What Drives Volumetrics?—Risking Petroleum Systems on the Alaskan North Slope

Carolyn Lampe¹, Robert Tscherny¹, Kenneth E. Peters², Kenneth J. Bird², and Leslie B. Magoon². (1) Integrated Exploration Systems, Ritterstrasse 23, 52072 Aachen, Germany, phone: 49-241-51586-50, fax: 49-241-51586-90, c.lampe@ies.de, (2) U.S. Geological Survey, 345 Middlefield Road MS-969, Menlo Park, CA 94025

The petroleum province of the Alaskan North Slope contains seven petroleum systems with complex geohistories. We examined the four major source-rock units within the Paleozoic to Mesozoic Ellesmerian and Beaufortian Sequences: the Kingak Shale, Shublik Formation, pebble shale unit, and Hue Shale or gamma ray zone (GRZ). Source-rock parameters and changing geometries within the basin during burial largely control the thermal maturation, expulsion, and accumulation history of each petroleum system (see Peters et al., this session).

Numerical models can be used to address uncertainties associated with input parameters, model resolution, or lack of information (e.g., thickness, richness, or kinetics for source rocks). Three key risk factors are (1) charge, including source-rock richness and maturity, (2) trap and seal quality, including prospect geometry, reservoir quality (porosity and permeability), and (3) relative timing of charge and trap formation. Petroleum systems modeling combines quantitative input on processes (factors 1 and 2) and timing (factor 3), which allows the principal exploration risk factors to be compared .

This study presents a three-dimensional, PVT-controlled, multi-component, 3-phase petroleum migration risk analysis to explain the observed distribution and sizes of individual accumulations on the Alaskan North Slope. PetroMod® risk technology was applied to constrain (1) erosional overburden of the Brookian foresets, (2) kinetics for the most important (Shublik and Kingak) source-rock units, and (3) seal integrity of the main reservoirs. Correlating the risk parameters with the observed data allows better quantification of model results and uncertainties.

Integrated Analysis of Petroleum Systems in 4-D
2005 AAPG Annual Convention (June 19-22, 2005) Technical Program