From oil field to geothermal reservoir: assessment for geothermal utilization of two regionally extensive Devonian carbonate aquifers in Alberta, Canada

Weydt, Leandra M.; Heldmann, Claus-Dieter J.; Machel, Hans G.; Sass, Ingo

doi:https://doi.org/10.5194/se-9-953-2018

Articles | Volume 9, issue 4

Solid Earth, 9, 953–983, 2018

https://doi.org/10.5194/se-9-953-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Solid Earth, 9, 953–983, 2018

https://doi.org/10.5194/se-9-953-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 9, issue 4

Research article 23 Jul 2018

Research article | 23 Jul 2018

From oil field to geothermal reservoir: assessment for geothermal utilization of two regionally extensive Devonian carbonate aquifers in Alberta, Canada

Leandra M. Weydt et al.

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Final revised paper (published on 23 Jul 2018)
Preprint (discussion started on 14 Dec 2017)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

SC1: 'Heat flow in the Hinton area, Alberta, Canada', Jacek Majorowicz, 20 Dec 2017
- AC2: 'Author’s comment on “Short comment 1 – Heat flow in the Hinton area, Alberta, Canada” by Jacek Majorowicz', Leandra Weydt, 11 Mar 2018
RC1: 'Review MS se-2017-129', Anonymous Referee #1, 21 Dec 2017
- AC1: 'Author’s comment on “Referee comment 1 – Review MS se-2017-129” by Anonymous Referee 1', Leandra Weydt, 11 Mar 2018
RC2: 'Reviewer 2 Comments to :From oil field to geothermal reservoir: First assessment for geothermal utilization of two regionally extensive Devonian carbonate aquifers in Alberta, Canada .', Anonymous Referee #2, 28 Dec 2017
- AC3: 'Author’s comment on “Referee comment 2 – Reviewer 2 Comments to: From oil field to geothermal reservoir: First assessment for geothermal utilization of two regionally extensive Devonian carbonate aquifers in Alberta, Canada” by Anonymous Referee 2', Leandra Weydt, 11 Mar 2018
RC3: 'review', Anonymous Referee #3, 23 Jan 2018
- AC5: 'Author’s comment on “Referee comment 3 – review” by Anonymous Referee 3', Leandra Weydt, 11 Mar 2018
RC4: 'general comment', Jean Borgomano, 12 Feb 2018
- AC4: 'Author’s comment on “Referee comment 4 – general comment” by Jean Borgomano', Leandra Weydt, 11 Mar 2018

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Leandra Weydt on behalf of the Authors (08 Apr 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (16 Apr 2018) by Elias Samankassou

RR by Anonymous Referee #2 (17 Apr 2018)

RR by Anonymous Referee #3 (27 Apr 2018)

Suggestions for revision or reasons for rejection

The authors have made some improvements to the original manuscript, but these are in general superficial. The work still suffers from making false an unsupported claims as well as not being placed into context of previous studies. In addition, I fail to see any meaningful contribution here. The authors examine porosity and permeability and make some qualitative statements regarding relevance to geothermal utilisation. But as it stands, the main conclusion in the paper is that there are parts of the Devonian reservoirs that have high permeability and this can be related to dolomitization. This has been known since the first major oil field in Alberta was discovered in one of these reefs in 1947.There has been extensive studies of these aquifer systems and their physical properties for petroleum reservoirs over the last 50 years (including one of the authors who has built a career on this) as well as more recently for potential as CO2 storage. So the very basic observations made by the authors don’t add anything new to what has been long known – or they fail to show how they have added any new knowledge. Despite being the stated main goal of the study, there is little done though to assess any geothermal potential based on the observations the do make – the key question is how much energy could be extracted and at what rates. The authors could do this if they went further, and used their data to estimate geothermal resource potential, and then maybe make some new and important contributions. But as it stands, I believe this manuscript is still not suitable for publication and I recommend rejection until substantial improvements to the work are made.

Other issues:
Title – the authors still claim that there work is the ‘First assessment’ of geothermal utilization of Devonian Aquifers in Alberta. This is clearly untrue and points to an overall problem of the authors not being aware of previous work in their study area. Just to name a few of the many previous studies done before:
Lam et al., 1982; 1985; Jones et al., 1985; Bachu et al., 1991; Weides et al., 2012; Grasby et al., 2011; Majorowicz et al., 1981; Gray et al, 2012; Fergusin and Ufondu, 2017.

