Diagenetic processes in a partially dolomitized carbonate reservoir: Casablanca oil field, Mediterranean Sea, offshore Spain
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| Format: | Artículo científico |
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Universitat de Barcelona
2013
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| author | N. RODRÍGUEZ-MORILLAS |
| author_facet | N. RODRÍGUEZ-MORILLAS |
| contents | Diagenetic processes in a partially dolomitized carbonate reservoir: Casablanca oil field, Mediterranean Sea, offshore Spain N. RODRÍGUEZ-MORILLAS E. PLAYÀ A. TRAVÉ J.D. MARTÍN-MARTÍN Ciencias de la Tierra Diagenesis Mediterranean Sea Dolomite reservoir Casablanca oil field Vug and fracture porosity 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. 2013 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50527426005 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.2 Vol.11 |
| format | Artículo científico |
| id | redalyc_50527426005 |
| institution | Redalyc |
| language | en |
| publishDate | 2013 |
| publisher | Universitat de Barcelona |
| spellingShingle | Diagenetic processes in a partially dolomitized carbonate reservoir: Casablanca oil field, Mediterranean Sea, offshore Spain N. RODRÍGUEZ-MORILLAS Ciencias de la Tierra Diagenesis Mediterranean Sea Dolomite reservoir Casablanca oil field Vug and fracture porosity Diagenetic processes in a partially dolomitized carbonate reservoir: Casablanca oil field, Mediterranean Sea, offshore Spain N. RODRÍGUEZ-MORILLAS E. PLAYÀ A. TRAVÉ J.D. MARTÍN-MARTÍN Ciencias de la Tierra Diagenesis Mediterranean Sea Dolomite reservoir Casablanca oil field Vug and fracture porosity 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. 2013 artículo científico 1695-6133 https://www.redalyc.org/articulo.oa?id=50527426005 en http://www.redalyc.org/revista.oa?id=505 Geologica Acta: an international earth science journal application/pdf Universitat de Barcelona Geologica Acta: an international earth science journal (España) Num.2 Vol.11 |
| title | Diagenetic processes in a partially dolomitized carbonate reservoir: Casablanca oil field, Mediterranean Sea, offshore Spain |
| topic | Ciencias de la Tierra Diagenesis Mediterranean Sea Dolomite reservoir Casablanca oil field Vug and fracture porosity |
| url | https://www.redalyc.org/articulo.oa?id=50527426005 |