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

Conference · Wed Mar 01 00:00:00 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-
• Journal Information: AAPG Bull.; (United States), Vol. 73:3; Conference: AAPG annual convention with DPA/EMD Divisions and SEPM, San Antonio, TX, USA, 23-26 Apr 1989
• Country of Publication: United States
• Language: English

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