Bench-Scale Evaluation of Solidification Technology for SAGD Waste Brines

摘要

In the Steam Assisted Gravity Drainage (SAGD) recovery of bitumen in theAlberta oil sands industry, waste brines are generated from evaporator and boiler blowdownstreams. For sites where deep brine-disposal wells are not practical, brines are typicallyconcentrated using evaporation and crystallization processes prior to truck-out to third-partywaste managers or processing by zero liquid discharge (ZLD) treatment facilities, which canemploy thermal drying. Less energy intensive and less expensive ZLD alternatives are ofinterest to the industry. Solidification/stabilization techniques have been used extensively as ameans of making waste sludges and brines suitable for landfill disposal in other industries, andthis approach was examined for SAGD applications. This paper presents the results of benchscaleinvestigations into the solidification of several SAGD waste brines from both producedwaterevaporator-based processes and from conventional warm lime softening processes. Inaddition, the results of an in-situ solidification approach, used to improve the operation of anexisting SAGD salt-waste landfill, will be presented. A wide spectrum of solidification agentswere examined, including cement and cement by-products, fly ashes, clays and lime. Tests forconfined and unconfined compressive strength (UCS), leachability and permeability wereperformed. The results indicated that a strong, stable solid waste could be produced for all ofthe brines examined. UCS values of greater than 10 psi were achieved. However, there weresignificant differences between the types of reagents, as well as the quantities needed for theindividual brines, indicating that site-specific testing may be beneficial.