Depositional framework and reservoir potential of an upper Cotton Valley (Knowles Limestone) patch reef, Milam County, Texas
The Knowles Limestone is an upper unit of the Cotton Valley Group, and in Milam County, Texas, it is approximately 350 ft (100 m) thick, consisting of shales, terrigenous dolomitic limestones, grainy limestones, and algal boundstones with stromatoporoids and corals. The boundstones represent an elongate, wave resistant, encrusted skeletal patch reef which probably developed on a subtle salt-generated topographic high. The reef appears to be slightly more than 1 mi (2 km) across in its narrowest lateral dimension as determined by facies correlations of three cored wells in the study area. Reef core boundstones and reef talus were consistently present downdip, and lagoonal to tidal-flat facies were common updip throughout Knowles deposition. The reef organisms eventually became overwhelmed with terrigenous sediment transported downdip as the tidal-flat environment prograded over the lagoonal, reef talus and reef core facies at the end of Knowles deposition. Early dolomitization of tidal fault and lagoonal facies has created local porous zones in some of these rocks. However, the reef, per se, is cemented by sparry calcite and is not a potential reservoir facies.
- Research Organization:
- Shell Oil Co., New Orleans, LA
- OSTI ID:
- 6570728
- Report Number(s):
- CONF-8310301-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:9; Conference: American Association of Petroleum Geologists eastern section meeting, Carbondale, IL, USA, 3 Oct 1983
- Country of Publication:
- United States
- Language:
- English
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