An Experimental and Numerical Study of Two-phase Flow in Horizontal Eccentric Annuli

The aerated fluids have a potential to increase rate of penetration, minimize formation damage, minimize lost circulation, reduce drill pipe sticking, and, therefore, assist in improving the productivity. The technology of drilling using aerated fluids in the area of offshore drilling is very common. The use of compressible drilling fluids in offshore technology has found applications in old depleted reservoirs and in the new fields with special drilling problems. However, the drilling performed with gas-liquid mixture, calculating the pressure losses and the performance of cutting transportation is more difficult than single-phase fluid due to the characteristics of multi-phase fluid flow. In case configured drilling is directional or horizontal, these types of calculations are becoming more difficult depending on the slope of the wells. Both hydraulic behavior and mechanism of cutting transportation of the drilling fluids formed by gas-liquid mixture are not fully understood yet, especially there is a large uncertainty in selection of most appropriate flow regarding two phases. In this study, gas-liquid flow inside horizontal eccentric annulus is simulated using an Eulerian-Eulerian computational fluid dynamics model for two-phase flow patterns in an annulus, i.e., dispersed bubble, dispersed annular, plug, slug, wavy annular. A flow loop was constructed in order to conduct experiments using air-water mixtures for various in-situ air and water flow velocities. A digital high speed camera is used for recording each test dynamically for identification of the liquid holdup and flow patterns.