Deep burial diagenesis in Rotliegende reservoirs of the NW German Basin

Conference · Tue May 01 04:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6755133

Ramseyer, K ^[1]; Gaupp, R; Matter, A

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1. Univ. of Bern (Switzerland)

A deeply buried Permian continental sequence forms the major gas reservoir in northwest Germany. Deposits of fluvial, eolian, and playa lake shoreline facies show the most favorable reservoir properties. Burial diagenesis is greatly influenced by primary depositional textures and eogenetic processes. However, growth of authigenic clay minerals (illite, kaolinite/dickite, chlorite) relates to changes in the chemistry and flow rate of formation waters. Three different mesogenetic fluid types can be recognized: (1) Alkaline fluids from basin center red beds: The presence of pore-lining chlorite in porous subarkoses of the playa shoreline facies probably is related to a compaction-driven influx of alkaline waters from the shaly, red bed sequences of the basin center. (2) Acidic fluids from coal-bearing Late Carboniferous sediments: An aureole of dickite/kaolinite, several hundred meters wide, is developed in Rotliegende arkosic sands where they are juxtaposed against Carboniferous horsts. In this zone, almost all feldspars were destroyed and the formation of dickite/kaolinite was followed by illite growth and bitumen impregnation. In an outer aureole with less extensive feldspar destruction, kandite minerals are not present, but a dense meshwork of well-crystallized, platy illite fills the pores. The intensity of illitization diminishes away from the Carboniferous sediments (i.e., with increasing distance of fluid migration). K-Ar ages reveal that this illite precipitated within a period when organic maturation products were expelled from the coal measures into Rotliegende sediments and when Paleozoic faults were reactivated. (3) Brines from overlying Zechstein evaporites: During late mesogenetic uplift local influxes of these brines resulted in the formation of pore-plugging carbonate and sulfate cements.

• OSTI ID: 6755133
• Report Number(s): CONF-900605--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000 -- Geosciences
ALUMINIUM COMPOUNDS
ALUMINIUM SILICATES
BITUMENS
CARBONIFEROUS PERIOD
CHLORITE MINERALS
CLAYS
COAL DEPOSITS
DIAGENESIS
EUROPE
FEDERAL REPUBLIC OF GERMANY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FAULTS
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
ILLITE
KAOLINITE
MATURATION
MINERAL RESOURCES
MINERALS
NATURAL GAS DEPOSITS
ORGANIC COMPOUNDS
ORGANIC MATTER
OTHER ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
PALEOZOIC ERA
RESERVOIR ROCK
RESOURCES
SEDIMENTARY BASINS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
TAR
WESTERN EUROPE