biffvernon wrote:Yes, I believe the key difference is that today's fracking for tight gas in shale involve pressures of an order of magnitude greater than what was used decades ago. It's the pressure that changes the way the process is handled and the potential safety risks.
Fracking pressure is related to depth and the fracture strength of the rock. Certainly fracking at 10,000' would involve more hydraulic horsepower than fracking at 5,000', but beyond needing the high pressure steel and pumps for the higher pressures, no, it is still pumping a fluid into the rock to open up natural pathways to get the proppant in. And in some cases, you don't even need proppant, changing the stress field is enough.
Currently in the Utica I don't know if they even need 3000psi for breakdown in a few of the more western areas, and yet you wander off to the east and in the same Devonian aged rock upsection from the Utica you might need 9000psi....both using the same techniques and equipment...one is not fracking because the pressure is less.
So order of magnitude? Nah. Even back in the 50's they were fracking in the 2000-3000psi range, no problem. Couldn't tell you what the deepest frack jobs were back then, terrible records until about the 80's when some of the modern information services like IHS began trying to keep track of it.