TRAPPING STYLES AS A KEY TO FUTURE EXPLORATION SUCCESS IN A MATURE FOREARC BASIN - THE COOK INLET OF ALASKA

The Cook Inlet sedimentary basin of Alaska covers an area of approximately 12,000 square miles. A cumulative total of >1.28 BBO and >6.63 TCFG have been produced in the basin since the first discovery was made at Swanson River in 1957. Most of the exploratory drilling in the basin was undertaken prior to 1968, when larger reserves were discovered on the North Slope of Alaska. Industry's attention and technology went northwards. High operating costs and low gas pricing also served to dull interest in further exploration in the basin. Cook Inlet is a fore-arc basin with 30,000 feet of Tertiary sedimentary fill plus a further 40,000 feet of Mesozoic section. There are up to five distinct petroleum systems, of which only three have been explored to any great degree. Structural complexity caused by wrench tectonics, poor seismic imaging, and challenging log analysis are the major obstacles to success in the basin. The author will show how these challenges can be met, in particular using a study of existing trapping mechanisms, log responses and through the application of improved seismic imaging, leading to future discoveries of oil and gas in this mature but still enticing hydrocarbon province.