A Multidisciplinary Approach To Reservoir Characterization: The Provost Upper Mannville B Pool

Abstract

Abstract The Provost Upper Mannville B Pool of the heavy oil belt in east central Alberta is contained in McLaren Formation sands of Upper Mannville (Lower Cretaceous) age. The reservoir is up to 35 m thick and contains local areas of underlying water, a water-in-oil transition zone and patches of overlying gas. The reservoir sands were deposited in fluvial environments filling the McLaren valley as it was aggraded during a sea level rise. The sands are mineralogically mature and composed predominantly of quartz. The reservoir pore systems are being characterized using petrographic image analysis techniques. Actual pore images obtained from thin sections are used to provide petrophysical data and to correlate the pore systems with geological facies. An important feature of the reservoir is the presence of zones of shale clasts in a sand matrix. These zones vary in thickness from several centimetres to several metres. Shale clasts constitute as much as 85% by volume in some zones and thus represent a significant barrier to vertical fluid flow. In order to numerically simulate the impact of the shale clast zones on recovery processes, parameters such as kh and kv have to be estimated. To arrive at realistic parameters, small-scale numerical models, based on actual clast distributions from core, have been constructed and equivalent alues for kh and kv have been obtained at the core and grid block scale. Introduction The oil sands and heavy oil deposits of western Canada with their impressive (471.6 × 109 m3(1–3)) resources represent Canada's "ace-in- the-hole" for future energy resources. Of these resources only a small portion is recoverable by mining methods. The greatest percentage must be recovered by in situ techniques. The oil sands and heavy oil reservoirs are complex and heterogeneous, and an integrated team of geologists, petrophysicists, reservoir engineers and numerical modellers is needed to develop processes specific to particular reservoirs for the recovery of these resources. These recovery processes need to be based on a detailed characterization of the reservoir. It was with this in mind that the Alberta Geological Survey, in its Joint Oil Sands Geology Program with the Alberta Oil Sands Technology and Research Authority (AOSTRA) and the Alberta Department of Energy, initiated a project to characterize oil sands/heavy oil reservoirs. The objective is to develop and evaluate techniques for the detailed characterization of oil sands and heavy oil reservoirs for use in numerical process simulations. This paper reports on studies carried out in the Provost Upper Mannville B Pool In this project a detailed geological characterization of the reservoir has served as a basis on which specific aspects of the reservoir description (or characterization) are focussed on, using novel techniques. The pore systems of the more "uniform" portions of the reservoir have been characterized at the pore scale using petrographic image analysis techniques and relating geology to permeability.