How Shell stopped Bonga oil leak in 5 days – Official

Emma Amaize

05 January 2012, Sweetcrude, WARRI – SHELL Petroleum Development Company, SPDC, yesterday, gave graphic details of how it combated in five days the less 40, 000 barrels of oil that leaked, December 20, 2011, from its Bonga FPSO, while transferring oil to a loading tanker, with Hercules Aircraft from United Kingdom and another plane from Ghana, which sprayed dispersants on the oil along five seaborne vessels.

It said what happened on December 20 was not an oil spillage, but a leakage during a routine operation of oil transfer to a loading tanker, and was, therefore, surprised at the avalanche of avalanche of spillage being claimed by some communities in the Niger-Delta from a leak it effectively plugged, five days after.

The clean up

According to an email statement to Vanguard by a top SPDC official, “We estimate that the volume of oil that leaked was less than 40,000 barrels. As you might be aware, the spill occurred during a routine operation to transfer oil from the Bonga FPSO to a loading tanker. To be clear, this was not a well failure, where oil will be gushing out without control. The Bonga leak was quickly brought under control as we shut the line on noticing the oil sheen on the surface of the water around the FPSO”.

“What made the difference to the management of the spill was the speed of response. On noticing an oil sheen on the surface of the water around the Bonga FPSO on December 20th, 2011, we shut down the export lines, thereby stopping the flow of oil; informed local government/regulatory authorities and mobilized emergency operations crews.

“We set up a Country Crisis Team and Emergency Response centres in Lagos and Warri who were in 24-hour connection with a support team at our Group offices in The Hague. We also got the support of many third parties including Clean Nigeria Associate (National tier-2 response agency), other IOCs – ExxonMobil, NOAC and government agencies – DPR, NOSDRA. UK-based Oil Spill Response flew in with a Hercules aircraft, assisted by another plan from Ghana, which sprayed dispersants on the oil along with five seaborne vessels. In addition, we deployed booms to stop the spread of the oil and skimmers to recover spilled oil”, he said.

According to him, “The oil was largely dispersed by Sunday, December 25, 2011 due to natural processes (dispersion, spreading and evaporation) and the integrated efforts of SNEPCo, government and our industry partners. Initial modeling suggested 50 per cent to total spill was gone via natural processes by December 22, 2011”.

“Oil disperses naturally though evaporation and bio-degradation. Dispersants speed up natural dispersion. Main benefits are that they remove concentrated oil from water surface and disperse oil into the water column where it naturally degrades. The magic you refer to is the combination of all these efforts and timely support from Government agencies including Customs and Immigration. The Minister of Environment acknowledged these efforts when she visited Bonga”, he added.

Oil on shoreline

He continued: “It is important to understand that the Bonga FPSO is 120km offshore, about one hour by a helicopter flight from Warri. There are no communities near the facility. As part of our emergency response planning, we envisage the most likely emergency response scenarios and plan accordingly. To ensure no oil from the Bonga leak reached the beach, we leveraged assets from around Shell’s global portfolio”.

“We also worked with and benefited from the assistance of our industry partners. Our main goal was to ensure the oil fully dispersed and that none of it reached the shore. We were successful.

“In addition to natural processes, our primary strategy was to disperse all of the oil offshore with dispersants. We attempted to install protective booms in the event any of the oil came close to shoreline areas. We performed continuous surveillance using aircraft and satellite to track and target the oil”, he added.

His words, “We believe the oil on the beach is not from Bonga. We made significant progress every day to disperse the oil that leaked from Bonga We were disappointed to see images of a third party spill which appeared to be from a vessel, in the middle of an area that we had previously cleaned up”.

“We are confident that any oil of that age, color and consistency that hits the beach is not ours. We are taking samples as part of the joint investigation which will be reviewed to provide evidence that this is not Bonga oil on the beach.. We advise all parties to wait for the outcome of the investigation of the oil sample which will be handled by a reputable lab overseas”, he further stated.

He asserted, “It will be good if all parties would wait for the outcome of the investigation. However, as any responsible corporate citizen would do, we are working closely with communities towards clean-up of the oil on some parts of the Western Niger Delta coastline, irrespective of its source. We have continued to engage communities on the cleanup, and also taken some community leaders on an over flight of the Bonga area during which they saw the oil around Bonga had dispersed”.

Dispersants used for the clean-up

on the dispersants that were used, he said, “We used Corexit 9500 and 9527 (which were also applied in the Gulf of Mexico) and Slickgone NS. Dispersants were specifically formulated for use in marine environments and they have low toxicity. They are less toxic than many products that people use at home every day in bathrooms or kitchens. Dispersants are about five times less toxic than oil and they are applied in very low volumes (1-5% of oil volume)”.

“By dispersing oil from high concentrations on surface of sea into water column where there is essentially unlimited dilution and microbial breakdown, exposure is reduced to the greatest extent possible. This process takes place in about a month and the waters recover quickly to background levels”, he said

About the Author