LINKING TIME AND GEOMETRY WITH PETROLEUM DISTRIBUTION — APPLIED 4D PETROLEUM SYSTEMS MODELING WITHIN THE ALASKA NORTH SLOPE

The petroleum province of the Alaskan North Slope comprises seven identified petroleum systems with complex maturation, migration and charge histories. We look at the four major source units in the area within the Paleozoic to Mesozoic Ellesmerian and Beaufortian Sequences, namely the Kingak Shale, Shublik Formation, pebble shale unit (PBS) and gamma ray zone (GRZ) source rocks. The maturation and expulsion history of these source units depends greatly on both the present-day and the paleo-basin geometry of the study area. The paleogeometry of the Ellesmerian and Beaufortian Sequences is mainly controlled by the diachronous deposition (progradation) of the overlying Brookian sequence from west to east. This resulted in western and eastern depocenters where the source rocks became thermally mature at different times.

Accurate basin geometry, temperature, and maturation history through time are needed to model the occurrence of multiple petroleum systems and their complex migration pathways to multiple reservoir rocks. A three-dimensional, pressure-volume-temperature controlled, multi-component (hydrocarbon fractions), 3-phase (oil, gas, water) petroleum migration model is presented that integrates changing basin geometry, thermal history, maturation, migration and accumulation through time to account for the petroleum distribution observed today on the North Slope.