Oil and gas exploration is a business of significant risk. The success stories are often chronicled at professional meetings while the failures get tucked away in “lessons learned” reports. The North Slope of Alaska has seen more than half a century of exploratory drilling, with its obvious successes but even more numerous failures. The potential reservoirs targeted for exploration on the North Slope, including those substantiated by drilling success, span across a wide range of ages and depositional environments. Each of the major reservoir targets has its share of “lessons learned”, some learned very early when exploratory methods were as crude as drilling near an oil seep. Other successes and failures have become more sophisticated as the data sets and techniques have become more refined, including detailed interpretation of 3-D seismic data sets, reservoir burial modeling, and hydrocarbon charge analysis.

Any exploration success has to satisfy the requirements of having a hydrocarbon charge available, a means to trap the hydrocarbons as they migrate, and a reservoir with the pore space to hold it but the permeability to release it upon request. Enough data exists to make generalizations about what critical risk has failed over large geographic areas of the North Slope. In some areas particular reservoirs (examples: Alpine) are absent in all wells drilled to date. In other areas particular reservoirs (example: lower Brookian) have been over-compacted in wells drilled to date. Still other areas have great looking reservoirs, but no structural or stratigraphic trap and thus are wet (examples: Ivishak, Kuparuk). This talk will identify some of the historical successes on the North Slope, but will also identify where our data sets document failure and profile examples of the “lessons learned”.