Sorrento-Mount Pearl-Siaana Field Complex, A Major Morrow Accumulation in Southeast Colorado

Stephen A. Sonnenberg

Pennsylvanian Morrow sandstones are oil and gas productive throughout a large area in southeast Colorado. The Sorrento-Mount Pearl-Siaana fields represent an area of 8,200 acres (3,319 ha) of continuous production at depths of 5,316-5,575 ft (1,620-1,699 m) from a middle Morrow sandstone reservoir. Recoverable reserves for the three fields are estimated to be over 20 million bbl of oil. The average ultimate recovery per well is 250,000 to 300,000 bbl of oil.

On the basis of subsurface mapping, productive sandstones are interpreted to be fluvial valley-fill deposits, consisting mainly of channel sandstone. The deposits are encased in marine shale and range in thickness from 0 to 72 ft (0 to 21.9 m).

The Sorrento-Mount Pearl-Siaana field complex is a large stratigraphic trap formed by a change of channel trend against regional structure. Paleostructure may have controlled the location of the valley-fill system. Present-day structure plays a minor role by creating multiple gas-oil and oil-water contacts in the fields.

AAPG Search and Discovery Article #91040©1987 AAPG Rocky Mountain Section Meeting, Boise, Idaho, September 13-16, 1987.