Pennsylvanian Morrow sandstones are oil and gas productive through a large area in southeastern Colorado. The Sorrento field is a recent Morrow discovery with reserves estimated at over 10 million bbl of oil over an area of 3,200 ac at depths of 5,400-5,600 ft (1,646-1,707 m). Minor production also occurs from the Mississippian Spergen and Saint Louis and the Pennsylvanian Marmaton.

Productive Morrow sandstones are interpreted on the basis of subsurface mapping to be fluvial valley-fill deposits, consisting mainly of channel sandstone. These deposits are encased in marine shale and range in thickness from 5 to 55 ft (1.5 to 16.7 m). Net pay ranges from 5 to 30 ft (1.5 to 9.1 m). Porosities average 19% and permeabilities range from 1 to 4,000 md.

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