Field Trip in Fort McMurray, Alberta: McMurray Formation Reservoir Analysis
Zexuan Wang, SA-6959
lithology, grain size, sedimentary structure, oil stain per- centage, clay percentage and other useful features on the logging sheets to determine the overall facies distribution, 3) characterise the reservoir properties and divide the forma- tion into several correlatable flow units to assess its potential performance, and 4) establish the lateral correlations based on stratigraphic continuity and surfaces.
Results Lithology
The dominated rock types are siliciclastic sedimentary rocks including sandstone that contains grain sizes which vary locally from very fine to very coarse, and also mudstone containing consistent clay-size particles. The subordinate rock types are pebble conglomerate that contain the sporadic presence of quartz pebble laminations, and paleosol (strictly, it belongs to unconsolidated surficial materials instead of rock).
Composition and Texture
Location of Fort McMurray, Alberta (from the Government of Alberts).
Introduction Objectives
McMurray Formation in the Athabasca Oil Sand area in the Western Canada Sedimentary Basin is regarded as the largest reservoir containing in-place oil sand, which has really interested geologists (Carrigy, 1959). The objectives of this report are: (1) use outcrop data to characterize the reservoir properties of the McMurray Formation; and (2) identify pos- sible flow units.
Methodology Materials
A measuring tape was used to provide a means for referenc- ing the outcrop measuring point elevations and a safety rope was used throughout the whole logging process to ensure our stability and safety when climbing along the outcrops surfaces. A basic hand lens, grain size card, hammer and logging sheets provided the means to facilitate observing and recording the essential information on the logging sheets with the scale of 1:50 (1 meter outcrop is denoted by 2 centimeters interval on the logs).
Procedure
The ultimate goal is to build the reservoir model, and the main steps are to 1) physically observe the well exposed outcrops which include Amphitheater, Daphne Island and Hangingstone, corresponding to different parts of McMurray formation respectively, 2) record the details which include
It is quite common in the sandstone to observe quartz minerals surrounded by dark, viscous bitumen rather than the clay. This kind of clean sandstone should be categorized as quartz arenite; however, the mudstone apparently is full of clay. The overall sandstone is fine-grained, well sorted and well rounded. The texture of the mudstone could not be physi- cally observed in detail.
Sedimentary structure and fabric
The major sedimentary structures contain planar stratifi- cation, planar cross bedding with both low and high angles, trough cross bedding, reversed cross bedding, small-scale soft sediment deformation, bioturbation which is mainly burrow in origin, mud rip-up clasts, ripple laminations, and differential weathering.
With respect to the sedimentary fabric, we could observe relatively unidirectional quartz pebbles and mud rip-up clasts, cross bedded sand, slightly dipping interbedding, and the sharp contacts between different patterns of bedding.
Visible oil stain
When we used the hammer to view the fresh surface, we could estimate the bitumen saturation in the sandstone was approximately 95% of pore space, indicating its oil abundance. In the mudstone, the pore volume was estimated at approxi- mately 10%, indicating the relative absence of oil. One impor- tant potential misinterpretation is that the visible oil stain in the coarse sandstone within the filled channel system does not appear satisfactory for production, but that apparent condition is due to the leak of oil outside the rock once it becomes less viscous in summer. So we should also assign a relatively high level of bitumen saturation within those areas.
Clay content
Clay content was based solely on the rough estimation of bitumen stauration. To make it straightforward, I regarded
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