The Sidoarjo Mudflow is an
ongoing eruption of gas and mud in East Java, Indonesia. Hot
mud has been flowing since May 2006 and it appears that the flow
will continue indefinitely. So far all efforts to stem the flow
On May 28, 2006, PT Lapindo
Brantas targeted gas 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, volcanic debris
and finally into permeable carbonate rocks. At this stage the
borehole was surrounded by a steel casing to help stabilize it.
At 5:00 a.m. local time 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.
The extra pressure formed fractures
around the borehole that propagated 1-2km to the surface and
emerged at the surface. 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.