sentences:  By the early 1990s, production from the heavy oil belt was some 40,000 cubic metres per day, and Husky was still one of Canada's biggest heavy oil producers.Heavy crude feedstock needs pre‐processing before it is fit for conventional refineries.This is called 'upgrading,' the key components of which include 1) removal of water, sand, physical waste and lighter products; 2) catalytic purification (hydrodemetallization, hydrodesulfurization and
  hydrodenitrogenation; and 3) hydrogenation though carbon rejection or catalytic hydrocracking.