diversify hydrocarbon production chain

The current crude oil processing chain is neat, but it lacks variety. My idea is to add other entry points for refineries: fuel gas and bitumen.
Fuel gas would require a change in the tech tree to bring cracking early, but I imagine a map gen setting where u can slide between on-island crude oil or FG. U could use the standard oil pumps for it or add some fracking mechanics. (It's generally quite unhealthy for populations and causes geological instability.) Perhaps the tradeoff could be that FG is present in higher amounts but requires more processing to get useful products.
Bitumen would be processed from a new map resource: tar sand. This would be an incredibly unhealthy and water-intensive form of oil, but would result in the intermediate product bitumen. Bitumen would be processed further into other oil products but could also provide an ingredient for a new surface: asphalt, which could be a cheaper/more effective alternative to concrete.

Also coal liquification.