April 18, 2018

This  week Oily Stuff continues it's stroll  thru the  annals of  homo sapient induced errors that has led  to some rather astonishing  oilfield  events over the years. Previously  we have been  in TurkmenistanMexico  and Namibia;  this week  we find  ourselves in Indonesia. 


On 3 March 2006, an Indonesian oil company named PT Lapindo Brantas spudded its Banjar-Panji No. 1 well in  the district of Sidojara in East Java. Onshore Java  is oily, very gassy country but unfortunately its existing fields and hydrocarbon zones are tucked in between numerous, over-pressured zones of volcanic ruble and geothermal flows in the subsurface. Its tough sledding for the best of drilling engineers. The proposed TD of the BJP-1 well was Miocene carbonates associated with reef mounds located about 9,000 feet deep.


The BJP-1 well was an offset to the Porong-1 well located about 4 miles away. The Porong well found non-commercial hydrocarbons in an anomalous looking reef  feature, but important pore pressure and frac gradient data was gleaned from the drilling of the Porong well that was, unfortunately, overlooked in  the BJP-1 well. 


The BJP-1 well immediately encountered over-pressured clastics  at shallow depths and associated drilling  problems

caused several key casing points to occur much shallower than necessary. 16 inch casing set below 20 inch casing in the well was not cemented very well, several leak off tests (LOT) failed and that string had to be remedially squeezed, twice. Below a string of 13 3/8ths, continued drilling problems actually led to two further proposed casing points being missed entirely. Over 5,200 feet of open hole existed below the 13 3/8ths casing shoe and 2,000 feet of known, over-pressured carbonate pay  was drilled underbalanced, with no protective casing string above it. Late in May of 2006 at a depth of 8,800 feet, the well kicked, the BOPS were closed and several large volumes of mud were pumped to try and kill the well. Its clear, at least to this dumb roughneck, that pump-in pressures exceeded frac gradients downhole  and that in turn caused  stress related faulting in the subsurface, or reactivated an existing fault,  and two days later an obvious underground blowout underway worked its way to  the surface about 300 feet away from the well. Very hot water from the carbonate pay zone mixed with clays in the openhole section below the 13 3/8ths casing shoe... and the Lapindo mud volcano was born, nicknamed "Lusi," for short. 

Brantas quickly  abandoned ship. It cut stuck drill  pipe, set  some cursory  cement plugs, rigged down and  moved the  hell out as fast as it could get gone.  Both of its working interest partners, including Santos, LTD of  Australia, wiggled out of  the mess  somehow, and over ensuing months  things went  from bad to worse. At one  point Lusi  was reported to be producing  an estimated 1,000,000 barrels of  mud per day.  Ultimately 13 people were killed  and over 60,000  people were  displaced from  their  homes from  mud flow  that  covered many  square miles.


The  operator of the  BJP-1 well  blamed an earthquake that  happened about  the  same time  it  was  taking  a kick  at TD and mud  started bubbling up  out of  the ground  near its well. The debate as  to whether  this  was  a man-made  mess or simply Mother Nature doing Her thing rages on. Many really good  papers have been written  about the Lusi  mud volcano but  probably nobody  knows it  all better than  an Australian  geologist named, Mark Tingay, and  he has an  excellent, three-part  series of  this  event on  his  blog, Critically Stressed. It  is very interesting  reading  and I highly recommend it.  


In 2017 the Lusi mud volcano pooped out for a brief time but  then urped  again and the  latest from East Java  is that it  is slowing  down a good bit,  after 12 years, but still bubbling.  


Shit happens, as

we say quite often in the oilfield, but this was a real doozy.











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