LITHOFACIES, PACKAGING, AND ARCHITECTURE OF A SLOPE CHANNEL LEVEE: CHANNEL 6 COMPLEX, ISAAC FORMATION, CASTLE CREEK, BRITISH COLUMBIA

Slope turbidite reservoirs are a major play-type in the Petroleum Industry. Unfortunately such reservoirs have relatively few good outcrop analogues due to the complicated tectonics required to both uplift and preserve these successions. The Windermere Supergroup contains excellent exposures of slope (Isaac Formation) and basin floor (Kaza Formation) turbidites, particularly at Castle Creek in the Cariboo Mountains of eastern British Columbia. This presentation discusses the levee facies of the Channel 6 Complex (C6C) at Castle Creek. The channel-fill sandstones of C6C are volumetrically insignificant in comparison to the surrounding levee sandstones, which are heterolithic turbidites that have both a high net:gross (>0.6) and potential reservoir volume (50 m thick by >500 m wide). C6C levee deposits are arranged in sheet-like, 1-3 m thick packages that start with laminated fine-grained T_d turbidites, and grade upwards through thin-bedded T_bcd sandstones to thick (~50 cm), medium to fine sand T_ab beds (subscripts denote portions of the Bouma sequence). Detailed mapping demonstrates that the T_ab beds are channel-like sediment bodies with internal amalgamation surfaces. The thick T_ab beds are sharply overlain by the next T_d mudstone. The lithofacies, packaging, and architecture of the C6C levee deposits were most likely a consequence of lateral accretion package-driven changes in channel volume, which controlled the degree of overbanking and hence the mass flow depositional processes on the levees. A reservoir analogous to the C6C levees would present production difficulties (e.g. compartmentalisation, poor vertical connectivity) that are best understood through outcrop studies.