Desenvolvimento de sistemas microemulsionados para limpeza e inversão da molhabilidade em poços de petróleo

Abstract

One way of accomplishing the drilling step is with the utilization of nonaqueous drilling fluid (O/SBM). Posteriorly, in cementation operation, it is necessary to efficiently remove that all fluid present in the wall of well to provide good cementation and improve the adhesion of cement-casing and cement-formation systems. If it is removed inefficiently, will result problems as a cement contamination, weak bond between the casing and the formation, migration of gas to surface, inducing unsuccessful cementation operation. With that, it is necessary the injection of intermediate products between the drilling fluid and the cement paste, known as washes and spacers, whose purpose is to revert wettability and remove mud from well walls. Based on this, the utilization of microemulsions systems as washes are being studied, due to the high affinity of the product with the drilling fluids and cement paste. Therefore, this work has the development of microemulsions systems to be used for cleaning and inversion wettability of wells as objective, applicate in stage before to the cementation of oil wells. For this, two ternary diagrams with the components were developed: N150 e T80, as surfactant nonionic; mixture of glycerin and water, as aqueous phase; and, vegetable oil, as oil phase. Then, two samples from each system with mass fractions of 40% FO, 55% T, 5% FA and 50% FO, 45% T, 5% FA were chosen, respectively. Posteriorly, the micro emulsions (ME) were characterized by the centrifuge test and particle size. Lastly, the rheology analysis were realized, removal efficiency of the drilling fluid in the beaker walls and inversion of the wettability of the A / O to O / A fluid by monitoring the electrical conductivity of the sample using the pure and diluted ME. From the obtained results, it was observed that the micro emulsions presented stability and particle size between 114 nm to 129.5 nm. The pure samples behaved as Newtonian fluids over the entire temperature range, 30 °C to 70 °C. However, the diluted samples were presented as Newtonian fluids only at temperatures above 50 ° C. Through the removal test, it was possible to conclude that all the samples, pure and diluted, were highly efficient in the removal of the drilling fluid (OBM), with 100% removal. Finally, only the diluted samples indicated electrical conductivity by reversing the wettability of the A / O to O / A drilling fluid. These products are innovative and is protected by patent of number BR1020170051650 (Instituto Nacional da Propriedade Intelectual