Sidoarjo mud flow

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Homes buried by the mud flow

The Sidoarjo mud flow, also informally named as Lusi from Lumpur Sidoarjo (lumpur is Indonesian term of mud), is an ongoing eruption of gas and mud from the earth in the subdistrict of Porong, Sidoarjo in East Java, Indonesia (20 kilometer south of Surabaya). It is considered to be a mud volcano. It appears that the flow will continue for an undetermined amount of time. So far, all efforts to stop the flow have failed.

Geological setting

Mud volcano systems are common on Earth, including on Java island and particularly in East Java province. Beneath the island of Java is a half-graben lying in the east-west direction, filled with overpressured marine carbonates and marine muds. It forms an inverted extensional basin which has been geologically active since the Paleogene epoch. The basin started to get overpressured during the Oligo-Miocene period. Some of the overpressured mud escapes to the surface forming mud volcanoes, which have been observed at Sangiran Dome and near Purwodadi city (200 km or 124 miles west of Lusi).

The East Java Basin contains a significant amount of oil and gas reserves and therefore the region is known as a major concession area for mineral exploration. The Porong subdistrict, 14 km south of Sidoarjo city, is known in the mineral industry as the Brantas Production Sharing Contract (PSC), an area of approximately 7,250 km² which consists of three oil and gas fields: Wunut, Carat and Tanggulangin. As of 2006, three companies — Santos (18%), MedcoEnergi (32%) and PT Lapindo Brantas (50%) — had concession rights for this area; PT Lapindo Brantas acted as an operator.

Mud eruption chronology

On 28 May 2006, PT Lapindo Brantas targeted gas in the Kujung Formation carbonates in the Brantas PSC area by drilling a borehole named the Banjar-Panji 1 exploration well. The drill string went into a thick clay seam (500–1,300 m deep), and then sands, shells, volcanic debris and into permeable carbonate rocks. At 5:00 a.m. local time (UTC+8), the drill string went deeper to about 2,834 m (9,298 feet), after which water, steam and a small amount of gas erupted at a location about 200 m southwest of the well. Two further eruptions occurred on the second and the third of June about 800–100 m northwest of the well, but these stopped on 5 June 2006. During these eruptions, hydrogen sulphide gas was released and local villages observed mud at hot temperature, around 60°C or 140°F.

From a model developed by a geologist, the drilling pipe penetrated the overpressured limestone, causing entrainment of mud by water. The influx of water to the well bore caused a hydrofracture, but the steam and water did not go through the borehole; they penetrated the surrounding overburden pressured strata. The pressure formed some fractures around the borehole to propagate to the surface 200 m away from the well. The most likely cause of these hydraulic fractures in the shallowest strata is by the unprotected drill string with a steel casing. Borehole protection by steel casing has been a common procedure in oil or gas exploration.

Impact

Satellite map of area before and after mud flow. From Nasa

After three months, the unprecedented event had made a river of mud on the surface with a total volume of at least 50,000 m³ with an estimated 7,000–150,000 m³ mudflow erupting every day. By early September 2006, a hot torrential mudflow inundated rice paddies and villages, covering an area of approximately 240 ha and resulting in the displacement of more than 11,000 people from eight villages in the Porong subdistrict. Twenty-five factories had to be abandoned. Rice fields and fish and shrimp ponds have been destroyed, which further threatened Sidoarjo's status as the biggest shrimp producer in Indonesia after Lampung. The Marine Resources and Fisheries Ministry has estimated a financial loss of 10.9 billion rupiahs (US$ 1.2 million) to the fisheries business in Tanggulangin and Porong subdistricts. President Susilo Bambang Yudhoyono declared the 400 ha area inundated by the mud flow as a disaster-prone area unfit for human habitation. As a consequence, 2,983 families had to be relocated to safer places.

On 23 November 2006, eleven fatalities were reported from the explosion of a gas pipe, possibly caused by the mud flow. The accident occurred because the ground subsided 2 m (6.5 feet) due to the significant outflow of mud and water, and a dike collapsed causing the state-owned Pertamina gas pipeline to rupture. The gas sent flames into the sky and according to the local people, they could feel the heat from one kilometer (0.6 miles) away.

As of February 2007, the erupted mud pool had an estimated total volume of 0.012 km³ (12 million liter), covered an area of 360 ha (1.4 miles²), was up to 10 m (32.8 feet) thick, buried four villages and 25 factories, displaced at least 11,000 people and the eruption was still ongoing. It was expected that the mud eruption will last for years to come and the area will experience a significant depression to form a caldera.

Infrastructure has been damaged extensively, including toll roads, railway tracks, power transmission systems, gas pipelines and national artery roads. Speaking in front of the People's Representative Council, the house speaker Agung Laksono declared that the state budget is needed to finance the infrastructure repairs, while PT Lapindo Brantas will be responsible for financing the repairs and also to pay 2.5 trillion rupiah for compensation to the victims. The Porong-Gempol toll road in East Java province has been significantly damaged by the mud flow and was practically inoperable.

The chairman of the national team to handle the disaster, Basuki Hadimuljono, indicated that a 12 km long 120 m wide corridor will be acquired west of the afflicted area to rebuilt the turnpike, and construct a rail line and gas pipe line to restore the disrupted links in the infrastructure. The costs will be carried by the public sector.

