Relationship of Ordovician and Silurian reservoir development to unconformities at Midland farms and Inez fields, Andrews County, Texas

Conference · Sat Mar 01 04:00:00 EST 1986 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6913507

Mear, C E; Becher, J W

Hydrocarbons are being produced at Midland Farms and Inez fields from Ellenburger dolomites and Fusselman limestones. Reservoirs developed there during Ordovician and Silurian periods of minor folding and faulting, followed by regional uplift and subaerial exposure of the carbonates. Vuggy, cavernous, and solution-enlarged fracture porosity was developed in the Lower Ordovician Ellenburger dolomites prior to deposition of the overlying Middle Ordovician shales of the Simpson Group. Vuggy and cavernous porosity developed in the Lower Silurian Fusselman crinoid-ostracod-pellet packstones and grainstones before deposition of the overlying Silurian Wristen shales. Montoya siliceous limestones of Late Ordovician age were truncated during a period of pre-Silurian erosion, but porosity development is not indicated in Montoya rock cuttings. Only minor amounts of porosity developed in the Lower to Middle Devonian Thirty-one packstones and wackestones as a result of uplift and erosion in the Middle Devonian. Regional compression during the post-Mississippian enhanced doubly plunging anticlines now having up to 91 m (300 ft) of closure at the Ellenburger through Thirty-one formations at Midland Farms and Inez fields. Fractures may have developed in Paleozoic limestones during this period of folding, but reservoir enhancement appears to have resulted only in the Ellenburger dolomites. Representative porosity measurements of the Ellenburger and Fusselman pay zones cannot be made from wireline log calculations, due to the fractured, vuggy, and cavernous nature of the porosity.

• Research Organization: Southland Royalty Co., Fort Worth, TX
• OSTI ID: 6913507
• Report Number(s): CONF-8604186-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 70:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
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03 NATURAL GAS
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ALKALINE EARTH METAL COMPOUNDS
ANTICLINES
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATE ROCKS
CARBONATES
DEVONIAN PERIOD
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FEDERAL REGION VI
GEOLOGIC AGES
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GEOLOGIC FORMATIONS
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LIMESTONE
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MINERAL RESOURCES
MINERALS
NATURAL GAS DEPOSITS
NORTH AMERICA
ORDOVICIAN PERIOD
OXYGEN COMPOUNDS
PALEOZOIC ERA
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
ROCKS
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SILURIAN PERIOD
TEXAS
USA