Characterizing a Hybrid Liquid Rich Shale Play and Identifying Hydrocarbon Producing Zone(s)
Amr El-Azhary1, Lavern Stasiuk1, Michele Asgar-Deen2, and Paul Taylor1
1Shell International Exploration and Production
2Shell Canada Limited.
Geochemical tools combined with an understanding of reservoir properties are crucial to maximizing the economics of a Liquid Rich Shale (LRS) play. The present work documents an integrated approach that links geology, geochemistry, petrophysics, organic petrography, basin modelling and petroleum engineering to understand the LRS play potential at various locations in the Western Canada Sedimentary Basin.
In the paper we discuss the integrated evaluation of a Jurassic Shale drilled in North America. The studied play can be subdivided to three Sub-members, with the Upper and Lower members exhibiting classic Type-II source rock characteristics with variable organic content (averaging about 6 wt% TOC). However, the Middle unit has relatively low TOC and significantly higher Rock-Eval S1 (moveable hydrocarbons). Organic petrography and core measurements suggest that the middle member has the highest porosity observed within the section. Geochemical analysis was used to demonstrate that the extracted hydrocarbons from the Middle section are geochemically distinct from the overlaying and underlying classic organic rich intervals. Furthermore, analysis of the produced oil at the well location showed a strong similarity to the Middle member extracts. Hence the geochemical data suggest that the bulk of oil production is coming from the middle member – an interpretation that was confirmed by independent production allocation methods. The produced oil API, GOR and molecular composition does not reflect the measured maturities of the Jurassic Shale at this location and suggests a component of up dip migration as well as fractionation during migration from the source to the “reservoir” unit.
Moreover, the stable carbon isotope analysis on the produced fluids suggests that the produced oil and gas may be derived from different sources or at different levels of thermal maturity. Independent interpretation of production logging tools suggests fracking into deeper reservoirs.
AAPG Search and Discovery Article #90186 © AAPG Geoscience Technology Workshop, Hydrocarbon Charge Considerations in Liquid-Rich Unconventional Petroleum Systems, November 5, 2013, Vancouver, BC, Canada