"The chief tangible cause for failure to discover large, new reserves is that about 80% of the world is controlled by state oil companies and is, therefore, unavailable for competitive investment and drilling. It is reasonable, in other words, that if companies must continue to prospect in the same 20% of the world's basins that the size of new discoveries should decline as it has.
There are, however, more fundamental and systemic reasons why petroleum E&P companies are in trouble. First, the Risk process discourages discovery of large reserves. The Risk evaluation model does not take diffusion theory into account adequately. By the time most companies decide to enter a new E&P play or trend, little opportunity remains and most remaining opportunity is in relatively small fields. Gulf of Mexico shelf and deepwater drilling and discovery patterns clearly show this.
Petroleum companies reward their management largely without regard or accountability for reserve additions through exploration and production. Poor company performance has led to repeated technical staff reductions over the past 30 years, which, in turn, have discouraged young people from entering petroleum-related fields. The result is a depleted work force that has little replacement potential, but remains unappreciated and inadequately rewarded by their employers.
At the same time, technical staffs have not adequately embraced inventive application of new technology and have, therefore, not developed new ideas for exploration and production. Seismic attribute analysis and deepwater facies models are believed by most to be the cutting edge of E&P but diffusion theory shows that, since everyone is using these approaches, they will yield limited future opportunities."
Clearly, state oil companies of countries such as those that make up OPEC haven't necessarily maximized their exploration efforts, since during the 1980's and 1990's oil prices were extremely low and failed to increase even with the US rate of inflation due to the massive amount of existing supply. The powerpoint is very well worth a read...