L’objectif d’un raffineur est avant tout de répondre à la demande en produits pétroliers. Aujourd’hui, le développement des transports routiers et aériens s’est accéléré, et la demande en produits légers est montée en flèche. Parallèlement, on brûle beaucoup moins de produits lourds pour produire de l’électricité ou pour se chauffer. La demande mondiale est environ de 40 % pour les produits légers (carburants), 40 % pour les produits moyens (fioul, gazole) et 20 % pour les produits lourds. Le seul pétrole correspondant à peu près à ces proportions est le brut léger du Sahara algérien. Mais la plupart des bruts extraits dans le monde contiennent plus de produits lourds. Des raffineries composées uniquement d’une tour de distillation, comme autrefois, ne suffisent donc plus. Il faut d’autres unités de production dont le but est de transformer (on dit aussi convertir) les produits lourds en produits légers. Pour cela, il existe plusieurs techniques de raffinage. C’est pour ces raisons de coûts de transformation que les bruts plus lourds coûtent moins cher que les légers techniques de raffinage

Au Canada, les raffineries utilisent principalement le procédé de craquage. Elles traitent un mélange de bruts légers et lourds de manière à fabriquer la gamme des produits demandés par les consommateurs canadiens. Par le passé, l´abondance des pétroles bruts légers et non corrosifs produits au pays et la demande de produits de distillation, comme le mazout de chauffage, plus élevée qu´ailleurs, ont réduit la nécessité d´installer une capacité de valorisation au Canada. Cependant, ces dernières années, les approvisionnements en bruts légers et non corrosifs ont diminué, et les bruts des nouvelles sources d´approvisionnement sont généralement plus lourds. Un grand nombre de raffineries canadiennes sont maintenant équipées d´installations de valorisation qui traitent les bruts les plus lourds actuellement produits.

Source OPEP 2007

Several factors will shape developments in the downstream sector in the years to come. Growing demand for oil products clearly means there will be a rising volume of crude oil that needs to be refined. Moreover, the oil products demand structure will change, with the expected continued move towards lighter products. At the same time, and driven by environmental concerns, product specifications are moving towards significantly cleaner products that will necessitate substantial reductions in sulphur content, as well as improvements in other quality parameters. To meet these challenges, the downstream sector will require significant investment to ensure that sufficient distillation capacity is in place, supported by adequate conversion and desulphurisation, as well as other secondary processes and facilities

In addition to crude distillation capacity, downstream conversion units and the associated support facilities will be required to meet the future product demand, as well as changing product specifications. In this respect, crude oil quality will increasingly play an important role in determining future refining requirements. Heavier crude oil will require increased conversion capacity to produce a higher portion of light products and sulphur content increases will necessitate modifications to intermediate processes, notably hydro-treating, hydrogen and sulphur recovery. However, by far the bigger refining challenge comes from the changing product slate and specifications. When considering the world as a whole, demand for residual fuel oil and other ‘heavy’ products is declining relative to demand for lighter products. This changing structure will require investment in conversion and desulphurisation capacity over the longer term, in addition to the projects already announced for the next few years.

As presented in Figure 5.5, all three major crude types — light, medium and heavy — will grow in terms of volume and with only marginal changes in terms of share. Heavy crudes will decrease their share from 13% in 2005, to 12% by 2015 and to 11% by Light crudes should first increase their share from 43% in 2005 to 44% in 2015, and then slip back to 43% by Medium crudes will keep their share stable at 41% throughout the forecast period. Condensates should witness steady growth, increasing from 3% in 2005 to 4% by In terms of sulphur content, the trends may be more predictable as most of the new oil is rather sour, while the losses tend to be sweet (<0.5% sulphur), but even then the deterioration may not be pronounced. This is especially valid in the period to 2010 where more detailed information about new production is available. Longer term, a moderate decline in overall crude quality is expected to occur and the average sulphur content is expected to increase to almost 1.4% by 2020 from 1.2% in 2005

Taking into account the most likely changes in the future supply and demand structure and the corresponding quality specifications, the global downstream sector will require 13.1 mb/d of additional distillation capacity, more than 7.5 mb/d of combined upgrading capacity, more than 18 mb/d of desulphurisation capacity and around 2 mb/d of capacity for other supporting processes such as alkylation, isomerisation and reforming, over the period 2006–2020. Requirements for all major refinery upgrading units — coking, cat-cracking, hydro-cracking — continue to be significant, but with hydro-cracking projected to take a progressively larger role.