Lapindo Hot Mud
This is not one of East Java cultural heritage or even Tourism destination, Lapindo hot mud is such a tragedy for
Sidoarjo people as victims of this thing happened. By this natural disaster, we should have to be more concern about the Earth and the society within the world.
The Sidoarjo mud flow or Lapindo mud, also informally abbreviated, a contraction of Lumpur Sidoarjo (lumpur is the Indonesian word for mud), is a mud volcano in the subdistrict of Porong, Sidoarjo in East Java, Indonesia that has been ongoing since May 2006. Approximately 2,500 m³ (88,000 cubic feet) of mud are expelled per day, which is equivalent to the contents of a dozen Olympic-size swimming pools. It appears that the flow will continue indefinitely. As of November 2008, the Sidoarjo mud flow is contained by levees, but further breakouts are possible.
Mud volcano systems are fairly common on Earth, 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 become overpressured during the Oligo-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 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
On May 28, 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’. 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, causing entrainment 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 1-2km 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. Borehole protection by steel casing is a common procedure in oil or gas exploration.
More info: www.sidoarjo.eastjava.com