Determinação da perda de carga de fluidos de perfuração no escoamento através de acessórios especiais

Abstract

The objective of this work is to evaluate the friction loss of drilling fluids during their flow thru special accessories, which are present in drilling columns of petroleum wells, named as: toll joints, stabilizer and ejectors. The tool joints are responsible for linking the tubes of the column, the stabilizers are pieces placed along the column helping giving drilling direction and the ejectors simulates the ejection of the drill. To make such evaluation it was built a pilot unit with the objective of simulate the prospection systems of petroleum, the flows were made in accessories that has similar geometry to the ones found in real systems, keeping the same dynamic similarly thru Reynolds and the geometric similarly according to the dimensions and characteristics of real petroleum unit flows. Thru the experimental data of rheology, flow rate and pressure drop, obtained in the pilot unit, it was determined the friction loss coefficient of the accessories and tested the existent correlations found in the literature referring to the calculus of friction loss during internal and external flown in tool joints. The experimental data obtained were compared to the data obtained thru computational simulation, which were used the following commercial codes CFD, GAMBIT® e FLUENT®. The evaluated drilling fluids were obtained from drilling probes, which were previously used in drilling operations. These fluids were constituted of polymeric solutions of organic or water base, and about their rheological properties, they were non-Newtonian fluids, pseudo plastics. The rheological model assumed was the power law model. The results revealed that the discharge coefficients obtained for the ejectors corroborates with the literature and the friction loss coefficients (for tool joints and ejector) vary according to the type of geometry and are very little sensitive to the type of fluid. The re-estimation of the parameters of the correlations of friction loss in tool joints, with internal and external flows, enabled to reach results in agreement with the experimental data and the simulations allowed analyzing the velocity and pressure profile along the tubes.