The present work refers to an experimental study on oil recovery by in-situ combustion. A specific apparatus holding a combustion tube of 100 cm in length and 6.9 cm internal diameter was designed and constructed for the study. Experimental tests were performed with a heavy oil of 12.8oAPI from a Brazilian onshore field. Plain air was injected at a constant rate of 3 SLPM, while the production pressure was set at 10 bar. The main purpose of this study was to survey the influence of clay content in the reservoir rock with initial oil saturations ranging from 25 to 50%. The results indicate that the in-situ combustion method is technically applicable to the rock-fluid system tested. Moreover, the tests were useful in providing the proper range of parameters for the oxidation reactions to occur. Clay has proved to play a key role on fuel deposition and, consequently, on propagation of the combustion front. In a clean sandpack medium, the combustion front was not self-sustained, while in presence of clay, in amount ranging from 4.5 to 10.0% mass fraction, sustainable combustion reactions were achieved. Front peak temperatures were recorded in the range of 457 - 501 oC, and for oil recovery factors were greater than 84%. From the set of data collected during the tests, results show combustion front velocities to span between 14.1 to 18.3 cm/h. Worth mentioning, upgradings of 3.2o to 8.4o API were observed in the produced oil. The basic combustion parameters - fuel consumption, air requirement, air-fuel ratio, atomic H/C ratio, oxygen utilization - obtained during the experiments are favorable to the implementation of in-situ combustion and shall be used as a guide to the pilot project planned for the field.
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