Remoção e inversão de molhabilidade com colchões lavadores microemulsionados para aplicação em cimentação de poços de petróleo

Abstract

The success in the oil search and the project cost is directly related to the drilling process. During this step, drilling fluid are injected to assist the removal of the generated fragments. After the drilling is completed the coating is placed and the space between the coating tube and the well will be cemented, and the drilling fluid must be completely removed to provide good cementation. This way, complementary fluids, known as flushing fluid, have primordial paper in this case, being injected to assist in cleaning the well wall and ensure the structure stability of the well in the cementing step. The flushing fluid exhibit chemical removal characteristics and have purpose the revert wettability. Thus, this study aims to develop microemulsions which act as potential flushing fluid, to be used for cleaning and inversion wettability of wells, before an operation of cementing oil wells. The flushing fluid (microemulsion) was formulated basically of vegetable oil, aqueous phase (NaCl 2% weight), and anionic surfactant. For the determination of the microemulsion zone, ternary diagrams were prepared using the surfactant (OCS/Alcohol). Thus, in a suitable beaker the components were mixed in the chosen fractions within the microemulsion region, obtaining the flushing fluid. This way, the samples were prepared with three components: vegetable oil (castor oil or pine oil), aqueous phase (NaCl 2%) and OCS/Alcohol (1:1) as surfactant. Posteriorly, removal tests and reversing wettability tests were realized to verify the efficiency of the flushing fluids formulated for future application in the oil industry. According to the removal test, using the pine oil as vegetable oil, all pure flushing fluid removed 100% of the drilling fluid and using castor oil as vegetable oil was obtained 24,24% of removal, respectively. Finally, through reversing wettability tests, only the samples with pine oil presented enough electrical conductivity to revert wettability of the A/O to O/A drilling fluid, used 80, 84 and 87.5 mL, respectively. This way, the range from 1 to 3, used pine oil, NaCl 2% and OCS/Alcohol, were the best formulation found to act as a potential flushing fluid. The results presented are according with the established standards by PROCELAB.