Sedimentology and paragenetic evolution of Mississippian Pekisko Formation, Minnehik-Buck Lake Field and adjacent area, Alberta, Canada

Minnehik-Buck Lake Gas Field, which is located in west central Alberta, lies along the subcrop edge of the Mississippian Pekisko Formation. The Pekisko Formation is separated from Jurassic Nordegg/Cretaceous Ellershe formations by a major unconformity surface that is formed during several Post-Mississippian exposures. Transgressive/regressive carbonate cycles of the Pekisko succession that were deposited on an inner-ramp, underwent extensive diagenetic alteration extending from early diagenesis on the sea floor to late diagenesis at depth. Reservoir characteristics are related to the depositional facies and diagenetic fabrics of the Pekisko carbonates. Calcite cementation, compaction, dolomitization, dissolution, and fracturing are major diagenetic events that influenced the reservoir characteristics during different stages of burial. Multi-stage dolomitization involving various diagenetic fluids and burial environments along with solution and fracturing of the Pekisko carbonates result in formation of the reservoir at the subcrop edge of the Pekisko strata.