Miocene marine shelf-bar and deltaic petroleum reservoirs of coastal Alabama and Mississippi/Alabama shelf

Conference · Wed Mar 01 04:00:00 EST 1989 · AAPG Bull.; (United States)

OSTI ID:5791857

Mink, R M; Mancini, E A; Bearden, B L

Middle and upper Miocene gas reservoirs found in coastal Alabama and the Mississippi/Alabama shelf are predominantly inner to middle neritic shelf-bar or deltaic sands. A Miocene delta system prograded from the west-northwest in offshore Louisiana-Mississippi into coastal Alabama and the Mississippi/Alabama shelf. Deltaic sedimentation primarily affected the western portion of the Mississippi/Alabama shelf, while neritic sedimentation predominated in the northeastern portion of the region in coastal Alabama. Basinal clays are prevalent in the southeastern portion of the Mississippi/Alabama shelf. The productive Miocene reservoir sands occur between depths of 1100 and 5100 ft and generally are from 10 to 200 ft thick. The quartz-rich sands range from fine to coarse grained and have subangular to rounded and moderately to well-sorted quartz grains. Reservoir porosity is primary intergranular and generally ranges from 21% to 35%, with permeabilities that may exceed 2000 md. The natural gas in these shallow reservoirs is primarily biogenic in origin. Productivity of the reservoirs is highly variable and is often characterized by high water saturation. Reservoir pressures, which generally range from 550 to 2300 psi, are also a major factor controlling productivity of these reservoirs. Middle Miocene reservoirs are most common in coastal Alabama, and upper Miocene reservoirs are most common in the Mississippi/Alabama shelf. Petroleum traps are principally sandstone porosity and permeability pinch-outs against regional dip with subtle closure and anticlinal nosing as secondary factors in many of the traps. These middle and upper Miocene gas sands are best delineated with relative amplitude seismic reflection data no which gas-charged sands are apparent as bright spots.

• Research Organization: Geological Survey of Alabama, Tuscaloosa (USA)
• OSTI ID: 5791857
• Report Number(s): CONF-890404-
• Conference Information: Journal Name: AAPG Bull.; (United States) Journal Volume: 73:3
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
ALABAMA
ALLUVIAL DEPOSITS
CENOZOIC ERA
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC TRAPS
GEOLOGY
MINERAL RESOURCES
MIOCENE EPOCH
MISSISSIPPI
NATURAL GAS DEPOSITS
NORTH AMERICA
PERMEABILITY
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
TERTIARY PERIOD
USA