Quantitative Basin Analysis of Kodiak Shelf Basin, Alaska: An Application of One and Two Dimensional Simulation Models

LIU JIANCHANG, and IAN LERCHE, University of South Carolina, Columbia, SC

Geological and geochemical data from six wells, and several seismic profiles from strata in a Cenozoic accretion belt, which occurs between the Aleutian volcanic arc and the Aleutian trench in the Kodiak Shelf, Alaska, have been used in quantitative basin analysis studies.

Applying both one-dimensional and two-dimensional fluid flow/compaction models to the basin has enabled a simulation to be made of the history of sedimentation, together with evolutionary behaviors for porosity, permeability, basement subsidence, fluid movement in the strata, formation pressure, paleoheat flux, maturation of organic carbon, and hydrocarbon generation and migration in specific locations and in a two-dimensional cross section of the basin.

From the model behaviors, five conclusions can be reached:1. The tomography method results show that there is no major difference in the erosion thickness from different locations around late Eocene time.2. The formation pressure in most of the basin is normal. Only in some locations close to areas where deposition rate was high and the strata were composed of mainly shale or mudstone is there any fluid overpressuring.3. The heat flow was relatively low (<1.0 HFU) and shows a gentle variation throughout the basinal history. There is a warming trend from the past (around 0.3 HFU prior to 30 m.y.) to present (0.6 HFU). Only in restricted locations, as shown in the two-dimensional modeling results, was the heat flow high (about 1.0 HFU). Therefore in most of the area, the sedimentary hermal maturity is low.4. Because of the low heat flux and low thermal maturity, hydrocarbon proneness seems poor except in a few isolated locations with higher heat flux. Since the TOC in most of the strata is low (<0.5%), therefore total hydrocarbon generation in the basin is low throughout the history of the basin.5. The results for fluid movement and hydrocarbon migration indicate that most of the oil and gas found in the strata migrated from other areas or strata. This result is in agreement with geochemical studies in the area.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)