What is silica sand?

 

Silica sand, also known as "frac sand", is a durable, round grain, crush-resistant material mined for use in the hydraulic fracturing ("fracking") process.  This process is used to gather energy resources such as oil, natural gas, or natural gas liquids from underground rock units that lack adequate pore spaces for these fluids to flow into a well.

 

How is frac sand used?

Some subsurface rock units, such as organic shale, contain large amounts of oil, natural gas, or natural gas liquids that will now flow freely because the rock either lacks permeability ot the pore spaces in the rock are so small that these fluids cannot flow through them.

 

Hydraulic fracturing solves the problem by generating fractures in the rock.  This is done by drilling a well into the rock, sealing the portion of the well in the petroleum-bearing zone, and pumping a mixture of water (98%), silica sand (1.97%) and trace amounts of chemicals and agents (0.03%) under high pressure into that portion of the well.

 

The chemical in the water creates a viscous gel that, in turn, facilitates the water's ability to carry grains of frac sand in suspension.  The frac sand is used to "prop" open the fractures; this is why it is called "proppant".