Canol Formation Oil Shale, Exhumation Charge, and Regional Geology of the Central Mackenzie, NWT

Transcription

1 Photo: Canol Fm near Arctic Red River Canol Formation Oil Shale, Exhumation Charge, and Regional Geology of the Central Mackenzie, NWT Hadlari T. Geological Survey of GSC 2018

2 Introduction Research made possible by the Geoscience for Energy and Minerals Program (GEM) Contributions by: Omid Ardakani (Organic Petrology) Jennifer Galloway, Kyle Sulphur, Kimberley Bell (Palynology) Andrew Durbano (compilation and drafting) Key publications by: Dale Issler (Thermochronology) Leanne Pyle (Petroleum Geology) Karen Fallas and Bernard MacLean (Geological maps)

3 Starting Point Norman Wells oilfield has produced well over 200 million barrels of oil since 1921 Source Rock Canol Formation, Devonian Reservoir Rock Kee Scarp Reef, Ramparts Fm, Devonian Conventional view of oil generation L. Cretaceous Tertiary The conventional perspective leads to certain contradictions, we will discuss these and then look more closely at the geological datasets

4 Geological Framework

5 West Paleozoic Mackenzie Platform East Keele Tectonic Zone Geological Framework

6 Geological Framework

7 200 m Upper Cret. Lower Cret. Paleoz. cbts Devonian Clastics KTZ / Keele Arch KTZ: Canol and Ramparts Fm were near surface in the Early Cretaceous.

8 Canol Fm Imperial Fm, clastic Canol Fm Hare Indian Fm In outcrop Canol Formation is a cliff-forming rock Bluefish Mbr Near Arctic Red River

9 The resistance to weathering is due to chert and dolomite Pyle et al (NTGO Report): XRD indicates Canol Fm comprises 82-90% modal quartz

10 Silica? (1974) Chert Layers Cross-Nichols 20x magnification

11 (1987) Organic geochemistry of oil from Norman Wells was compared with Canol Fm and Bluefish Mbr Canol Fm is source rock, not Bluefish Mbr. Thermal maturation during L. Cretaceous-Tertiary sediment loading If oil was generated in the Cret-Tertiary, then why Canol Fm and not Hare Indian Fm (Bluefish Mbr)? Source Rock

12 Reservoir is a Devonian Reef underlain by the Bluefish Mbr and draped by the Canol Formation Yose et al. (2001) Reservoir

13 Fractured carbonate reservoir (Laramide) Light oil (38 API) and not biodegraded Yose et al. (2001) Reservoir

14 Cretaceous thermal maturity from Rock-Eval Consistent with L.Cretaceous-Tertiary maximum temperatures and therefore oil generation Basal Cretaceous thermal maturity map (Tmax) Tmax Hadlari et al Peel Project Volume

15 AFT Thermal History Vitrinite Thermal Maturity Gap Thermal history from East Mackay well indicates pre-cretaceous maximum temperature and therefore oil generation Issler et al. (2005)

16 Starting Point: Two models Pre-Cretaceous oil generation Fits AFT data from Devonian sandstone Problems: How was light oil retained in the reservoir with no biodegradation for >200 Ma? sub-cret. unconformity Why was it only preserved in the reef at Norman Wells? L.Cretaceous-Tertiary oil generation Explains oil quality, Cret. Rock-Eval, structure Problems: Need to discount AFT data and the vitrinite well data Should have been a flood of oil generated from Devonian source rocks * Why was it only preserved in the reef at Norman Wells? 2009

17 New Approach 1) Can we better understand the thermal history? Palynology of Cretaceous Rock-Eval samples Organic petrology of Cretaceous Rock-Eval samples AFT dataset, a closer look 2) How does the structure relate? Regional tectonics The Norman Range 3) Integrate advances in unconventional resources? Shale oil and hydraulic fracturing Canol Formation and Norman Wells Point of departure: all the data are valid, how do they fit together?

18 Palynology of Cretaceous Rock-Eval samples Radioactive shale of Slater River Fm Tmax ~420 L.Cretaceous strata contain abundant Devonian spores (Sweet / Galloway) Hadlari et al. (2009) Tmax AR Sweet Thermal maturity is inherited via recycling from the Devonian

19 Lower Cretaceous Martin House Fm Upper Cretaceous Trevor Fm Reworked Indigeneous Contribution by: J. Galloway

20 Trevor Fm Slater R. Fm MFS Arctic Red Fm By: Kyle Sulphur (U. Calgary) and J. Galloway (GSC)

21 Organic Petrology of Cretaceous Rock-Eval samples Tmax 433 TOC 1.85% reworked vitrinite same view under UV light Relatively high Tmax directly above the mid-cretaceous unconformity. MFS has Tmax ~420 green/yellow fluorescing algae C ; 09-TH-02-C; Slater River Formation Immature / early maturity By: Omid Ardakani (GSC)

22 Organic Petrology of Canol Fm sample engulfed host rock solid bitumen solid bitumen 50 µm 200 µm C ; 07-TH-03-A; Canol Formation solid bitumen Dry gas zone: Canol sample from the Mackenzie Mtn front 50 µm By: Omid Ardakani (GSC)

