Brine and hydrocarbon evolution during the filling of the Cantarell Oil Field (Gulf of Mexico)

• Published in: Journal of geochemical exploration 2003-05, Vol.78, p.399-403
• Main Authors: Martinez-Ibarra, R., Tritlla, J., Cedillo-Pardo, E., Grajales-Nishimura, J.M., Murillo-Muñetón, G.
• Format: Article
• Language: English
• Subjects: Cantarell Oil Field; Earth sciences; Earth, ocean, space; Exact sciences and technology; Hydrocarbon migration; Hydrocarbons; México; Porosity; Saddle dolomite; Sedimentary rocks
• ISSN: 0375-6742; 1879-1689
• DOI: 10.1016/S0375-6742(03)00085-2

The main oil reservoir in the Cantarell Field, offshore Campeche, consists of a dolomitized carbonate breccia with an ejectsseal on top, considered to have been formed during the Chicxulub impact event. Two different dolomitization events have been identified associated with the reservoir. The first generation (D1) is a bright-red luminescent saddle dolomite while the second generation is a minute, non-luminescent dolomite (D2). Brine fluid inclusions show an evolution from D1 to D2 to higher temperatures (from 80–120 to 100–120 °C) and salinities (from 2–8 to 6–8 wt.% eq. NaCl). Hydrocarbon-bearing fluid inclusions evolved from heavy oils to light oils in D1 (from core to rim), while in D2, all inclusions appear to be formed by heavy oil with an 'API similar to the oil contained in the present reservoir. These facts suggest that the end of the dolomitization process was closely related with the beginning of the main accumulation of oil into the reservoir, displacing the aqueous fluids and precluding the precipitation of carbonates.