Ferramenta assistida por ultrassom de alta potência para a prevenção de incrustação de carbonato de cálcio

Abstract

Inorganic salt scale can cause extensive damage to oil industry installations. There are several ways that are already used to avoid them, for example, chemical and physical inhibitors. This paper proposes a calcium carbonate scale physical inhibitor assisted by ultrasound. Two approaches have been taken: (i) bonded piezoelectric ceramics directly into a tube section and (ii) Langevin ultrasonic transducers coupled to a pipe section. Initially, an investigation was made of the piezoelectric ceramic use a coupled to a section external wall of pipeline filled with water. In this configuration, tests were carried out to determine pressure zones and conductivity with solutions of calcium chloride and sodium carbonate as precursors. Such tests were important for the study, as they showed: (i) the existence of acoustic pressure zones, confirming that there is ultrasonic action in the pipe section and (ii) the influence of ultrasound on calcium carbonate precipitation, by decreasing the induction time. Despite the low power used, ultrasound was able to promote the calcium carbonate crystals precipitation acceleration. In addition, assembled arrangement modeling and simulation were carried out in order to confirm the result obtained in the tests with piezoelectric ceramics glued to the tube wall. In the second approach, an ultrasonic tool was developed with Langevin-type transducers. Through modeling and simulation in the COMSOL Multiphysics® software, the configuration of 56 transducers distributed in groups of eight by seven steel rings was achieved, in a tube measuring one meter and 1 1/2” in diameter, Schedule pattern with 48.26 mm outside diameter. Tests were carried out with aluminum sheets and tests with calcium carbonate in the laboratory, for which the tool was assembled with three rings. The laboratory tests were carried out in the high-pressure line of the Interdisciplinary Center of Fluid Dynamics - NIDF, with initial pressures of 8 and 20 bar and final pressure of 80 bar. In addition to the pressure curve, the average particle size and the test specimen masses were measured. The material embedded in the specimens was analyzed using a scanning electron microscope (SEM). Despite the tool having been tested with three of the seven rings, the tests demonstrated that there is feasibility of using the tool in oil wells.