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Title: Origin and geometry of Red River Dolomite Reservoirs, Western Williston Basin

Journal Article · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:6735549

Remarkably uniform distribution of limestone, laminated dolomite, and anhydrite as determined from compensated neutron-density logs suggests that the entire Ordovician Red River Formation of the central Williston Basin was deposited in subtidal ''brining-upward'' sequences. Study of cores and thin sections verifies this locally dolomitized fossiliferous wackestones and packstones, laminated to evenly bedded unfossiliferous mudstones (dolomitized in many wells), and bedded anhydrite. No evidence of subaerial exposure was observed in these rock units. Dolomitization in the Red River ''C'' zone is highly localized. An empirical study of dolomite distribution using data from well logs reveals the presence of dozens of pods of dolomite immediately beneath the ''C'' anhydrite. The pods are up to 200 ft (60 m) thick and 1 mi (1.6 km) in diameter and consist of concentered lenses of (1) tight (locally anhydritic) cryptocrystalline dolomite up to 40 ft (12.2 m) thick and 3,300 ft (1,000 m) in diameter, (2) fine to medium-grained porous dolomite that forms the reservoirs, and (3), still farther from the cryptocrystalline dolomite, relatively tight partly dolomitized limestones. could have been found through application of this model and others could be more efficiently developed.

Research Organization:
Buttercup Energy Ltd., Denver, CO
OSTI ID:
6735549
Journal Information:
Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:5
Country of Publication:
United States
Language:
English