Fluid inclusion evidence for the migration of anomalously hot fluids in the Silurian/Devonian Hunton Group below the pre-Mississippian unconformity surface, Anadarko basin, Oklahoma

Conference · Mon Jan 01 04:00:00 EST 1996 · AAPG Bulletin

OSTI ID:6860317

Schwalm, A J ^[1]; Burruss, R C ^[2]

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1. South Dakota School of Mines and Technology, Rapid City, SD (United States)
2. Geological Survey, Denver, CO (United States)

Fluid inclusion assemblages in vug- and fracture-filling diagenetic minerals in the carbonates of the Hunton Group record anomalously high homogenization temperatures and salinities. Temperature profiles of single wells display maxima directly below or close to the unconformity with the overlying Woodford Shale, and decrease gradually or abruptly downward. In a few wells, suitable diagenetic minerals directly above the unconformity in the Woodford Shale contain fluid inclusions with homogenization temperatures comparable to those below the anomaly. Highest temperatures coincide with a high-permeability zone developed towards the top of the Hunton carbonates. The thickness and permeability of this zone depends on the development of a paleokarst after Hunton deposition and are controlled by the paleogeographical position within the basin. Depending on the location within the basin, fluids evolve generally from meteoric or moderately saline (up to [approximately]10 weight% NaCl equivalent) with temperatures of 80[degrees] to 120[degrees]C to highly saline (up to [approximately]26 weight% NaCl equivalent) with temperatures up to 260[degrees]C, followed by a decrease in temperature with either increasing or decreasing salinities. Associated petroleum inclusions suggest that the hottest temperatures coincide with peak petroleum migration. Temperature anomalies are highest in the north near the Hunton subcrop on the basin shelf where the total Hunton thickness is generally <100 feet, and the strongly karsted carbonates are sandwiched in between the Woo and Sylvan Shales resulting in a highly focused flow.

• OSTI ID: 6860317
• Report Number(s): CONF-960527--
• Conference Information: Journal Name: AAPG Bulletin Journal Volume: 5
• Country of Publication: United States
• Language: English

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