Descriptions - Federal 42-27, Yellowhair Field, Sec. 27, T22N, R5E, Harding Co., SD, Red River D Zone
Reported Core Interval 9019-9070
Adjusted Core Interval 9033-9084
9019.0-9031.4 - Brown, borrowed and dolomitic, skeletal lime mudstone to lime wackestone and burrowed dolomudstone at the top of the unit. Burrow structures are dominantly circular, subhorizontal Planolites with less common branching Thalassinoides. Occluding cement is finely disseminated anhydrite. Oil staining is good within the better dolomitized intervals. A thin skeletal bed is present at 9025-26 and contain brachiopod and solitary coral fragments.
9031.4-9033.0 - Gray, skeletal lime mudstone to wackestone. Skeletal fragments are dominantly small crinoids. At the top of the unit, thin lime mudstone and shale beds (Kerogenites) are present. Stylolitization is common, and there is no visible porosity or oil staining.
9033.0-9038.0 - Brown, burrowed and dolomitic, skeletal lime mudstone to lime wackestone and burrowed dolomudstone. Burrow structures are dominantly circular, subhorizontal Planolites with less common branching Thalassinoides. Occluding cement is finely disseminated anhydrite. Oil staining is good.
9038.0-9042.0 - Brown, burrowed and skeletal lime mudstone to lime wackestone. Burrow structures are dominantly branching Thalassinoides and less common circular, subhorizontal Planolites. There is no visible porosity or oil staining.
9042.0-9046.0 - Gray, skeletal lime mudstone to wackestone. Skeletal fragments are dominantly small crinoids with lesser amounts of brachiopods and solitary coral fragments.
9046.0-9070.0 - Brown, burrowed and dolomitic, skeletal lime mudstone to lime wackestone and burrowed dolomudstone. Burrow structures are dominantly circular, subhorizontal Planolites with less common branching Thalassinoides. Occluding cement is finely disseminated anhydrite. Oil staining is good in the upper and middle portion of this unit.