Summary

The Cenomanian-Turonian strata, including the Favel Formation and Morden Member, in south-western Manitoba and eastern Saskatchewan were deposited along the eastern margin of the Cretaceous Interior Seaway. The succession is comprised of siliciclastic and carbonate-rich units with very different hydrocarbon source rock and reservoir properties as reflected in their different sedimentology, geochemistry and petrophysics. To characterize these different mudrock facies quantitative and qualitative geochemical analyses was carried out at variable scales to capture the heterogeneous character of these deposits. Geochemical data are generally powerful proxies for determination of source and reservoir rock properties. We apply a multi-disciplinary approach using integration of sedimentology and geochemistry to better characterize the distribution and origin of the various minerals in these heterogeneous, fine-grained deposits. To understand the geochemical aspect of these strata different techniques including energy-dispersive X-ray fluorescence (ED-XRF) and X-ray diffraction (XRD) are utilized to develop a high-resolution, whole-rock geochemical dataset. Geochemical data aid in understanding the distribution and lateral variation of sedimentary rocks, which can then be extrapolated to the reservoir facies between the two study areas. Further, complementary geochemical analyses including mass spectrometry techniques are integrated to quantify low-concentration, trace constituents and rare earth elements (REE). This approach constructs a framework for understanding the geochemical factors impacting reservoir properties and also helps in upscaling these core-scale measurements to reservoir scale.

Introduction

In mudstones there is a strong relationship between the relative proportions of major mineral phases and their related main and trace elements to depositional environment, ocean and formation water chemistry and organic richness. These in turn are closely linked to the mudstone reservoir properties. For example the relative proportions of silica, carbonate and clay minerals, as well as their types, has a direct impact on the reservoir characteristics such as pore type and volume, hydrocarbon storage and flow capacity. In addition, rock rheological properties are mainly dependant on mineralogical content and organic richness. The studied units including the Turonian Favel Formation is comprised of carbonate and organic-rich mudstones overlain by non-calcareous organic-rich mudstones of the Carlile Formation representing two different source rock and reservoir rock. Favel Formation can be divided in two members, the lower Keld Member and the upper Assiniboine Member. Correspondingly, Carlile Formation is comprised of lower Morden and upper Boyne Member. In this research, sedimentology and geochemistry of carbonate-rich Keld and Assiniboine members in addition to the clastic Morden Member are examined using available core wells in southwestern Manitoba and eastern Saskatchewan, as well as formation outcrops along the edge of the Manitoba escarpment (Figure 1).

URTeC 1618654

This content is only available via PDF.
You can access this article if you purchase or spend a download.