Diagenesis of fluvial sands in Norphlet Formation (Upper Jurassic), Escambia County, Alabama

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

OSTI ID:5880792

Keighin, C W; Schenk, C J

The Upper Jurassic Norphlet Formation is an important hydrocarbon reservoir in Baldwin and Mobile Counties and offshore in Mobile Bay, Alabama. The formation is not productive in the Little Escambia Creek field, Escambia County, but underlies the productive Smackover Formation at a depth of approximately 15,500 ft (4725 m). The Norphlet sandstones examined in cores from two drill holes are largely fluvial in origin and consist of moderately to well-sorted, very fine to coarse-grained feldspathic sandstones extensively altered by a complex sequence of diagenetic reactions. Visible evidence of chemical and mechanical compaction is relatively minor in the sandstones. Paucity of compaction suggests that extensive early cementation by anhydrite and/or calcite reduced compaction; these cements were subsequently removed by migrating fluids. Porosity, both intergranular and intragranular, is generally well developed. Intergranular pores are due primarily to partial to complete dissolution of cements and mineral grains, especially feldspar. Intragranular pores are largely the result of partial leaching of rock fragments and of microporosity formed by precipitation of clay minerals in earlier dissolution pores.

• Research Organization: Geological Survey, Denver, CO (USA)
• OSTI ID: 5880792
• 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
ALABAMA
ALLUVIAL DEPOSITS
CLAYS
DIAGENESIS
FEDERAL REGION IV
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
JURASSIC PERIOD
MESOZOIC ERA
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NORTH AMERICA
PETROLEUM DEPOSITS
POROSITY
RESERVOIR ROCK
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
USA