Case Studies - CAN002 - Pneumatic Fracturing

Pneumatic Fracturing - Calgary, Alberta, Canada

ARS performed a project at a former gas station site in northwestern Calgary. Prior to ARS' involvement, the consultant had been successfully applying a patented bio-inoculant formula in reducing BTEX and TPH to levels below clean-up criteria to a depth of 10 ft bgs. The bio-inoculants, which included enzymes, bacteria, and nutrients, were pumped into 2-inch screened wells located throughout the site. However, soils at depths greater than 10 feet contained higher silt and clay contents that prevented effective substrate delivery by conventional hydraulic injection.

In April 2002, ARS performed Pneumatic Fracturing at two separate areas of the property to increase the bulk permeability of the formation at depths greater than 10 feet bgs. Over a two-day period, five boreholes at each area were pneumatically fractured at depths from 10 to 23.5 feet bgs. Based on field data collected during the fracturing operations, including surface heave measurements and lateral pressure response in surrounding monitoring wells and boreholes, greater than 30 feet of fracturing ROI was evidenced. A total area of approximately 12,500 ft2 was enhanced by the fracturing. Through the creation of a dense fracture network in the subsurface, the permeability of the soils were increased and effective injection of the bio-inoculants in the target zone was accomplished. After fracturing, each borehole was converted to a 2-inch injection well, which was used to introduce a proprietary substrate into the fractured zones. Post-fracture injections performed in all ten wells indicated that injection rates increased by an average factor of five. As much as 30,000 US gallons of the bio-inoculant were injected in one single application in May of 2002.

 

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