Desenvolvimento de um processo de separação de emulsão com o uso de radiação microondas para a caracterização de petróleo extrapesado

Abstract

In this work is proposed a procedure for separation in laboratory scale of extra-heavy crude oil emulsions with high dissolved water and salt content, using microwave radiation in a closed system. The emulsion was introduced into a high pressure quartz vessel and water was added. The separation of the emulsion was done in microwave oven with maximun power and pressure of 800 W of power and 70 bar, respectively. Homogeneity was evalueted taking into account the shaking time, heating temperature and the depth level of the sample. The following parameters were evaluated for the proposed procedure: sample mass, water content, microwave irradiation time, power and the necessity of additional extraction steps. The proposed procedure using microwave radiation for emulsion separation presented efficiency over 95% being possible to have a oil with water content below 1% v/v for emulsions from 11,1 to 14,2 °API. This conditio n was reached with the use of sucessive extractions and a subsequent centrifugation step. The oil was characterized before and after the emulsion separation procedure and the resulting water phase. Water content and concentration of Ba, Ca, Cl, S, Sr, Fe, P, Mg, Ni, N, K, Na e V were evaluated after decomposition for further determination by inductively coupled plasma optical emission spectrometry and by ion chromatography. Simulated distillation was performed and density, viscosity and total acid number (TAN) measured, before and after the emulsion separation procedure using microwave radiation. No significant was obtened between the results obtained before and after emulsion separation procedure for the majority of the elements studied. The concentration of some element (Ca, Mg, Na, K e Cl) was reduced from 53 to 99% (m/m). Using the proposed procedure, it was possible to separate the water and the salt from extra-heavy crude oil emulsions in an analytic scale. The results obtained were considered suitable when compared to the method used by Petrobras (N-2499/93). The proposed procedure is simple and fast, requires a small sample amount and does not require the use of organic solvents and it can be performed in about 1 hour.