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Canyon sandstones in the Midland basin were originally thought to be part of the Canyon Group, but are actually downdip equivalents of fluvial and deltaic sandstones in the Cisco and Wolfcamp Groups. The repetitive, ordered sequence of sedimentary structures and the texture and composition of these basinal sandstones indicate that they are deposited by turbidity currents.
Canyon sandstones were deposited as constructive turbidite channels. Bedset associations and reservoir morphology of constructive turbidite channels exhibit changes from upper-fan channels at Jameson field to middle-fan channels at Rock Pen field and to distal-fan channels and interchannel areas at Burnt Rock field. The upper-fan channels at Jameson field are commonly more than 50 ft (15 m) thick and consist of incomplete "AE" bedsets up to 6 ft (2 m) thick. The middle-fan channel at Rock Pen field averages 30 ft (9 m) thick, but displays similar incomplete "AE" sequences up to 3 ft (1 m) thick. Distal channels are thinner, have limited lateral extent compared to upper- and middle-fan channels, and consist of better
developed Bouma sequences. Few sequences exceed thicknesses of 1 ft (0.3 m) in distal channels.
Canyon sandstones are low-permeability reservoirs, with mean porosity and permeability of 10% and 0.2 md, respectively. Isoporosity and isopermeability maps indicate that porosity and permeability are greatest in turbidite channels and decrease laterally. Interchannel sandstones have limited lateral extent and make poor reservoirs.
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