Synthetic proppants can be engineered from industrial and domestic waste materials, including mixed glass cullet, mine tailings and even drill-cuttings from shale gas wells themselves, according to a new study released by Penn State.
In hydraulic fracturing – a process necessary to unlock the hydrocarbons contained in shale deposits – the rock is cracked by water pumped at high pressure. The water cracks the rock creating small fissures to release the gas and oil. A proppant is a substance – usually sand – that is carried with the water that literally ‘props’ the fissures open to let the gas flow freely up the wellbore. Silica sand is the most frequently used type of proppant, although synthetic proppants are also slowly being adopted.
Writing in American Ceramic Society Bulletin, Penn State scientists John Hellmann and Barry Scheetz, explain that although silica sand is the most commonly used proppant in hydraulic fracturing operations, it has serious drawbacks.
“Silica sand is relatively inexpensive, available and has a long track record of use as a proppant,” said Hellmann. “However, sand particles are quite angular and tend to pack. It also typically exhibits lower crush strengths and results in lower permeabilities relative to synthetic proppants, like the ones we are researching. Spherical particles, characteristic of the synthetic proppants, flow better, require less water and chemical additives for placement, and maintain higher permeability for longer periods of time than angular sand particles.”
While silica sand is successfully deployed in fracking operations in relatively shallow deposits, such as in the Marcellus shale, Hellmann believes that engineered synthetic proppants, which are substantially stronger and more spherical, will be required for deeper deposits that contain other condensed phases and that experience substantially higher closer stresses, such as the Utica and Bakken plays.
“Our engineered materials have the potential to not only provide a new source of high-performance proppants, but at the same time do so in a potentially more environmentally conscious way,” said Hellmann. “Waste materials are diverted from landfills and are used to engineer proppants that are more efficient, requiring less water and less chemical additives in the hydrofracturing process – that’s a pretty green message.”
The up-take of ceramic proppants might also be caused by the simple fact that exploration companies are beginning to experience sand shortages. Earlier this month, Morgan Stanley reported that with the booming shale gas production and companies using more sand to increase the productivity of the wells, sand demand is predicted to grow at the rate of 96 per cent in 2016 from 2013, compared with just 76 per cent of sand capacity growth.
So far the situation resulted in a boom among sand producers. In June, Halliburton – one of the world’s largest oil field services companies – announced a new long-term frac sand purchase agreement with Hi-Crush Partners. The new agreement increased the annual minimum committed volumes under the previous agreements, extended the term through December 31, 2018 and required Halliburton to pay a specified price for a specified minimum volume of frac sand each month.
The deal with Hi-Crush was symptomatic of the increased demand for proppants with silica sand providers experiencing booming profits and increased share value.
But there is more. As a result the high demand for silica sand, Morgan Stanley predicts that sand prices could increase as much as 50 per cent. This price increase would narrow the price gap between sand and ceramic proppants and given the superior performance of the latter it may result in the higher adoption of synthetic proppants. Especially if manufacturing proppants from waste can further reduce the price of the synthetic alternative to sand.
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