Technologies May Ease Frac-Related Water Concerns

Technologies May Ease Frac-Related Water Concerns by Pat Roche, June 28, 2006, Daily Oil Bulletin
With an ever-increasing share of Western Canada’s natural gas supply coming from low-permeability reservoirs, there is a growing need for fracture stimulations. This means a greater need for fresh water to mix frac fluids and increased costs related to disposal of used frac water. Also, there is growing uneasiness about the impact of shallow frac jobs on nearby oil and water wells, but there’s no wholly satisfactory way of modelling the impact of shallow frac treatments. Technological solutions to address all three issues were discussed in presentations at a recent Petroleum Technology Alliance Canada conference on water innovation in the oilpatch. … About 5,000 to 7,000 wells were drilled in southeastern Alberta and southwestern Saskatchewan each year from 2001 to 2005. The estimated water consumption is about one million cubic metres per year. Common water sources include municipal supplies, irrigation canals and other fresh-water bodies. Fulton said essentially all water used for shallow-gas well fracturing is withdrawn from the South Saskatchewan River Basin, where water allocations are being closely scrutinized. While water consumption for fracing might not be a big part of the overall picture, Fulton pointed out it is occurring in an area where water resources are already over-allocated. Some of the water used in frac jobs stays in the formation and the rest is trucked to disposal wells. “Every drop of fresh water that went into that (frac) fluid is lost to the water cycle,” said Fulton. … Besides cost and logistical concerns for producers whose wells are being fraced, there are questions about the impact of shallow frac treatments on nearby water and hydrocarbon wells. The Alberta Energy and Utilities Board recently announced new pre-fracturing reporting requirements and restrictions on shallow fracturing near water wells. These steps were taken following incidents where shallow fracturing operations affected nearby oilfield wells, according to Pat McLellan, president of Advanced Geotechnology Inc.

While there are several ways of modelling frac treatments, McLellan said there is no proven, calibrated model or numerical simulator with a history of successful predictability for shallow CBM, shale gas and tight-sands fracing. “We do not have a robust design process to confidently predict the size, shape and growth rate of the stimulated zone as a function of pressure, injection rate and time,” McLellan said about shallow fracing. To improve the design process for shallow fracture stimulations — and to reduce the risk of affecting shallow groundwater and hydrocarbon zones — Advanced Geotechnology is spearheading a joint industry research project. The project just got off the ground…. The goal of the joint industry project is to develop a design process and predictive tools or models for engineering frac jobs at depths of less than 600 metres in CBM, shale gas and sandstone reservoirs. McLellan said the aim is to reduce the economic and environmental risks associated with inefficient well stimulation treatment, design and implementation. The first phase of the joint industry project is to review existing research, analyze recent Alberta incidents, critique modelling options and develop and test an analytical and/or numerical model. [Emphasis added]

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