--> Porosity Characterization of the Cardium Formation at East and West Pembina Field, Alberta, Canada

AAPG Annual Convention and Exhibition

Datapages, Inc.Print this page

Porosity Characterization of the Cardium Formation at East and West Pembina Field, Alberta, Canada

Abstract

The Cardium tight oil play in the Pembina region is a highly heterogeneous reservoir dominated by intensely bioturbated muddy sandstones, with the majority of the effective porosity occuring in sand filled burrows that are encased in low permeability muddy sediments. Due to the heterogeneous nature of the porosity distribution within the Cardium Formation in the Pembina Field, routine core analysis methods and observations often fail to provide data that is characteristic of this reservoir. In order to assess reservoir properties with more accuracy and identify preferential analytical techniques that are best suited for interpretations of such bioturbated muddy sandstone reservoirs, a broad range of additional data sets have been incorporated; including thin sections, scanning electron microscope (SEM) observations, Quantitative Evaluation of Minerals by Scanning Electron Microscopy (QEMSCAN), x-ray diffraction analysis (XRD), mercury injection capillary pressure (MICP), profile permeability and permeability regains. In addition to confirming the heterogeneous nature of the porosity and permeability trends within the Cardium tight oil reservoirs, the data shows that the Cardium in the Pembina area is comprised of two distinct regions, East and West Pembina, which are characterized by different diagenetic characteristics and thereby, pore geometries. Diagenetic features in the West include increased mechanical compaction due to burial and an abundance of diagenetic cements including ferroan calcite. Within the East Pembina area, a significant increase in open intergranular porosity is likely not just a function of the 300 to 400 metre shallower burial, but may be a result of earlier oil charging in this up dip area. However, an increased variety and abundance of clays is also present in the East Pembina area when compared to West Pembina and have implications on the reservoir, for example, fluid sensitivity issues. This study highlights the necessity of additional data collection and integration beyond well logs and the observation of core in such muddy bioturbated tight reservoirs. Results and methodology from this study can be applied to the Cardium tight oil play or to other similar tight siliciclastic reservoirs.