Secondary porosity in immature Late Cretaceous and Tertiary sandstones, northeast Alaska and northwest Canada

Conference · Tue May 01 00:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6688012

Myers, M D ^[1]; Smith, T N ^[2]

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1. Univ. of Alaska, Fairbanks (USA)
2. State Div. of Oil and Gas, Anchorage, AK (USA)

Petrographic and scanning electron microscope analysis of Upper Cretaceous to lower Eocene sandstone from outcrops west of the Mackenzie delta and in the central Arctic National Wildlife Refuge (ANWR) reveals secondary porosity. Recognizing this secondary porosity is important for oil and gas exploration because early diagenesis has eliminated most primary porosity in these immature litharenites. The litharenites are dominated by grains of quartz, cherty argillite, chert, volcanic rock fragments, variable amounts of feldspar, and minor amounts of metamorphic rock fragments. Because of the abundance of ductile grains all deep burial (probable burial to depths in excess of 3,000 m), these sandstones have suffered the loss of most primary porosity. Additional reduction of primary porosity has occurred due to the formation of minor amount of precompaction rim cement (carbonate, chlorite, and illite/smectite) and syncompaction quartz overgrowths. Dissolution of framework grains and, to a lesser degree, matrix has resulted in secondary porosities of up to 8% in outcrop samples. Framework grains commonly dissolved include volcanic rock fragments, feldspar, chert, cherty argillite, argillite, and quartz. Two processes are responsible for the dissolution. The first process is the direct dissolution of grains. The second process involves two steps in which grains and matrix are initially replaced by carbonate cement followed by dissolution of the cement and creation of secondary porosity. Secondary porosity is reported to exceed 20% in subsurface samples in northwest Canada.

• OSTI ID: 6688012
• Report Number(s): CONF-900605-; CODEN: AABUD
• Journal Information: AAPG Bulletin (American Association of Petroleum Geologists); (USA), Vol. 74:5; Conference: Annual convention and exposition of the American Association of Petroleum Geologists, San Francisco, CA (USA), 3-6 Jun 1990; ISSN 0149-1423
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
ALASKA
PETROLEUM DEPOSITS
RESERVOIR ROCK
POROSITY
YUKON TERRITORY
CHLORITE MINERALS
CRETACEOUS PERIOD
DISSOLUTION
EXPLORATION
ILLITE
PETROGRAPHY
QUARTZ
SANDSTONES
SCANNING ELECTRON MICROSCOPY
SMECTITE
TERTIARY PERIOD
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
CANADA
CENOZOIC ERA
CHALCOGENIDES
CLAYS
ELECTRON MICROSCOPY
FEDERAL REGION X
GEOLOGIC AGES
GEOLOGIC DEPOSITS
MESOZOIC ERA
MICROSCOPY
MINERAL RESOURCES
MINERALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RESOURCES
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
SILICON OXIDES
USA
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences