire. Samudra Suraksha, which was towed away by another multi-purpose support vessel, Samudra Prabha, sank on August 1, about 12 nautical miles from the Mumbai coastline.

Eleven persons were killed in the accident and 11 others are reported missing. Of the 383 personnel onboard the BHN complex, the Samudra Suraksha and a nearby offshore rig Noble Charlie Yester, 361 were rescued. The rescue, carried out in bad weather, was a coordinated effort by the ONGC personnel using Pawan Hans helicopters, offshore supply vessels and vessels of the Navy and the Coast Guard.

ONGC officials claim that it is "a mystery" how Samudra Suraksha, a dynamically positioned vessel, which can remain stable on the sea, went out of control and hit the riser. The vessel has computer-controlled thrusters that can hold it in one position on the sea. Why did it go so close to the BHN platform when it is supposed to remain at least a few hundred metres away from it? What is even more puzzling is how Samudra Suraksha, which got towed away and remained afloat for five days, sank on August 1? ONGC officials said the vessel had developed a hole through which water gushed in and destabilised it.

Subir Raha, Chairman and Managing Director of ONGC, told a media conference in Mumbai on July 28 that "In terms of loss of property, this has been the most serious accident in our history." He described the BHN as "a total loss". The accident has caused a production loss of about 1.20 lakh barrels of oil and about 4.4 million cubic metres of gas a day. Engineers working round the clock hope to restore 70 per cent of the production in four weeks. Raha, who was at the Mumbai docks to receive the first boatload of survivors, said that despite the courageous attempts by the ONGC personnel onboard the BHN, the fire could not be controlled. Conditions on the high seas were difficult and the men were ordered to abandon the platform. "Platform abandonment is part of our safety training procedures, and luckily, the personnel executed the platform abandonment as trained and in due order," he said.

THE Mumbai High field occupies the pride of place among the ONGC's various oil and gas fields. It is India's biggest hydrocarbon reserve. The Mumbai High basin is situated in the Arabian Sea, about 160 km off the Mumbai coast. Ever since its discovery in 1974, it has remained the largest producer of oil in the country. According to "Mumbai High, 30 Years, A Historical and Pictorial Perspective", published by the ONGC in 2004, the Mumbai High Basin is 75 km long and stretches across 25 km. On January 31, 1974, the ONGC first began drilling for oil in the Arabian Sea with an offshore rig called Sagar Samrat, in an area identified by seismic studies to have sedimentary deposits, which could contain oil. Three weeks later, on February 18, oil was found. The field has more than 551 oil wells and 33 gas wells.

In all 227 ONGC workmen were at the BHN complex, manning the facilities that processed oil and gas. Risers carried the hydrocarbons from the wells located nearby to the BHN platform. After separation oil and the gas are sent onshore by separate undersea pipelines. While gas is compressed and sent by pipelines, oil pumped under a certain pressure flows through separate pipelines. Both reach Uran, where they are processed further.

About 300 metres from the BHN is another platform called NA, from which wells are drilled. The unmanned NA was the first platform to be installed in the Mumbai High Basin. Below the NA is about half a dozen producing wells. The NA is an unmanned platform. In the vicinity, there is a third platform called BHF with wells situated below. The BHF platform has residential quarters. The BHN, the NA and the BHF platforms are connected to one another by bridges. Close by is the Water Injection North (WIN) platform, which also has residential quarters. An additional water injection platform was commissioned there recently. All these are interconnected by bridges. Close to the NA platform, a privately owned rig called Noble Charlie Yester, under charter with the ONGC, was drilling a well.

Supplies to these platforms are made by multi-purpose support vessels, which are big in size, and smaller offshore supply vessels. The vessels have divers and fire-fighting equipment. Equipment to and from the platforms are transferred by cranes onboard these vessels. Normally, the multi-purpose support vessels and the offshore supply vessels are allowed to go near the platforms only when the sea conditions are normal.

On July 27, Samudra Suraksha was positioned near the BHN platform. A cook aboard the vessel had cut his fingers. Around 4-05 p.m., when the cook was being transferred from the vessel to the BHN complex, where medical attention was available, the vessel reportedly lost control and collided with a pipeline. The riser broke and oil started leaking. The oil caught fire and gas, under high pressure, began to escape. A ball of flame reportedly fell on the BHN platform. The fire was so intense that the BHN crumbled into the sea in two hours. A helicopter onboard the platform was also lost. Samudra Suraksha caught fire and its personnel had to abandon it. Samudra Prabha tried to put out the fire. Personnel onboard Noble Charlie Yester, which also was affected by the fire, jumped into the sea.

The flow of oil and gas from the affected wells was shut down with the help of sub-surface safety valves. Since the platforms were connected by bridges, those on BHN could quickly escape to other platforms by following the evacuation procedures under the disaster management plan.

Survivors, who arrived by rescue boats of the Coast Guard at the Victoria Docks in the Mumbai harbour, had horrifying tales to tell. Many of them were in deep shock and reluctant to recall the incident. Some of them began to cry.

P.K. Mishra, an ONGC engineer aboard Samudra Suraksha, said the fire was so sudden and intense that it hardly gave them time to think about using lifeboats. "I was drinking tea with some colleagues when we heard an explosion. We then saw the fire. My colleagues and I grabbed the lifejackets, climbed down a ladder, jumped into the sea and swam really hard to get away from the platform," Mishra said. Some men jumped right off the platform, which was 35 feet high. Mishra looked shaken and tired but relieved. He said they floated in the turbulent waters for about five hours in the darkness before being saved by rescue boats. "I cannot believe I am alive," he kept saying.

Manohar Koshe, another engineer, actually saw Samudra Suraksha hit the legs of the platform. He said he saw the vessel being tossed around in rough waters and when it hit the platform, he was sure there was no way they could survive. "We did not seem to have a chance," he said. Koshe was among the lucky few who were able to get hold of lifeboats and row to safety. "We struggled in the lifeboats for an hour and then we were in the open sea," he said. A vessel, Ship Tern, picked them up. Koshe claimed that it took the BHN less than 15 minutes to go down. He believes that the crude oil spill on the platform caught fire.

Another version is that an offshore supply vessel hit the oil riser. This version, dismissed by ONGC officials as a case of rumour-mongering, discounts the possibility of Samudra Suraksha, which can remain stable on the sea, losing control and getting tossed about.

Raha said the ONGC had serious difficulties in mounting the rescue operations because Mumbai itself was under a deluge on that day. The ONGC's offshore control room in Bandra East was without power. Emergency power supply facility also failed because of the flooding. A three-member committee headed by S.K. Manglik, former Chairman and Managing Director of the ONGC, has been appointed to investigate the accident.