QUANTIFYING PRODUCED AND INJECTED WATER IN SOUTHEASTERN SASKATCHEWAN

Water injection has historically been used in Saskatchewan conventional oil and gas production, but with the rise of newer more water-intensive unconventional production methods, concerns over groundwater impacts and water management have grown. Coupled with an increasing number of inactive or abandoned wells and lack of data it has become increasingly difficult to determine the effect of long-term water injection on groundwater quality and movement. Since the 1950’s oil and gas wells in southeastern Saskatchewan and along Manitoba’s western border have produced 3.87 x 10⁹ m³ of water, and injected 4.57 x 10⁹ m³ for use in oil recovery or through disposal wells into nonproducing formations. Since 2005 there has been a major increase in production due to development in the Bakken formation accounting for 46.2% (1.79 x 10⁹ m³) of water produced and 46.8 % (2.14 x 10⁹ m³) of water injected since the 1950s. In some case the amount of yearly injected water can exceed 6 times the background regional groundwater recharge rate. However, the effect of long-term injection on groundwater quality and pressures remains uncertain. Injection into nonproducing formations could result in the overpressuring of formations, as well as contamination due to subsurface leaks from imperfectly cemented oil and gas wells or decaying legacy wells. To better understand these effects an investigation into the formations fluid budgets and well inventory is being conducted to identify the formations most at risk to overpressuring and to contamination from leaking wells.