The hydrogeological characterization of oil fields in north-central Alberta for exploration purposes.

摘要

A petroleum hydrogeological study was conducted in the Panny-Senex region of north-central Alberta (Tps.89-102, Rs.23W4-14W5) focusing on the Granite Wash, Keg River and Slave Point Formations. The study proceeded in three phases. First structure contour maps, structural cross-sections and hydraulic conductivity maps were generated. Second water and oil flow fields were mapped, flow rates calculated and the distribution patterns of water chemistry, water temperature, and oil density of the reservoir formations were mapped. Finally the effect of water flow on oil migration and accumulation in the study area was considered. Techniques for culling water chemistry, temperature and pressure data and for dealing with the problem of production drawdown are presented.;In the southwest half of the study area, hydraulic heads in the Keg River, and possibly the Slave Point Aquifers, are controlled by the overlying water table topography. A vertically ascending discharge plume at Tp.94 Rs.6 and 7 W5, extends from the basement to the sub-Cretaceous unconformity. Discharge is focussed at the ground surface by the intersection of the Wabasca and Loon River channels. In the northeast, on the other hand, water flows laterally updip to low elevation outcrops beyond the study area. Down-dip, density-driven flow is locally significant.;At the regional scale of the present study, lithology is the dominant control on water chemistry, with flow producing local scale anomalies. Conduction dominates heat flow since water flow rates are too small for forced convection to be significant. The pattern of oil density variations is likewise unrelated to water flow.;Oil is often but not exclusively trapped in regions of hydraulic head minima. An oil head map of the Keg River Aquifer shows an elongate zone of high accumulation potential parallel to the Keg River reef edge between Tp.96 R.10 W5 and Tp.94 R.9 W5. Conventional migration theories cannot explain the presence of oil in the study area since the source rock is absent on the Peace River Arch, down dip from the study area. Northward water flow is promoted as the agent responsible for deflecting oil into the study area.