David Persons – For Energy Pipeline – September 3, 2014
Hydraulic fracturing is the key technology that is spurring the current oil and natural gas boom in shale plays in Colorado and around the country.
The key to its success may be surprising.
It’s not the millions of gallons of water that is used for each well drilled.
It’s not even the highly-guarded mix of chemicals used to lubricate each drilling hole.
The single most important ingredient — one that makes the entire fracturing process work so well — is sand.
Oil company officials say the best way to explain it is to describe the hydraulic fracturing process from the beginning.
Fracturing starts with a mixture of water and sand that is pressurized and introduced into deep shale and rock formations, often with the aid of additives that help guide the water and sand down the hole.
The force of the water creates a number of tiny fissures. The sand then finds its way into cracks and “props” them open, as a proppant allowing the trapped natural gas and liquids to travel back to the surface.
Without the sand to hold open the fissures, the fracturing process would not be nearly as successful.
“It’s an essential part of the process,” said Doug Hock, Encana’s Manager of media relations.
With sand so common around Colorado, it would seem that “frac sand” would be easy to come by and plentiful.
As it turns out, that is not the case.
That’s because “frac sand,” the kind preferred by most oil and gas companies operating in the DJ Basin, is a special kind of sand — one that is more commonly found in Wisconsin and other states.
What is frac sand?
“Frac sand” is a high-purity quartz (silica) sand with very durable and very round grains, according to geology.com.
It is a crush-resistant material — with a compressive strength between 6,000 and 14,000 pounds per square inch — produced for use in the hydraulic fracturing process to produce petroleum fluids, such as oil, natural gas and natural gas liquids from rock units that lack adequate pore space for these fluids to flow to a well. Most “frac sand” is a natural material made from high purity sandstone, the website reported.
The characteristics of a high-quality “frac sand” include: high-purity silica sand, grain size perfectly matched to job requirements, spherical shape that enables it to be carried in hydraulic fracturing fluid with minimal turbulence, and durability to resist the crushing forces of closing fractures.
“Frac sand” is produced in a range of sizes from as small as 0.1 millimeter in diameter to over 2 millimeters in diameter depending upon customer specifications. Most of the “frac sand” consumed is between 0.4 and 0.8 millimeters in size.
Size and shape of “frac sand” does matter, according to oil and gas company officials operating in the DJ Basin.