...and the NSW Mine Safety Investigation Unit reveals coal seam gas exploration and mining company, Metgaso Limited, did not install and plug the well with sufficient understanding of the processes involved.
On July 14 this year six Metgasco workers were placed into a "very high" risk situation during the shutdown operation of the Kingfisher E01 well on the outskirts of Casino, when 200m of steel drill pipes shot out of the well without warning.
The incident followed an attempt to drill through a special plug installed 200m down the 2km well shaft to "bleed off" rising pressure....
Flying metres into the air, the pipes fell to earth around the site, missing the six fleeing workers but causing extensive damage to surrounding equipment.
In an indication of the force, one of the drill pipes was ejected out of the drill site and into a neighbouring paddock.
The Mine Safety Investigation Unit reported the well had experienced "continuously rising pressure" during its lifespan due to loss of well integrity.
"Loss of integrity ... meant that gas under pressure could migrate between the inside and outside of the (well) casing," it stated.
It suggested efforts to monitor and control this building pressure had failed; one of the causes was an "insufficient understanding" of the level of pressure build-up, and the plug was installed too close to the surface.
The workers report running away from the workover rig towards safe muster points and in doing so saw sparks and a brief ignition of gas above the rig as the last of the pipes ejected from the well....
The causes and circumstances surrounding the incident are being investigated by the department’s Investigation Unit.
