Reservoir Characterization and Net Pay Determination of the Transitional Offshore to Offshore Facies Belts of the Cardium Formation, East Pembina

This study presents the reservoir architecture and characterization of the offshore to transitional offshore facies belts of the Cardium Formation in East Pembina, west-central Alberta. The Late Cretaceous Cardium Formation “conventional” shoreface sandstone and conglomerate reservoir facies host some of the largest oil accumulations in western Canada. Recent advances in horizontal drill technology with multi stage hydraulic fracturing have improved EUR such that the low permeability unconventional offshore deposits of the Cardium are a viable economic target.

Detailed core observations investigating the sedimentology, grain size distribution, ichnology and petrography led to the delineation of six facies within the offshore to transitional offshore marine environment. The Cardium exhibits a typical shoreface assemblage with lower permeability mud rich sandstones coarsening upward to a higher permeability sand rich facies. Inter-well facies correlations of the offshore deposits reveal surprisingly high variability within the facies architecture over relative short distances of 2-3 miles. The complexity and variability of the lateral and vertical facies associations of the muddy sandstone reservoir requires the integration of core data to map the most productive play fairways within the offshore facies belts.

Development of the Cardium tight-oil reservoir as a resource play also requires a thorough examination and determination of net pay parameters to quantify the total remaining reserves. The unconventional reservoir unit is composed of shaly sandstones, isolated sandstone beds and highly bioturbated sand-filled trace fossil assemblages. The importance and influence of bioturbation on the improvement of overall reservoir quality is apparent in cores. Correlation of core facies with their associated petrophysical log parameters provides a quantitative means for measuring total net sandstone distribution. The study predicts the OOIP in the low permeability facies, assisting in the determination of the remaining recoverable oil within this reservoir and delineating fairways for optimal horizontal drilling programs.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California