A model for porosity evolution in shale reservoirs: An example from the Upper Devonian Duvernay Formation, Western Canada Sedimentary Basin

AAPG Bulletin ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 1017-1044 ◽  
Author(s):  
Tian Dong ◽  
Nicholas B. Harris ◽  
Julia M. McMillan ◽  
Cory E. Twemlow ◽  
Brent R. Nassichuk ◽  
...  
Keyword(s):  
Sedimentary Basin ◽  
Upper Devonian ◽  
Western Canada ◽  
Porosity Evolution ◽  
Western Canada Sedimentary Basin ◽  
Shale Reservoirs ◽  
Canada Sedimentary Basin

Organic facies in Devonian and Mississippian strata of Western Canada Sedimentary Basin: relation to kerogen type, paleoenvironment, and paleogeography

2004 ◽  
Vol 52 (3) ◽  
pp. 234-255 ◽  
Author(s):  
L.D. Stasiuk ◽  
M.G. Fowler
Keyword(s):  
Shallow Water ◽  
Sedimentary Basin ◽  
Black Shales ◽  
Upper Devonian ◽  
Source Rocks ◽  
Western Canada ◽  
Western Canada Sedimentary Basin ◽  
Organic Facies ◽  
Kerogen Type ◽  
Canada Sedimentary Basin

Abstract Petrographic analyses of dispersed organic matter (including macerals and palynomorphs), siliceous and calcareous microfossil assemblages and microtextures (e.g. stromatolitic) have been used to define and interpret five organic facies and regionally map their distribution for the following informal groupings of potential hydrocarbon source rocks in the Western Canada Sedimentary Basin: Upper Devonian Woodbend group, Upper Devonian Winterburn group and Upper Devonian to Lower Mississippian black shales of the Exshaw and Bakken formations. Five petrographic organic facies (A–E) are defined for the potential source rocks based on assemblages of alginites, acritarchs, sporinites, siliceous microfossils and algal mat microtextures. Organic facies A, B (prasinophyte alginites and acritarchs) and C (coccoidal alginite), represent accumulation in relatively deep (basin), intermediate (shelf-platform), and shallow water depths (bank-reef margin to lagoonal). Organic facies D is defined by siliceous microfossils (e.g. Radiolaria) and accumulated in deep basinal to outer shelf settings immediately east of an ancient Pacific Ocean, or south of an ancient Arctic Ocean. This facies may reflect regions of upwelling which extended into intracratonic and epicontinental settings. Organic facies E, characterized by stromatolitic microtextures with or without coccoidal alginite, only occur within Upper Devonian Winterburn Group shallow water, restricted shelf to lagoonal dolostones associated with evaporites. As a whole, the regional distribution of organic facies is related to paleogeography, paleobathymetry or paleostructure in the source rocks. Surprisingly, petrographic organic facies do not show strong positive correlation with kerogen type as defined by Hydrogen-Oxygen indices or TOC-S2 plots.

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