Fom the viewpoint of those who suggest that there is no problem, the discussion that swirls over the future of global oil supplies often seems to focus on the large volumes of oil that still remain in place around the world. The critical point, however, is not that this oil exists, but rather the rate at which it can be recovered. This is perhaps most obviously pertinent to the discussion of oil coming from the Bakken formation in North Dakota, where the rapid decline in individual well performance means that a great many wells must be developed and remain on line in the out years to sustain any significant flow past peak. As I noted last week, it is a point that clearly was missed by Leonardo Maugeri, and equally by George Monbiot, who has finally been swayed to the side of the cornucopians, after years of doubt.

But the issue of individual well flow rates are an increasingly critical factor when future oil production in oilfields around the world are considered, and this holds equally true when the fields in Saudi Arabia are discussed.

The history of oil production from Saudi Arabia has largely come from individual wells that produced in the thousands of barrels a day. In order to sustain that production over decades, it has been necessary to ensure that 1) the pressure differential between the well and the rock are sustained; 2) that the rock has an adequate permeability to ensure that flow continues at a steady state; 3) that the oil itself is of relatively low viscocity and is thus able to easily flow through the rock; and 4) that there is a sufficient thickness and extent in the reservoir to allow such sustained production.

All of those factors came together in the giant fields that provided high levels of production over many decades, most particularly in the northern segments of Ghawar.

Yet those conditions are less commonly congruent in the fields that Aramco must now exploit to address the coming falls in production from the historic sources. These “best of the rest” (as the late Matt Simmons called them) must now increasingly carry the burden of sustaining Saudi production fail, individually, on differing grounds from meeting those earlier parameters. Collectively and in the face of Ghawar’s decline, they will only be able to sustain production to their original targets and will not provide replacement production as the oldest and larger begin to fade. I would remind you of the curve that Euan put up back in 2007.