Diagenetic processes in a partially dolomitized carbonate reservoir : Casablanca oil field, Mediterranean Sea, offshore Spain
Rodríguez Morillas, Noelia (Centro Tecnológico de Repsol)
Playà i Pous, Elisabet (Universitat de Barcelona. Departament de Geoquímica, Petrologia i Prospecció Geològica)
Travé i Herrero, Anna (Universitat de Barcelona. Departament de Geoquímica, Petrologia i Prospecció Geològica)
Martín-Martín, J. D. (Consejo Superior de Investigaciones Científicas (Espanya). Institut de Ciències de la Terra Jaume Almera)
Consejo Superior de Investigaciones Científicas (Espanya). Group of Dynamics of the Lithosphere (GDL)

Data:	2013
Resum:	Mesozoic and Neogene carbonates located in the Valencia Trough (offshore Spain, western Mediterranean Sea) are oil reservoirs. This paper investigates the diagenetic evolution of the Upper Jurassic limestones, currently dolomitized, that constitute the main reservoir of the Casablanca oil field. Core samples from Casablanca-1A well have been studied to determine the diagenetic products and their relation with porosity evolution, and to reconstruct the fluid flow history prior to and during oil emplacement. On the basis of petrological observations and geochemical analyses (major, minor and trace element composition and oxygen, carbon and strontium isotope composition), a major dolomitization event is recognized postdating subaerial exposure, erosion and karstification. The dolomitization event originated two replacive dolomites (RD1 and RD2) and two dolomite cements (saddle dolomite cement, SDC, and milky-white dolomite cement, MDC) which are partially cogenetic. RD1, RD2 and SDC precipitated at increasing temperatures (over 60ºC and below 110ºC), probably from meteoric water mixed with marine water. The last dolomite type (milky-white dolomite cement) precipitated with increasing burial conditions and by arrival of hydrothermal fluids during the Miocene. The post-dolomitization sequence comprises precipitation of calcite cement and partial calcitization of all previous dolomites. The oxygen, carbon and strontium isotope compositions suggest that this calcite cementation occurred from meteoric waters mixed with Burdigalian - Langhian marine waters trapped in the sediments and expelled by compaction in the moderate to deep burial realm. Normal faults were the conduits for upward migration of these fluids as well as for later oil expulsion from the Burdigalian - Langhian source rocks. Late corrosion associated with organic acid-enriched fluids took place prior or simultaneously to oil migration during the Pliocene, enhancing porosity and increasing reservoir quality.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan aquestes es distribueixin sota la mateixa llicència que regula l'obra original i es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Casablanca oil field ; Dolomite reservoir ; Vug and fracture porosity ; Diagenesis ; Mediterranean Sea
Publicat a:	Geologica acta, Vol. 11, Núm. 2 (Juny 2013) , p. 195-214, ISSN 1696-5728

Adreça alternativa: https://raco.cat/index.php/GeologicaActa/article/view/265940
Adreça alternativa: https://revistes.ub.edu/index.php/GEOACTA/article/view/105.000001839
DOI: 10.1344/105.000001839

20 p, 2.0 MB

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