23 An aside Integrate palynology and detrital zircon analysis to show the sometimes dominant role of sediment recycling Erosion of Dev.- Miss. strata was the dominant sediment source for Upper Cretaceous strata Consistent with recycling organic matter from Dev- Miss strata

24 Outcrop Well Correlation Slater River Fm Hadlari et al. (2009) Tmax

25 Outcrop Well Correlation East MacKay I-77 Slater River Fm Hadlari et al. (2009) Tmax Issler et al. (2005)

26 Outcrop Well Correlation East MacKay I-77 Vitrinite reflectance shows thermal maturity gap across sub-cretaceous unconformity Hadlari et al. (2009) Tmax Issler et al. (2005) Issler et al. (2005)

27 AFT Thermal History Devonian sample Issler et al (2005) Cretaceous sample Slater R. Fm immature Powell et al (2018)

28 AFT Thermal History L.Cret burial Devonian sample Issler et al (2005) Cretaceous sample Slater R. Fm immature Powell et al (2018)

29 Regional Structure Mazzotti and Hyndman (2002) Strain from Yakutat collision is presently translated across the Cordillera, by a lower crustal detachment, to the Mackenzie Mountains

30 Regional Structure The Norman Range is presently seismically active Hyndman et al. (2005)

31 How Norman Wells is unique Hanging wall of a thrust fault Young foreland structure, presently active Shallow m depth Yose et al. (2001) Reservoir

32 Summary of geological constraints 1. Devonian source rock, Canol Fm Siliceous and organic-rich 2. Maximum burial in early Mesozoic Pre-Cretaceous oil generation 3. Fractured carbonate reservoir Light non-biodegraded oil 4. Thrust fault hanging wall Young structure, Tertiary The years were marked by much discussion of shale oil systems, organoporosity, and fracking

33 Oil Shale: Strength increases linearly with pressure Strength decreases nonlinearly with temperature due to mechanical properties of kerogen, suppressing fracture [strength] Zeuch (1983) Rheology of oil shale

34 1 Imperial 3 km depth, Eocene Hare Indian Ramparts Canol Exhumation starts Older Paleozoic 2 Exhumation Fault initiation Post-Eocene Rocks are shallower as exhumation proceeds 3 Exhumation Fault is active Canol is brittle fractures form Up-dip oil migration, Oil pools in reef 2012 CSPG

35 Exhumation Model Assumption: Oil was generated from all Devonian source rocks prior to the Cretaceous, migrated, and subsequently lost. A fraction is retained within the Canol Fm, hence oil shale. Hadlari (2015)

36 Exhumation Model During exhumation Canol Formation passes through a brittle-ductile transition. Fracturing and overpressure due to exhumation result in up-dip oil migration until it pools in the reservoir. English (2016) Exhumation charge Hadlari (2015)

37 Additional Pieces Is that all? Not quite: Mapping of Canol Formation Rock-Eval data Cross-plots of Rock-Eval data

38 Data: Canol Formation Rock-Eval data of the Mackenzie Corridor, southern NT to the southern Mackenzie Delta, extracted from Fowler et al (2003) GSC Open File 1579

39 Depth of Norman Wells reservoir Data: Canol Formation Rock-Eval data of the Mackenzie Corridor, southern NT to the southern Mackenzie Delta, extracted from Fowler et al (2003) GSC Open File 1579

40 Data: Fowler et al (2003) GSC Open File 1579 Pyle et al (2014) NTGO Open File Pyle et al (2015) Thermal Maturity map (Tmax)

41 Depth Data: Fowler et al (2003) Pyle et al (2014)

42 Depth Depth Attribute the S2 anomaly to carryover from S1 (cf Jarvie 2012) Data: Fowler et al (2003) Pyle et al (2014)

43 Depth Data: Fowler et al (2003) Pyle et al (2014)

44 Oil migration Depth Data: Fowler et al (2003) Pyle et al (2014)

45 Next step: 1) Subset of the data, Central and northern Mackenzie 2) Average multiple measurements from each well location 3) Map the distribution of S1 and S1/TOC 4) Calculate the distance to the nearest known fault

46 Great Bear Lake Mackenzie Mountains Durbano et al (2017) S1 map of the Canol Fm

47 Great Bear Lake Mackenzie Mountains Durbano et al (2017) S1/TOC map of the Canol Fm

48 vs Depth (S1+S2) /TOC Depth (m)

49 vs Depth (S1+S2) /TOC (S1+S2) /TOC

50 vs Depth (S1+S2) /TOC near (S1+S2) /TOC Far from a fault

51 (S1+S2) /TOC near (S1+S2) /TOC Far from a fault

52 (S1+S2) /TOC Depth (m)

53 (S1+S2) /TOC Depth (m)

54 (S1+S2) /TOC Depth (m)

55 Is this the ductile-brittle transition zone for the Canol Fm? (S1+S2) /TOC Depth (m)

56 Conclusion There is much to do in terms of reviewing the methodology We can say: 1) Peak thermal maturity was achieved prior to the Cretaceous Hydrocarbons were generated, expelled, and multiple exploration wells indicate that they have been lost to the system 2) Unique characters of the prolific Norman Wells oilfield are the lithology/rheology of the source rock, the shallow structural setting, and active tectonics 3) The model of very young exhumation charge is consistent with available data