An automated waste liquid injection system for dirty liquids was designed and implemented in an unconsolidated sandstone formation in southeastern Alberta. This development was based on previous waste sand injection in central Alberta. Waste liquids consisting of contaminated water, heavy oil, and fine-grained particulate matter are being diluted and injected under formation fracture pressures. Monitoring for environmental security and process control includes precision tiltmetres and comprehensive pressure analysis. Injectivity, transmissivity, reservoir pressure evolution, and fracture closure pressure calculations based on pressure fall-off and step-rate tests allow the formation state to be continuously re-evaluated. The reservoir is not being impaired by the continued injection of dirty liquids.

This article first describes Slurry Fracture Injection (SFI) history and principles, the site geology, and recompletion strategy. Then, data from the trial period and the summer operations are presented and analyzed. The use of SFI in this new application seems to be highly successful, and the nature of the process and controllable factors are discussed in the context of preserving target formation injectivity.

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