Basin-Scale Distribution of Organic Matter in Unconventional Plays: Results From 3-D Stratigraphic Modeling of the Montney and Doig Formations (Triassic, Alberta-British Columbia, Canada)

Abstract

In self-sourced reservoirs, the occurrence of hydrocarbons is correlated to in-situ organic content and thermal maturity, while the effective extraction of this resource depends, among other parameters, on the brittleness of the reservoir that is mainly controlled by mineralogy and rock fabric. The aim of this study is to improve the understanding of sedimentary organic matter heterogeneities in unconventional plays, based on outcrop and well data from the Triassic Montney and Doig Fms. The workflow comprises 3 steps: (1) Well correlations, based on sequence stratigraphy, providing an understanding of the 3D stratigraphic architecture of the basin. (2) Integration of Rock-Eval VI and ICP-MS/AES analysis of samples distributed along a basin-wide cross-section to identify the factors controlling the organic content heterogeneities (production, dilution, preservation). (3) A process-based forward modeling of the stratigraphic evolution of the basin with Dionisos-Flow © providing a quantification of the controlling factors as well as 3-D distribution of reservoir heterogeneities at basin-scale. The stratigraphic architecture of the Montney and Doig Fms has been subdivided into four third-order sequences. The sequences 1 and 2 are relatively poor in organic matter, whereas sequence 3 presents intermediate organic content and concentration Corg can reach up to 10wt% in sequence 4. Even if the four sequences present similar sedimentary environments, from to offshore, they present drastically different organic matter distribution, from pool to concentric shapes. The integration of the geochemical analyses in the stratigraphic framework showed that the organic content in the Montney and Doig Fms is controlled by the anoxia and primary productivity dynamics and that they are highly linked to both regional geodynamic and stratigraphic evolution. Lastly, stratigraphic forward modeling provided the opportunity to simulate the complex distribution of organic matter content heterogeneities. The dynamic of anoxia and primary productivity can thus be spatially and temporally quantified and integrated into basin analysis.

AAPG Datapages/Search and Discovery Article #90259 ©2016 AAPG Annual Convention and Exhibition, Calgary, Alberta, Canada, June 19-22, 2016