"Fracture fluids introduced into producing wells result in suspended production, substantial remediation costs and pose a potential safety hazard," reported the OGC.

The agency also confirmed the uncertain nature of the technology: "Fracture propagation via large scale hydraulic fracturing operations has proven difficult to predict. Existing planes of weakness in target formations may result in fracture lengths that exceed initial design expectations."

Similar incidents have been reported across the United States. In North Dakota's booming Bakken shale oil fields, one engineer recently reported at least four incidents in which fracking fluids shot "into offset wells 1,500 to 2,200 feet away in transverse direction, pumping sand-laden slurry to surface."

At industry conferences engineers frequently bemoan the unpredictability of fracturing behaviour. Highly-pressurized fluids from unconventional wells have "communicated" with nearby oil and gas wells in Colorado and Utah. In one Texas accident fracking fluids invaded five adjacent vertical wells, stopping gas production altogether.

In 2009 Mike Vincent, a Colorado-based fracturing consultant, reported to the Society of Petroleum Engineers that, "Contrary to common expectations there are numerous examples of fractures intersecting offset wells (existing oil or natural gas wells near the well being fractured) but subsequently providing little or no sustained hydraulic connection between the wells. There is an understandable reluctance to publish reports documenting the intersection of adjacent wellbores with hydraulic fractures. Such information could unnecessarily alarm regulators or adjacent leaseholders who may infer that well spacing or fracture treatments are allowing unexpected capture of reserves."

"In the design of hydraulic fractures, it is necessary to make simplifying assumptions," Vincent wrote. "Although computing tools have improved, as an industry we remain incapable of fully describing the complexity of the fracture, reservoir and fluid flow regimes." Industry, he adds, rarely publishes information about the technology's many failures and accidents.

Fracking is safe: Alberta Tories

Given the unpredictability of complex fracturing operations, groups of citizens in New York are now lobbying for better regulation, baseline water monitoring and at least 4,000 ft setbacks from water wells and aquifers. Other jurisdictions such as Quebec, Bulgaria, New York and France have banned the practice or imposed moratoriums due to water concerns.

Alberta's Tories, which have ruled the province for 40 years and are heavily dependent on oil and gas revenues, contend that hydraulic fracking is perfectly safe and requires no review.

Yet the ERCB admits that as many as five well communication incidents have occurred during the fracking of some 2,000 horizontal wells since 2008. The companies involved include Talisman, Bonterra, Yangarra and Bellatrix. Industry insiders suggest the real number is probably much higher.

The Midway incident made global headlines because it connected one well to an existing operation at an unprecedented distance of 1.2 km away.

Alberta's regulator did not answer any questions submitted by The Tyee, but forwarded a Jan. 23 press release asking oil and gas companies to "immediately report any instance of unintended inter-well communication to the nearest ERCB Field Office."

Numerous central Alberta families now have flaming or contaminated drinking water after industry dotted the province's farm belt with poorly regulated and experimental coal bed methane wells over the last decade.

"Yes, people are being harmed and poisoned but we believe it's not just about the people," Ronalie Campbell, a rancher, told a Ponoka audience last week. "It's about the water, the resource we all need to live. It's our job to tell the people the truth." Her family lost its water in 2005 after extensive and repeated fracking in the area.

In 2006 the ERCB issued an interim order that restricted shallow fracturing of gas reservoirs after the practice contaminated groundwater:

"Information provided by industry to date shows that there may not always be a complete understanding of fracture propagation at shallow depths and that programs are not always subject to rigorous engineering design," said the order.

When wells 'communicate'

In Australia the shallow fracking of coal seams also resulted in groundwater contamination and a major ongoing government investigation.

In addition, Jessica Ernst, an oil patch consultant, recently sued Encana Corporation for $33 million for contaminating a freshwater aquifer in southern Alberta in 2004 after the company extensively fracked coal seams near her home. The claim alleges that Alberta Environment and the ERCB "failed to follow the investigation and enforcement processes that they had established and publicized."

New studies show that fracking can impact rocks over an extensive area. A 2011 study by Denbury Resources (an independent US firm) and presented to the US Environmental Protection Agency, found that hydraulic fracturing operations in the Barnett Shale cracked rock over a vast underground area in Texas. Cumulative frack jobs can also increase the probability of contaminating or invading other wells.

One operation propelled 17,000 pounds of water and 250,000 pounds of sand at a rate of 100 barrels of fluid per minute into shale rock. All of that brute force cracked open rocks over an 150-acre area during a six-stage frack job.

Concluded the Denbury study: "Even with the tools available to perform fracture diagnostics, operators are still faced with challenges that are difficult to predict. As well density increases, it becomes increasingly probable that wells will communicate either through previously created fractures or through adjacent wellbores and then into previously created fractures."

Industry calls hydraulic fracturing a proven technology that has dramatically increased oil and gas reserves on the continent by allowing industry to access previously uneconomic resources.

But independent scientists and industry insiders contend that 60-year-old assumptions about the technology initially used for vertical wells no longer hold true.

When combined with horizontal drilling, which can stretch a mile long underground, hydraulic fracturing can open different kinds of reservoirs, "challenging the fundamental assumptions upon which our existing candidate selection and design methodology are built."

(Full Disclosure: Andrew Nikiforuk is an Alberta landowner but not a member of the ASRG.)

[Tags: Energy, Environment, Politics, Rights and Justice.]