Muddy and dolomitic rip-up clasts in Triassic fluvial sandstones: Origin and impact on potential reservoir properties (Argana Basin, Morocco)
| Autor: | José Arribas, César Viseras, Saturnina Henares, Giuseppe Cultrone |
|---|---|
| Přispěvatelé: | Ministerio de Economía y Competitividad (España), European Commission |
| Jazyk: | angličtina |
| Rok vydání: | 2016 |
| Předmět: |
020209 energy
Stratigraphy Fluvial sandstones Dolomite Geochemistry Fluvial Geology Rip-up clasts 02 engineering and technology Structural basin 010502 geochemistry & geophysics 01 natural sciences Triassic Diagenesis Petrography Clastic rock 0202 electrical engineering electronic engineering information engineering Geomorphology Phreatic 0105 earth and related environmental sciences Reservoir |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| Popis: | The significance of rip-up clasts as sandstone framework grains is frequently neglected in the literature being considered as accessory components in bulk sandstone composition. However, this study highlights the great value of muddy and dolomitic rip-up clast occurrence as: (a) information source about low preservation potential from floodplain deposits and (b) key element controlling host sandstone diagenetic evolution and thus ultimate reservoir quality. High-resolution petrographic analysis on Triassic fluvial sandstones from Argana Basin (T6 and T7/T8 units) highlights the significance of different types of rip-up clasts as intrabasinal framework components of continental sediments from arid climates. On the basis of their composition and ductility, three main types are distinguished: (a) muddy rip-up clasts, (b) dolomitic muddy rip-up clasts and (c) dolomite crystalline rip-up clasts. Spatial distribution of different types is strongly facies-related according to grain size. Origin of rip-up clasts is related to erosion of coeval phreatic dolocretes, in different development stages, and associated muddy floodplain sediments. Cloudy cores with abundant inclusions and clear outer rims of dolomite crystals suggest a first replacive and a subsequent displacive growth, respectively. Dolomite crystals are almost stoichiometric. This composition is very similar to that of early sandstone dolomite cement, supporting phreatic dolocretes as dolomite origin in both situations. Sandstone diagenesis is dominated by mechanical compaction and dolomite cementation. A direct correlation exists between: (1) muddy rip-up clast abundance and early reduction of primary porosity by compaction with irreversible loss of intergranular volume (IGV); and (2) occurrence of dolomitic rip-up clasts and dolomite cement nucleation in host sandstone, occluding adjacent pores but preserving IGV. Both processes affect reservoir quality by generation of vertical and 3D fluid flow baffles and barriers that compartmentalize the reservoir. These findings may provide quantitative useful data for the better understanding of reservoir quality in analogous hydrocarbon-bearing basins such as the Bay of Fundy, Nova Scotia (Canada). Funding was provided by research projects CGL2013-43013-R (MINECO-FEDER), CGL2011-22709, CGL2014-52670-P and MAT02012-34473, as well as by the research group RNM369 and RNM179 (JA). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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