Refracking Brings Old Oil & Gas Wells to Life

Canada Encana Corp Invested $2 Millions to Refrack Wells in Louisiana

A fracking boom isn't enough for U.S. oil and gas producers - they're now starting the re-fracking boom.

Wells sunk as little as three years ago are being fracked again, the latestinnovationin the technology-driven shale oil revolution. Hydraulic fracturing, which has upended global energymarketsby liftingU.S. crudeoil output to a 25-year high, has been troubled by quick declines in oil and gas output.

The development highlights how producers must constantly invest and tinker, both to raise overall oil recovery rates that can be as low as 5 percent and to limit steep drops in production suffered by wells drilled into tight oil deposits.

Canada's Encana Corp invested $2 million to refrack two wells in Louisiana's Haynesville shale formation earlier this year, after seeing its production in the area dip 27 percent from 2012 levels.

"There were a significant number of wells that we considered unstimulated," said David Martinez, Encana's senior manager for Haynesville development.

Using minuscule plastic balls, known as diverting agents, pumped at high speeds with water into the old wells, most of which are three to five years old, Encana blocked some the older fractures, or cracks.

"The thought is that the diverting agent will go to the cracks with the least amount of pressure," bypassing cracks with higher pressure and boosting the pressure of the entire well so output climbs, Martinez said.

He said the process can't be as precisely controlled as an initial round of hydraulic fracturing, in which water, chemicals and sand into are blasted into rock to unlock oil and gas.

Fracking has been used on about 1 million wells bored since 2007, and oil and gas companies now fracture as many as 35,000 wells each year, according to FracFocus, the national fracking chemical registry.

Refracking cost Encana about $1 million per well, compared with about $12 million for wells it drilled in 2012. Encana is no longer drilling new wells in the Haynesville formation, executives said.

Since it isn't clear how long the benefits of a refracking last, Encana plans to collect more data when it refracks five more Haynesville wells this quarter, Martinez said.

If those prove fruitful it may consider expanding the practice to its holdings in the Denver-Julesburg Basin of Colorado and the Eagle Ford formation in Texas.

Another Haynesville operator, Dallas-basedExco Resources Inc, said it boosted output from a 2010 refracked test well by 1.3 million cubic feet of gas per day. It didn't say how much gas it was producing before the refracking. Average initial production from new wells Exco drilled in the second quarter was 12.9 million cubic feet per day.

Some of Exco's Haynesville wells after four years were producing about a fifth of what they did in their first year, with output declining 69 percent that first year alone, according to the company.

Source: Reuters

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• Fracking
• Water Wells
• Governance & Planning