A few years ago, the U.S. was scratching to find oil anywhere it could. That led us into debates about drilling in ANWR, oil shale, off shore drilling, and hydraulic fracturing. To a large extent the debates have quieted. This is partly because we've gone ahead with hydraulic fracturing in many locations. But what is this practice and how does it work?
Hydraulic fracturing, or fracking, entails using high pressure fluid to create small cracks in rock surrounding a drill site. Oil in small pockets in this rock then becomes accessible to pump out. Every oil field supply company that services the fracking industry needs to create equipment with precision to ensure the process succeeds.
Fracking fluid, which can include various chemicals depending on the job, is pumped into a section of an oil well sealed by plugs at each end. Pressure is increased until the surrounding rock fractures enough for oil to seep out. But when the pressure is removed and the fluid is piped out, the weight of the rock tends to close up the cracks before the oil can be extracted. So specialized frac sand is mixed with the fluid as a proppant. When the fluid is removed, this sand fills the cracks to "prop" them open. The fluid is then sent to disposal by pipeline. Care must be taken by pipeline construction companies to be sure this fluid remains contained.
The fluid is mixed with the sand in a blender just before it is pumped down the well. The sand itself is highly engineered for optimal sphericity, crush strength, and long-term conductivity. By the time the fluid injection begins, everything has to be in place to prevent stoppage. Hundreds of tons of sand are on site in special storage containers. Cleated conveyor belting designed to move sand are on hand with backup engines.
If all goes well, the process will yield many barrels of oil that had previously been inaccessible. Another important challenge is reducing external effects by knowing where ground water is before drilling and disposing of used frac fluid properly.
