Aerobic and anaerobic biodegradation of petroleum from Pampo Sul Field, Campos Basin, RJ, Brazil / Biodegradação aerobia e anaerobia de petroleo do Campo Pampo Sul, Bacia de Campos, RJ

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The main purpose of this thesis was the simulation of petroleum biodegradation processes under reservoir aerobic, anaerobic or mixed conditions. The biodegradation experiments were first adapted to the laboratory scale in order to simulate different reservoir conditions taking care to select the best parameters to accelerate million times the biodegradation process to permit the evaluation of biomarker depletion in few months instead of geological times. This goal was obtained by increasing the bacterial density which produced the required process acceleration. Comparison of naturally biodegraded and laboratory degraded petroleum provided evidence that biodegradation process mimetization was successful. Comparison of the three degradation experiments revealed that aerobic microbiota preferentially degrades even carbon number n-alkanes, anaerobic preferred odd carbon number n-alkanes and mixed did not show any preference. Under aerobiosis the degradation preference was hydrocarbons >hopanes and homohopanes (25-norhopanes enrichment) >esteranes >tricyclic terpanes. Among homohopanes higher homologs were preferencialy depleted and the steranes biodegradation preference was aaa20R >>abb 20R + abb 20S aaa 20S >>diasteranes, decreasing with the carbon number [C27 >C28 >C29]. Under anaerobiosis the depletion preference was hydrocarbons >esteranes >hopanes e homohopanes >25-norhopanes >tricyclic terpanes. For the homohopanes the degradation order was different from observed in aerobiosis with a preference for the low molecular weight homologs. Steranes biodegradation was not sensitive to aerobic or anaerobic conditions. The mixed aerobic experiment revealed that the degradation followed the aerobic pattern until 90 days and after 120 days the pattern changed to anaerobic like degradation. The identification of the microorganisms using cultivation independent techniques revealed that most microorganisms in these experiments were aerobic but could survive under anaerobic conditions. During bacterial growth there was an increasing oil solubilization by reduction in interfacial tension due to the production of exopolymeric substances (EPS) which were evaluated leading to the identification of surfactin a biopolymer mainly produced by Bacillus species. Finally the main contribution of this research was to reproduce in the lab the reservoir biodegradation under aerobic, anaerobic and mixed conditions

ASSUNTO(S)

biossurfactante biossurfactant petróleo enzymatic activity atividade enzimatica petroleum campos basin

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