Bonga oil field, Nigeria

The Bonga Field is an oilfield in the sea off Nigeria, about 120 kilometres southwest of the Niger Delta. It sits in water about 1,000 metres deep and covers roughly 60 square kilometres. It was discovered in 1996 and started producing in November 2005.

Instead of a platform fixed to the sea floor, Bonga uses a floating factory ship called an FPSO, short for Floating Production Storage and Offloading vessel. The field makes both oil and natural gas. Oil is loaded onto tankers, and the gas travels by pipeline back to Nigeria to be turned into liquefied natural gas. The field is estimated to hold about 6,000 million barrels of oil. The globe marks it as an oil site in the Gulf of Guinea.

Finding the oil

The block was first studied with a 3D seismic survey in 1993 and 1994, which maps rock layers under the sea floor using sound waves. The first discovery well was started in September 1995.

The government approved development in 2002. Smaller neighbors were found later: Bonga SW in May 2001 and Bonga North in 2004. Shell Nigeria runs the field and owns 55 percent. ExxonMobil has 20 percent, and Nigerian Agip and Elf Aquitaine hold 12.5 percent each.

A floating factory

The Bonga FPSO was built by Samsung Heavy Industries and then towed to Newcastle upon Tyne in England to have its processing equipment installed. It processes about 225,000 barrels of stabilised crude oil per day.

Oil from the wells under the sea comes up through pipes called risers to the ship, is stored in its tanks, and is offloaded to tankers. The field started with 16 wells for producing oil and injecting water, and the plan was to grow to nearly 40.

Troubles and new plans

In June 2008 production stopped for three weeks after an attack by the Movement for the Emancipation of the Niger Delta. In December 2011 an oil spill, probably under 40,000 barrels, made a slick about 185 kilometres long, probably the worst in the area for a decade.

In 2023 the main FPSO produced its one-billionth barrel. In December 2024 Shell decided to invest in Bonga North, a project of 16 wells expected to cost about 5 billion US dollars.

On the globe

The model shows a giant floating production ship on the open sea off Nigeria.