cinguetti reserves, page-11

tastarga is on the right track. If one is looking at a single field production profile, you will most likely get to peak production after maybe 6 months, hold that for maybe 18 months to 2 or 3 years depending on field size, and then have an exponential decline after that, with a very long flat low production tail. Take a look at Barrow Island history to see this. Offshore the long tail is usually not economic, so at some stage the field will be shut in leaving producible volumes in the ground. Your NPV analysis will tell you when this will occur, and how much will be left. Of course if the price of the bbl goes up, then the evil shutin day is postponed. As it will also be if pressure maintenance/water injection is employed.
The field life production profile is probably the most critical and sometimes the most difficult of NPV inputs. To estimate this one needs to do a full cycle reservoir simulation study, and this in turn depends upon a heap of field specific subsurface data. Which of course is not made available. However for those really keen, a look at historical rates from similarly sized fields can give a fair indication. Try a look at Laminaria for example.