Sequence Stratigraphic and Depositional Settings of Highstand Deltaic and Lowstand Valley-Fill Deposits of the Middle and Upper Pennsylvanian Cleveland and Marmaton Tight-Gas Sandstones, Northwest Anadarko Basin
Although gas production from the low-permeability (tight) Cleveland and Marmaton Formations in the northwest Anadarko Basin started in the mid-1950’s, the sequence-stratigraphic and depositional settings of their reservoir sandstones in the primary producing area are poorly known. Analysis of closely spaced log sections of approximately 800 wells and ~250 ft (~75 m) of 5 conventional cores in these stratigraphically adjacent units indicates that they compose a succession of highstand deltaic and lowstand incised-valley-fill deposits with strong tidal signatures that accumulated on a broad shelf. The Cleveland section in the producing area, 100-300 ft (30-92 m) thick, includes six fourth-order, westerly sourced deltaic highstand systems tracts that become more limestone rich upsection as the unit grades into overlying Kansas City Formation carbonates. A prominent, 40-to-80-ft-thick (12-to-24-m) lowstand incised-valley system occurs in the middle Cleveland, consisting dominantly of fine-grained estuarine sandstones exhibiting abundant draped ripples and flaser bedding. Fluvial sandstones bearing abundant shale clasts occur locally at the base. The valley-fill sandstones and the underlying highstand deltaic topset beds into which the valley system locally incises compose the primary reservoir zone in the Cleveland. The underlying Marmaton succession (80-550 ft [24-170 m] thick) comprises a highstand progradational parasequence set of three fourth-order, northeasterly sourced deltaic sequences showing no evidence of valley incision. The primary reservoir zone, the Hepler sandstone, comprises the topset beds of the uppermost sequence and overlying beds of the unusually sandy and thick (140 ft [43 m]) transgressive systems tract.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009