The Amazon challenge: Petrobras builds the Urucu – Coari – Manaus Pipeline

Swelling bodies of water, unfavourable soil conditions and the threat of tropical diseases were just some of the challenges overcome by project managers and engineers during the construction of Brazil’s 661 km Urucu – Coari – Manaus Pipeline.

As one of Brazil’s biggest natural gas transportation developments, the Urucu – Coari – Manaus Pipeline is designed to transport gas produced in the Solimões Basin in Urucu, to Manaus, the capital city of the state of Amazonas, located in northern Brazil.

The SolimÕes Basin is Brazil’s second largest gas reserve, holding an estimated 52.8 Bcm of gas. Currently, 4.1 MMcm/d of gas is transported through the pipeline, with capacity to increase to 5.5 MMcm/d of gas once construction on the Juaruna and Coari compressor stations is completed in October 2010.

The main trunkline is divided into two sections:

  • An 18 inch diameter, 278 km Urucu to Coari API 5L X65 steel pipeline section; and,
  • A 20 inch diameter, 383 km Coari to Manaus API 5L X70 steel pipeline section.

Between Coari and Manaus, seven laterals totalling approximately 140 km in length have been built to supply the municipalities of Coari, Codajás, Anori, Anamã, Caapiranga, Manacapuru and Iranduba, as well as two additional branches to supply the Aparecida and Mauá power stations in Manaus.

Converting to gas

The Urucu – Coari – Manaus Pipeline was developed to monetise the gas reserves in the SolimÕes Basin and to replace the liquid fuel used for power generation at the Manaus plants.

Until the gas pipeline was built, nearly 80 per cent of the natural gas in the Urucu province had to be re-injected into the gas field as there had been no way to transport the product to the market.

Petrobras has said that the pipeline will be the driving force for a change in the power consumption of Amazonas state, once the region’s power plants begin to substitute liquid fuel for natural gas.

A tale in three spreads

Construction on the pipeline began in July 2006, and was split into three spreads through the Amazon Rainforest.

Section A – Urucu to Coari

The first spread involved converting the 18 inch diameter, 279 km Urucu to Coari section from LPG to natural gas service. A 10 inch diameter pipeline was then constructed to transport LPG, which came online in February 2009.

Section B1 – Coari to Anamã

The 20 inch diameter, 196 km second spread provided many challenges, beginning with access and transportation. Helicopters capable of supporting up to 4.5 t were used to transport pipe where there was no land or river access. Lengths of pipe were tied to 80 m long wire ropes and lowered by helicopter onto the pipeline spread. This method was used along 75 km of the pipeline route.

Petrobras used several techniques traditionally used for laying pipes in the sea or underwater, burying the onshore pipeline using ‘platform barge pushing’ and horizontal directional drilling (HDD) to install the pipeline. The solution allowed for work to continue even during the rainy season, between November and June, in hard-to-access areas.

Section B2 – Anamã to Manaus

The final 186 km Anamã to Manaus section of the pipeline route traverses through 135 communities and associated urban infrastructure, including 46 km of roads within close proximity to the gas pipeline.

Petrobras conducted awareness campaigns with the local communities, as well as environmental educational courses and social projects. Compensation for the construction of the pipeline was negotiated through agreements with the Amazonas state government.

Engineering solutions to Amazonian challenges

The Amazon region is characterised by intense rainfall, which causes massive variations in the level of bodies of water – known as igarapés – and rivers, in some cases by as much as 13 m. The rainfall also impacted soil conditions, which posed a challenge for machine transportation and worker access to job sites, with some areas taking up to six hours to traverse.

A Petrobras spokesperson said “In order to overcome these difficulties, specific to the Amazon region and never before seen in the construction of other gas pipelines in Brazil, Petrobras adopted novel solutions in a few sections of the construction.”

Barge work

In flooded sections of the pipeline spread, barges were turned into floating construction sites, where pipes were welded to form sections measuring 1 km each. Attached to floats and barrels, the sections were transported by tow boats to other barges, where they were coupled to pipe sections that had already been set into position. The ties were then undone, one by one, in order to lower the pipes onto the ranges that had previously been cleared in the flooded areas. At least 6,000 floats and barrels were used in the operation.

“This solution allowed work to continue throughout the period in which the rivers flood, from November to June, in sections where access by land is difficult and during which the gas pipeline is completely submerged,” said a Petrobras spokesperson.

Directional drilling

Petrobras also deployed additional measures to preserve the Amazon’s rivers and riverbanks. Along the 661 km of trunkline, 19 river crossings were completed using HDD. The longest and deepest was the tunnel made under the Solimões River. It is 1.8 km long and runs at a depth of 102 m.

The pipeline workforce

In order to reduce worker transportation times, 22 camp sites were installed in the jungle along the pipeline route. Each camp was capable of lodging 160 people, and was based on the model adopted by the Brazilian army for survival in the forest.

Approximately 70 per cent of the labour workforce was hired locally.

“When building a gas pipeline in an area where there is a fragile ecosystem, one of the principles was to attenuate the impacts construction had on the region. One of the alternatives was to use local labour to the greatest possible extent and avoid migration to the region,” a Petrobras spokesperson said.

At peak construction 8,900 people worked directly on the pipeline site, and about 8.7 per cent of those were women. Another 26,700 jobs were created indirectly from the project. Petrobras estimates that 95 per cent of the material used during the pipeline’s construction was made in Brazil, and up to 85 per cent of machines and equipment used had been sourced locally.

Supplying the future

The Urucu – Coari – Manaus Pipeline was inaugurated by Brazilian President Luiz Inácio Lula da Silva in November 2009 at a ceremony held at the first gas recipient from the new trunkline, the Isaac Sabbá Refinery in Raman.

Mr Lula da Silva said that he expects Amazonas state’s power stations – including seven in Manaus with a combined installed capacity of 725 MW of electricity – to convert from liquid fuels to natural gas by September 2010, in time for the pipeline to become fully operational in October. The converted power stations have been coming on line in stages, with the first commissioned in January 2010. Currently, there are two more power stations to be converted and commissioned. The conversion to natural gas will mean a carbon emissions saving of nearly 1.2 MMt/a.

Petrobras subsidiary Transpetro now operates the pipeline via 24-hour remote control monitoring located at the National Operational Control Centre in Rio de Janeiro. In the event of a gas leakage, the system will shut down automatically.

The project is an important step to changing the face of power generation in northern Brazil, which has tapped into the previously under-utilised gas resources in Amazonas state, securing the region’s energy supply for the future.

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