Well of the Week - Image is everything
You must admit that, given the current industry focus on CCUS, geothermal, resource plays, SAGD and other endeavours, geomechanics is having a bit of a moment (again). Additionally, readers cognizant of the geomechanical focus of Enlighten’s President, choosing 100/15-09-074-04W5/00 as the first Petro Ninja – Enlighten Geoscience Well of the Week for 2024 and focusing on image logs but not geomechanics might seem off brand.
In fact, this article was conceived as a follow-up to the previous WotW discussion on the use of dipmeter data to guide whipstock wellbores to a full Keg River reef build-up. Can a workflow successful in carbonates be amended for clastic reservoirs?
Of course, it can! Now if I were taking the easy way out, this discussion would riff off one or two of the excellent applications of Image logs in the oil sands. But how about if we look at a less capital-intensive use case? Something more suitable for a start-up notwithstanding the high cost of running image logs when they were first introduced.
The Mitsue Field, discovered in 1964, ranks as the third largest Elk Point oil field (Meijer Drees, 1994). At Mitsue, oil is trapped along an updip pinchout of a large fluvio-deltaic complex. It was straightforward to postulate the existence of feeder channels as attractive exploration targets. Step-out drilling beyond the main field was, however, hampered by the complex sedimentation. In short, how could you possibly figure where the channel went?
This conundrum was the essence of the challenge faced by Glen Isle Exploration in their quest to carve out a niche in the WCSB. And, in an example of technological developments coinciding with practical needs, Formation MicroScanner and Formation MicroImager logs came on the scene.
Regardless of the extra expense, Glen Isle incorporated image logs in their logging program. Interpreting these logs for bed dips (Figure 1) and coalescing this information into a directional histogram (Figure 2), they were able to predict the presence of the pay intervals as their play evolved. Understanding the crossbedding allowed the alignment of follow-up wells with the heart of the channel and improved step-out success (as illustrated in Figure 3).
Figure 1. Sample FMS log interpreted for bedding dip direction. (Dueck and Pauuwe (1994)).
Figure 2. Azimuthal histogram of crossbedding orientation. (Dueck and Pauuwe (1994)).
Figure 3. Development of step-out drilling informed by knowledge of sedimentation patterns. (Dueck and Pauuwe (1994)).
This innovative use of breaking technology is another example of how creative thinking has always been a characteristic of successful exploration in western Canada.
Dueck, R. N. and Paauwe, E. F. W., 1994. The use of borehole imaging techniques in the exploration for stratigraphic traps: an example from the Middle Devonian Gilwood channels in north-central Alberta. Bulletin of Canadian Petroleum Geology. v. 42 (2): 137–154. doi: https://doi.org/10.35767/gscpgbull.42.2.137
Meijer Drees, N.C. (1994): Devonian Elk Point Group of the Western Canada Sedimentary Basin: in Geological Atlas of the Western Canada Sedimentary Basin, G.D. Mossop and I. Shetsen (comp.), Canadian Society of Petroleum Geologists and Alberta Research Council, https://ags.aer.ca/atlas-the-western-canada-sedimentary-basin/chapter-10-devonian-elk-point-group