--> Surface Monitoring of Injected CO2 in the Buracica Field Area, Reconcavo Basin, Brazil, Mello, Carlos B.; Gonçalves, Ronaldo C.; Miller, Dennis J.; Dino, Rodolfo; Magnier, Caroline; Rouchon, Virgile, #90100 (2009)

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Surface Monitoring of Injected CO2 in the Buracica Field Area, Reconcavo Basin, Brazil

Mello, Carlos B.1
 Gonçalves, Ronaldo C.1
 Miller, Dennis J.1
 Dino, Rodolfo1
 Magnier, Caroline2
 Rouchon, Virgile2

1Geoquímica, Petrobras, Rio de Janeiro, Brazil.
2
Geochimie, Institute Francais du Petrole,
Paris, France.

The Reconcavo Basin, located in the state of Bahia (NE Brazil), has an area of 11,500 square kilometers and contains 80 producing hydrocarbon fields. This investigation refers to the Buracica oil field, located 120 km from the state capital (Salvador), where oil recovery has been enhanced by injection of water and CO2, thus contributing for the reduction of greenhouse gas emissions by partially storing CO2 within the reservoir. Surface CO2 leakage monitoring in part of the field using surface geochemistry techniques was undertaken, by which soil CO2 was measured in situ using probes connected to a micro gas chromatograph (µGC) and a portable gas detector (Orion Plus). Soil gas sampling techniques were further developed, adapted to the contamination-free requirements for isotopic and noble gas analysis. The gas collected in soils, at hydrocarbon producing wells, and the CO2 injected in the reservoir were analyzed for elemental composition (GC), isotopic composition of CO2 carbon (GCCIRMS) and noble gas composition (MS). Results have shown that the complementarily of the isotopic ratios of carbon and noble gas enable the differentiation of the CO2 found in soils from that in the injected gas, and from the gas mixtures present in the hydrocarbon reservoir. Furthermore, field data indicate that surface CO2 concentrations are probably influenced by parameters intrinsic to the nature of the soil (sample depth, mineralogy, soil humidity, porosity and permeability). This paper discusses a specific methodology for surface monitoring of injected CO2 in the Buracica oil field area using gas geochemistry techniques.

AAPG Search and Discover Article #90100©2009 AAPG International Conference and Exhibition 15-18 November 2009, Rio de Janeiro, Brazil