Mitigation

A network of dams and barriers has been erected to contain the mud. On September 26 barriers failed, resulting in the flooding of more villages. Further strengthening of the dam system appears to contain the sludge and since the end of September no further reports of breaches have been released.

The displaced population has been given temporary shelter. President Susilo Bambang Yudhoyono has authorized further flow of mud to be pumped into the Porong River that will take it to the local sea. Pumping of sludge into the sea started on October 16. Ideas have been submitted for the use of the mud, as it could be used for bricks and other building material. The heat of the process may be usable for thermal energy. There has also been an effort to stop and/or lessen the effects of the mud flow through the dropping of chains of concrete balls into the crater. The hope is to shrink the size of the evacuation tube and thus slow the rate of flow.

Drilling operations have been seriously hampered, with continual delays forced upon the relief well drilling team, due to lack of funding. Drilling operations have been suspended until the implementation of the National Government Team's plan to plug the flow with concrete "balls", a plan widely accepted to offer more inherent dangers than chances of success (and potentially induce further flows to the surface in an area already severely weakened). The first series of concrete balls was lowered into the mud volcano on 24th February 2007. It is planned that up to 1500 such balls will be deployed. On 19th March 2007, after hundreds of balls had been dropped into the mouth of the hole, the flow of mud stopped for a period of 30 minutes.

Investigation

Cause

Mudflow, photo taken on July 21 2006

Controversy exists to what had triggered the eruption, whether the event was a natural disaster or not. On one side, mainly PT Lapindo Brantas, the May 2006 earthquake had triggered the mud flow eruption rather than their drilling activities. Two days before the mud eruption, a earthquake of magnitude 6.3 on the Richter scale hit the south coast of Central Java and Yogyakarta provinces kiling 6,234 people and leaving 1.5 million homeless. At a hearing before the parliamentary members, senior executives of PT Lapindo Brantas argued that the earthquake was so powerful that it had created deep underground faults, allowing the mud to flow thousands of meters away, and that their company presence was coincidental, which should exempt them from paying compensation damage to the victims. If the cause of the incident is natural, then the government of Indonesia has the responsibility for the damage instead. This argument was further recurrently echoed by Aburizal Bakrie, the Indonesian Minister of Welfare at that time, whose family firm controls the operator company PT Lapindo Brantas.

Geologists disregarded the natural cause and mentioned that the earthquake is merely coincidental. The earthquake could have generated a new fracture system and weakened strata surrounding the Banjar-Panji 1 well, but it does not support the formation of a hydraulic fracture to create the main eruption vent 200 m away from the borehole. Apart from that, there was no other mud volcano reported on Java after the earthquake and the main drilling site is 300 km (186.5 miles) away from the earthquake's epicenter which was estimated to have only magnitude 2 on Richter scale at the drilling site (the same effect as of a heavy truck passing over the area).

Legal case

On 5 June 2006, MedcoEnergi (one partner company in the Brantas PSC area) sent a letter to PT Lapindo Brantas which accused them of breaching safety procedures during the drilling process. The letter further attributes "gross negligence" to the operator company for not equipping the well bore with safety steel casing. Soon afterwards vice president Jusuf Kalla announced that PT Lapindo Brantas and the owner, the Bakrie Group, must compensate thousands of victims affected by the mud flows. A criminal investigation was then started against several senior executives of the company because the drilling operation has put the lives of local people at risk.

Aburizal Bakrie frequently said that he is not involved in the company's operation and further detached himself from the incident. Even in his capacity as Minister of Welfare, Aburizal Bakrie was reluctant to visit the disaster site. Aburizal Bakrie's family business group, Bakrie Group, one of the owners of PT Lapindo Brantas, had been trying to distance themselves from the Lusi incident. Afraid of being liable for the disaster, Bakrie Group announced that they would sell PT Lapindo Brantas to an offshore company for only $2, but Indonesia's Capital Markets Supervisory Agency blocked the sale. A further attempt was made to try to sell to a company registered in the Virgin Islands, the Freehold Group, for US$1 million, which was also halted by the government supervisory agency for being an invalid sale. Lapindo Brantas was asked to pay about 2.5 trillion rupiah (about US$ 276.8 million) to the victims and about 1.3 trillion rupiah as additional costs to stop the flow. Some analysts predict that the Bakrie Group will try any attempts, including the announcement of bankruptcy, to avoid the cost of clean up which could amount to US$ 1 billion.

On 15 August 2006, the East Java police seized the Banjar-Panji 1 well to secure it for the court case. The Indonesian environmental watchdog, WALHI, have meanwhile filed suit against PT Lapindo Brantas, President Susilo Bambang Yudhoyono, the Indonesian Minister of Energy, the Indonesian Minister of Environmental Affairs and local officials.

After some investigations by independent experts, police have concluded the mud flow as an "underground blow out", triggered by the driling activity. It is further noted that the steel casing lining had not been used which could prevent the disaster. Thirteen Lapindo Brantas' executives and engineers faced twelve charges of violating Indonesian laws.

See also

• Environmental issues in Indonesia
• Industrial disasters

External links

• Bakrie & Brothers homepage
• Pictures by Greenpeace
• Satellite imagery by CRISP / National University of Singapore
• Notes from Indonesian Geoscientist dedicated for the Sidoarjo mud flow