I think it depends on which one you're talking about. Last week Shell announced a major new technology for its upgrading process, which I think has something like a 10% reduction on the heat use. That was a four- or five-year project. Some can happen fairly quickly; some are very long term. A carbon capture storage project can take a while. When you look at the big step changes, we may be talking decades.
On December 5th, 2006. See this statement in context.