The Bakken, as well as other shale oil areas, is not one homogeneous area where equal amounts of can be found. David Hughes in DRILLING DEEPER puts it this way, though here he is talking about gas wells, the same applies to oil wells:
All shale gas plays invariably have “core” areas or “sweet spots”, where individual well production is highest and hence the economics are best. Sweet spots are targeted and drilled off early in a play’s lifecycle, leaving lesser quality rock to be drilled as the play matures (requiring higher gas prices to be economic); thus the number of wells required to offset field decline inevitably increases with time.
However the Bakken, at least through the September North Dakota Industrial Commission production report, has given no real indication that the Bakken is even close to peaking. But a closer look at the data makes me believe that is all about to change.
The NDIC issues a Daily Activity Report where they list permits issued as well as wells completed and wells released from the tight hole confidential list. These reports usually, but not always, also give the number of barrels of oil per day and barrels of water per day for the first 24 hours of production. I have gone through every day, back to November 1st, 2013 and collected the data on every well listed that gives production numbers and copied that data to Excel. In that one year and three weeks I have gathered the data form every one of the 2,171 wells that give production numbers. Sorting these wells by well number, which is the original permit number, gives some startling results.
To smooth the chart I created a 200 well average of barrels per day per well. The first point on the chart is therefore the average to the 200th well, #23890 and the last point is the 200 well average to the 2171st well, #28971. As you can see there has been a continuous, though erratic, decline in first 24 hour production as the well numbers increase.
Breaking this down according to well numbers we see production peaked with the 2400s and have steady decline since. Every group of well numbers do not contain the same number of wells.