NEWS : SIDOARJO MUD FLOW
Sidoarjo Mud Flow prior to the eruption, August 28, 2004. NASA ASTERsatellite image
Sidoarjo Mud Flow, November 11.2008
Sidoarjo mud flow, October 20, 2009. NASA ASTER satellite image. Red areas indicate plants in this false-color image
Sidoarjo mud flow
From Wikipedia, the free encyclopedia
The Sidoarjo mud flow or Lapindo mud, also informally abbreviated as Lusi, a contraction of Lumpur Sidoarjo (lumpur is theIndonesian word for mud), is a mud volcano in the subdistrict ofPorong, Sidoarjo in East Java, Indonesia that has been ongoing since May 2006. Approximately 30,000 m³ (1 million cubic feet) of mud — equivalent to the contents of a dozen Olympic-size swimming pools — are expelled per day. It is expected that the flow will continue for the next 30 years. Although the Sidoarjo mud flow has been contained by levees since November 2008, resultant flooding regularly disrupts local highways and villages. Further breakouts of mud are still possible.
Mud volcano systems are fairly common on Earth, and particularly in East Java province. Beneath the island of Java is a half-grabenlying in the east-west direction, filled with overpressured marinecarbonates and marine muds. It forms an inverted extensionalbasin which has been geologically active since the Paleogeneepoch. The basin started to become overpressured during theOligo–Miocene period. Some of the overpressured mud escapes to the surface to form mud volcanoes, which have been observed at Sangiran Dome and near Purwodadi city, 200 km (124 miles) west of Lusi.
The East Java Basin contains a significant amount of oil and gasreserves and therefore the region is known as a major concession area for mineral exploration. The Porong subdistrict, 14 km south ofSidoarjo 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 May 28, 2006, PT Lapindo Brantas targeted gas in the Kujung Formation carbonates in the Brantas PSC area by drilling a boreholenamed the ‘Banjar-Panji 1 exploration well’. In the first stage of drilling the drill string first went through a thick clay seam (500–1,300 m deep), then sands, shells, volcanic debris and finally into permeable carbonate rocks. At this stage the borehole was surrounded by a steel casing to help stabilise it. At 5:00 a.m. local time (UTC+8) a second stage of drilling began and the drill string went deeper, to about 2,834 m (9,298 ft), this time without a protective casing, 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 800–1000 m northwest of the well, but these stopped on June 5, 2006. During these eruptions, hydrogen sulphide gas was released and local villagers observed hot mud, thought to be at a temperature of around 60 °C (140 °F).
From a model developed by geologists working in the UK, the drilling pipe penetrated the overpressured limestone, causingentrainment of mud by water. The influx of water to the well bore caused a hydrofracture, but the steam and water did not enter the borehole; they penetrated the surrounding overburden and pressured strata. The extra pressure formed fractures around the borehole that propagated 1–2 km to the surface and emerged 200 m away from the well. The most likely cause of these hydraulic fractures was the unprotected drill string in the second stage of drilling. While steel casing is used to protect the well bore in oil or gas exploration, this protection can only be applied in stages after each new section of the hole is drilled, see drilling for oil.
There was controversy as to what triggered the eruption and whether the event was a natural disaster or not. According to PT Lapindo Brantas it was the May 2006 earthquake that triggered the mud flow eruption, and not their drilling activities. Two days before the mud eruption, an earthquake of moment magnitude 6.3 hit the south coast of Central Java and Yogyakarta provinces killing 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 determined to be natural, then the government of Indonesia has the responsibility to cover the damage instead. This argument was also recurrently echoed by Aburizal Bakrie, the Indonesian Minister of Welfare at that time, whose family firm controls the operator company PT Lapindo Brantas.
However the UK team of geologists downplayed Lapindo’s argument and concluded that the earthquake was merely coincidental. While it could have generated a new fracture system and weakened strata surrounding the Banjar-Panji 1 well, it could not have been the cause of the formation of the hydraulic fracture that created the main vent 200 m (660 ft) away from the borehole. Additionally there was no other mud volcano reported on Java after the earthquake and the main drilling site is 300 km (190 mi) away from the earthquake’s epicenter. The intensity of the earthquake at the drilling site was estimated to have been only magnitude 2 on Richter scale, the same effect as of a heavy truck passing over the area.
On June 5, 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 former 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 emulate many US mining companies and pursue bankruptcy to avoid the cost of clean up, which could amount to US$ 1 billion.
