Abstract

The Late Jurassic–Early Cretaceous Monteith Formation (Minnes Group) records incipient foredeep deposition in the Deep Basin of northwestern Alberta and British Columbia. The uppermost lithostratigraphic unit of the Monteith Formation, informally referred to as the Monteith A, is investigated with data from 550 wells, which includes wireline log suites from each well and approximately 540 m of core from 29 wells, across a 17,500 km2 area (T58–72, R6-20W6M). These data provide the basis for characterization of fine-grained, organic-rich interchannel deposits and channel-belt sandstone bodies. Channel-belt sandstone body dimensions are estimated to range from 4.1–12.6 m thick and 514–2851 m wide. Channel-belt sandstone body stacking patterns are variable laterally and vertically with the most amalgamated architecture present in the plains, in the southern portion of the area studied (T58–70) and within the lower section of the Monteith A interval.

Stratigraphic architecture imparts a significant control on natural gas production from the Monteith A as almost all of the current production is coincident with amalgamated channel-belt units. The most prolific production from the Monteith A is in the Foothills where natural fractures enhance permeability within highly amalgamated channel-belts. In the Plains where channel-belts are highly amalgamated, gas distribution and producibility are controlled by inter-and intra-channel-belt architecture and associated zones of enhanced permeability. These zones of enhanced permeability are likely controlled by primary reservoir properties, diagenetic alteration and natural fractures. Heterogeneous reservoir quality and a relatively thin reservoir interval (typically 20–60 m thick) make horizontal wells and hydraulic fracturing a more efficient development strategy than vertical wells. An area >3000 km2 characterized by amalgamated channel-belt architecture is present in the lower portion of the Monteith A and may provide a widespread, ideal target suitable for horizontal drilling.

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