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Impact of early dolomitization on multi-scale petrophysical heterogeneities and fracture intensity of low-porosity platform carbonates (Albian-Cenomanian, southern Apennines, Italy)
- Source :
- Marine and Petroleum Geology. 73:462-478
- Publication Year :
- 2016
- Publisher :
- Elsevier BV, 2016.
-
Abstract
- Petrographic, petrophysical and fracture analyses were carried out on middle Cretaceous platform carbonates of the southern Apennines (Italy) that represent an outcrop analogue of the Val d’Agri and Tempa Rossa reservoirs of the Basilicata region. The studied outcrops, which are made of interlayered limestones and dolomites of inner platform environment, were selected to study the impact of dolomitization on reservoir properties and the control of dolomite texture on fracture development. Two types of dolomites – both formed during very early diagenesis – were found interlayered, at a metre scale, with micrite-rich limestones (mainly mudstones and wackestones). Dolomite A is fine-to medium crystalline and makes non-planar mosaics. Dolomite B is coarse-crystalline and makes planar-s and planar-e mosaics. The intercrystalline space of the planar-e subtype of dolomite B is either open or filled by un-replaced micrite or by late calcite or saddle dolomite cement. Dolomite A and dolomite B have similar average porosities of 3.7 and 3.1% respectively, which are significantly higher than the average porosity of limestones (1.4%). Their poro-perm relationships are similar, with the notable exception of planar-e type B dolomites, which generally display higher permeability values. The intensity of top bounded fractures is distinctly lower in coarse-crystalline dolomites than in fine-crystalline dolomites and limestones, both at the macro- and the micro-scale. On the other hand neither lithology (i.e. limestone vs. dolomite) nor dolomite crystal size control the intensity of perfect bed-bounded fractures, which is strictly controlled by the fracture layer thickness. Our results provide information that could be used as guidance for the characterization and modelling of fractured carbonate reservoirs made of interlayered limestones and dolomites.
- Subjects :
- Apennine
Carbonate
010504 meteorology & atmospheric sciences
Micrite
Lithology
Outcrop
Stratigraphy
Dolomite
Geochemistry
Mineralogy
010502 geochemistry & geophysics
Oceanography
01 natural sciences
Petrography
chemistry.chemical_compound
Geophysic
0105 earth and related environmental sciences
Geology
Cretaceou
Diagenesis
Fracture
Structural diagenesi
Geophysics
chemistry
Dolomitization
Economic Geology
Subjects
Details
- ISSN :
- 02648172
- Volume :
- 73
- Database :
- OpenAIRE
- Journal :
- Marine and Petroleum Geology
- Accession number :
- edsair.doi.dedup.....c56f7c4b73406ee462c235e75ff301d7