Sleen; 1965



On the left is the Nederlandse Aardolie Maatschappij BV (NAM) No. 2 Steen underway near the village of 't Haantje, Netherlands, 1965.


In late November NAM encountered several over-pressured zones in the Germanic Trias formations of the Jurassic, in route to a total depth of 6,555 feet. They were getting their asses kicked, actually; total gas had been increasing steadily and weighing up the mud was leading to lost circulation problems. A decision was made to set a protective string of casing and while coming out of the hole the well kicked hard, the BOP was closed, and several thousand barrels of mud were pumped to kill it.


The crew then attempted to go back in the hole with drill pipe and hit a bridge at about 1,100 feet. Any attempts to wash down thru the bridge result in lost circulation, interlaced with kicks; always a fun way to spend a weekend, on a choke manifold with your butt puckered up. Things went from bad to worse on the Sleen 2 when the drill pipe became stuck.


On December 1 some big gas bubbles were seen in the reserve pit some 50 feet from the wellbore and within four hours those bubbles turned in a full blown breach of surface casing and the well started to crater. The location was evacuated. An hour later the entire rig, nearby trees and farm buildings were almost all completely gone, sunk into the crater that was an boiling mud and water 30 feet high.



The well began to belch massive amounts of water and gas and within hours the crater grew to 5 acres in size. Around the crater, several hundred feet away, breaches in the surface that looked like ant mounds could be seen boiling drilling mud.




Red Adair, in late December 1965, was three years off the great fire in Algeria, in 1961. Business was good for him and Boots and Coots; they're tending to 2-3 well control matters per month, around the world, around the clock. Adair got paid by NAM to travel to the Netherlands to have a look at the Sleen No. 2 crater and the best he can offer is to drill a relief well. He is on a plane headed back to Houston within hours of arrival.

The NAM Sleen 3 relief well was spud 2,500 feet from the blowout well by December 18, 1969. So unstable was the ground around the blowout crater that a thick, iron reinforced cement foundation was built for the rig's substructure to sit on and the reserve pit was lined with cement.



Within two weeks the relief well was properly deviated to the top of the Bundsandstein formation, within 100 feet of the Sleen 2 bottom hole location. A kick occurred and mud returns were lost.












An estimated 1,200,000 pounds of cement were pumped down the relief well over seven weeks before bubbling ceased in the crater and surrounding area. The relief well never entirely squeezed off.


The drilling rig and stuck drill pipe were never seen again.





Here is the Sleen 2 blowout crater today, full of runoff like a shallow lake. Subsidence around the old, buried well bore is still occurring. Water wells in the area have been studied and found to have high methane levels and groundwater sources over a stacked, vertical section above 1,500 feet seem to be slightly over pressured, likely still being charged by communication with the blowout well and the events that occurred 56 years ago.


Its often a good idea to not mess with Mama Nature.