This article from Heatingoil.com says while the forecast from Glen Sweetnam, the director of the International Economic and Greenhouse Gas Division at the Energy Information Administration (EIA), credits a reduction in investment for most of the decline, the presence of biodiesel will also play a role in petroleum’s possible fall:
This transition toward lower oil demand can be seen in the heating oil industry itself, which—through a combination of industry leadership and legislative mandate—is adopting blends of biodiesel and heating oil. Biodiesel blends will lower overall oil demand while supplying consumers with a more efficient and cleaner-burning heating fuel. As with Sweetnam’s forecast that declining oil production could happen next year, many heating oil users will see changes by next heating season—in Massachusetts all heating oil will have to contain 2 percent biodiesel by July 1, 2010, and pending legislation in Connecticut and Pennsylvania would have a similar effect on heating oil users in those states in the next three to four years.
It’s the “above ground” factors, such as biodiesel, and not the amount of oil in the ground that will have the biggest effects on petroleum production.