The Famous Duri Oil Field

Duri to Dumai Road Construction in 1958

Eighty years ago, CALTEX discovered the huge Duri oil field in the Rokan block in Riau, Sumatera.

Oil was found at a shallow depth of 400 feet when CALTEX began drilling its exploration wells in 1941. After CALTEX managed to obtain the approval from the newly formed government of Indonesia to operate in the Rokan block under a work contract scheme, oil production began in 1954.

The giant Duri field – 10 km wide and 18 km long – is one of the many oil fields discovered in the Rokan block. Minas is another giant oil field discovered in this block.

Oil production peaked at 65,000 BOPD in the 1960s.

Due to the high viscosity of the low gravity oil, to enhance the production, the steam injection was introduced in 1985.

The Duri steam flood project was so successful that it became one of the largest and the best steam floods in the world.

Thanks to the successful steam injection, Duri oil production increased significantly to 185,000 BOPD.

After 30 years of the steam flood, the production had declined to about 50,000 BOPD by 2017.

With more than 2.6 billion barrels of cumulative oil produced, the giant Duri field is still producing today.

Chevron will hand over the operatorship of the Duri field and the Rokan block to Pertamina in August 2021.

The West Seno Oil Field

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From top left clockwise: The tension leg platform of West Seno (TLP-A), a drilling support vessel, and the floating production unit (FPU).

Discovered by Unocal in 1998, the West Seno field, lying in water depths of about 3200 feet, is the first deepwater oil field in Indonesia.

Located in the Strait of Makassar, the West Seno field is about 50 km away from the giant Attaka field and 60 km from the Santan terminal in East Kalimantan.

The oil and gas are produced through a tension leg platform (TLP) which is also the first of its kind in Indonesia.

The floating topside of the tension leg platform is attached to the seafloor by four 3200 feet long tendons having a diameter of 26 inches and a wall thickness of 1.036 inches.

Currently, all the subsea wells are produced from platform TLP-A which can accommodate 28 wells. Unocal originally had planned to build two tension leg platforms.

Oil production from the West Seno wells began in 2003 and currently, they are producing about 1200 BOPD. The fluids from the subsea wells are initially separated into oil and gas on the FPU (Floating Production Unit).

The separated oil and gas are then transmitted via two 12-inch diameter and 60 km long pipelines to the onshore facilities at Santan for final handling and storage.

One of the oil production challenges of West Seno is handling the difficult-to-break emulsions. The emulsions are hard to break due to the presence of certain chemicals in the fluid, the decreasing fluid temperature as it rises to the surface, and the motion of the floating platform.

The West Seno offshore production facilities also handle the production from the nearby Bangka field. Bangka field produces about 1000 barrels of condensate daily and 40 MMSCF of gas per day.

The development of the West Seno field was made possible by having a favorable PSC profit splits of 35 percent instead of the regular 15 percent for shelf developments.

The field is currently operated by Chevron.

History of the Giant Attaka Oilfield

Pres. Soeharto di Santan

Fifty years ago, Union Oil of California (UNOCAL) along with its partner, INPEX, discovered the giant offshore oil field Attaka in East Kalimantan.

General Soeharto, the president of Indonesia at that time, then inaugurated the Attaka field and the Santan terminal on 22 January 1973.

In the early days of Attaka and the Santan terminal, there were many workers from the US and UK. Over time, they were gradually replaced by Indonesian workers.

Unocal operated the oil field for 25 years from its East Kalimantan headquarters located in Balikpapan. The Attaka field was subsequently acquired and operated by Chevron, and then by Pertamina Hulu Kalimantan Timur beginning on 25 October 2018.

At 50 years old, the field is still producing today.

Thousands of oil people – expatriates from many nations and Indonesians from every region – have visited and worked in the offshore facilities and the onshore Santan terminal including me.

I worked in the Attaka field as “Production Foreman” in 1980. I hope you like this snippet of the history of Attaka and the Santan terminal.

If you like to read more about the Attaka field here is The Ten Interesting Facts About Attaka.

WRITTEN BY

Jamin Djuang – Chief Learning Officer of LDI Training and author of The Story of Oil and Gas: How Oil and Gas Are Explored, Drilled and Produced

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The Giant Carcara and the Pre-Salt Basin

A semisubmersible drilling rig

 

The Giant Carcara Oil Field

The giant Carcara is a pre-salt oil and gas field located in the Santos basin offshore Brazil. It lies in water depths of 2027 meters and is one of the biggest discoveries in the world. It was discovered by Petrobras in 2012.

The oil reservoir lies in the pre-salt layer and its total thickness is more than 400 meters. It is estimated to contain recoverable reserves of more than one billion barrels of oil.

Operated by Equinor, oil production from the Carcara field is scheduled to start in 2024. Two FPSOs will be used to produce the oil and gas.

The Interesting Pre-Salt Basins

Oil was discovered in the Pre-Salt Basin in offshore Brazil in 2005. Oil-rich formations sit deep in the water and under thick layers of rock and salt.

Pre-salt basins were formed more than 100 million years ago when the South American and African continents separated, and therefore pre-salt layers are especially common off the coast of Africa and Brazil.

The hydrocarbon sits under layers of salt formations that are 2000 meters thick. The pre-salt production rates are some of the highest in the world for deepwater fields.

In Africa, the first pre-salt oil discoveries took place in Angola in 1983. The presence of pre-salt basins in eastern offshore Brazil and western offshore of Africa is proof that the South American and African continents were connected at one time.

This article was written by Jamin Djuang, a published author of “The Story of Oil and Gas: How Oil and Gas Are Explored, Drilled and Produced” for readers who have not seen an oil field.