Machinedesign 5933 Fracking Editorial Water Consideration 0 0

Two vital resources: Water and natural gas

June 6, 2013
Global energy demand outpaces supply, so within the next decade, Americans can expect gasoline shortages, blackouts, and the general instability of an energy crisis. Sale gas buys us time ... but like energy use, global water demand outpaces practical supply.
Global energy demand outpaces supply, so within the next decade, Americans can expect gasoline shortages, blackouts, and the general instability of an energy crisis. This inevitable development will trump the status quo to prompt a cohesive U. S. energy policy — or so says John Hofmeister, former President of Shell Oil Co., and member of the U. S. Energy Security Council.

If Hofmeister’s right, shale gas buys us time. Like bees working fields of flowers, 2,000 rigs now service half a million wells in the U. S., jailbreaking fuel to the tune of 24 trillion cubic feet a year. Mostly due to horizontal drilling and hydraulic fracturing, natural-gas output from shale has tripled since 2007, according to the U. S. Dept. of Energy. New wells abound, as do jobs and promises of economic benefit.

Shale gas is a panacea with well-known caveats. Fracked wells are said to release methane, risk explosions and spills, and consume epic amounts of water. In a lackluster finale to an otherwise elegant process, that chemical-laden H2O is typically left in the ground or hauled to sites that store industrial slurries.

Here’s the catch: Like energy use, global water demand outpaces practical supply. In predictions almost as dire as Hofmeister on energy, the United Nations and the World Health Organization forecast fresh water will be scarcer over coming decades. Oklahoma and Texas are already in a water war exacerbated by fracking consumption near the Red River. The Supreme Court will rule on the case this month.

Only consistent regulation can spur the fragmented industry to use water more prudently. One option is to repeal a 2005 law that exempts fracking from the EPA Safe Drinking Water Act.

In fact, oil and gas suppliers have the engineering prowess to meet higher standards. For example, the Water & Process Technology division of General Electric Co., Trevose, Pa., makes truck-mounted vapor recompressors that boil water out of frack additives right on site. Aqua-Pure Ventures Inc., Calgary, Canada, sells a similar module that uses steam from one cycle to power the next for better efficiency. OriginOil Inc., Los Angeles, makes separators that use electromagnetic waves and bubblers to filter additives and coagulated hydrocarbons out of frack water. Verenium Corp., San Diego, sells enzymes to replace acids for dissolving the guar in frack-water proppants. Halliburton Intl. Inc., Houston, manufactures food-ingredient-based CleanStim as a safer alternative to traditional chemicals.

One Canadian company goes even further with a waterless process. GasFrac Energy Services Inc., Calgary, makes equipment that fracks wells with liquid petroleum gas (propane) infused with viscosifying additives. It doesn’t muck up millions of gallons of water. It pulls more fuel out of wells. All the propane is reclaimed.

Water is polar, so it has a notoriously high surface tension of 72 dyn/cm and tends to get stuck in the capillaries of fracks. In contrast, propane (C3H8) has a surface tension of just 7 dyn/cm, so it easily slips into shale’s nooks and crannies. That helps rig pressure reach deeper into well formations and crack open more recesses. Low surface tension also helps when the process is reversed and pressure is released: Water tends to plug formations, but propane lets more gas flow out for collection. Propane has half the specific gravity of water and small volumes do the job, so tanking sufficient supplies to wells takes fewer trips. After a well tap, propane doesn’t necessitate separate transport back out of the site like water, because it mixes with natural gas and trucks out with the fuel.

Using such technologies to address fracking water usage could alleviate groundwater overdraws documented by the U. S. Government Accountability Office and others. Watersheds to benefit include those overlapping the Marcellus and Utica formations, and the Great Plains’ mighty but dwindling Ogallala aquifer over several heavily tapped gas and oil deposits.

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