WASHINGTON, D.C.: Amidst the rise of "re-fracs" in the U.S. as part of the efforts to boost domestic oil production, American shale oil producers are successfully returning to existing wells and giving them a second, high-pressure blast.

The re-fracs, which are increasingly popular as shale oil producers look to take advantage of $100 per barrel crude, without making large investments in new wells and fields, were triggered by the global oil shortage, causing U.S. President Joe Biden to call upon shale producers to spend more of their profits on increasing output.

However, the firms have been under pressure from their shareholders to focus on returns, rather than production growth.

Since January, shortages of steel, diesel and workers have doubled oilfield inflation, making re-fracing even more attractive as a discounted way of increasing production.

According to experts, re-fracing can be up to 40 percent cheaper than drilling a new well.

It can also double or triple oil flows from aging wells, said Garrett Fowler, chief operating officer for ResFrac, a firm that helps producers install re-fracing, which has seen about twice as many inquiries compared to prior years.

For oil producers, re-fracs can add output to existing pipelines while being affordable, as their shorter completion time can be scheduled between work on new wells, said Catherine Oster, head of Devon Energy's mid-continent properties.

"You go back and find where you may be under-completed and under-fracked in the beginning," she added, as quoted by Reuters.

ResFrac's Fowler said the most common re-frac method is to place a steel liner inside the original well bore and then blast holes through the steel casing to access the reservoir, and in some cases, the process uses half as much steel and frac sand, compared to drilling a new well.

U.S. oil production remains about one million barrels per day (bpd) below the 12.8 million bpd peak, with output being limited by the rapid decline of shale wells. Flat spending could restrain output to current levels.

Stephen Ingram, a regional vice president at top U.S. hydraulic fracturing firm Halliburton, said, "Techniques like re-fracturing will allow the industry to continue to harvest the oil and gas out of these reservoirs."

Matt Johnson, CEO of energy consultancy Primary Vision Network, said, "Considering inflation, supply chain issues and rising wages, now is a great time for operators to start looking at wells for re-frac opportunities," as reported by Reuters.