Origin of Na-Ca-Cl brines in Jurassic and Cretaceous reservoirs of Gulf Coast
Na-Ca-Cl brines in Jurassic and Cretaceous reservoirs in the Gulf Coast have been attributed to the diagenesis of concentrated Jurassic seawater related to Louann Salt deposition and alternatively to the diagenesis of brines produced by halie dissolution. These brines contain up to 35,000 mg/L Ca, up to 4000 mg/L, from 400 to 2400 mgL Br, and up to 13,000 mg/L K. Mutual relationships of Na, Cl, total divalent cations minus sulfate and bicarbonate, K, and Br are similar to those in seawater that has been evaporated past the initial stage of halite deposition, particularly when the K content of the brine exceeds 5000 mg/L. The concentrations of divalent cations and K increase, and the mutual relationships of all the dissolved salts become increasingly similar to those in seawater with increasing proximity to bedded salt. The abundance of authigenic K-feldspar in rocks above the salt beds explains the relatively rapid decrease in the K content of the brines upsection. The Ca and K contents of Jurassic Gulf Coast brines are similar to those in Na-Ca-Cl brines in feldspar-poor carbonate sequences in other basins.
- Research Organization:
- Chevron Oil Field Research Co., La Habra, CA
- OSTI ID:
- 6000997
- Report Number(s):
- CONF-850322-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 69:2; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
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