Tombua-Landana

Location and Geology

The Tombua-Landana oil project is located approximately 80 kilometers offshore Angola, in the eastern part of Block 14 in the Lower Congo Basin, west Africa. The fields are situated in water depths ranging from 900 to 1,700 feet (274 to 518 meters), with the production platform itself in about 1,200 feet (366 meters) of water.

Discoveries and Reservoirs

The Tombua field was discovered in 1997 by the Tombua-1 well, and the Landana field was discovered in 2001 by the 14-6X/6XST-1 well. The reservoirs are of the Lower Miocene CN3 age and consist of high-quality sands deposited in a deepwater slope valley environment on the northwestern flank of the Congo River fan. These reservoirs are trapped by a combination of structural and stratigraphic traps.

Project Development

• Investment and Partners: The project involved an investment of $3.8 billion. Chevron operates the field with a 31% interest, while its partners include Sonangol Pesquisa e Producao (20%), Eni Angola Exploration BV (20%), Total E&P Angola (20%), and Galp Energia Exploracao e Producao (9%).
• Construction and Timeline: Construction began in September 2006, and the project came onstream in September 2009. The project received government approval in November 2006, and pre-drilling activities started in 2007.
• Infrastructure: The project features a 1,554-foot (474-meter) compliant piled tower (CPT), one of the world’s tallest man-made structures, supported by a four-leg configuration secured to the seafloor by 12 foundation piles. The platform includes an integrated deck with production facilities and a 120-person accommodation building. It has 38 well slots and is capable of simultaneous production and drilling operations using a tender-assisted drilling (TAD) rig.

Production and Capacity

• Oil Production: The project is expected to reach peak production of 100,000 barrels of crude oil per day by 2011. The recoverable resources are estimated at 350 million barrels.
• Gas Production: The associated natural gas is processed and commercialized through the Angola Liquefied Natural Gas project in Soyo, Angola. The platform has a capacity for 210 million cubic feet per day of gas.
• Water Management: The project is designed for zero discharge of produced water and zero routine gas flaring. Produced water is treated and reinjected into the reservoirs.

Technological Innovations

• Drilling and Production: The project utilized a TAD rig moored near the production platform for drilling operations. This was the first use of a tender-assisted drilling rig for a fixed structure in deepwater.
• Environmental Considerations: The project incorporates advanced technologies such as sulfate removal membranes for seawater treatment and a system to treat and reinject produced water into the reservoirs, ensuring no discharge into the ocean.
• Subsea System: The subsea system includes two subsea manifolds, one for production and one for water injection. Two export pipelines were installed for gas and oil, connecting to the BBLT export pipelines.

Operational Highlights

• Benguela Belize Lobito Tomboco (BBLT) Project: The Tombua-Landana project is part of the larger BBLT development in Block 14. The BBLT project started oil production in January 2006 with the Benguela Belize field, followed by the Lobito-Tomboco field in June 2006.
• Local Engagement: The project engaged local suppliers for key components and had a significant local workforce, with Angolans comprising more than 80% of the in-country workforce.

Safety and Execution

• Installation Challenges: The installation process involved dual-crane lifts for greater control and capacity, emphasizing safety due to the use of large pieces of steel, cranes, and heavy machinery.

The Tombua-Landana project is a significant milestone in Chevron's deepwater developments in Angola, showcasing innovative technologies and a strong commitment to environmental sustainability and local engagement.