Petrological insights into thermal maturity, source rocks, migration, diagenesis

L.D. Stasiuk and N.S.F Wilson

Natural Resources Canada

Geological Survey of Canada

Thermal maturity – 2002-03 progress

• Reassess Vitrinite %Ro from Evenchick et al, 2002 (~ 160

samples).• New Vitrinite % Ro and Tmax

from Rock Eval for about ~ 200 samples.

R2 = 0.7838

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

4.50

5.00

0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00

New Vitrinite %Ro measurements

Old

vitr

inite

%Ro

mes

urem

ents

Reassess Vitrinite %Ro from Evenchick et al, 2002

400

420

440

460

480

500

520

540

560

580

0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00

%RoR vitrinite

Tmax

(oC

)

BowserBasin - olddataType III

New data

Petrology of Organic Matter and Rock Eval Petrology of Organic Matter and Rock Eval Evaluation of Potential Source RocksEvaluation of Potential Source Rocks

Osadetz et al. have defined ‘Effective Petroleum Systems’ in Bowser Basin related to petroleum stains / shows proposed to

come from:

1. a Paleozoic carbonate marine source rock deposited in a mesohaline to hypersaline setting (for stains in Muskaboo Creek Assemblage at Tsatia Mountain);

2. Mesozoic lacustrine – non-marine source rocks (for stains in Triangle zone)

3. Mesozoic normal marine source rock in Richie Well stains (e.g. 6745’) and in stains near Bucking Horse & Spatsizi River intersect.

Aptian to Albian to Campanian Tango Creek Formation; Non-marine potential hydrocarbon

source rocks

Black shales (44/89, 872-875/92 series) :

Bowser Basin: 1.34 - 2.54, 8.4 % TOC just North of Kitchener Lake.

Sustut Basin 4.7 % TOC, near Stikine River-Cullivan Creek crossing for source rocks in the mid-late oil window (0.90 to 1.2 %Ro vitrinite).

Coaly partings: 60-70 % TOC

Aptian to Albian to Campanian Tango Creek Formation: non-marine potential hydrocarbon source

rocks in triangle zone

Rock Eval pyrolysis for Tango Creek, Triangle Zone and Sustut Basin (for Rocks with vitrinite %Ro > 1.0 – 1.5 and

Tmax > 450 C – i.e. late oil window to condensate - dry gas

0

200

400

600

800

0 25 50 75 100

(OI (mg CO2/g TOC)

Type I

Type II

Type III

0

200

400

600

800

0 25 50 75 100

(OI (mg CO2/g TOC)

Type I

Type II

Type III

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

%To

tal O

rgan

ic C

arbo

n C-439420 C-439421 C-439422C-439423 C-439424 C-439425C-439426 C-439427 C-439428

Rock Eval pyrolysis for Tango Creek ?? for coals and black shales with vitrinite %Ro > 1.2-2.5 and Tmax > 480-560 C –

i.e. condensate - dry gas

Tango Creek shales – 8 % Total Organic Carbon

Terrestrial – cuticular organic matter in coals and shales Terrestrial – cuticular organic matter in coals and shales Upper Jurassic to Upper Cretaceous deltaic deposits, Upper Jurassic to Upper Cretaceous deltaic deposits,

Bowser and Sustut basins Bowser and Sustut basins

Terrestrial – cuticular organic matter in coals and shales Terrestrial – cuticular organic matter in coals and shales Upper Jurassic to Upper Cretaceous deltaic deposits, Upper Jurassic to Upper Cretaceous deltaic deposits,

Bowser and Sustut basins Bowser and Sustut basins

Vitrinite %Ro = 0.87

Aptian to Albian to Campanian Tango Creek Formation; Aptian to Albian to Campanian Tango Creek Formation; Non-marine potential hydrocarbon source rocks – coals ? Non-marine potential hydrocarbon source rocks – coals ?

Aptian to Albian to Campanian Tango Creek Formation; Aptian to Albian to Campanian Tango Creek Formation; Non-marine potential hydrocarbon source rocks – coals ? Non-marine potential hydrocarbon source rocks – coals ?

875/92

EP-95-001b EP-95-004a EP-95-017a EP-95-023 b EP-95-025a EP-95-034a EP-95-044b EP-95-051c EP-95-055c EP-95-056a EP-95-061c EP-95-065a EP-95-067c EP-95-071c EP-95-074a EP-95-085a EP-95-107c EP-95-135b

EP-95-146b EP-95-187

0.01.02.03.04.05.06.07.08.09.0

10.011.012.013.014.015.0

% T

otal

Org

anic

car

bon

Rock Eval pyrolysis for Skelhorne assemblage for coals and black shales with vitrinite %Ro of 2.6- 5.0 and Tmax > 600 oC

– i.e. dry dry gas to sub-green schist

0

200

400

600

800

0 25 50 75 100

(OI (mg CO2/g TOC)

Type I

Type II

Type III

Recycled lacustrine Type I kerogen source rock clasts in Eagles Nest

Assemblage (reworked from Muskaboo Creek ??)

Recycled lacustrine Type I kerogen source rock clasts in Eagles Nest Assemblage (reworked from Muskaboo

Creek ??) Vitrinite %Ro 0.80-0.90.

Fluorescent light White light

Fluorescent light

Recycled lacustrine Type I kerogen source rock clasts in Eagles Nest Assemblage showing Pediastrum like

morphology (freshwater, e.g. lacustrine algae)

Modern

0

200

400

600

800

0 25 50 75 100

(OI (mg CO2/g TOC)

Type I

Type II

Type III

•Some Pediastrum species also is characteristic of the littoral zone of oligotrophic waters

Crude oil generation from recycled lacustrine Type I kerogen source rock clasts in Eagles Nest Assemblage and

migration of higher API oils in microfractures

High maturity recycled possible lacustrine Type I kerogen source rock clasts in Tango Creek, Eagles Nest and

Todagin assemblage; Gas Zone, 1.0 to 1.4 %Ro

Evenchick et al., 2002

Recycled lacustrine Type I kerogen source rock clasts in Eagles Nest Assemblage (reworked from Muskaboo

Creek ??)

•Some Pediastrum species also characteristic of the littoral zone of oligotrophic waters

Sedimentary petrologySedimentary petrology

EP-91-91

Calcite filled porosity with HC inclusions

EP-91-91

Pyrobitumen lining pores - dissolution - HC inclusions

EP-91-91

Leached Pore space

EP-91-91

Calcite cements

Pyrobitumen +

HC Inclusions

Pore space – Fewer HC incs

EP-89-101