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Well of the Week – All the colours of the rainbow

She comes in colours everywhere

She combs her hair

She's like a rainbow

Coming, colours in the air

Oh, everywhere

She comes in colours

She’s a rainbow; Jagger and Richards

While the Stones were exploring the genre of psychedelic rock, companies were evaluating Devonian rocks in northwestern Alberta. The result of the former effort was not one of their best ever songs. The latter resulted in 100/07-32-109-08W6/00, the discovery well for the Keg River reef play and the current Petro NinjaEnlighten Geoscience Well of the Week.

The 7-32 well was drilled by Banff Oil and discovered the Rainbow – Zama field. (As an aside, the names involved, Banff, Rainbow and Zama, seem like those in a B-movie script about the Canadian oil industry? What could be more romantic for a 1960’s movies than seismologists in float planes?).

Figure 1. Definitely not the Rolling Stones in front of their tour plane. Actually an Imperial Oil Seismic Crew in the Zama Lake/Rainbow Lake Region, Summer 1950. Glenbow Archives (S-236-46) . (2012).

But back to the Rainbow Lake discovery. And it was a big discovery. It isn’t often that an Alberta Society of Petroleum Geologists luncheon makes the front page of the New York Times Financial pages, but the talk on Rainbow-Zama did.

The Rainbow Reef member, and its 435’ of 38.7o API oil and 251’ of gas pay at 7-32, gets most of the glory, but there was also 48’ of Upper Muskeg oil pay and 23’ and 17’ of gas pay in the Slave Point and Sulphur Point, respectively (Hriskevich, 1966). See Figure 2 for a schematic cross section outlining the relationship between the different pay zones.

Figure 2. Schematic Cross Section across Keg River reefs and related units (Langton and Chin, 1968).

Although the discovery was massive, the discrete pinnacle reefs required the acquisition of an enormous amount of seismic data to find these thick but areally minute reefs, and a run on the pencil crayons needed to interpret all of those seismic lines. Figure 3 provides a block diagram of the distribution of the Keg River reefs.

Figure 3. Block diagram illustrating the nature of Keg River Pinnacle Reef play (Langton and Chin, 1968).

The effort didn’t go to waste, as within 2 years a total of 29 oil and gas bearing reefs had been discovered. Significant new finds were few and far between in the 1960s and Rainbow Lake was a welcome bit of good news for an industry in the low part of a discovery cycle. It also presages the future of the conventional industry.

As shown by the production history plot from for 7-32 in Figure 4, Keg River pinnacles can be prolific. But each one is a unique exploration event. The discovery was enormous but, as with many other plays, it required a number of repeated discoveries to move the needle on a reserves basis.

Figure 4. Cumulative production history plot for 100/07-32-109-08W6/00. Courtesy of Petro Ninja.


M. E. Hriskevich; Stratigraphy of Middle Devonian and Older Rocks of Banff Aquitaine Rainbow West 7-32 Discovery Well, Alberta. Bulletin of Canadian Petroleum Geology 1966; 14 (2): 241–265. doi:

J. R. Langton and G. E. Chin; Rainbow Member Facies and Related Reservoir Properties, Rainbow Lake, Alberta. Bulletin of Canadian Petroleum Geology 1968; 16 (1): 104–143. doi:

RETROactive, Exploring Alberta's Past. 2023. Zama. [accessed 2023-05-10).


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