By JACOB DENNIS, Product Development Engineer, Scovan
In its relentless pursuit to advance technologies that reduce environmental footprints, Scovan continues to develop the ORSIL™ technology to manage waste streams generated in a SAGD facility in a more environmentally friendly and cost-effective manner. By converting a waste stream that currently requires truck transportation to off-site disposal into a stream safe to dispose of with on-site wells, truck traffic and its associated emissions, safety concerns, and operating costs are all reduced.
SAGD operators are deploying advanced steam generation technologies that have lower water intensity such as evaporators with drum boilers, Once Through Steam Generators (OTSG) with higher concentration factors, or Indirect Fired Steam Generators (IFSG). However, these technologies come with their own unique challenge in that the operators must manage disposal of high TDS waste streams laden with higher concentrations of silica, organics and other contaminants. Due to the limitations placed on Class 1b disposal wells these waste streams must be trucked out to a third-party facility for further treatment and/or disposal, though many operators have their own disposal wells. Operators incur additional third-party disposal fees, trucking fees and carry the associated greenhouse gas (GHG) burden.
The ORSIL™ process is a patent pending technology which effectively removes silica and organics from wastewater streams in a multi-step process which creates a solid phase that is suitable for landfill (Class II) and an aqueous phase which can be deep well injected (Class 1b). This process has been proven, at the pilot scale, to reduce silica concentrations below 100 mg/L and Total Suspended Solids (TSS) below 10 μm in the aqueous phase. Testing has also shown that dissolved organics is an important parameter that needs to be managed. The filterability of the suspended solids produced by silica reduction is directly related to the removal of dissolved organics. To date, the ORSIL™ process has been used to successfully treat evaporator blowdown, OTSG blowdown, IFSG blowdown and raw produced water from numerous SAGD operations in the Fort McMurray region.
The testing has demonstrated that meeting deep well injection requirements require a multiple step process. While the chemical and physical reactions in each step can be evaluated independently, they appear to work in a synergistic way and the success of the treatment depends on using all the steps. The ORSIL™ process consists of two main Steps:
A Carbon dioxide (CO2) treatment
B FeCl3 and MgO/Lime treatment
Each of these steps can be further broken down into three stages, consisting of chemical addition, agitation, and dewatering. The three Stages for Step B are below:
1 Chemical addition: three stages of chemical addition are added to the waste stream
2 Agitation: the treated stream is slowly agitated at elevated temperatures for a defined period. During this stage, the silica and organics are removed as solids form in the mixture.
3 Solids Separation: the formed solids are separated from an aqueous phase through dewatering via a filter press.
Scovan owns a self-contained ORSIL™ based pilot unit within an 8’x40’ sea can unit having all the necessary equipment to conduct a 1m3 batch test. Clients wanting to test the ORSIL™ technology on their own wastewater streams or wanting to have the chemistry fined-tuned for their unique waters can make use of our mobile pilot unit. Scovan is currently in the preliminary stages of developing a full-scale commercial product offering.
At Scovan, we believe the ORSIL™ technology will provide SAGD operators in Alberta an opportunity to push the limit on steam generation technology without worrying about the management of the resultant waste stream. ORSIL™ has the potential to provide a more environmentally friendly and cost-effective solution than current SAGD wastewater disposal methods.
Originally published in Scovan’s IGNITE Vol. 4
