Flow through annulus is frequent in drilling and work-over operations. Annular flow is also utilized in some fracturing treatments. In all these applications, Newtonian and non-Newtonian fluids are widely used. Therefore the knowledge of annular flow performance of these fluids becomes important for planning and design of well-bore hydraulics. Existing knowledge about the behavior of non-Newtonian fluids in annulus is very limited due to their complex behaviour. A range of correlations is available in the literature for both Newtonian and non-Newtonian fluids in laminar and turbulent flow regime. Selection of the appropriate correlation for the desired fluid and flow regime is very important for the accurate determination of friction losses.

Experimental and simulation study has been undertaken to investigate the flow behavior and friction pressure losses of Newtonian and non-Newtonian fluids in concentric annuli. Computational Fluid Dynamics (CFD) has been used along with limited experimentation on a field-scale set up to validate the simulation results. The fluids investigated are water and frequently used concentrations of guar and Xanthan fluids. CFD simulations have been performed for different annular dimensions in flow range encompassing both the laminar and turbulent flow regimes. The annular dimensions used in the simulations cover the range used in the industry. The frictional losses of non-Newtonian fluids exhibiting drag-reducing characteristics have been investigated through experiments.

Based on the comparison with simulation results recommendations are made to use the appropriate correlations for Newtonian and non-Newtonian fluids in the laminar and turbulent flow regime.Improved correlations are proposed to determine frictional losses of non-Newtonian fluids exhibiting drag-reducing characteristics. These correlations are based on experimental data gathered for a wide range of concentrations of guar and Xanthan fluids. The recommendations made along with the correlations presented in this study will greatly improve the accuracy of determining friction pressure losses in concentric annuli.

Keywords:
reservoir surveillance, correlation, concentration, drilling fluid property, flow rate, production control, production monitoring, modeling & simulation, drilling fluid formulation, non-newtonian fluid
Subjects:
Drilling Fluids and Materials, Well & Reservoir Surveillance and Monitoring, Drilling fluid selection and formulation (chemistry, properties)
Copyright 2005, Society of Petroleum Engineers
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