Page 2, Line 17: The authors continue to make false claims regarding the place of Alberta in global CO2 emissions. The Environment Canada data they reference does not support their claim. They may have miss-read the table of reported emissions rather than the relevant table of total emissions. Environment Canada has clearly recorded that Saskatchewan is the largest per Capita Co2 emitter in Canada for the last decade or so. As well, the reference they cite as support does not make reference to Alberta in a global context. There are clearly jurisdictions within the United States that have higher per capita emissions than any province in Canada. I could not find the data easily, but I am sure there would be jurisdictions within Saudi Arabia or other major oil producing regions of the world that would also have larger per capita emissions.
Page 2, Line 24: The authors continue to make inappropriate political comments. How do they know that Alberta has favoured ‘business over environment’ .. are they privy to secret cabinet documents that can support that claim? What does it even mean, does not every political jurisdiction in the world have to make that choice to balance development and environmental protection every day? I’ve been to Germany, were the authors are from, many times – and I see a heavily industrialised country with very little natural environment left – they have a centuries long history of favouring industrial development over environmental protection. Maybe that’s the reason Alberta has such a high rate of tourists from Germany who come to see true nature? So then, what gives the authors the right to speculate that Alberta will not change to be more environmentally concerned – especially as the province has recently made a major political shift to a government that is advancing climate polices. Certainly Germany has not shown any positive trends as they are Europe’s largest producer and burner of coal and are the worlds largest producer of lignite, the dirtiest coal there is. Will Germany’s ‘business over environment’ policies every change? Hard to say. This all reminds me of a recent news headline I saw titled: “Germany is a coal-burning, gas guzzling climate change hypocrite’. Perhaps this may offend the authors, much as their comments on Alberta politics offends me as an Albertan – in the end though, none of this belongs in a science discussion and I’m perplexed why they insist to keep these inappropriate political comments in a science paper.

Page 3, Line 5: This claim of ‘few hard data’ is false. The authors are only referring to geothermal studies. However the Devonian Reef systems in Alberta hosted major oil and gas pools and as such have been the subject of extensive investigation of there petrophysicsal properties and aspects such as porosity, permeability etc. There are numerous studies and papers on this. Fergusin and Ufondu, 2017 examined all available data. A simple search for ‘Nisku Reservoir’ returns over 2000 results on Google Scholar. In addition to extensive petroleum industry research, these reservoirs have also been examined for CO2 storage, and as such there has been also extensive work done to characterise hydrogeological properties for that purpose.

Page 4, line 6: This claim is not true, there have been early studies that have done detailed assessments of geothermal potential of Devonian aquifers, including those that the authors now include in the reference list (e.g. Lam and Jones). As well, Fergusin and Ufondu, 2017 also examined Devonian systems. The authors need to do a better job at describing previous work and how their contribution is different and adds to that.
Page 5, line 1: British Columbia is not north of Alberta, and as the authors define the WCSB as east of the Rocky Mountains, then it does not extend to the SW into BC as that area is within the Rocky Mountains. Also, I would not say that the portion with in Saskatchewan is ‘minor’ at all.
Page 6, ln 10: These comments have uncertain value, is there a problem with data just because its ‘old’? If the data was collected in acceptable means then its perfectly fine. These comments only have value if there are new data measurement techniques that supersede previous work. As well, the outcrops indicated aren’t really inaccessible.

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ED: Publish subject to minor revisions (review by editor) (17 May 2018) by Elias Samankassou

AR by Leandra Weydt on behalf of the Authors (31 May 2018) Author's response Manuscript

ED: Publish subject to technical corrections (05 Jun 2018) by Elias Samankassou

ED: Publish subject to technical corrections (05 Jun 2018) by Elias Samankassou(Executive Editor)

AR by Leandra Weydt on behalf of the Authors (13 Jun 2018) Author's response Manuscript

Short summary

This study focuses on the assessment of the geothermal potential of two extensive upper Devonian aquifer systems within the Alberta Basin (Canada). Our work provides a first database on geothermal rock properties combined with detailed facies analysis (outcrop and core samples), enabling the identification of preferred zones in the reservoir and thus allowing for a more reliable reservoir prediction. This approach forms the basis for upcoming reservoir studies with a focus on 3-D modelling.