On August 15, 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 a suit against PT Lapindo Brantas, President Susilo Bambang Yudhoyono, the Indonesian Minister of Energy, the Indonesian Minister of Environmental Affairs and local officials.
After investigations by independent experts, police have concluded the mud flow was an “underground blow out“, triggered by the drilling activity. It is further noted that the steel casing lining had not been used which could have prevented the disaster. Thirteen Lapindo Brantas’ executives and engineers face twelve charges of violating Indonesian laws.
As of October 30, 2008, the mud flow is still ongoing at a rate of 100,000 m3 per day. A study has found that the mud volcano is collapsing under its own weight, possibly beginning calderaformation.. The researchers say the subsidence data could help determine how much of the local area will be affected by Lusi. Their research used GPS and satellite data recorded between June 2006 and September 2007 that showed the area affected by Lusi had subsided by between .5 and 14.5 metres (1 ft 8 in and 47 ft 7 in) per year. The scientists found that if Lusi continued to erupt for three to 10 years at the constant rates measured during 2007 then the central part of the volcano could subside by between 44 and 146 m (144 and 479 ft). They propose the subsidence is due to the weight of mud and collapse of rock strata due to the excavation of mud from beneath the surface. Their study has also found that while some parts of Sidoarjo are subsiding others are rising suggesting that the Watukosek fault system has been reactivated due to the eruption.
Workers helping to relocate families after new hot gas flows began to appear have been injured. The workers were taken to a local hospital to undergo treatment for severe burns. In Siring Barat, 319 more families have been displaced and in Kelurahan Jatirejo, 262 new families are also going to be affected by the new flows of gas. Protesting families took to the streets demanding compensations, which in turn added more delays to the already stressed detour road for Jalan Raya Porong and the The Porong-Gempol toll road.
The government has stated that their heart is with the people, although the cabinet meeting on how to disperse the compensation has been delayed until further notice. Local official, Saiful Ilah, signed a statement announcing that “The government is going to defend the people of Siring.” After this announcement all protests came to an end and traffic flow returned to normal an hour later.
New mudflows spots have begun in April 2010, this time on Porong Highway, which is the main road linking Surabaya with Probolinggoand islands to the east including Bali, despite roadway thickening and strengthening. A new highway is planned to replace this one however are held up by land acquisition issues. The main railway also runs by the area, which is in danger of explosions due to seepage of methane and ignition could come from something as simple as a tossed cigarette.
On 23 October 2008 a public relations agency in London, acting for one of the oil well’s owners, started to widely publicise what it described as “new facts” on the origin of the mud volcano, which were subsequently presented at an American Association of Petroleum Geologists conference in Cape Town, South Africa on 28 October 2008 (see next section). The assertion of the geologists and drillers from Energi Mega Persada was that “At a recent Geological Society of London Conference, we provided authoritative new facts that make it absolutely clear that drilling could not have been the trigger of LUSI.” Other verbal reports of the conference in question indicated that the assertion was by no means accepted uncritically, and that when the novel data is published, it is certain to be scrutinised closely.
After hearing the (revised) arguments from both sides for the cause of the mud volcano at the American Association of Petroleum Geologists International Convention in Cape Town in October 2008, the vast majority of the conference session audience present (consisting of AAPG oil and gas professionals) voted in favor of the view that the Lusi (Sidoarjo) mudflow had been induced by drilling. On the basis of the arguments presented, 42 out of the 74 scientists came to the conclusion that drilling was entirely responsible, while 13 felt that a combination of drilling and earthquake activity was to blame. Only 3 thought that the earthquake was solely responsible, and 16 geoscientists believed that the evidence was inconclusive.
The report of the debate and its outcomes was published in AAPG Explorer Magazine.
In February 2010, a group led by experts from Britain’s Durham University said the new clues bolstered suspicions the catastrophe was caused by human error. In journal Marine and Petroleum Geology, Professor Richard Davies, of the Centre for Research into Earth Energy Systems (CeREES), said that drillers, looking for gasnearby, had made a series of mistakes. They had overestimated the pressure the well could tolerate, and had not placed protective casing around a section of open well. Then, after failing to find any gas, they hauled the drill out while the hole was extremely unstable. By withdrawing the drill, they exposed the wellhole to a “kick” from pressurised water and gas from surrounding rock formations. The result was a volcano-like inflow that the drillers tried in vain to stop.