The Nsolv Process
How It Works
Step 1 – Solvent purification. The Nsolv process requires a substantially pure solvent (generally propane or butane) in order to function effectively; therefore, the first step in the process is the simple distillation of the solvent, removing non-condensable gases such as methane.
Step 2 – Solvent heating. The purified solvent is then warmed and turned into solvent vapour.
Step 3 – Solvent vapour injection. Warm solvent vapour is pumped into the injection well. When it reaches the extraction chamber, it condenses and dissolves the bitumen, draining downward to the production well as a solution of both solvent and partially upgraded oil. Naturally occurring water and non-condensable gases are also produced. Coke-forming asphaltenes are sequestered in the reservoir.
Step 4 – Separation. Upon being pumped up to surface, the partially upgraded oil mixed with solvent is separated into three components: oil for sale, solvent and naturally occurring water. The oil is sent to refineries for further processing. The solvent is pumped back into the separator and re-purified before being recycled back into the reservoir. Gaseous impurities removed from the solvent, such as methane, are used to fire up the solvent heater.
Step 5 – Solvent make-up. Nsolv estimates that a solvent quantity equivalent to 20-30% of the extracted oil must be added to the system as make-up. As the chamber grows, the make-up solvent is continually replenished. At the end of a well’s life, the solvent can be recovered and reused on another well or marketed.