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.
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.
The average crude oil production in Indonesia in 2018 is 803,000 barrels per day according to SKK Migas of Indonesia.
Here are the top ten crude oil-producing companies in Indonesia in 2018.
Chevron Pacific Indonesia – 209,000 BOPD
Chevron is the biggest oil producer in Indonesia in 2018 and has been a leading oil producer in Indonesia for more than 90 years. It started operating in Indonesia in 1924 under Standard Oil Company of California (SOCAL).
Chevron operated oilfields in Sumatera and East Kalimantan. It’s East Kalimantan assets came from the acquisition of Unocal in 2005. Chevron handed back all the assets in East Kalimantan to the Indonesia government on October 24, 2018, after 50 years of operation under Unocal and Chevron.
Currently, Chevron’s oil production comes mainly from the oil fields located in Riau, Sumatera under the Rokan Production Sharing Contract. The biggest oil field in the Rokan PSC is the Duri field which has been under steam-flood since 1985 and is one of the largest steam flood projects in the world. Minas is another giant oil field that Chevron discovered and operated in the Rokan Block.
ExxonMobil Cepu Ltd – 208,000 BOPD
ExxonMobil Cepu Ltd is the operator of the Cepu block located in Central Java and East Java. The Cepu Cooperation Contract (KKS) was signed on 17 September 2005 and will continue until 2035. ExxonMobil holds a 45% interest in the Cepu block.
ExxonMobil started exploration in 1999, and the oil from the Banyu Urip field started to flow in December 2008.
Pertamina EP – 79,000 BOPD
Pertamina EP operated 21 oil and gas fields located in various parts of Indonesia. These oilfields are managed under five asset groups based on their geographical locations.
Located in North Sumatera and some parts of South Sumatera, the Asset One oilfields include Rantau Field, Pangkalan Susu Field, Lirik Field, Jambi Field, dan Ramba Field.
Located in South Sumatera, the Asset Two oilfields include Prabumulih Field, Pendopo Field, Limau Field dan Adera Field.
Located in West Jawa, the oilfields included in Asset Three are Subang Field, Jatibarang Field dan Tambun Field.
Located in Central and East Jawa, the Asset Four oilfields include Cepu Field, Poleng Field dan Matindok Field.
Located in the eastern part of Indonesia, the oilfields in Asset Five are Sangatta Field, Bunyu Field, Tanjung Field, Sangasanga Field, Tarakan Field dan Papua Field.
Pertamina Hulu Mahakam – 42,000 BOPD
Pertamina Hulu Mahakam became the operator of the oil and gas fields located in the Mahakam Block on 1 January 2018. The fields were previously discovered and operated by Total along with Inpex as its partner. They acquired the block in 1966.
Several giant oil and gas fields are located in this block such as the Handil field, the Tunu field, and the Peciko field.
Pertamina Hulu Energi OSES (Offshore South East Sumatera) – 30,000 BOPD
Pertamina Hulu Energi OSES became the operator of the oil fields in Block South East Sumatera on September 6, 2018. The fields were previously operated by CNOOC, China National Offshore Oil Company.
Pertamina Hulu Energi ONWJ – 29,000 BOPD
Pertamina Hulu Energi ONWJ (PHE ONWJ) is currently the operator of the Offshore North West Java (ONWJ) production sharing contract following the change of company ownership from BP to Pertamina in July 2009.
The contract area, located in the Java Sea, covers an area of approximately 8,300 square kilometers – stretching from the North of Cirebon to Kepulauan Seribu.
The giant Ardjuna field is located in this Production Sharing Contract area. It was discovered by ARCO – Atlantic Richfield Company – in 1969 and operated by ARCO until BP – British Petroleum – acquired ARCO in 2000.
The production facilities consist of 670 wells, 170 shallow water platforms, 40 processing and service facilities and some 1,600 kilometers of sub-sea pipeline.
Medco EP Natuna – 16,000 BOPD
Medco EP Natuna, a subsidiary of Medco Energi, is the operator of the South Natuna Sea Block B. The field was initially operated by ConocoPhillips until Medco Energi acquired it in 2016.
Besides producing oil, Medco EP Natuna also supplies gas to Singapore using a 656 KM long 28” subsea pipeline.
Petronas Carigali (Ketapang) – 15,000 BOPD
Petronas Carigali Ketapang operates the Bukit Tua Field located in the Ketapang Block in East Java. Bukit Tua is an oil field but with a significant amount of associated gas. The offshore field is situated at a water depth of about 57 m.
The production facilities consist of wellhead platforms, an FPSO – Floating Production, Storage and Offloading – and onshore receiving facilities (ORF) in Gresik.
PetroChina International Jabung – 14,000 BOPD
PetroChina International Jabung operates the prolific Jabung Block located in Jambi in Central Sumatera.
The company produces crude oil, condensate, LPG and gas. PetroChina supplies gas to Singapore using a 450 KM long subsea pipeline.
An interesting aspect of the block is that PetroChina discovered the fractured basement rock contains a significant quantity of gas that can flow at significant rates.
Pertamina Hulu Kalimantan Timur – 13,000 BOPD
Pertamina Hulu Kalimantan Timur operates the East Kalimantan-Attaka Work Area. Chevron was the previous operator of the work area until it handed over the operatorship to Pertamina on October 25, 2018.
Attaka, the famous giant oil field is located in this block. The Attaka field was discovered and operated by Unocal until Chevron acquired it in 2005.
The oil fields in this work area are in the late declining phase. Around one billion barrels of oil and 3 TCF of gas have been produced from this work area.