Diagenesis and pore water evolution in the Keuper reservoir, Paris Basin (France)

Journal Article · Wed Sep 01 00:00:00 EDT 1993 · Journal of Sedimentary Petrology; (United States)

DOI:https://doi.org/10.1306/D4267C44-2B26-11D7-8648000102C1865D· OSTI ID:5962322

Spotl, C; Matter, A ^[1]; Brevart, O ^[2]

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1. Univ. Bern, (Switzerland). Geologisches Inst.
2. Societe Nationale Elf-Aquitaine, Pau (France). Centre Scientifique et Technique Jean Feger

Keuper (Upper Triassic) fluvial sandstones and nonmarine carbonate rocks form a major oil reservoir in the western Paris Basin at burial depths of [approximately] 2km. Early-diagenetic processes comprise red-bed-type diagenesis and extensive dolocrete formation both in fluvial channels and in fine-grained over-bank sediments. Locally significant paleokarst created vuggy dissolution porosity in the carbonate units and probably also caused leaching of detrital alkali feldspar grains. Oxygen, carbon, and strontium isotope analyses of various eogenetic cements indicate a nonmarine pore-water composition. Ferroan carbonates, authigenic albite and potassium feldspar, quartz, sulfates, sulfides, and clay minerals formed subsequent to major mechanical compaction. Their isotopic compositions record significant changes in the chemistry of the parent pore water. Cl-Br relationships of the present-day pore water reveal that fluids saturated with respect to halite flushed the reservoir during burial. Based on radiogenic dating of illite cements, influx of warm brines into the reservoir most likely occurred during the earliest Cretaceous. The authors suggest that uplift of the Vosges crustal block created a hydraulic head in the eastern part of the basin and established a gravity-driven fluid flow system, displacing interstitial brines from the Keuper evaporites from the eastern part towards the western part of the basin. A second gravity-driven fluid flow system was established during the Oligocene by major uplift, and freshwater flushed the Keuper reservoir, causing brine dilution. The present-day pore water in the study area is still saline and mass-balance calculations indicate that the ratio of basinal brines to Tertiary meteoric water is about 1:2.

• OSTI ID: 5962322
• Journal Information: Journal of Sedimentary Petrology; (United States), Vol. 63:5; ISSN 0022-4472
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
58 GEOSCIENCES
FRANCE
PETROLEUM DEPOSITS
INTERSTITIAL WATER
CHEMICAL COMPOSITION
RESERVOIR ROCK
DIAGENESIS
CARBONATE ROCKS
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
ISOTOPE RATIO
SANDSTONES
SEDIMENTARY BASINS
TRIASSIC PERIOD
WATER CHEMISTRY
CHEMISTRY
DEVELOPED COUNTRIES
EUROPE
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GROUND WATER
HYDROGEN COMPOUNDS
MESOZOIC ERA
MINERAL RESOURCES
OXYGEN COMPOUNDS
RESOURCES
ROCKS
SEDIMENTARY ROCKS
WATER
WESTERN EUROPE
020200* - Petroleum- Reserves
Geology
& Exploration
580000 - Geosciences