This isn't the old fracking we were used to. Usually the old methods involved nitrogen or propane and pressures were relatively low (generally around 1,000 psi or less).
The new methods are called "hydro fracking", lots of water (millions of gallons), very high pressure 17,000-20,000 psi! Various chemicals added (surfactants, propellants, biocides,lubricants, solvents,etc.) and lots of "fracking sand" (could be plastic pellets).
The old wells were vertical wells and usually the frack took place at the target zone (or a few perforated target zones). The wells in the shale and tight sands are nearly all horizontal.....when they get to the target zone they run horizontally down the shale seam up to 2km. Then they perforate down the casing and multi-stage frack down the whole length of the horizontal bore at intervals....some as high as every ten meters (depending on how "tight" the shale/sands are).
It is literally blasting the shale/sands apart by brute force. The frack sand is forced into the fractures and hold them open to let the gas/oil flow. All the chemical goodies help to dissolve the oil so it can flow easier.
This high pressure multi stage fracking process has been described as "extreme subterranean chaos" by the USA, EPA. It is very hard to control where the frack goes...a natural fault in a formation can expand beyond control....likely what happened here.
The new methods are called "hydro fracking", lots of water (millions of gallons), very high pressure 17,000-20,000 psi! Various chemicals added (surfactants, propellants, biocides,lubricants, solvents,etc.) and lots of "fracking sand" (could be plastic pellets).
The old wells were vertical wells and usually the frack took place at the target zone (or a few perforated target zones). The wells in the shale and tight sands are nearly all horizontal.....when they get to the target zone they run horizontally down the shale seam up to 2km. Then they perforate down the casing and multi-stage frack down the whole length of the horizontal bore at intervals....some as high as every ten meters (depending on how "tight" the shale/sands are).
It is literally blasting the shale/sands apart by brute force. The frack sand is forced into the fractures and hold them open to let the gas/oil flow. All the chemical goodies help to dissolve the oil so it can flow easier.
This high pressure multi stage fracking process has been described as "extreme subterranean chaos" by the USA, EPA. It is very hard to control where the frack goes...a natural fault in a formation can expand beyond control....likely what happened here.
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