Chemical and stable isotope composition (18O/16O, 2H/1H) of formation waters from the Carabobo Oilfield, Venezuela

Authors

  • T. BOSCHETTI Department of Chemistry, life sciences and Environmental Sustainability, University of Parma Parco Area delle Scienze, 43124, Parma, Italy. http://orcid.org/0000-0002-5994-9750
  • B. ANGULO Departamento de investigación estratégica en exploración. Instituto Tecnológico Venezolano del Petróleo (INTEVEP), Petróleos de Venezuela S.A. (PDVSA) Apartado 76343, Caracas 1070-A, Los Teques, Venezuela.
  • F. QUINTERO Departamento de investigación estratégica en exploración. Instituto Tecnológico Venezolano del Petróleo (INTEVEP), Petróleos de Venezuela S.A. (PDVSA) Apartado 76343, Caracas 1070-A, Los Teques, Venezuela.
  • J. VOLCÁN Instituto de Ciencias de la Tierra. Universidad Central de Venezuela Apartado 3895, Caracas 1010-A, Venezuela
  • A. CASALINS Estudios integrados, Petrolera Sinovensa Torre BVC, Barcelona 6001, Venezuela

Keywords:

Orinoco Oil Belt, Carabobo area, Formation water, Chemical and isotope composition.

Abstract

In this short note, we present the first data on stable isotope composition of the oilfield waters from Carabobo area of the Faja Petrolífera del Orinoco “Hugo Chávez” (Orinoco Oil Belt). From a chemical point of view, the formation waters show a main Na-Cl level (TDS up to 30g/l) with a dilution trend toward Na-HCO3 composition (down to 1g/l). Until now, such a clear net chemical compositional trend was ascribed to a meteoric dilution (fresh/ brackish bicarbonate) of the seawater endmember (the saltiest chloride). The isotope results of this study reveal that the seawater mother water was modified during a high-temperature thrusting event (120–125°C), forming 18O-enriched diagenetic water (up to +4‰), which was diluted in recent times by glacial meltwater and presentday meteoric water. The hypothetical presence of flood by a meteoric paleo-water also offers new hints to explain the low API gravity (<10°API biodegraded, extra heavy oil) and composition of the local crude.

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Published

2018-06-25

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Section

Short note