Getting Down to the Nitty Gritty of Fracturing

The ever-increasing number of hydraulic fracturing applications used to economically produce shale reservoirs impacts various businesses that profit from this phenomenon.

Think sand mining/processing, for example.

Typically, it takes millions of pounds of sand to fracture only one well. Commonly referred to as “proppant,” the sand “props” open the many fractures created by high-pressure injection of sand-containing, chemically treated water into the dense rock.

As the water flows out at the end of the pressurized treatment, the proppant remains, preventing fracture collapse as the pressure declines. This enables the once-entrapped hydrocarbons to wend their way along the fractures to the borehole for production.

Total industry sand consumption for the year 2014 is estimated to be 95 billion pounds, according to a recent report by Houston-based PacWest Consulting Partners, which has been referenced widely by myriad print sources.

This amount exceeds 2013 use by 30 percent.

The industry’s near-insatiable demand for this resource likely will continue to grow. A recent Bloomberg article predicted that deepwater offshore hydraulic fracturing is on track to be the next major iteration of the ongoing unconventional resources boom.

If you own the right type of sand, and plenty of it, you’re golden.

Diamonds in the Rough

Therein lies the catch.

For the most part, the sand must be comprised of round grains that are crush-proof when subjected to enormous pressures. Detritus created from crushing would impede fluid flow enhanced by the spherical grains, potentially sealing the newly created fractures.

Industry sand favorites are Ottawa sand (also known as Northern White) and Brown Sand.

Color-free, clear Ottawa grains are pure silica and hard enough to be essentially on par with diamonds. Sourced from the Ordovician-age St. Peter sandstone, the industry-prized Ottawa is found in the mid-western United States, with a high concentration in Illinois.

Brown Sand is relatively plentiful in Texas, where it’s known as “Brady Brown.” Even though a slightly lower tier than Ottawa, it is especially prized by drillers in the Lone Star State, given its proximity to the myriad well sites there.

Building a Better Sand Grain

Don’t write off the innumerable remaining sands across the United States, though.

Processing, such as resin-coating sand grains to increase hardness, can alter certain less desirable sands to make them suitable for a particular area.

The Louisiana Geology Survey (LGS) recently conducted a small-scale preliminary investigation of sands, which are in plentiful supply in this hydrocarbon-rich state. The investigation was the initial step to assess the potential for economic development of silica sand deposits there to use as proppants for hydraulic fracturing.

LGS research associate Riley Milner led the research effort, which included samples from only four locales, owing to cost constraints.

The areas sampled are near Sicily Island and Aimwell in the Catahoula sandstone, and the Amite River Basin. Two samples were collected in the Catahoula and two in the basin, and subsequently subjected to laboratory analysis.

“All four samples were right on the borderline as being acceptable for proppant in terms of sphericity, acid solubility, bulk density and stress,” Milner said.

“Other analyses by pit owners in the Amite River Basin and other locations in the Sparta sand are all right on the borderline,” he noted.

Already, there is a business operation in Sibley, La., specializing in resin coating of fracturing sands. A pit owner near Natchez, Miss., is mining the Catahoula sand, apparently with the idea of resin coating, according to Milner.

“In Sibley, they’re resin-coating the Texas Brown, which is being shipped in,” he said. “They’re processing about 100 rail cars a day on a spur right off the railroad.

“There’s a guy in the Amite Basin in East Feliciana who is hydro-washing sand and selling it as a proppant to a company in Houston to go offshore,” Milner said. “He has a jet wash system where if the grains are broken, it washes these broken ones out, retaining the strongest and roundest grains.”

As to Milner’s preliminary findings, the sand studied might not be suited for deep Louisiana plays such as the well-known Haynesville Shale or the Tuscaloosa Marine Shale.

Yet not all wells are at great depths.

“If they resin-coated it, it could go up to 15,000 psi crush strength,” he said. “Right now, it’s right at 7,000 psi.

“In shallower wells, this could be used for fracing.”

Milner is convinced of the need to expand this initial study effort into a full-blown research program.

“This preliminary study of silica sand resources in Louisiana for proppant has shown to warrant further study of natural sand resources in the state,” he said.

“With all the drilling, along with the businesses processing sands for proppant, we need to do a statewide analysis of sands,” he said. “There’s a lot of sand in southeast Louisiana along the Amite, the Comite, in Tangipahoa and that region, and it’s good enough quality for glass.

“There are a lot of things Louisiana sands can be used for that are not being dealt with,” he emphasized. “There’s potential for other areas of development far beyond fill, concrete aggregate and the like.

“That’s what this study was about.”